All of lore.kernel.org
 help / color / mirror / Atom feed
* [RFC v2 0/7] Improve RISC-V Perf support using SBI PMU extension
@ 2021-05-28 18:43 ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:43 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

This series adds improved perf support for RISC-V based system using
SBI PMU extension[1]. It is based on a platform driver instead of a existing
arch specific implementation. The new perf implementation has adopted a modular
approach where most of the generic event handling is done in the core library
while individual PMUs need to only implement necessary features specific to
the PMU. This is easily extensible and any future RISC-V PMU implementation
can leverage this. Currently, SBI PMU driver & legacy PMU driver are implemented
as a part of this series.

The SBI based driver provides more advanced features such as event configure
start/stop. This version does not implement counter overflow
& filtering yet. That will implemented in the future on top of this series
using "Sscofpmf" extension. 

The legacy driver tries to reimplement the existing minimal perf under a new
config to maintain backward compatibility. This implementation only allows
monitoring of always running cycle/instruction counters. Moreover, they can
not be started or stopped. In general, this is very limited and not very useful.
That's why, I am not very keen to carry the support into the new driver.
However, I don't want to break perf for any existing hardware platforms.
If nobody really uses perf currently, I will be happy to drop PATCH 4.

This series has been tested in Qemu on RV64 only. Qemu[2] & OpenSBI [3] patches
are required to test it. Qemu changes are not backward compatible. That means,
you can not use perf anymore on older Qemu versions with latest OpenSBI
and/or Kernel. However, newer kernel will just use legacy pmu driver if
old OpenSBI is detected or hardware doesn't implement mcountinhibit.

Here is an output of perf stat while running hackbench.

[root@fedora-riscv riscv]# perf stat -e r8000000000000007 -e r8000000000000006 \
-e r0000000000000002 -e r0000000000000004 -e branch-misses -e cache-misses \
-e cycles -e instructions ./hackbench -pipe 15 process 15

Running with 15*40 (== 600) tasks.
Time: 1.548

 Performance counter stats for './hackbench -pipe 15 process 15':

             7,103      r8000000000000007     (62.56%) --> SBI_PMU_FW_IPI_RECVD
             7,767      r8000000000000006     (12.19%) --> SBI_PMU_FW_IPI_SENT
                 0      r0000000000000002     (24.79%) --> a custom raw event described in DT
     <not counted>      r0000000000000004     (0.00%)  --> non-supported raw event described in DT
                 0      branch-misses         (12.65%) 
                 0      cache-misses          (25.36%)
    27,978,868,702      cycles                (38.12%)
    27,849,527,556      instructions          # 1.00  insn per cycle  (50.46%)

       2.431195184 seconds time elapsed

       1.553153000 seconds user
      13.615924000 seconds sys

The patches can also be found in the github[4].

[1] https://lists.riscv.org/g/tech-unixplatformspec/message/950
[2] https://github.com/atishp04/qemu/tree/riscv_pmu_v1
[3] https://github.com/atishp04/opensbi/tree/riscv_pmu_v2
[4] https://github.com/atishp04/linux/tree/riscv_pmu_v2

Changes from v1->v2
1. Implemented the latest SBI PMU extension specification.
2. The core platform driver was changed to operate as a library while only
   sbi based PMU is built as a driver. The legacy one is just a fallback if
   SBI PMU extension is not available.

Atish Patra (7):
RISC-V: Remove the current perf implementation
RISC-V: Add CSR encodings for all HPMCOUNTERS
RISC-V: Add a perf core library for pmu drivers
RISC-V: Add a simple platform driver for RISC-V legacy perf
RISC-V: Add RISC-V SBI PMU extension definitions
RISC-V: Add perf platform driver based on SBI PMU extension
Documentation: riscv: Remove the old documentation

Documentation/riscv/pmu.rst         | 255 -------------
arch/riscv/Kconfig                  |  13 -
arch/riscv/include/asm/csr.h        |  58 +++
arch/riscv/include/asm/perf_event.h |  72 ----
arch/riscv/include/asm/sbi.h        |  94 +++++
arch/riscv/kernel/Makefile          |   1 -
arch/riscv/kernel/perf_event.c      | 485 -------------------------
drivers/perf/Kconfig                |  25 ++
drivers/perf/Makefile               |   5 +
drivers/perf/riscv_pmu.c            | 328 +++++++++++++++++
drivers/perf/riscv_pmu_legacy.c     |  92 +++++
drivers/perf/riscv_pmu_sbi.c        | 537 ++++++++++++++++++++++++++++
include/linux/cpuhotplug.h          |   1 +
include/linux/perf/riscv_pmu.h      |  61 ++++
14 files changed, 1201 insertions(+), 826 deletions(-)
delete mode 100644 Documentation/riscv/pmu.rst
delete mode 100644 arch/riscv/kernel/perf_event.c
create mode 100644 drivers/perf/riscv_pmu.c
create mode 100644 drivers/perf/riscv_pmu_legacy.c
create mode 100644 drivers/perf/riscv_pmu_sbi.c
create mode 100644 include/linux/perf/riscv_pmu.h

--
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 0/7] Improve RISC-V Perf support using SBI PMU extension
@ 2021-05-28 18:43 ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:43 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

This series adds improved perf support for RISC-V based system using
SBI PMU extension[1]. It is based on a platform driver instead of a existing
arch specific implementation. The new perf implementation has adopted a modular
approach where most of the generic event handling is done in the core library
while individual PMUs need to only implement necessary features specific to
the PMU. This is easily extensible and any future RISC-V PMU implementation
can leverage this. Currently, SBI PMU driver & legacy PMU driver are implemented
as a part of this series.

The SBI based driver provides more advanced features such as event configure
start/stop. This version does not implement counter overflow
& filtering yet. That will implemented in the future on top of this series
using "Sscofpmf" extension. 

The legacy driver tries to reimplement the existing minimal perf under a new
config to maintain backward compatibility. This implementation only allows
monitoring of always running cycle/instruction counters. Moreover, they can
not be started or stopped. In general, this is very limited and not very useful.
That's why, I am not very keen to carry the support into the new driver.
However, I don't want to break perf for any existing hardware platforms.
If nobody really uses perf currently, I will be happy to drop PATCH 4.

This series has been tested in Qemu on RV64 only. Qemu[2] & OpenSBI [3] patches
are required to test it. Qemu changes are not backward compatible. That means,
you can not use perf anymore on older Qemu versions with latest OpenSBI
and/or Kernel. However, newer kernel will just use legacy pmu driver if
old OpenSBI is detected or hardware doesn't implement mcountinhibit.

Here is an output of perf stat while running hackbench.

[root@fedora-riscv riscv]# perf stat -e r8000000000000007 -e r8000000000000006 \
-e r0000000000000002 -e r0000000000000004 -e branch-misses -e cache-misses \
-e cycles -e instructions ./hackbench -pipe 15 process 15

Running with 15*40 (== 600) tasks.
Time: 1.548

 Performance counter stats for './hackbench -pipe 15 process 15':

             7,103      r8000000000000007     (62.56%) --> SBI_PMU_FW_IPI_RECVD
             7,767      r8000000000000006     (12.19%) --> SBI_PMU_FW_IPI_SENT
                 0      r0000000000000002     (24.79%) --> a custom raw event described in DT
     <not counted>      r0000000000000004     (0.00%)  --> non-supported raw event described in DT
                 0      branch-misses         (12.65%) 
                 0      cache-misses          (25.36%)
    27,978,868,702      cycles                (38.12%)
    27,849,527,556      instructions          # 1.00  insn per cycle  (50.46%)

       2.431195184 seconds time elapsed

       1.553153000 seconds user
      13.615924000 seconds sys

The patches can also be found in the github[4].

[1] https://lists.riscv.org/g/tech-unixplatformspec/message/950
[2] https://github.com/atishp04/qemu/tree/riscv_pmu_v1
[3] https://github.com/atishp04/opensbi/tree/riscv_pmu_v2
[4] https://github.com/atishp04/linux/tree/riscv_pmu_v2

Changes from v1->v2
1. Implemented the latest SBI PMU extension specification.
2. The core platform driver was changed to operate as a library while only
   sbi based PMU is built as a driver. The legacy one is just a fallback if
   SBI PMU extension is not available.

Atish Patra (7):
RISC-V: Remove the current perf implementation
RISC-V: Add CSR encodings for all HPMCOUNTERS
RISC-V: Add a perf core library for pmu drivers
RISC-V: Add a simple platform driver for RISC-V legacy perf
RISC-V: Add RISC-V SBI PMU extension definitions
RISC-V: Add perf platform driver based on SBI PMU extension
Documentation: riscv: Remove the old documentation

Documentation/riscv/pmu.rst         | 255 -------------
arch/riscv/Kconfig                  |  13 -
arch/riscv/include/asm/csr.h        |  58 +++
arch/riscv/include/asm/perf_event.h |  72 ----
arch/riscv/include/asm/sbi.h        |  94 +++++
arch/riscv/kernel/Makefile          |   1 -
arch/riscv/kernel/perf_event.c      | 485 -------------------------
drivers/perf/Kconfig                |  25 ++
drivers/perf/Makefile               |   5 +
drivers/perf/riscv_pmu.c            | 328 +++++++++++++++++
drivers/perf/riscv_pmu_legacy.c     |  92 +++++
drivers/perf/riscv_pmu_sbi.c        | 537 ++++++++++++++++++++++++++++
include/linux/cpuhotplug.h          |   1 +
include/linux/perf/riscv_pmu.h      |  61 ++++
14 files changed, 1201 insertions(+), 826 deletions(-)
delete mode 100644 Documentation/riscv/pmu.rst
delete mode 100644 arch/riscv/kernel/perf_event.c
create mode 100644 drivers/perf/riscv_pmu.c
create mode 100644 drivers/perf/riscv_pmu_legacy.c
create mode 100644 drivers/perf/riscv_pmu_sbi.c
create mode 100644 include/linux/perf/riscv_pmu.h

--
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 1/7] RISC-V: Remove the current perf implementation
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:43   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:43 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The current perf implementation in RISC-V is not very useful as it can not
count any events other than cycle/instructions. Moreover, perf record
can not be used or the events can not be started or stopped.

Remove the implementation now for a better platform driver in future
that will implement most of the missing functionality.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/Kconfig                  |  13 -
 arch/riscv/include/asm/perf_event.h |  72 -----
 arch/riscv/kernel/Makefile          |   1 -
 arch/riscv/kernel/perf_event.c      | 485 ----------------------------
 4 files changed, 571 deletions(-)
 delete mode 100644 arch/riscv/kernel/perf_event.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a8ad8eb76120..5872e5b62fdf 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -354,19 +354,6 @@ config RISCV_ISA_C
 
 	   If you don't know what to do here, say Y.
 
-menu "supported PMU type"
-	depends on PERF_EVENTS
-
-config RISCV_BASE_PMU
-	bool "Base Performance Monitoring Unit"
-	def_bool y
-	help
-	  A base PMU that serves as a reference implementation and has limited
-	  feature of perf.  It can run on any RISC-V machines so serves as the
-	  fallback, but this option can also be disable to reduce kernel size.
-
-endmenu
-
 config FPU
 	bool "FPU support"
 	default y
diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
index 062efd3a1d5d..dc6d5803c0e2 100644
--- a/arch/riscv/include/asm/perf_event.h
+++ b/arch/riscv/include/asm/perf_event.h
@@ -9,77 +9,5 @@
 #define _ASM_RISCV_PERF_EVENT_H
 
 #include <linux/perf_event.h>
-#include <linux/ptrace.h>
-#include <linux/interrupt.h>
-
-#ifdef CONFIG_RISCV_BASE_PMU
-#define RISCV_BASE_COUNTERS	2
-
-/*
- * The RISCV_MAX_COUNTERS parameter should be specified.
- */
-
-#define RISCV_MAX_COUNTERS	2
-
-/*
- * These are the indexes of bits in counteren register *minus* 1,
- * except for cycle.  It would be coherent if it can directly mapped
- * to counteren bit definition, but there is a *time* register at
- * counteren[1].  Per-cpu structure is scarce resource here.
- *
- * According to the spec, an implementation can support counter up to
- * mhpmcounter31, but many high-end processors has at most 6 general
- * PMCs, we give the definition to MHPMCOUNTER8 here.
- */
-#define RISCV_PMU_CYCLE		0
-#define RISCV_PMU_INSTRET	1
-#define RISCV_PMU_MHPMCOUNTER3	2
-#define RISCV_PMU_MHPMCOUNTER4	3
-#define RISCV_PMU_MHPMCOUNTER5	4
-#define RISCV_PMU_MHPMCOUNTER6	5
-#define RISCV_PMU_MHPMCOUNTER7	6
-#define RISCV_PMU_MHPMCOUNTER8	7
-
-#define RISCV_OP_UNSUPP		(-EOPNOTSUPP)
-
-struct cpu_hw_events {
-	/* # currently enabled events*/
-	int			n_events;
-	/* currently enabled events */
-	struct perf_event	*events[RISCV_MAX_COUNTERS];
-	/* vendor-defined PMU data */
-	void			*platform;
-};
-
-struct riscv_pmu {
-	struct pmu	*pmu;
-
-	/* generic hw/cache events table */
-	const int	*hw_events;
-	const int	(*cache_events)[PERF_COUNT_HW_CACHE_MAX]
-				       [PERF_COUNT_HW_CACHE_OP_MAX]
-				       [PERF_COUNT_HW_CACHE_RESULT_MAX];
-	/* method used to map hw/cache events */
-	int		(*map_hw_event)(u64 config);
-	int		(*map_cache_event)(u64 config);
-
-	/* max generic hw events in map */
-	int		max_events;
-	/* number total counters, 2(base) + x(general) */
-	int		num_counters;
-	/* the width of the counter */
-	int		counter_width;
-
-	/* vendor-defined PMU features */
-	void		*platform;
-
-	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
-	int		irq;
-};
-
-#endif
-#ifdef CONFIG_PERF_EVENTS
-#define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
-#endif
 
 #endif /* _ASM_RISCV_PERF_EVENT_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index d3081e4d9600..40d2c85a3a6a 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -50,7 +50,6 @@ obj-$(CONFIG_MODULE_SECTIONS)	+= module-sections.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
 obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 
-obj-$(CONFIG_RISCV_BASE_PMU)	+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
 obj-$(CONFIG_RISCV_SBI)		+= sbi.o
diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c
deleted file mode 100644
index c835f0362d94..000000000000
--- a/arch/riscv/kernel/perf_event.c
+++ /dev/null
@@ -1,485 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
- * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
- * Copyright (C) 2009 Jaswinder Singh Rajput
- * Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
- * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra
- * Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
- * Copyright (C) 2009 Google, Inc., Stephane Eranian
- * Copyright 2014 Tilera Corporation. All Rights Reserved.
- * Copyright (C) 2018 Andes Technology Corporation
- *
- * Perf_events support for RISC-V platforms.
- *
- * Since the spec. (as of now, Priv-Spec 1.10) does not provide enough
- * functionality for perf event to fully work, this file provides
- * the very basic framework only.
- *
- * For platform portings, please check Documentations/riscv/pmu.txt.
- *
- * The Copyright line includes x86 and tile ones.
- */
-
-#include <linux/kprobes.h>
-#include <linux/kernel.h>
-#include <linux/kdebug.h>
-#include <linux/mutex.h>
-#include <linux/bitmap.h>
-#include <linux/irq.h>
-#include <linux/perf_event.h>
-#include <linux/atomic.h>
-#include <linux/of.h>
-#include <asm/perf_event.h>
-
-static const struct riscv_pmu *riscv_pmu __read_mostly;
-static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
-
-/*
- * Hardware & cache maps and their methods
- */
-
-static const int riscv_hw_event_map[] = {
-	[PERF_COUNT_HW_CPU_CYCLES]		= RISCV_PMU_CYCLE,
-	[PERF_COUNT_HW_INSTRUCTIONS]		= RISCV_PMU_INSTRET,
-	[PERF_COUNT_HW_CACHE_REFERENCES]	= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_CACHE_MISSES]		= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BRANCH_MISSES]		= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BUS_CYCLES]		= RISCV_OP_UNSUPP,
-};
-
-#define C(x) PERF_COUNT_HW_CACHE_##x
-static const int riscv_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
-[PERF_COUNT_HW_CACHE_OP_MAX]
-[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
-	[C(L1D)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(L1I)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(LL)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(DTLB)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] =  RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] =  RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(ITLB)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(BPU)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-};
-
-static int riscv_map_hw_event(u64 config)
-{
-	if (config >= riscv_pmu->max_events)
-		return -EINVAL;
-
-	return riscv_pmu->hw_events[config];
-}
-
-static int riscv_map_cache_decode(u64 config, unsigned int *type,
-			   unsigned int *op, unsigned int *result)
-{
-	return -ENOENT;
-}
-
-static int riscv_map_cache_event(u64 config)
-{
-	unsigned int type, op, result;
-	int err = -ENOENT;
-		int code;
-
-	err = riscv_map_cache_decode(config, &type, &op, &result);
-	if (!riscv_pmu->cache_events || err)
-		return err;
-
-	if (type >= PERF_COUNT_HW_CACHE_MAX ||
-	    op >= PERF_COUNT_HW_CACHE_OP_MAX ||
-	    result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
-		return -EINVAL;
-
-	code = (*riscv_pmu->cache_events)[type][op][result];
-	if (code == RISCV_OP_UNSUPP)
-		return -EINVAL;
-
-	return code;
-}
-
-/*
- * Low-level functions: reading/writing counters
- */
-
-static inline u64 read_counter(int idx)
-{
-	u64 val = 0;
-
-	switch (idx) {
-	case RISCV_PMU_CYCLE:
-		val = csr_read(CSR_CYCLE);
-		break;
-	case RISCV_PMU_INSTRET:
-		val = csr_read(CSR_INSTRET);
-		break;
-	default:
-		WARN_ON_ONCE(idx < 0 ||	idx > RISCV_MAX_COUNTERS);
-		return -EINVAL;
-	}
-
-	return val;
-}
-
-static inline void write_counter(int idx, u64 value)
-{
-	/* currently not supported */
-	WARN_ON_ONCE(1);
-}
-
-/*
- * pmu->read: read and update the counter
- *
- * Other architectures' implementation often have a xxx_perf_event_update
- * routine, which can return counter values when called in the IRQ, but
- * return void when being called by the pmu->read method.
- */
-static void riscv_pmu_read(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	u64 prev_raw_count, new_raw_count;
-	u64 oldval;
-	int idx = hwc->idx;
-	u64 delta;
-
-	do {
-		prev_raw_count = local64_read(&hwc->prev_count);
-		new_raw_count = read_counter(idx);
-
-		oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
-					 new_raw_count);
-	} while (oldval != prev_raw_count);
-
-	/*
-	 * delta is the value to update the counter we maintain in the kernel.
-	 */
-	delta = (new_raw_count - prev_raw_count) &
-		((1ULL << riscv_pmu->counter_width) - 1);
-	local64_add(delta, &event->count);
-	/*
-	 * Something like local64_sub(delta, &hwc->period_left) here is
-	 * needed if there is an interrupt for perf.
-	 */
-}
-
-/*
- * State transition functions:
- *
- * stop()/start() & add()/del()
- */
-
-/*
- * pmu->stop: stop the counter
- */
-static void riscv_pmu_stop(struct perf_event *event, int flags)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
-	hwc->state |= PERF_HES_STOPPED;
-
-	if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
-		riscv_pmu->pmu->read(event);
-		hwc->state |= PERF_HES_UPTODATE;
-	}
-}
-
-/*
- * pmu->start: start the event.
- */
-static void riscv_pmu_start(struct perf_event *event, int flags)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
-		return;
-
-	if (flags & PERF_EF_RELOAD) {
-		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
-
-		/*
-		 * Set the counter to the period to the next interrupt here,
-		 * if you have any.
-		 */
-	}
-
-	hwc->state = 0;
-	perf_event_update_userpage(event);
-
-	/*
-	 * Since we cannot write to counters, this serves as an initialization
-	 * to the delta-mechanism in pmu->read(); otherwise, the delta would be
-	 * wrong when pmu->read is called for the first time.
-	 */
-	local64_set(&hwc->prev_count, read_counter(hwc->idx));
-}
-
-/*
- * pmu->add: add the event to PMU.
- */
-static int riscv_pmu_add(struct perf_event *event, int flags)
-{
-	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct hw_perf_event *hwc = &event->hw;
-
-	if (cpuc->n_events == riscv_pmu->num_counters)
-		return -ENOSPC;
-
-	/*
-	 * We don't have general conunters, so no binding-event-to-counter
-	 * process here.
-	 *
-	 * Indexing using hwc->config generally not works, since config may
-	 * contain extra information, but here the only info we have in
-	 * hwc->config is the event index.
-	 */
-	hwc->idx = hwc->config;
-	cpuc->events[hwc->idx] = event;
-	cpuc->n_events++;
-
-	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
-
-	if (flags & PERF_EF_START)
-		riscv_pmu->pmu->start(event, PERF_EF_RELOAD);
-
-	return 0;
-}
-
-/*
- * pmu->del: delete the event from PMU.
- */
-static void riscv_pmu_del(struct perf_event *event, int flags)
-{
-	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct hw_perf_event *hwc = &event->hw;
-
-	cpuc->events[hwc->idx] = NULL;
-	cpuc->n_events--;
-	riscv_pmu->pmu->stop(event, PERF_EF_UPDATE);
-	perf_event_update_userpage(event);
-}
-
-/*
- * Interrupt: a skeletion for reference.
- */
-
-static DEFINE_MUTEX(pmc_reserve_mutex);
-
-static irqreturn_t riscv_base_pmu_handle_irq(int irq_num, void *dev)
-{
-	return IRQ_NONE;
-}
-
-static int reserve_pmc_hardware(void)
-{
-	int err = 0;
-
-	mutex_lock(&pmc_reserve_mutex);
-	if (riscv_pmu->irq >= 0 && riscv_pmu->handle_irq) {
-		err = request_irq(riscv_pmu->irq, riscv_pmu->handle_irq,
-				  IRQF_PERCPU, "riscv-base-perf", NULL);
-	}
-	mutex_unlock(&pmc_reserve_mutex);
-
-	return err;
-}
-
-static void release_pmc_hardware(void)
-{
-	mutex_lock(&pmc_reserve_mutex);
-	if (riscv_pmu->irq >= 0)
-		free_irq(riscv_pmu->irq, NULL);
-	mutex_unlock(&pmc_reserve_mutex);
-}
-
-/*
- * Event Initialization/Finalization
- */
-
-static atomic_t riscv_active_events = ATOMIC_INIT(0);
-
-static void riscv_event_destroy(struct perf_event *event)
-{
-	if (atomic_dec_return(&riscv_active_events) == 0)
-		release_pmc_hardware();
-}
-
-static int riscv_event_init(struct perf_event *event)
-{
-	struct perf_event_attr *attr = &event->attr;
-	struct hw_perf_event *hwc = &event->hw;
-	int err;
-	int code;
-
-	if (atomic_inc_return(&riscv_active_events) == 1) {
-		err = reserve_pmc_hardware();
-
-		if (err) {
-			pr_warn("PMC hardware not available\n");
-			atomic_dec(&riscv_active_events);
-			return -EBUSY;
-		}
-	}
-
-	switch (event->attr.type) {
-	case PERF_TYPE_HARDWARE:
-		code = riscv_pmu->map_hw_event(attr->config);
-		break;
-	case PERF_TYPE_HW_CACHE:
-		code = riscv_pmu->map_cache_event(attr->config);
-		break;
-	case PERF_TYPE_RAW:
-		return -EOPNOTSUPP;
-	default:
-		return -ENOENT;
-	}
-
-	event->destroy = riscv_event_destroy;
-	if (code < 0) {
-		event->destroy(event);
-		return code;
-	}
-
-	/*
-	 * idx is set to -1 because the index of a general event should not be
-	 * decided until binding to some counter in pmu->add().
-	 *
-	 * But since we don't have such support, later in pmu->add(), we just
-	 * use hwc->config as the index instead.
-	 */
-	hwc->config = code;
-	hwc->idx = -1;
-
-	return 0;
-}
-
-/*
- * Initialization
- */
-
-static struct pmu min_pmu = {
-	.name		= "riscv-base",
-	.event_init	= riscv_event_init,
-	.add		= riscv_pmu_add,
-	.del		= riscv_pmu_del,
-	.start		= riscv_pmu_start,
-	.stop		= riscv_pmu_stop,
-	.read		= riscv_pmu_read,
-};
-
-static const struct riscv_pmu riscv_base_pmu = {
-	.pmu = &min_pmu,
-	.max_events = ARRAY_SIZE(riscv_hw_event_map),
-	.map_hw_event = riscv_map_hw_event,
-	.hw_events = riscv_hw_event_map,
-	.map_cache_event = riscv_map_cache_event,
-	.cache_events = &riscv_cache_event_map,
-	.counter_width = 63,
-	.num_counters = RISCV_BASE_COUNTERS + 0,
-	.handle_irq = &riscv_base_pmu_handle_irq,
-
-	/* This means this PMU has no IRQ. */
-	.irq = -1,
-};
-
-static const struct of_device_id riscv_pmu_of_ids[] = {
-	{.compatible = "riscv,base-pmu",	.data = &riscv_base_pmu},
-	{ /* sentinel value */ }
-};
-
-static int __init init_hw_perf_events(void)
-{
-	struct device_node *node = of_find_node_by_type(NULL, "pmu");
-	const struct of_device_id *of_id;
-
-	riscv_pmu = &riscv_base_pmu;
-
-	if (node) {
-		of_id = of_match_node(riscv_pmu_of_ids, node);
-
-		if (of_id)
-			riscv_pmu = of_id->data;
-		of_node_put(node);
-	}
-
-	perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW);
-	return 0;
-}
-arch_initcall(init_hw_perf_events);
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 1/7] RISC-V: Remove the current perf implementation
@ 2021-05-28 18:43   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:43 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The current perf implementation in RISC-V is not very useful as it can not
count any events other than cycle/instructions. Moreover, perf record
can not be used or the events can not be started or stopped.

Remove the implementation now for a better platform driver in future
that will implement most of the missing functionality.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/Kconfig                  |  13 -
 arch/riscv/include/asm/perf_event.h |  72 -----
 arch/riscv/kernel/Makefile          |   1 -
 arch/riscv/kernel/perf_event.c      | 485 ----------------------------
 4 files changed, 571 deletions(-)
 delete mode 100644 arch/riscv/kernel/perf_event.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a8ad8eb76120..5872e5b62fdf 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -354,19 +354,6 @@ config RISCV_ISA_C
 
 	   If you don't know what to do here, say Y.
 
-menu "supported PMU type"
-	depends on PERF_EVENTS
-
-config RISCV_BASE_PMU
-	bool "Base Performance Monitoring Unit"
-	def_bool y
-	help
-	  A base PMU that serves as a reference implementation and has limited
-	  feature of perf.  It can run on any RISC-V machines so serves as the
-	  fallback, but this option can also be disable to reduce kernel size.
-
-endmenu
-
 config FPU
 	bool "FPU support"
 	default y
diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
index 062efd3a1d5d..dc6d5803c0e2 100644
--- a/arch/riscv/include/asm/perf_event.h
+++ b/arch/riscv/include/asm/perf_event.h
@@ -9,77 +9,5 @@
 #define _ASM_RISCV_PERF_EVENT_H
 
 #include <linux/perf_event.h>
-#include <linux/ptrace.h>
-#include <linux/interrupt.h>
-
-#ifdef CONFIG_RISCV_BASE_PMU
-#define RISCV_BASE_COUNTERS	2
-
-/*
- * The RISCV_MAX_COUNTERS parameter should be specified.
- */
-
-#define RISCV_MAX_COUNTERS	2
-
-/*
- * These are the indexes of bits in counteren register *minus* 1,
- * except for cycle.  It would be coherent if it can directly mapped
- * to counteren bit definition, but there is a *time* register at
- * counteren[1].  Per-cpu structure is scarce resource here.
- *
- * According to the spec, an implementation can support counter up to
- * mhpmcounter31, but many high-end processors has at most 6 general
- * PMCs, we give the definition to MHPMCOUNTER8 here.
- */
-#define RISCV_PMU_CYCLE		0
-#define RISCV_PMU_INSTRET	1
-#define RISCV_PMU_MHPMCOUNTER3	2
-#define RISCV_PMU_MHPMCOUNTER4	3
-#define RISCV_PMU_MHPMCOUNTER5	4
-#define RISCV_PMU_MHPMCOUNTER6	5
-#define RISCV_PMU_MHPMCOUNTER7	6
-#define RISCV_PMU_MHPMCOUNTER8	7
-
-#define RISCV_OP_UNSUPP		(-EOPNOTSUPP)
-
-struct cpu_hw_events {
-	/* # currently enabled events*/
-	int			n_events;
-	/* currently enabled events */
-	struct perf_event	*events[RISCV_MAX_COUNTERS];
-	/* vendor-defined PMU data */
-	void			*platform;
-};
-
-struct riscv_pmu {
-	struct pmu	*pmu;
-
-	/* generic hw/cache events table */
-	const int	*hw_events;
-	const int	(*cache_events)[PERF_COUNT_HW_CACHE_MAX]
-				       [PERF_COUNT_HW_CACHE_OP_MAX]
-				       [PERF_COUNT_HW_CACHE_RESULT_MAX];
-	/* method used to map hw/cache events */
-	int		(*map_hw_event)(u64 config);
-	int		(*map_cache_event)(u64 config);
-
-	/* max generic hw events in map */
-	int		max_events;
-	/* number total counters, 2(base) + x(general) */
-	int		num_counters;
-	/* the width of the counter */
-	int		counter_width;
-
-	/* vendor-defined PMU features */
-	void		*platform;
-
-	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
-	int		irq;
-};
-
-#endif
-#ifdef CONFIG_PERF_EVENTS
-#define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
-#endif
 
 #endif /* _ASM_RISCV_PERF_EVENT_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index d3081e4d9600..40d2c85a3a6a 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -50,7 +50,6 @@ obj-$(CONFIG_MODULE_SECTIONS)	+= module-sections.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o
 obj-$(CONFIG_DYNAMIC_FTRACE)	+= mcount-dyn.o
 
-obj-$(CONFIG_RISCV_BASE_PMU)	+= perf_event.o
 obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
 obj-$(CONFIG_RISCV_SBI)		+= sbi.o
diff --git a/arch/riscv/kernel/perf_event.c b/arch/riscv/kernel/perf_event.c
deleted file mode 100644
index c835f0362d94..000000000000
--- a/arch/riscv/kernel/perf_event.c
+++ /dev/null
@@ -1,485 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
- * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
- * Copyright (C) 2009 Jaswinder Singh Rajput
- * Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
- * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra
- * Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
- * Copyright (C) 2009 Google, Inc., Stephane Eranian
- * Copyright 2014 Tilera Corporation. All Rights Reserved.
- * Copyright (C) 2018 Andes Technology Corporation
- *
- * Perf_events support for RISC-V platforms.
- *
- * Since the spec. (as of now, Priv-Spec 1.10) does not provide enough
- * functionality for perf event to fully work, this file provides
- * the very basic framework only.
- *
- * For platform portings, please check Documentations/riscv/pmu.txt.
- *
- * The Copyright line includes x86 and tile ones.
- */
-
-#include <linux/kprobes.h>
-#include <linux/kernel.h>
-#include <linux/kdebug.h>
-#include <linux/mutex.h>
-#include <linux/bitmap.h>
-#include <linux/irq.h>
-#include <linux/perf_event.h>
-#include <linux/atomic.h>
-#include <linux/of.h>
-#include <asm/perf_event.h>
-
-static const struct riscv_pmu *riscv_pmu __read_mostly;
-static DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
-
-/*
- * Hardware & cache maps and their methods
- */
-
-static const int riscv_hw_event_map[] = {
-	[PERF_COUNT_HW_CPU_CYCLES]		= RISCV_PMU_CYCLE,
-	[PERF_COUNT_HW_INSTRUCTIONS]		= RISCV_PMU_INSTRET,
-	[PERF_COUNT_HW_CACHE_REFERENCES]	= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_CACHE_MISSES]		= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BRANCH_MISSES]		= RISCV_OP_UNSUPP,
-	[PERF_COUNT_HW_BUS_CYCLES]		= RISCV_OP_UNSUPP,
-};
-
-#define C(x) PERF_COUNT_HW_CACHE_##x
-static const int riscv_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
-[PERF_COUNT_HW_CACHE_OP_MAX]
-[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
-	[C(L1D)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(L1I)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(LL)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(DTLB)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] =  RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] =  RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(ITLB)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-	[C(BPU)] = {
-		[C(OP_READ)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_WRITE)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-		[C(OP_PREFETCH)] = {
-			[C(RESULT_ACCESS)] = RISCV_OP_UNSUPP,
-			[C(RESULT_MISS)] = RISCV_OP_UNSUPP,
-		},
-	},
-};
-
-static int riscv_map_hw_event(u64 config)
-{
-	if (config >= riscv_pmu->max_events)
-		return -EINVAL;
-
-	return riscv_pmu->hw_events[config];
-}
-
-static int riscv_map_cache_decode(u64 config, unsigned int *type,
-			   unsigned int *op, unsigned int *result)
-{
-	return -ENOENT;
-}
-
-static int riscv_map_cache_event(u64 config)
-{
-	unsigned int type, op, result;
-	int err = -ENOENT;
-		int code;
-
-	err = riscv_map_cache_decode(config, &type, &op, &result);
-	if (!riscv_pmu->cache_events || err)
-		return err;
-
-	if (type >= PERF_COUNT_HW_CACHE_MAX ||
-	    op >= PERF_COUNT_HW_CACHE_OP_MAX ||
-	    result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
-		return -EINVAL;
-
-	code = (*riscv_pmu->cache_events)[type][op][result];
-	if (code == RISCV_OP_UNSUPP)
-		return -EINVAL;
-
-	return code;
-}
-
-/*
- * Low-level functions: reading/writing counters
- */
-
-static inline u64 read_counter(int idx)
-{
-	u64 val = 0;
-
-	switch (idx) {
-	case RISCV_PMU_CYCLE:
-		val = csr_read(CSR_CYCLE);
-		break;
-	case RISCV_PMU_INSTRET:
-		val = csr_read(CSR_INSTRET);
-		break;
-	default:
-		WARN_ON_ONCE(idx < 0 ||	idx > RISCV_MAX_COUNTERS);
-		return -EINVAL;
-	}
-
-	return val;
-}
-
-static inline void write_counter(int idx, u64 value)
-{
-	/* currently not supported */
-	WARN_ON_ONCE(1);
-}
-
-/*
- * pmu->read: read and update the counter
- *
- * Other architectures' implementation often have a xxx_perf_event_update
- * routine, which can return counter values when called in the IRQ, but
- * return void when being called by the pmu->read method.
- */
-static void riscv_pmu_read(struct perf_event *event)
-{
-	struct hw_perf_event *hwc = &event->hw;
-	u64 prev_raw_count, new_raw_count;
-	u64 oldval;
-	int idx = hwc->idx;
-	u64 delta;
-
-	do {
-		prev_raw_count = local64_read(&hwc->prev_count);
-		new_raw_count = read_counter(idx);
-
-		oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
-					 new_raw_count);
-	} while (oldval != prev_raw_count);
-
-	/*
-	 * delta is the value to update the counter we maintain in the kernel.
-	 */
-	delta = (new_raw_count - prev_raw_count) &
-		((1ULL << riscv_pmu->counter_width) - 1);
-	local64_add(delta, &event->count);
-	/*
-	 * Something like local64_sub(delta, &hwc->period_left) here is
-	 * needed if there is an interrupt for perf.
-	 */
-}
-
-/*
- * State transition functions:
- *
- * stop()/start() & add()/del()
- */
-
-/*
- * pmu->stop: stop the counter
- */
-static void riscv_pmu_stop(struct perf_event *event, int flags)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
-	hwc->state |= PERF_HES_STOPPED;
-
-	if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
-		riscv_pmu->pmu->read(event);
-		hwc->state |= PERF_HES_UPTODATE;
-	}
-}
-
-/*
- * pmu->start: start the event.
- */
-static void riscv_pmu_start(struct perf_event *event, int flags)
-{
-	struct hw_perf_event *hwc = &event->hw;
-
-	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
-		return;
-
-	if (flags & PERF_EF_RELOAD) {
-		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
-
-		/*
-		 * Set the counter to the period to the next interrupt here,
-		 * if you have any.
-		 */
-	}
-
-	hwc->state = 0;
-	perf_event_update_userpage(event);
-
-	/*
-	 * Since we cannot write to counters, this serves as an initialization
-	 * to the delta-mechanism in pmu->read(); otherwise, the delta would be
-	 * wrong when pmu->read is called for the first time.
-	 */
-	local64_set(&hwc->prev_count, read_counter(hwc->idx));
-}
-
-/*
- * pmu->add: add the event to PMU.
- */
-static int riscv_pmu_add(struct perf_event *event, int flags)
-{
-	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct hw_perf_event *hwc = &event->hw;
-
-	if (cpuc->n_events == riscv_pmu->num_counters)
-		return -ENOSPC;
-
-	/*
-	 * We don't have general conunters, so no binding-event-to-counter
-	 * process here.
-	 *
-	 * Indexing using hwc->config generally not works, since config may
-	 * contain extra information, but here the only info we have in
-	 * hwc->config is the event index.
-	 */
-	hwc->idx = hwc->config;
-	cpuc->events[hwc->idx] = event;
-	cpuc->n_events++;
-
-	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
-
-	if (flags & PERF_EF_START)
-		riscv_pmu->pmu->start(event, PERF_EF_RELOAD);
-
-	return 0;
-}
-
-/*
- * pmu->del: delete the event from PMU.
- */
-static void riscv_pmu_del(struct perf_event *event, int flags)
-{
-	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
-	struct hw_perf_event *hwc = &event->hw;
-
-	cpuc->events[hwc->idx] = NULL;
-	cpuc->n_events--;
-	riscv_pmu->pmu->stop(event, PERF_EF_UPDATE);
-	perf_event_update_userpage(event);
-}
-
-/*
- * Interrupt: a skeletion for reference.
- */
-
-static DEFINE_MUTEX(pmc_reserve_mutex);
-
-static irqreturn_t riscv_base_pmu_handle_irq(int irq_num, void *dev)
-{
-	return IRQ_NONE;
-}
-
-static int reserve_pmc_hardware(void)
-{
-	int err = 0;
-
-	mutex_lock(&pmc_reserve_mutex);
-	if (riscv_pmu->irq >= 0 && riscv_pmu->handle_irq) {
-		err = request_irq(riscv_pmu->irq, riscv_pmu->handle_irq,
-				  IRQF_PERCPU, "riscv-base-perf", NULL);
-	}
-	mutex_unlock(&pmc_reserve_mutex);
-
-	return err;
-}
-
-static void release_pmc_hardware(void)
-{
-	mutex_lock(&pmc_reserve_mutex);
-	if (riscv_pmu->irq >= 0)
-		free_irq(riscv_pmu->irq, NULL);
-	mutex_unlock(&pmc_reserve_mutex);
-}
-
-/*
- * Event Initialization/Finalization
- */
-
-static atomic_t riscv_active_events = ATOMIC_INIT(0);
-
-static void riscv_event_destroy(struct perf_event *event)
-{
-	if (atomic_dec_return(&riscv_active_events) == 0)
-		release_pmc_hardware();
-}
-
-static int riscv_event_init(struct perf_event *event)
-{
-	struct perf_event_attr *attr = &event->attr;
-	struct hw_perf_event *hwc = &event->hw;
-	int err;
-	int code;
-
-	if (atomic_inc_return(&riscv_active_events) == 1) {
-		err = reserve_pmc_hardware();
-
-		if (err) {
-			pr_warn("PMC hardware not available\n");
-			atomic_dec(&riscv_active_events);
-			return -EBUSY;
-		}
-	}
-
-	switch (event->attr.type) {
-	case PERF_TYPE_HARDWARE:
-		code = riscv_pmu->map_hw_event(attr->config);
-		break;
-	case PERF_TYPE_HW_CACHE:
-		code = riscv_pmu->map_cache_event(attr->config);
-		break;
-	case PERF_TYPE_RAW:
-		return -EOPNOTSUPP;
-	default:
-		return -ENOENT;
-	}
-
-	event->destroy = riscv_event_destroy;
-	if (code < 0) {
-		event->destroy(event);
-		return code;
-	}
-
-	/*
-	 * idx is set to -1 because the index of a general event should not be
-	 * decided until binding to some counter in pmu->add().
-	 *
-	 * But since we don't have such support, later in pmu->add(), we just
-	 * use hwc->config as the index instead.
-	 */
-	hwc->config = code;
-	hwc->idx = -1;
-
-	return 0;
-}
-
-/*
- * Initialization
- */
-
-static struct pmu min_pmu = {
-	.name		= "riscv-base",
-	.event_init	= riscv_event_init,
-	.add		= riscv_pmu_add,
-	.del		= riscv_pmu_del,
-	.start		= riscv_pmu_start,
-	.stop		= riscv_pmu_stop,
-	.read		= riscv_pmu_read,
-};
-
-static const struct riscv_pmu riscv_base_pmu = {
-	.pmu = &min_pmu,
-	.max_events = ARRAY_SIZE(riscv_hw_event_map),
-	.map_hw_event = riscv_map_hw_event,
-	.hw_events = riscv_hw_event_map,
-	.map_cache_event = riscv_map_cache_event,
-	.cache_events = &riscv_cache_event_map,
-	.counter_width = 63,
-	.num_counters = RISCV_BASE_COUNTERS + 0,
-	.handle_irq = &riscv_base_pmu_handle_irq,
-
-	/* This means this PMU has no IRQ. */
-	.irq = -1,
-};
-
-static const struct of_device_id riscv_pmu_of_ids[] = {
-	{.compatible = "riscv,base-pmu",	.data = &riscv_base_pmu},
-	{ /* sentinel value */ }
-};
-
-static int __init init_hw_perf_events(void)
-{
-	struct device_node *node = of_find_node_by_type(NULL, "pmu");
-	const struct of_device_id *of_id;
-
-	riscv_pmu = &riscv_base_pmu;
-
-	if (node) {
-		of_id = of_match_node(riscv_pmu_of_ids, node);
-
-		if (of_id)
-			riscv_pmu = of_id->data;
-		of_node_put(node);
-	}
-
-	perf_pmu_register(riscv_pmu->pmu, "cpu", PERF_TYPE_RAW);
-	return 0;
-}
-arch_initcall(init_hw_perf_events);
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 2/7] RISC-V: Add CSR encodings for all HPMCOUNTERS
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/include/asm/csr.h | 58 ++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 87ac65696871..e4d369830af4 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -89,9 +89,67 @@
 #define CSR_CYCLE		0xc00
 #define CSR_TIME		0xc01
 #define CSR_INSTRET		0xc02
+#define CSR_HPMCOUNTER3		0xc03
+#define CSR_HPMCOUNTER4		0xc04
+#define CSR_HPMCOUNTER5		0xc05
+#define CSR_HPMCOUNTER6		0xc06
+#define CSR_HPMCOUNTER7		0xc07
+#define CSR_HPMCOUNTER8		0xc08
+#define CSR_HPMCOUNTER9		0xc09
+#define CSR_HPMCOUNTER10	0xc0a
+#define CSR_HPMCOUNTER11	0xc0b
+#define CSR_HPMCOUNTER12	0xc0c
+#define CSR_HPMCOUNTER13	0xc0d
+#define CSR_HPMCOUNTER14	0xc0e
+#define CSR_HPMCOUNTER15	0xc0f
+#define CSR_HPMCOUNTER16	0xc10
+#define CSR_HPMCOUNTER17	0xc11
+#define CSR_HPMCOUNTER18	0xc12
+#define CSR_HPMCOUNTER19	0xc13
+#define CSR_HPMCOUNTER20	0xc14
+#define CSR_HPMCOUNTER21	0xc15
+#define CSR_HPMCOUNTER22	0xc16
+#define CSR_HPMCOUNTER23	0xc17
+#define CSR_HPMCOUNTER24	0xc18
+#define CSR_HPMCOUNTER25	0xc19
+#define CSR_HPMCOUNTER26	0xc1a
+#define CSR_HPMCOUNTER27	0xc1b
+#define CSR_HPMCOUNTER28	0xc1c
+#define CSR_HPMCOUNTER29	0xc1d
+#define CSR_HPMCOUNTER30	0xc1e
+#define CSR_HPMCOUNTER31	0xc1f
 #define CSR_CYCLEH		0xc80
 #define CSR_TIMEH		0xc81
 #define CSR_INSTRETH		0xc82
+#define CSR_HPMCOUNTER3H	0xc83
+#define CSR_HPMCOUNTER4H	0xc84
+#define CSR_HPMCOUNTER5H	0xc85
+#define CSR_HPMCOUNTER6H	0xc86
+#define CSR_HPMCOUNTER7H	0xc87
+#define CSR_HPMCOUNTER8H	0xc88
+#define CSR_HPMCOUNTER9H	0xc89
+#define CSR_HPMCOUNTER10H	0xc8a
+#define CSR_HPMCOUNTER11H	0xc8b
+#define CSR_HPMCOUNTER12H	0xc8c
+#define CSR_HPMCOUNTER13H	0xc8d
+#define CSR_HPMCOUNTER14H	0xc8e
+#define CSR_HPMCOUNTER15H	0xc8f
+#define CSR_HPMCOUNTER16H	0xc90
+#define CSR_HPMCOUNTER17H	0xc91
+#define CSR_HPMCOUNTER18H	0xc92
+#define CSR_HPMCOUNTER19H	0xc93
+#define CSR_HPMCOUNTER20H	0xc94
+#define CSR_HPMCOUNTER21H	0xc95
+#define CSR_HPMCOUNTER22H	0xc96
+#define CSR_HPMCOUNTER23H	0xc97
+#define CSR_HPMCOUNTER24H	0xc98
+#define CSR_HPMCOUNTER25H	0xc99
+#define CSR_HPMCOUNTER26H	0xc9a
+#define CSR_HPMCOUNTER27H	0xc9b
+#define CSR_HPMCOUNTER28H	0xc9c
+#define CSR_HPMCOUNTER29H	0xc9d
+#define CSR_HPMCOUNTER30H	0xc9e
+#define CSR_HPMCOUNTER31H	0xc9f
 
 #define CSR_SSTATUS		0x100
 #define CSR_SIE			0x104
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 2/7] RISC-V: Add CSR encodings for all HPMCOUNTERS
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/include/asm/csr.h | 58 ++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 87ac65696871..e4d369830af4 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -89,9 +89,67 @@
 #define CSR_CYCLE		0xc00
 #define CSR_TIME		0xc01
 #define CSR_INSTRET		0xc02
+#define CSR_HPMCOUNTER3		0xc03
+#define CSR_HPMCOUNTER4		0xc04
+#define CSR_HPMCOUNTER5		0xc05
+#define CSR_HPMCOUNTER6		0xc06
+#define CSR_HPMCOUNTER7		0xc07
+#define CSR_HPMCOUNTER8		0xc08
+#define CSR_HPMCOUNTER9		0xc09
+#define CSR_HPMCOUNTER10	0xc0a
+#define CSR_HPMCOUNTER11	0xc0b
+#define CSR_HPMCOUNTER12	0xc0c
+#define CSR_HPMCOUNTER13	0xc0d
+#define CSR_HPMCOUNTER14	0xc0e
+#define CSR_HPMCOUNTER15	0xc0f
+#define CSR_HPMCOUNTER16	0xc10
+#define CSR_HPMCOUNTER17	0xc11
+#define CSR_HPMCOUNTER18	0xc12
+#define CSR_HPMCOUNTER19	0xc13
+#define CSR_HPMCOUNTER20	0xc14
+#define CSR_HPMCOUNTER21	0xc15
+#define CSR_HPMCOUNTER22	0xc16
+#define CSR_HPMCOUNTER23	0xc17
+#define CSR_HPMCOUNTER24	0xc18
+#define CSR_HPMCOUNTER25	0xc19
+#define CSR_HPMCOUNTER26	0xc1a
+#define CSR_HPMCOUNTER27	0xc1b
+#define CSR_HPMCOUNTER28	0xc1c
+#define CSR_HPMCOUNTER29	0xc1d
+#define CSR_HPMCOUNTER30	0xc1e
+#define CSR_HPMCOUNTER31	0xc1f
 #define CSR_CYCLEH		0xc80
 #define CSR_TIMEH		0xc81
 #define CSR_INSTRETH		0xc82
+#define CSR_HPMCOUNTER3H	0xc83
+#define CSR_HPMCOUNTER4H	0xc84
+#define CSR_HPMCOUNTER5H	0xc85
+#define CSR_HPMCOUNTER6H	0xc86
+#define CSR_HPMCOUNTER7H	0xc87
+#define CSR_HPMCOUNTER8H	0xc88
+#define CSR_HPMCOUNTER9H	0xc89
+#define CSR_HPMCOUNTER10H	0xc8a
+#define CSR_HPMCOUNTER11H	0xc8b
+#define CSR_HPMCOUNTER12H	0xc8c
+#define CSR_HPMCOUNTER13H	0xc8d
+#define CSR_HPMCOUNTER14H	0xc8e
+#define CSR_HPMCOUNTER15H	0xc8f
+#define CSR_HPMCOUNTER16H	0xc90
+#define CSR_HPMCOUNTER17H	0xc91
+#define CSR_HPMCOUNTER18H	0xc92
+#define CSR_HPMCOUNTER19H	0xc93
+#define CSR_HPMCOUNTER20H	0xc94
+#define CSR_HPMCOUNTER21H	0xc95
+#define CSR_HPMCOUNTER22H	0xc96
+#define CSR_HPMCOUNTER23H	0xc97
+#define CSR_HPMCOUNTER24H	0xc98
+#define CSR_HPMCOUNTER25H	0xc99
+#define CSR_HPMCOUNTER26H	0xc9a
+#define CSR_HPMCOUNTER27H	0xc9b
+#define CSR_HPMCOUNTER28H	0xc9c
+#define CSR_HPMCOUNTER29H	0xc9d
+#define CSR_HPMCOUNTER30H	0xc9e
+#define CSR_HPMCOUNTER31H	0xc9f
 
 #define CSR_SSTATUS		0x100
 #define CSR_SIE			0x104
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 3/7] RISC-V: Add a perf core library for pmu drivers
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

Implement a perf core library that can support all the essential perf
features in future. It can also accommodate any type of PMU implementation
in future. Currently, both SBI based perf driver and legacy driver
implemented uses the library. Most of the common perf functionalities
are kept in this core library wile PMU specific driver can implement PMU
specific features. For example, the SBI specific functionality will be
implemented in the SBI specific driver.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig           |   8 +
 drivers/perf/Makefile          |   1 +
 drivers/perf/riscv_pmu.c       | 326 +++++++++++++++++++++++++++++++++
 include/linux/cpuhotplug.h     |   1 +
 include/linux/perf/riscv_pmu.h |  60 ++++++
 5 files changed, 396 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu.c
 create mode 100644 include/linux/perf/riscv_pmu.h

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 77522e5efe11..fc42ab613ea0 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -56,6 +56,14 @@ config ARM_PMU
 	  Say y if you want to use CPU performance monitors on ARM-based
 	  systems.
 
+config RISCV_PMU
+	depends on RISCV
+	bool "RISC-V PMU framework"
+	default y
+	help
+	  Say y if you want to use CPU performance monitors on RISCV-based
+	  systems.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index 5260b116c7da..76e5c50e24bb 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_FSL_IMX8_DDR_PMU) += fsl_imx8_ddr_perf.o
 obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
+obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
 obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
new file mode 100644
index 000000000000..c184aa50134d
--- /dev/null
+++ b/drivers/perf/riscv_pmu.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This implementation is based on old RISC-V perf and ARM perf event code
+ * which are in turn based on sparc64 and x86 code.
+ */
+
+#include <linux/cpumask.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+
+static unsigned long csr_read_num(int csr_num)
+{
+#define switchcase_csr_read(__csr_num, __val)		{\
+	case __csr_num:					\
+		__val = csr_read(__csr_num);		\
+		break; }
+#define switchcase_csr_read_2(__csr_num, __val)		{\
+	switchcase_csr_read(__csr_num + 0, __val)	 \
+	switchcase_csr_read(__csr_num + 1, __val)}
+#define switchcase_csr_read_4(__csr_num, __val)		{\
+	switchcase_csr_read_2(__csr_num + 0, __val)	 \
+	switchcase_csr_read_2(__csr_num + 2, __val)}
+#define switchcase_csr_read_8(__csr_num, __val)		{\
+	switchcase_csr_read_4(__csr_num + 0, __val)	 \
+	switchcase_csr_read_4(__csr_num + 4, __val)}
+#define switchcase_csr_read_16(__csr_num, __val)	{\
+	switchcase_csr_read_8(__csr_num + 0, __val)	 \
+	switchcase_csr_read_8(__csr_num + 8, __val)}
+#define switchcase_csr_read_32(__csr_num, __val)	{\
+	switchcase_csr_read_16(__csr_num + 0, __val)	 \
+	switchcase_csr_read_16(__csr_num + 16, __val)}
+
+	unsigned long ret = 0;
+
+	switch (csr_num) {
+	switchcase_csr_read_32(CSR_CYCLE, ret)
+	switchcase_csr_read_32(CSR_CYCLEH, ret)
+	default :
+		break;
+	}
+
+	return ret;
+#undef switchcase_csr_read_32
+#undef switchcase_csr_read_16
+#undef switchcase_csr_read_8
+#undef switchcase_csr_read_4
+#undef switchcase_csr_read_2
+#undef switchcase_csr_read
+}
+
+/*
+ * Read the CSR of a corresponding counter.
+ */
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr)
+{
+	if (csr < CSR_CYCLE || csr > CSR_HPMCOUNTER31H ||
+	   (csr > CSR_HPMCOUNTER31 && csr < CSR_CYCLEH)) {
+		pr_err("Invalid performance counter csr %lx\n", csr);
+		return -EINVAL;
+	}
+
+	return csr_read_num(csr);
+}
+
+static unsigned long riscv_pmu_ctr_get_mask(struct perf_event *event)
+{
+	int cwidth;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (!rvpmu->ctr_get_width)
+	/**
+	 * If the pmu driver doesn't support counter width, set it to default maximum
+	 * allowed by the specification.
+	 */
+		cwidth = 63;
+	else {
+		if (hwc->idx == -1)
+			/* Handle init case where idx is not initialized yet */
+			cwidth = rvpmu->ctr_get_width(0);
+		else
+			cwidth = rvpmu->ctr_get_width(hwc->idx);
+	}
+
+	return GENMASK_ULL(cwidth, 0);
+}
+
+static u64 riscv_pmu_event_update(struct perf_event *event)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	u64 prev_raw_count, new_raw_count;
+	unsigned long cmask;
+	u64 oldval, delta;
+
+	if (!rvpmu->ctr_read)
+		return 0;
+
+	cmask = riscv_pmu_ctr_get_mask(event);
+
+	do {
+		prev_raw_count = local64_read(&hwc->prev_count);
+		new_raw_count = rvpmu->ctr_read(event);
+		oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+					 new_raw_count);
+	} while (oldval != prev_raw_count);
+
+	delta = (new_raw_count - prev_raw_count) & cmask;
+	local64_add(delta, &event->count);
+	local64_sub(delta, &hwc->period_left);
+
+	return delta;
+}
+
+static void riscv_pmu_stop(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+
+	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+
+	if (!(hwc->state & PERF_HES_STOPPED)) {
+		riscv_pmu_event_update(event);
+		if (rvpmu->ctr_stop) {
+			rvpmu->ctr_stop(event);
+			hwc->state |= PERF_HES_STOPPED;
+		}
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+}
+
+static int riscv_pmu_event_set_period(struct perf_event *event, u64 *init_val)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 left = local64_read(&hwc->period_left);
+	s64 period = hwc->sample_period;
+	u64 max_period;
+	int ret = 0;
+	unsigned long cmask = riscv_pmu_ctr_get_mask(event);
+
+	max_period = cmask;
+	if (unlikely(left <= -period)) {
+		left = period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	if (unlikely(left <= 0)) {
+		left += period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	/*
+	 * Limit the maximum period to prevent the counter value
+	 * from overtaking the one we are about to program. In
+	 * effect we are reducing max_period to account for
+	 * interrupt latency (and we are being very conservative).
+	 */
+	if (left > (max_period >> 1))
+		left = (max_period >> 1);
+
+	local64_set(&hwc->prev_count, (u64)-left);
+	*init_val = (u64)(-left) & max_period;
+	perf_event_update_userpage(event);
+
+	return ret;
+}
+
+static void riscv_pmu_start(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	u64 init_val;
+
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	if (flags & PERF_EF_RELOAD) {
+		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+
+		/*
+		 * Set the counter to the period to the next interrupt here,
+		 * if you have any.
+		 */
+	}
+
+	hwc->state = 0;
+	riscv_pmu_event_set_period(event, &init_val);
+	rvpmu->ctr_start(event, init_val);
+	perf_event_update_userpage(event);
+}
+
+static int riscv_pmu_add(struct perf_event *event, int flags)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx;
+
+	idx = rvpmu->ctr_get_idx(event);
+	if (idx < 0)
+		return idx;
+
+	hwc->idx = idx;
+	cpuc->events[idx] = event;
+	cpuc->n_events++;
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+	if (flags & PERF_EF_START)
+		riscv_pmu_start(event, PERF_EF_RELOAD);
+
+	/* Propagate our changes to the userspace mapping. */
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void riscv_pmu_del(struct perf_event *event, int flags)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+
+	cpuc->events[hwc->idx] = NULL;
+	riscv_pmu_stop(event, PERF_EF_UPDATE);
+	cpuc->n_events--;
+	if (rvpmu->ctr_clear_idx)
+		rvpmu->ctr_clear_idx(event);
+	perf_event_update_userpage(event);
+	hwc->idx = -1;
+}
+
+static void riscv_pmu_read(struct perf_event *event)
+{
+	riscv_pmu_event_update(event);
+}
+
+static int riscv_pmu_event_init(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	int mapped_event;
+	u64 event_config = 0;
+	unsigned long cmask;
+
+	hwc->flags = 0;
+	mapped_event = rvpmu->event_map(event, &event_config);
+	if (mapped_event < 0) {
+		pr_debug("event %x:%llx not supported\n", event->attr.type,
+			 event->attr.config);
+		return mapped_event;
+	}
+
+	/*
+	 * idx is set to -1 because the index of a general event should not be
+	 * decided until binding to some counter in pmu->add().
+	 * config will contain the information about counter CSR
+	 * the idx will contain the counter index
+	 */
+	hwc->config = event_config;
+	hwc->idx = -1;
+	hwc->event_base = mapped_event;
+
+	if (!is_sampling_event(event)) {
+		/*
+		 * For non-sampling runs, limit the sample_period to half
+		 * of the counter width. That way, the new counter value
+		 * is far less likely to overtake the previous one unless
+		 * you have some serious IRQ latency issues.
+		 */
+		cmask = riscv_pmu_ctr_get_mask(event);
+		hwc->sample_period  =  cmask >> 1;
+		hwc->last_period    = hwc->sample_period;
+		local64_set(&hwc->period_left, hwc->sample_period);
+	}
+
+	return 0;
+}
+
+struct riscv_pmu *riscv_pmu_alloc(void)
+{
+	struct riscv_pmu *pmu;
+	int cpuid, i;
+	struct cpu_hw_events *cpuc;
+
+	pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
+	if (!pmu)
+		goto out;
+
+	pmu->hw_events = alloc_percpu_gfp(struct cpu_hw_events, GFP_KERNEL);
+	if (!pmu->hw_events) {
+		pr_info("failed to allocate per-cpu PMU data.\n");
+		goto out_free_pmu;
+	}
+
+	for_each_possible_cpu(cpuid) {
+		cpuc = per_cpu_ptr(pmu->hw_events, cpuid);
+		cpuc->n_events = 0;
+		for (i = 0; i < RISCV_MAX_COUNTERS; i++)
+			cpuc->events[i] = NULL;
+	}
+	pmu->pmu = (struct pmu) {
+		.event_init	= riscv_pmu_event_init,
+		.add		= riscv_pmu_add,
+		.del		= riscv_pmu_del,
+		.start		= riscv_pmu_start,
+		.stop		= riscv_pmu_stop,
+		.read		= riscv_pmu_read,
+	};
+
+	return pmu;
+
+out_free_pmu:
+	kfree(pmu);
+out:
+	return NULL;
+}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4a62b3980642..7b629fd636bf 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -121,6 +121,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,
 	CPUHP_AP_PERF_ARM_ACPI_STARTING,
 	CPUHP_AP_PERF_ARM_STARTING,
+	CPUHP_AP_PERF_RISCV_STARTING,
 	CPUHP_AP_ARM_L2X0_STARTING,
 	CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
 	CPUHP_AP_ARM_ARCH_TIMER_STARTING,
diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
new file mode 100644
index 000000000000..72802b2df0cd
--- /dev/null
+++ b/include/linux/perf/riscv_pmu.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 SiFive
+ * Copyright (C) 2018 Andes Technology Corporation
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ */
+
+#ifndef _ASM_RISCV_PERF_EVENT_H
+#define _ASM_RISCV_PERF_EVENT_H
+
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/interrupt.h>
+
+#ifdef CONFIG_RISCV_PMU
+
+/*
+ * The RISCV_MAX_COUNTERS parameter should be specified.
+ */
+
+#define RISCV_MAX_COUNTERS	128
+#define RISCV_OP_UNSUPP		(-EOPNOTSUPP)
+#define RISCV_PMU_PDEV_NAME	"riscv-pmu"
+
+struct cpu_hw_events {
+	/* currently enabled events */
+	int			n_events;
+	/* currently enabled events */
+	struct perf_event	*events[RISCV_MAX_COUNTERS];
+	/* currently enabled counters */
+	DECLARE_BITMAP(used_event_ctrs, RISCV_MAX_COUNTERS);
+};
+
+struct riscv_pmu {
+	struct pmu	pmu;
+	char		*name;
+
+	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
+	int		irq;
+
+	int		num_counters;
+	u64		(*ctr_read)(struct perf_event *event);
+	int		(*ctr_get_idx)(struct perf_event *event);
+	int		(*ctr_get_width)(int idx);
+	void		(*ctr_clear_idx)(struct perf_event *event);
+	void		(*ctr_start)(struct perf_event *event, u64 init_val);
+	void		(*ctr_stop)(struct perf_event *event);
+	int		(*event_map)(struct perf_event *event, u64 *config);
+
+	struct cpu_hw_events	__percpu *hw_events;
+};
+
+#define to_riscv_pmu(p) (container_of(p, struct riscv_pmu, pmu))
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr);
+struct riscv_pmu *riscv_pmu_alloc(void);
+
+#endif /* CONFIG_RISCV_PMU */
+
+#endif /* _ASM_RISCV_PERF_EVENT_H */
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 3/7] RISC-V: Add a perf core library for pmu drivers
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

Implement a perf core library that can support all the essential perf
features in future. It can also accommodate any type of PMU implementation
in future. Currently, both SBI based perf driver and legacy driver
implemented uses the library. Most of the common perf functionalities
are kept in this core library wile PMU specific driver can implement PMU
specific features. For example, the SBI specific functionality will be
implemented in the SBI specific driver.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig           |   8 +
 drivers/perf/Makefile          |   1 +
 drivers/perf/riscv_pmu.c       | 326 +++++++++++++++++++++++++++++++++
 include/linux/cpuhotplug.h     |   1 +
 include/linux/perf/riscv_pmu.h |  60 ++++++
 5 files changed, 396 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu.c
 create mode 100644 include/linux/perf/riscv_pmu.h

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 77522e5efe11..fc42ab613ea0 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -56,6 +56,14 @@ config ARM_PMU
 	  Say y if you want to use CPU performance monitors on ARM-based
 	  systems.
 
+config RISCV_PMU
+	depends on RISCV
+	bool "RISC-V PMU framework"
+	default y
+	help
+	  Say y if you want to use CPU performance monitors on RISCV-based
+	  systems.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index 5260b116c7da..76e5c50e24bb 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_FSL_IMX8_DDR_PMU) += fsl_imx8_ddr_perf.o
 obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
+obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
 obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
new file mode 100644
index 000000000000..c184aa50134d
--- /dev/null
+++ b/drivers/perf/riscv_pmu.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This implementation is based on old RISC-V perf and ARM perf event code
+ * which are in turn based on sparc64 and x86 code.
+ */
+
+#include <linux/cpumask.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/printk.h>
+#include <linux/smp.h>
+
+static unsigned long csr_read_num(int csr_num)
+{
+#define switchcase_csr_read(__csr_num, __val)		{\
+	case __csr_num:					\
+		__val = csr_read(__csr_num);		\
+		break; }
+#define switchcase_csr_read_2(__csr_num, __val)		{\
+	switchcase_csr_read(__csr_num + 0, __val)	 \
+	switchcase_csr_read(__csr_num + 1, __val)}
+#define switchcase_csr_read_4(__csr_num, __val)		{\
+	switchcase_csr_read_2(__csr_num + 0, __val)	 \
+	switchcase_csr_read_2(__csr_num + 2, __val)}
+#define switchcase_csr_read_8(__csr_num, __val)		{\
+	switchcase_csr_read_4(__csr_num + 0, __val)	 \
+	switchcase_csr_read_4(__csr_num + 4, __val)}
+#define switchcase_csr_read_16(__csr_num, __val)	{\
+	switchcase_csr_read_8(__csr_num + 0, __val)	 \
+	switchcase_csr_read_8(__csr_num + 8, __val)}
+#define switchcase_csr_read_32(__csr_num, __val)	{\
+	switchcase_csr_read_16(__csr_num + 0, __val)	 \
+	switchcase_csr_read_16(__csr_num + 16, __val)}
+
+	unsigned long ret = 0;
+
+	switch (csr_num) {
+	switchcase_csr_read_32(CSR_CYCLE, ret)
+	switchcase_csr_read_32(CSR_CYCLEH, ret)
+	default :
+		break;
+	}
+
+	return ret;
+#undef switchcase_csr_read_32
+#undef switchcase_csr_read_16
+#undef switchcase_csr_read_8
+#undef switchcase_csr_read_4
+#undef switchcase_csr_read_2
+#undef switchcase_csr_read
+}
+
+/*
+ * Read the CSR of a corresponding counter.
+ */
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr)
+{
+	if (csr < CSR_CYCLE || csr > CSR_HPMCOUNTER31H ||
+	   (csr > CSR_HPMCOUNTER31 && csr < CSR_CYCLEH)) {
+		pr_err("Invalid performance counter csr %lx\n", csr);
+		return -EINVAL;
+	}
+
+	return csr_read_num(csr);
+}
+
+static unsigned long riscv_pmu_ctr_get_mask(struct perf_event *event)
+{
+	int cwidth;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (!rvpmu->ctr_get_width)
+	/**
+	 * If the pmu driver doesn't support counter width, set it to default maximum
+	 * allowed by the specification.
+	 */
+		cwidth = 63;
+	else {
+		if (hwc->idx == -1)
+			/* Handle init case where idx is not initialized yet */
+			cwidth = rvpmu->ctr_get_width(0);
+		else
+			cwidth = rvpmu->ctr_get_width(hwc->idx);
+	}
+
+	return GENMASK_ULL(cwidth, 0);
+}
+
+static u64 riscv_pmu_event_update(struct perf_event *event)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct hw_perf_event *hwc = &event->hw;
+	u64 prev_raw_count, new_raw_count;
+	unsigned long cmask;
+	u64 oldval, delta;
+
+	if (!rvpmu->ctr_read)
+		return 0;
+
+	cmask = riscv_pmu_ctr_get_mask(event);
+
+	do {
+		prev_raw_count = local64_read(&hwc->prev_count);
+		new_raw_count = rvpmu->ctr_read(event);
+		oldval = local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+					 new_raw_count);
+	} while (oldval != prev_raw_count);
+
+	delta = (new_raw_count - prev_raw_count) & cmask;
+	local64_add(delta, &event->count);
+	local64_sub(delta, &hwc->period_left);
+
+	return delta;
+}
+
+static void riscv_pmu_stop(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+
+	WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+
+	if (!(hwc->state & PERF_HES_STOPPED)) {
+		riscv_pmu_event_update(event);
+		if (rvpmu->ctr_stop) {
+			rvpmu->ctr_stop(event);
+			hwc->state |= PERF_HES_STOPPED;
+		}
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+}
+
+static int riscv_pmu_event_set_period(struct perf_event *event, u64 *init_val)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 left = local64_read(&hwc->period_left);
+	s64 period = hwc->sample_period;
+	u64 max_period;
+	int ret = 0;
+	unsigned long cmask = riscv_pmu_ctr_get_mask(event);
+
+	max_period = cmask;
+	if (unlikely(left <= -period)) {
+		left = period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	if (unlikely(left <= 0)) {
+		left += period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	/*
+	 * Limit the maximum period to prevent the counter value
+	 * from overtaking the one we are about to program. In
+	 * effect we are reducing max_period to account for
+	 * interrupt latency (and we are being very conservative).
+	 */
+	if (left > (max_period >> 1))
+		left = (max_period >> 1);
+
+	local64_set(&hwc->prev_count, (u64)-left);
+	*init_val = (u64)(-left) & max_period;
+	perf_event_update_userpage(event);
+
+	return ret;
+}
+
+static void riscv_pmu_start(struct perf_event *event, int flags)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	u64 init_val;
+
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	if (flags & PERF_EF_RELOAD) {
+		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+
+		/*
+		 * Set the counter to the period to the next interrupt here,
+		 * if you have any.
+		 */
+	}
+
+	hwc->state = 0;
+	riscv_pmu_event_set_period(event, &init_val);
+	rvpmu->ctr_start(event, init_val);
+	perf_event_update_userpage(event);
+}
+
+static int riscv_pmu_add(struct perf_event *event, int flags)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+	int idx;
+
+	idx = rvpmu->ctr_get_idx(event);
+	if (idx < 0)
+		return idx;
+
+	hwc->idx = idx;
+	cpuc->events[idx] = event;
+	cpuc->n_events++;
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+	if (flags & PERF_EF_START)
+		riscv_pmu_start(event, PERF_EF_RELOAD);
+
+	/* Propagate our changes to the userspace mapping. */
+	perf_event_update_userpage(event);
+
+	return 0;
+}
+
+static void riscv_pmu_del(struct perf_event *event, int flags)
+{
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+
+	cpuc->events[hwc->idx] = NULL;
+	riscv_pmu_stop(event, PERF_EF_UPDATE);
+	cpuc->n_events--;
+	if (rvpmu->ctr_clear_idx)
+		rvpmu->ctr_clear_idx(event);
+	perf_event_update_userpage(event);
+	hwc->idx = -1;
+}
+
+static void riscv_pmu_read(struct perf_event *event)
+{
+	riscv_pmu_event_update(event);
+}
+
+static int riscv_pmu_event_init(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	int mapped_event;
+	u64 event_config = 0;
+	unsigned long cmask;
+
+	hwc->flags = 0;
+	mapped_event = rvpmu->event_map(event, &event_config);
+	if (mapped_event < 0) {
+		pr_debug("event %x:%llx not supported\n", event->attr.type,
+			 event->attr.config);
+		return mapped_event;
+	}
+
+	/*
+	 * idx is set to -1 because the index of a general event should not be
+	 * decided until binding to some counter in pmu->add().
+	 * config will contain the information about counter CSR
+	 * the idx will contain the counter index
+	 */
+	hwc->config = event_config;
+	hwc->idx = -1;
+	hwc->event_base = mapped_event;
+
+	if (!is_sampling_event(event)) {
+		/*
+		 * For non-sampling runs, limit the sample_period to half
+		 * of the counter width. That way, the new counter value
+		 * is far less likely to overtake the previous one unless
+		 * you have some serious IRQ latency issues.
+		 */
+		cmask = riscv_pmu_ctr_get_mask(event);
+		hwc->sample_period  =  cmask >> 1;
+		hwc->last_period    = hwc->sample_period;
+		local64_set(&hwc->period_left, hwc->sample_period);
+	}
+
+	return 0;
+}
+
+struct riscv_pmu *riscv_pmu_alloc(void)
+{
+	struct riscv_pmu *pmu;
+	int cpuid, i;
+	struct cpu_hw_events *cpuc;
+
+	pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
+	if (!pmu)
+		goto out;
+
+	pmu->hw_events = alloc_percpu_gfp(struct cpu_hw_events, GFP_KERNEL);
+	if (!pmu->hw_events) {
+		pr_info("failed to allocate per-cpu PMU data.\n");
+		goto out_free_pmu;
+	}
+
+	for_each_possible_cpu(cpuid) {
+		cpuc = per_cpu_ptr(pmu->hw_events, cpuid);
+		cpuc->n_events = 0;
+		for (i = 0; i < RISCV_MAX_COUNTERS; i++)
+			cpuc->events[i] = NULL;
+	}
+	pmu->pmu = (struct pmu) {
+		.event_init	= riscv_pmu_event_init,
+		.add		= riscv_pmu_add,
+		.del		= riscv_pmu_del,
+		.start		= riscv_pmu_start,
+		.stop		= riscv_pmu_stop,
+		.read		= riscv_pmu_read,
+	};
+
+	return pmu;
+
+out_free_pmu:
+	kfree(pmu);
+out:
+	return NULL;
+}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 4a62b3980642..7b629fd636bf 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -121,6 +121,7 @@ enum cpuhp_state {
 	CPUHP_AP_PERF_ARM_HW_BREAKPOINT_STARTING,
 	CPUHP_AP_PERF_ARM_ACPI_STARTING,
 	CPUHP_AP_PERF_ARM_STARTING,
+	CPUHP_AP_PERF_RISCV_STARTING,
 	CPUHP_AP_ARM_L2X0_STARTING,
 	CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
 	CPUHP_AP_ARM_ARCH_TIMER_STARTING,
diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
new file mode 100644
index 000000000000..72802b2df0cd
--- /dev/null
+++ b/include/linux/perf/riscv_pmu.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 SiFive
+ * Copyright (C) 2018 Andes Technology Corporation
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ */
+
+#ifndef _ASM_RISCV_PERF_EVENT_H
+#define _ASM_RISCV_PERF_EVENT_H
+
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/interrupt.h>
+
+#ifdef CONFIG_RISCV_PMU
+
+/*
+ * The RISCV_MAX_COUNTERS parameter should be specified.
+ */
+
+#define RISCV_MAX_COUNTERS	128
+#define RISCV_OP_UNSUPP		(-EOPNOTSUPP)
+#define RISCV_PMU_PDEV_NAME	"riscv-pmu"
+
+struct cpu_hw_events {
+	/* currently enabled events */
+	int			n_events;
+	/* currently enabled events */
+	struct perf_event	*events[RISCV_MAX_COUNTERS];
+	/* currently enabled counters */
+	DECLARE_BITMAP(used_event_ctrs, RISCV_MAX_COUNTERS);
+};
+
+struct riscv_pmu {
+	struct pmu	pmu;
+	char		*name;
+
+	irqreturn_t	(*handle_irq)(int irq_num, void *dev);
+	int		irq;
+
+	int		num_counters;
+	u64		(*ctr_read)(struct perf_event *event);
+	int		(*ctr_get_idx)(struct perf_event *event);
+	int		(*ctr_get_width)(int idx);
+	void		(*ctr_clear_idx)(struct perf_event *event);
+	void		(*ctr_start)(struct perf_event *event, u64 init_val);
+	void		(*ctr_stop)(struct perf_event *event);
+	int		(*event_map)(struct perf_event *event, u64 *config);
+
+	struct cpu_hw_events	__percpu *hw_events;
+};
+
+#define to_riscv_pmu(p) (container_of(p, struct riscv_pmu, pmu))
+unsigned long riscv_pmu_ctr_read_csr(unsigned long csr);
+struct riscv_pmu *riscv_pmu_alloc(void);
+
+#endif /* CONFIG_RISCV_PMU */
+
+#endif /* _ASM_RISCV_PERF_EVENT_H */
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 4/7] RISC-V: Add a simple platform driver for RISC-V legacy perf
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The old RISC-V perf implementation allowed counting of only
cycle/instruction counters using perf. Restore that feature by implementing
a simple platform driver under a separate config to provide backward
compatibility. Any existing software stack will continue to work as it is.
However, it provides an easy way out in future where we can remove the
legacy driver.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig            |  9 ++++
 drivers/perf/Makefile           |  3 ++
 drivers/perf/riscv_pmu_legacy.c | 92 +++++++++++++++++++++++++++++++++
 include/linux/perf/riscv_pmu.h  |  1 +
 4 files changed, 105 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu_legacy.c

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index fc42ab613ea0..1546a487d970 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -64,6 +64,15 @@ config RISCV_PMU
 	  Say y if you want to use CPU performance monitors on RISCV-based
 	  systems.
 
+config RISCV_PMU_LEGACY
+	depends on RISCV_PMU
+	bool "RISC-V legacy PMU implementation"
+	default y
+	help
+	  Say y if you want to use the legacy CPU performance monitor
+	  implementation on RISC-V based systems. This only allows counting
+	  of cycle/instruction counter and will be removed in future.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index 76e5c50e24bb..e8aa666a9d28 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -11,6 +11,9 @@ obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
 obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
+ifeq ($(CONFIG_RISCV_PMU), y)
+obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
+endif
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
 obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
diff --git a/drivers/perf/riscv_pmu_legacy.c b/drivers/perf/riscv_pmu_legacy.c
new file mode 100644
index 000000000000..0978f0b675b4
--- /dev/null
+++ b/drivers/perf/riscv_pmu_legacy.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This implementation is based on old RISC-V perf and ARM perf event code
+ * which are in turn based on sparc64 and x86 code.
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/platform_device.h>
+
+#define RISCV_PMU_LEGACY_CYCLE		0
+#define RISCV_PMU_LEGACY_INSTRET	1
+#define RISCV_PMU_LEGACY_NUM_CTR	2
+
+static int pmu_legacy_ctr_get_idx(struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+
+	if (event->attr.type != PERF_TYPE_HARDWARE)
+		return -EOPNOTSUPP;
+	if (attr->config == PERF_COUNT_HW_CPU_CYCLES)
+		return RISCV_PMU_LEGACY_CYCLE;
+	else if (attr->config == PERF_COUNT_HW_INSTRUCTIONS)
+		return RISCV_PMU_LEGACY_INSTRET;
+	else
+		return -EOPNOTSUPP;
+}
+
+/* For legacy config & counter index are same */
+static int pmu_legacy_event_map(struct perf_event *event, u64 *config)
+{
+	return pmu_legacy_ctr_get_idx(event);
+}
+
+static u64 pmu_legacy_read_ctr(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+	u64 val;
+
+	if (idx == RISCV_PMU_LEGACY_CYCLE) {
+		val = riscv_pmu_ctr_read_csr(CSR_CYCLE);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = (u64)riscv_pmu_ctr_read_csr(CSR_CYCLEH) << 32 | val;
+	} else if (idx == RISCV_PMU_LEGACY_INSTRET) {
+		val = riscv_pmu_ctr_read_csr(CSR_INSTRET);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = ((u64)riscv_pmu_ctr_read_csr(CSR_INSTRETH)) << 32 | val;
+	} else
+		return 0;
+
+	return val;
+}
+
+static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 initial_val = pmu_legacy_read_ctr(event);
+
+	/**
+	 * The legacy method doesn't really have a start/stop method.
+	 * It also can not update the counter with a initial value.
+	 * But we still need to set the prev_count so that read() can compute
+	 * the delta. Just use the current counter value to set the prev_count.
+	 */
+	local64_set(&hwc->prev_count, initial_val);
+}
+
+/**
+ * This is just a simple implementation to allow legacy implementations
+ * compatible with new RISC-V PMU driver framework.
+ * This driver only allows reading two counters i.e CYCLE & INSTRET.
+ * However, it can not start or stop the counter. Thus, it is not very useful
+ * will be removed in future.
+ */
+void riscv_pmu_legacy_init(struct riscv_pmu *pmu)
+{
+	pr_info("Legacy PMU implementation is available\n");
+
+	pmu->num_counters = RISCV_PMU_LEGACY_NUM_CTR;
+	pmu->ctr_start = pmu_legacy_ctr_start;
+	pmu->ctr_stop = NULL;
+	pmu->event_map = pmu_legacy_event_map;
+	pmu->ctr_get_idx = pmu_legacy_ctr_get_idx;
+	pmu->ctr_get_width = NULL;
+	pmu->ctr_clear_idx = NULL;
+	pmu->ctr_read = pmu_legacy_read_ctr;
+}
diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
index 72802b2df0cd..26f8f25df395 100644
--- a/include/linux/perf/riscv_pmu.h
+++ b/include/linux/perf/riscv_pmu.h
@@ -53,6 +53,7 @@ struct riscv_pmu {
 
 #define to_riscv_pmu(p) (container_of(p, struct riscv_pmu, pmu))
 unsigned long riscv_pmu_ctr_read_csr(unsigned long csr);
+void riscv_pmu_legacy_init(struct riscv_pmu *pmu);
 struct riscv_pmu *riscv_pmu_alloc(void);
 
 #endif /* CONFIG_RISCV_PMU */
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 4/7] RISC-V: Add a simple platform driver for RISC-V legacy perf
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The old RISC-V perf implementation allowed counting of only
cycle/instruction counters using perf. Restore that feature by implementing
a simple platform driver under a separate config to provide backward
compatibility. Any existing software stack will continue to work as it is.
However, it provides an easy way out in future where we can remove the
legacy driver.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig            |  9 ++++
 drivers/perf/Makefile           |  3 ++
 drivers/perf/riscv_pmu_legacy.c | 92 +++++++++++++++++++++++++++++++++
 include/linux/perf/riscv_pmu.h  |  1 +
 4 files changed, 105 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu_legacy.c

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index fc42ab613ea0..1546a487d970 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -64,6 +64,15 @@ config RISCV_PMU
 	  Say y if you want to use CPU performance monitors on RISCV-based
 	  systems.
 
+config RISCV_PMU_LEGACY
+	depends on RISCV_PMU
+	bool "RISC-V legacy PMU implementation"
+	default y
+	help
+	  Say y if you want to use the legacy CPU performance monitor
+	  implementation on RISC-V based systems. This only allows counting
+	  of cycle/instruction counter and will be removed in future.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index 76e5c50e24bb..e8aa666a9d28 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -11,6 +11,9 @@ obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
 obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
+ifeq ($(CONFIG_RISCV_PMU), y)
+obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
+endif
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
 obj-$(CONFIG_ARM_SPE_PMU) += arm_spe_pmu.o
diff --git a/drivers/perf/riscv_pmu_legacy.c b/drivers/perf/riscv_pmu_legacy.c
new file mode 100644
index 000000000000..0978f0b675b4
--- /dev/null
+++ b/drivers/perf/riscv_pmu_legacy.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This implementation is based on old RISC-V perf and ARM perf event code
+ * which are in turn based on sparc64 and x86 code.
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/platform_device.h>
+
+#define RISCV_PMU_LEGACY_CYCLE		0
+#define RISCV_PMU_LEGACY_INSTRET	1
+#define RISCV_PMU_LEGACY_NUM_CTR	2
+
+static int pmu_legacy_ctr_get_idx(struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+
+	if (event->attr.type != PERF_TYPE_HARDWARE)
+		return -EOPNOTSUPP;
+	if (attr->config == PERF_COUNT_HW_CPU_CYCLES)
+		return RISCV_PMU_LEGACY_CYCLE;
+	else if (attr->config == PERF_COUNT_HW_INSTRUCTIONS)
+		return RISCV_PMU_LEGACY_INSTRET;
+	else
+		return -EOPNOTSUPP;
+}
+
+/* For legacy config & counter index are same */
+static int pmu_legacy_event_map(struct perf_event *event, u64 *config)
+{
+	return pmu_legacy_ctr_get_idx(event);
+}
+
+static u64 pmu_legacy_read_ctr(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+	u64 val;
+
+	if (idx == RISCV_PMU_LEGACY_CYCLE) {
+		val = riscv_pmu_ctr_read_csr(CSR_CYCLE);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = (u64)riscv_pmu_ctr_read_csr(CSR_CYCLEH) << 32 | val;
+	} else if (idx == RISCV_PMU_LEGACY_INSTRET) {
+		val = riscv_pmu_ctr_read_csr(CSR_INSTRET);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = ((u64)riscv_pmu_ctr_read_csr(CSR_INSTRETH)) << 32 | val;
+	} else
+		return 0;
+
+	return val;
+}
+
+static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	u64 initial_val = pmu_legacy_read_ctr(event);
+
+	/**
+	 * The legacy method doesn't really have a start/stop method.
+	 * It also can not update the counter with a initial value.
+	 * But we still need to set the prev_count so that read() can compute
+	 * the delta. Just use the current counter value to set the prev_count.
+	 */
+	local64_set(&hwc->prev_count, initial_val);
+}
+
+/**
+ * This is just a simple implementation to allow legacy implementations
+ * compatible with new RISC-V PMU driver framework.
+ * This driver only allows reading two counters i.e CYCLE & INSTRET.
+ * However, it can not start or stop the counter. Thus, it is not very useful
+ * will be removed in future.
+ */
+void riscv_pmu_legacy_init(struct riscv_pmu *pmu)
+{
+	pr_info("Legacy PMU implementation is available\n");
+
+	pmu->num_counters = RISCV_PMU_LEGACY_NUM_CTR;
+	pmu->ctr_start = pmu_legacy_ctr_start;
+	pmu->ctr_stop = NULL;
+	pmu->event_map = pmu_legacy_event_map;
+	pmu->ctr_get_idx = pmu_legacy_ctr_get_idx;
+	pmu->ctr_get_width = NULL;
+	pmu->ctr_clear_idx = NULL;
+	pmu->ctr_read = pmu_legacy_read_ctr;
+}
diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
index 72802b2df0cd..26f8f25df395 100644
--- a/include/linux/perf/riscv_pmu.h
+++ b/include/linux/perf/riscv_pmu.h
@@ -53,6 +53,7 @@ struct riscv_pmu {
 
 #define to_riscv_pmu(p) (container_of(p, struct riscv_pmu, pmu))
 unsigned long riscv_pmu_ctr_read_csr(unsigned long csr);
+void riscv_pmu_legacy_init(struct riscv_pmu *pmu);
 struct riscv_pmu *riscv_pmu_alloc(void);
 
 #endif /* CONFIG_RISCV_PMU */
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 5/7] RISC-V: Add RISC-V SBI PMU extension definitions
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

This patch adds all the definitions defined by the SBI PMU extension.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/include/asm/sbi.h | 94 ++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 0d42693cb65e..9a1cb78df15c 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -27,6 +27,7 @@ enum sbi_ext_id {
 	SBI_EXT_IPI = 0x735049,
 	SBI_EXT_RFENCE = 0x52464E43,
 	SBI_EXT_HSM = 0x48534D,
+	SBI_EXT_PMU = 0x504D55,
 };
 
 enum sbi_ext_base_fid {
@@ -70,6 +71,99 @@ enum sbi_hsm_hart_status {
 	SBI_HSM_HART_STATUS_STOP_PENDING,
 };
 
+
+enum sbi_ext_pmu_fid {
+	SBI_EXT_PMU_NUM_COUNTERS = 0,
+	SBI_EXT_PMU_COUNTER_GET_INFO,
+	SBI_EXT_PMU_COUNTER_CFG_MATCH,
+	SBI_EXT_PMU_COUNTER_START,
+	SBI_EXT_PMU_COUNTER_STOP,
+	SBI_EXT_PMU_COUNTER_FW_READ,
+};
+
+#define RISCV_PMU_RAW_EVENT_MASK GENMASK_ULL(55, 0)
+#define RISCV_PMU_RAW_EVENT_IDX 0x20000
+
+/** General pmu event codes specified in SBI PMU extension */
+enum sbi_pmu_hw_generic_events_t {
+	SBI_PMU_HW_NO_EVENT			= 0,
+	SBI_PMU_HW_CPU_CYCLES			= 1,
+	SBI_PMU_HW_INSTRUCTIONS			= 2,
+	SBI_PMU_HW_CACHE_REFERENCES		= 3,
+	SBI_PMU_HW_CACHE_MISSES			= 4,
+	SBI_PMU_HW_BRANCH_INSTRUCTIONS		= 5,
+	SBI_PMU_HW_BRANCH_MISSES		= 6,
+	SBI_PMU_HW_BUS_CYCLES			= 7,
+	SBI_PMU_HW_STALLED_CYCLES_FRONTEND	= 8,
+	SBI_PMU_HW_STALLED_CYCLES_BACKEND	= 9,
+	SBI_PMU_HW_REF_CPU_CYCLES		= 10,
+
+	SBI_PMU_HW_GENERAL_MAX,
+};
+
+/**
+ * Special "firmware" events provided by the firmware, even if the hardware
+ * does not support performance events. These events are encoded as a raw
+ * event type in Linux kernel perf framework.
+ */
+enum sbi_pmu_fw_generic_events_t {
+	SBI_PMU_FW_MISALIGNED_LOAD	= 0,
+	SBI_PMU_FW_MISALIGNED_STORE	= 1,
+	SBI_PMU_FW_ACCESS_LOAD		= 2,
+	SBI_PMU_FW_ACCESS_STORE		= 3,
+	SBI_PMU_FW_ILLEGAL_INSN		= 4,
+	SBI_PMU_FW_SET_TIMER		= 5,
+	SBI_PMU_FW_IPI_SENT		= 6,
+	SBI_PMU_FW_IPI_RECVD		= 7,
+	SBI_PMU_FW_FENCE_I_SENT		= 8,
+	SBI_PMU_FW_FENCE_I_RECVD	= 9,
+	SBI_PMU_FW_SFENCE_VMA_SENT	= 10,
+	SBI_PMU_FW_SFENCE_VMA_RCVD	= 11,
+	SBI_PMU_FW_SFENCE_VMA_ASID_SENT	= 12,
+	SBI_PMU_FW_SFENCE_VMA_ASID_RCVD	= 13,
+
+	SBI_PMU_FW_HFENCE_GVMA_SENT	= 14,
+	SBI_PMU_FW_HFENCE_GVMA_RCVD	= 15,
+	SBI_PMU_FW_HFENCE_GVMA_VMID_SENT = 16,
+	SBI_PMU_FW_HFENCE_GVMA_VMID_RCVD = 17,
+
+	SBI_PMU_FW_HFENCE_VVMA_SENT	= 18,
+	SBI_PMU_FW_HFENCE_VVMA_RCVD	= 19,
+	SBI_PMU_FW_HFENCE_VVMA_ASID_SENT = 20,
+	SBI_PMU_FW_HFENCE_VVMA_ASID_RCVD = 21,
+	SBI_PMU_FW_MAX,
+};
+
+/* SBI PMU event types */
+enum sbi_pmu_event_type {
+	SBI_PMU_EVENT_TYPE_HW = 0x0,
+	SBI_PMU_EVENT_TYPE_CACHE = 0x1,
+	SBI_PMU_EVENT_TYPE_RAW = 0x2,
+	SBI_PMU_EVENT_TYPE_FW = 0xf,
+};
+
+/* SBI PMU event types */
+enum sbi_pmu_ctr_type {
+	SBI_PMU_CTR_TYPE_HW = 0x0,
+	SBI_PMU_CTR_TYPE_FW,
+};
+
+/* Flags defined for config matching function */
+#define SBI_PMU_CFG_FLAG_SKIP_MATCH	(1 << 0)
+#define SBI_PMU_CFG_FLAG_CLEAR_VALUE	(1 << 1)
+#define SBI_PMU_CFG_FLAG_AUTO_START	(1 << 2)
+#define SBI_PMU_CFG_FLAG_SET_MINH	(1 << 3)
+#define SBI_PMU_CFG_FLAG_SET_SINH	(1 << 4)
+#define SBI_PMU_CFG_FLAG_SET_UINH	(1 << 5)
+#define SBI_PMU_CFG_FLAG_SET_VSINH	(1 << 6)
+#define SBI_PMU_CFG_FLAG_SET_VUINH	(1 << 7)
+
+/* Flags defined for counter start function */
+#define SBI_PMU_START_FLAG_SET_INIT_VALUE (1 << 0)
+
+/* Flags defined for counter stop function */
+#define SBI_PMU_STOP_FLAG_RESET (1 << 0)
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 5/7] RISC-V: Add RISC-V SBI PMU extension definitions
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

This patch adds all the definitions defined by the SBI PMU extension.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 arch/riscv/include/asm/sbi.h | 94 ++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 0d42693cb65e..9a1cb78df15c 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -27,6 +27,7 @@ enum sbi_ext_id {
 	SBI_EXT_IPI = 0x735049,
 	SBI_EXT_RFENCE = 0x52464E43,
 	SBI_EXT_HSM = 0x48534D,
+	SBI_EXT_PMU = 0x504D55,
 };
 
 enum sbi_ext_base_fid {
@@ -70,6 +71,99 @@ enum sbi_hsm_hart_status {
 	SBI_HSM_HART_STATUS_STOP_PENDING,
 };
 
+
+enum sbi_ext_pmu_fid {
+	SBI_EXT_PMU_NUM_COUNTERS = 0,
+	SBI_EXT_PMU_COUNTER_GET_INFO,
+	SBI_EXT_PMU_COUNTER_CFG_MATCH,
+	SBI_EXT_PMU_COUNTER_START,
+	SBI_EXT_PMU_COUNTER_STOP,
+	SBI_EXT_PMU_COUNTER_FW_READ,
+};
+
+#define RISCV_PMU_RAW_EVENT_MASK GENMASK_ULL(55, 0)
+#define RISCV_PMU_RAW_EVENT_IDX 0x20000
+
+/** General pmu event codes specified in SBI PMU extension */
+enum sbi_pmu_hw_generic_events_t {
+	SBI_PMU_HW_NO_EVENT			= 0,
+	SBI_PMU_HW_CPU_CYCLES			= 1,
+	SBI_PMU_HW_INSTRUCTIONS			= 2,
+	SBI_PMU_HW_CACHE_REFERENCES		= 3,
+	SBI_PMU_HW_CACHE_MISSES			= 4,
+	SBI_PMU_HW_BRANCH_INSTRUCTIONS		= 5,
+	SBI_PMU_HW_BRANCH_MISSES		= 6,
+	SBI_PMU_HW_BUS_CYCLES			= 7,
+	SBI_PMU_HW_STALLED_CYCLES_FRONTEND	= 8,
+	SBI_PMU_HW_STALLED_CYCLES_BACKEND	= 9,
+	SBI_PMU_HW_REF_CPU_CYCLES		= 10,
+
+	SBI_PMU_HW_GENERAL_MAX,
+};
+
+/**
+ * Special "firmware" events provided by the firmware, even if the hardware
+ * does not support performance events. These events are encoded as a raw
+ * event type in Linux kernel perf framework.
+ */
+enum sbi_pmu_fw_generic_events_t {
+	SBI_PMU_FW_MISALIGNED_LOAD	= 0,
+	SBI_PMU_FW_MISALIGNED_STORE	= 1,
+	SBI_PMU_FW_ACCESS_LOAD		= 2,
+	SBI_PMU_FW_ACCESS_STORE		= 3,
+	SBI_PMU_FW_ILLEGAL_INSN		= 4,
+	SBI_PMU_FW_SET_TIMER		= 5,
+	SBI_PMU_FW_IPI_SENT		= 6,
+	SBI_PMU_FW_IPI_RECVD		= 7,
+	SBI_PMU_FW_FENCE_I_SENT		= 8,
+	SBI_PMU_FW_FENCE_I_RECVD	= 9,
+	SBI_PMU_FW_SFENCE_VMA_SENT	= 10,
+	SBI_PMU_FW_SFENCE_VMA_RCVD	= 11,
+	SBI_PMU_FW_SFENCE_VMA_ASID_SENT	= 12,
+	SBI_PMU_FW_SFENCE_VMA_ASID_RCVD	= 13,
+
+	SBI_PMU_FW_HFENCE_GVMA_SENT	= 14,
+	SBI_PMU_FW_HFENCE_GVMA_RCVD	= 15,
+	SBI_PMU_FW_HFENCE_GVMA_VMID_SENT = 16,
+	SBI_PMU_FW_HFENCE_GVMA_VMID_RCVD = 17,
+
+	SBI_PMU_FW_HFENCE_VVMA_SENT	= 18,
+	SBI_PMU_FW_HFENCE_VVMA_RCVD	= 19,
+	SBI_PMU_FW_HFENCE_VVMA_ASID_SENT = 20,
+	SBI_PMU_FW_HFENCE_VVMA_ASID_RCVD = 21,
+	SBI_PMU_FW_MAX,
+};
+
+/* SBI PMU event types */
+enum sbi_pmu_event_type {
+	SBI_PMU_EVENT_TYPE_HW = 0x0,
+	SBI_PMU_EVENT_TYPE_CACHE = 0x1,
+	SBI_PMU_EVENT_TYPE_RAW = 0x2,
+	SBI_PMU_EVENT_TYPE_FW = 0xf,
+};
+
+/* SBI PMU event types */
+enum sbi_pmu_ctr_type {
+	SBI_PMU_CTR_TYPE_HW = 0x0,
+	SBI_PMU_CTR_TYPE_FW,
+};
+
+/* Flags defined for config matching function */
+#define SBI_PMU_CFG_FLAG_SKIP_MATCH	(1 << 0)
+#define SBI_PMU_CFG_FLAG_CLEAR_VALUE	(1 << 1)
+#define SBI_PMU_CFG_FLAG_AUTO_START	(1 << 2)
+#define SBI_PMU_CFG_FLAG_SET_MINH	(1 << 3)
+#define SBI_PMU_CFG_FLAG_SET_SINH	(1 << 4)
+#define SBI_PMU_CFG_FLAG_SET_UINH	(1 << 5)
+#define SBI_PMU_CFG_FLAG_SET_VSINH	(1 << 6)
+#define SBI_PMU_CFG_FLAG_SET_VUINH	(1 << 7)
+
+/* Flags defined for counter start function */
+#define SBI_PMU_START_FLAG_SET_INIT_VALUE (1 << 0)
+
+/* Flags defined for counter stop function */
+#define SBI_PMU_STOP_FLAG_RESET (1 << 0)
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

RISC-V SBI specification added a PMU extension that allows to configure
/start/stop any pmu counter. The RISC-V perf can use most of the generic
perf features except interrupt overflow and event filtering based on
privilege mode which will be added in future.

It also allows to monitor a handful of firmware counters that can provide
insights into firmware activity during a performance analysis.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig         |   8 +
 drivers/perf/Makefile        |   1 +
 drivers/perf/riscv_pmu.c     |   2 +
 drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
 4 files changed, 548 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu_sbi.c

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 1546a487d970..2acb5feaab35 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
 	  implementation on RISC-V based systems. This only allows counting
 	  of cycle/instruction counter and will be removed in future.
 
+config RISCV_PMU_SBI
+	depends on RISCV_PMU
+	bool "RISC-V PMU based on SBI PMU extension"
+	default y
+	help
+	  Say y if you want to use the CPU performance monitor
+	  using SBI PMU extension on RISC-V based systems.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index e8aa666a9d28..7bcac4b5a983 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
 obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
 ifeq ($(CONFIG_RISCV_PMU), y)
 obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
+obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
 endif
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
index c184aa50134d..596af3a40948 100644
--- a/drivers/perf/riscv_pmu.c
+++ b/drivers/perf/riscv_pmu.c
@@ -15,6 +15,8 @@
 #include <linux/printk.h>
 #include <linux/smp.h>
 
+#include <asm/sbi.h>
+
 static unsigned long csr_read_num(int csr_num)
 {
 #define switchcase_csr_read(__csr_num, __val)		{\
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
new file mode 100644
index 000000000000..80dd1de428c4
--- /dev/null
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This code is based on ARM perf event code which is in turn based on
+ * sparc64 and x86 code.
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/platform_device.h>
+
+#include <asm/sbi.h>
+
+union sbi_pmu_ctr_info {
+	unsigned long value;
+	struct {
+		unsigned long csr:12;
+		unsigned long width:6;
+#if __riscv_xlen == 32
+		unsigned long reserved:13;
+#else
+		unsigned long reserved:45;
+#endif
+		unsigned long type:1;
+	};
+};
+
+/**
+ * RISC-V doesn't have hetergenous harts yet. This need to be part of
+ * per_cpu in case of harts with different pmu counters
+ */
+static union sbi_pmu_ctr_info *pmu_ctr_list;
+
+struct pmu_event_data {
+	union {
+		union {
+			struct hw_gen_event {
+				uint32_t event_code:16;
+				uint32_t event_type:4;
+				uint32_t reserved:12;
+			} hw_gen_event;
+			struct hw_cache_event {
+				uint32_t result_id:1;
+				uint32_t op_id:2;
+				uint32_t cache_id:13;
+				uint32_t event_type:4;
+				uint32_t reserved:12;
+			} hw_cache_event;
+		};
+		uint32_t event_idx;
+	};
+};
+
+static const struct pmu_event_data pmu_hw_event_map[] = {
+	[PERF_COUNT_HW_CPU_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_CPU_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_INSTRUCTIONS]		= {.hw_gen_event = {
+							SBI_PMU_HW_INSTRUCTIONS,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_CACHE_REFERENCES]	= {.hw_gen_event = {
+							SBI_PMU_HW_CACHE_REFERENCES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_CACHE_MISSES]		= {.hw_gen_event = {
+							SBI_PMU_HW_CACHE_MISSES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= {.hw_gen_event = {
+							SBI_PMU_HW_BRANCH_INSTRUCTIONS,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BRANCH_MISSES]		= {.hw_gen_event = {
+							SBI_PMU_HW_BRANCH_MISSES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BUS_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_BUS_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= {.hw_gen_event = {
+							SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= {.hw_gen_event = {
+							SBI_PMU_HW_STALLED_CYCLES_BACKEND,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_REF_CPU_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_REF_CPU_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+};
+
+#define C(x) PERF_COUNT_HW_CACHE_##x
+static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
+[PERF_COUNT_HW_CACHE_OP_MAX]
+[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+	[C(L1D)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(L1I)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event =	{C(RESULT_ACCESS),
+					C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
+					C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(LL)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(DTLB)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(ITLB)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(BPU)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(NODE)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+};
+
+static int pmu_sbi_ctr_get_width(int idx)
+{
+	return pmu_ctr_list[idx].width;
+}
+
+static int pmu_sbi_ctr_get_idx(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct sbiret ret;
+	int idx;
+	uint64_t cbase = 0;
+	uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
+	unsigned long cflags = 0;
+
+	/* retrieve the available counter index */
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
+			cflags, hwc->event_base, hwc->config, 0);
+	if (ret.error) {
+		pr_debug("Not able to find a counter for event %lx config %llx\n",
+			hwc->event_base, hwc->config);
+		return sbi_err_map_linux_errno(ret.error);
+	}
+
+	idx = ret.value;
+	if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
+		return -ENOENT;
+
+	/* Additional sanity check for the counter id */
+	if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
+		return idx;
+	else
+		return -ENOENT;
+}
+
+static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
+{
+
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	int idx = hwc->idx;
+
+	clear_bit(idx, cpuc->used_event_ctrs);
+}
+
+static int pmu_event_find_cache(u64 config)
+{
+	unsigned int cache_type, cache_op, cache_result, ret;
+
+	cache_type = (config >>  0) & 0xff;
+	if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+		return -EINVAL;
+
+	cache_op = (config >>  8) & 0xff;
+	if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
+		return -EINVAL;
+
+	cache_result = (config >> 16) & 0xff;
+	if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+		return -EINVAL;
+
+	ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
+
+	return ret;
+}
+
+static bool pmu_sbi_is_fw_event(struct perf_event *event)
+{
+	u32 type = event->attr.type;
+	u64 config = event->attr.config;
+
+	if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
+		return true;
+	else
+		return false;
+}
+
+static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
+{
+	u32 type = event->attr.type;
+	u64 config = event->attr.config;
+	int bSoftware;
+	u64 raw_config_val;
+	int ret;
+
+	switch (type) {
+	case PERF_TYPE_HARDWARE:
+		if (config >= PERF_COUNT_HW_MAX)
+			return -EINVAL;
+		ret = pmu_hw_event_map[event->attr.config].event_idx;
+		break;
+	case PERF_TYPE_HW_CACHE:
+		ret = pmu_event_find_cache(config);
+		break;
+	case PERF_TYPE_RAW:
+		/*
+		 * As per SBI specification, the upper 7 bits must be unused for
+		 * a raw event. Use the MSB (63b) to distinguish between hardware
+		 * raw event and firmware events.
+		 */
+		bSoftware = config >> 63;
+		raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
+		if (bSoftware) {
+			if (raw_config_val < SBI_PMU_FW_MAX)
+				ret = (raw_config_val & 0xFFFF) |
+				      (SBI_PMU_EVENT_TYPE_FW << 16);
+			else
+				return -EINVAL;
+		} else {
+			ret = RISCV_PMU_RAW_EVENT_IDX;
+			*econfig = raw_config_val;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static u64 pmu_sbi_ctr_read(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+	struct sbiret ret;
+	union sbi_pmu_ctr_info info;
+	u64 val = 0;
+
+	if (pmu_sbi_is_fw_event(event)) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
+				hwc->idx, 0, 0, 0, 0, 0);
+		if (!ret.error)
+			val = ret.value;
+	} else {
+		info = pmu_ctr_list[idx];
+		val = riscv_pmu_ctr_read_csr(info.csr);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
+	}
+
+	return val;
+}
+
+static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
+{
+	struct sbiret ret;
+	struct hw_perf_event *hwc = &event->hw;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
+			1, 1, ival, 0, 0);
+	if (ret.error)
+		pr_err("Starting counter idx %d failed with error %d\n",
+			hwc->idx, sbi_err_map_linux_errno(ret.error));
+}
+
+static void pmu_sbi_ctr_stop(struct perf_event *event)
+{
+	struct sbiret ret;
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	unsigned long flag = 0;
+
+	if (cpuc->events[hwc->idx] == NULL)
+		flag = SBI_PMU_STOP_FLAG_RESET;
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
+	if (ret.error)
+		pr_err("Stopping counter idx %d failed with error %d\n",
+			hwc->idx, sbi_err_map_linux_errno(ret.error));
+}
+
+static int pmu_sbi_find_num_ctrs(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+
+static int pmu_sbi_get_ctrinfo(int nctr)
+{
+	struct sbiret ret;
+	int i, num_hw_ctr = 0, num_fw_ctr = 0;
+	union sbi_pmu_ctr_info cinfo;
+
+	pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
+	if (!pmu_ctr_list)
+		return -ENOMEM;
+
+	for (i = 0; i <= nctr; i++) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
+		if (ret.error)
+			/* The logical counter ids are not expected to be contiguous */
+			continue;
+		cinfo.value = ret.value;
+		if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
+			num_fw_ctr++;
+		else
+			num_hw_ctr++;
+		pmu_ctr_list[i].value = cinfo.value;
+	}
+
+	pr_info("There are %d firmware & %d hardware counters available\n",
+		num_fw_ctr, num_hw_ctr);
+
+	return 0;
+}
+
+static int pmu_sbi_starting_cpu(unsigned int cpu)
+{
+	/* Enable the access for TIME csr only from the user mode now */
+	csr_write(CSR_SCOUNTEREN, 0x2);
+
+	return 0;
+}
+
+static int pmu_sbi_dying_cpu(unsigned int cpu)
+{
+	/* Disable all counters access for user mode now */
+	csr_write(CSR_SCOUNTEREN, 0x0);
+
+	return 0;
+}
+
+
+static int pmu_sbi_device_probe(struct platform_device *pdev)
+{
+	struct riscv_pmu *pmu = NULL;
+	int num_counters;
+
+	pmu = riscv_pmu_alloc();
+	if (!pmu)
+		return -ENOMEM;
+
+	if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
+		sbi_probe_extension(SBI_EXT_PMU) <= 0) {
+		/* Fall back to the legacy implementation */
+		riscv_pmu_legacy_init(pmu);
+		return 0;
+	}
+
+	pr_info("SBI PMU extension is available\n");
+
+	num_counters = pmu_sbi_find_num_ctrs();
+	if (num_counters < 0) {
+		pr_err("SBI PMU extension doesn't provide any counters\n");
+		return -ENODEV;
+	}
+
+	/* cache all the information about counters now */
+	if (pmu_sbi_get_ctrinfo(num_counters))
+		return -ENODEV;
+
+	pmu->num_counters = num_counters;
+	pmu->ctr_start = pmu_sbi_ctr_start;
+	pmu->ctr_stop = pmu_sbi_ctr_stop;
+	pmu->event_map = pmu_sbi_event_map;
+	pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
+	pmu->ctr_get_width = pmu_sbi_ctr_get_width;
+	pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
+	pmu->ctr_read = pmu_sbi_ctr_read;
+
+	perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
+
+	cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
+			  "perf/riscv/pmu:starting",
+			  pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
+
+	return 0;
+}
+
+static struct platform_driver pmu_sbi_driver = {
+	.probe		= pmu_sbi_device_probe,
+	.driver		= {
+		.name	= RISCV_PMU_PDEV_NAME,
+	},
+};
+
+static int __init pmu_sbi_devinit(void)
+{
+	int ret;
+	struct platform_device *pdev;
+
+	ret = platform_driver_register(&pmu_sbi_driver);
+	if (ret)
+		return ret;
+
+	pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		platform_driver_unregister(&pmu_sbi_driver);
+		return PTR_ERR(pdev);
+	}
+
+	return ret;
+}
+device_initcall(pmu_sbi_devinit)
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

RISC-V SBI specification added a PMU extension that allows to configure
/start/stop any pmu counter. The RISC-V perf can use most of the generic
perf features except interrupt overflow and event filtering based on
privilege mode which will be added in future.

It also allows to monitor a handful of firmware counters that can provide
insights into firmware activity during a performance analysis.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 drivers/perf/Kconfig         |   8 +
 drivers/perf/Makefile        |   1 +
 drivers/perf/riscv_pmu.c     |   2 +
 drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
 4 files changed, 548 insertions(+)
 create mode 100644 drivers/perf/riscv_pmu_sbi.c

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 1546a487d970..2acb5feaab35 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
 	  implementation on RISC-V based systems. This only allows counting
 	  of cycle/instruction counter and will be removed in future.
 
+config RISCV_PMU_SBI
+	depends on RISCV_PMU
+	bool "RISC-V PMU based on SBI PMU extension"
+	default y
+	help
+	  Say y if you want to use the CPU performance monitor
+	  using SBI PMU extension on RISC-V based systems.
+
 config ARM_PMU_ACPI
 	depends on ARM_PMU && ACPI
 	def_bool y
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index e8aa666a9d28..7bcac4b5a983 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
 obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
 ifeq ($(CONFIG_RISCV_PMU), y)
 obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
+obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
 endif
 obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
index c184aa50134d..596af3a40948 100644
--- a/drivers/perf/riscv_pmu.c
+++ b/drivers/perf/riscv_pmu.c
@@ -15,6 +15,8 @@
 #include <linux/printk.h>
 #include <linux/smp.h>
 
+#include <asm/sbi.h>
+
 static unsigned long csr_read_num(int csr_num)
 {
 #define switchcase_csr_read(__csr_num, __val)		{\
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
new file mode 100644
index 000000000000..80dd1de428c4
--- /dev/null
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RISC-V performance counter support.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ *
+ * This code is based on ARM perf event code which is in turn based on
+ * sparc64 and x86 code.
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/perf/riscv_pmu.h>
+#include <linux/platform_device.h>
+
+#include <asm/sbi.h>
+
+union sbi_pmu_ctr_info {
+	unsigned long value;
+	struct {
+		unsigned long csr:12;
+		unsigned long width:6;
+#if __riscv_xlen == 32
+		unsigned long reserved:13;
+#else
+		unsigned long reserved:45;
+#endif
+		unsigned long type:1;
+	};
+};
+
+/**
+ * RISC-V doesn't have hetergenous harts yet. This need to be part of
+ * per_cpu in case of harts with different pmu counters
+ */
+static union sbi_pmu_ctr_info *pmu_ctr_list;
+
+struct pmu_event_data {
+	union {
+		union {
+			struct hw_gen_event {
+				uint32_t event_code:16;
+				uint32_t event_type:4;
+				uint32_t reserved:12;
+			} hw_gen_event;
+			struct hw_cache_event {
+				uint32_t result_id:1;
+				uint32_t op_id:2;
+				uint32_t cache_id:13;
+				uint32_t event_type:4;
+				uint32_t reserved:12;
+			} hw_cache_event;
+		};
+		uint32_t event_idx;
+	};
+};
+
+static const struct pmu_event_data pmu_hw_event_map[] = {
+	[PERF_COUNT_HW_CPU_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_CPU_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_INSTRUCTIONS]		= {.hw_gen_event = {
+							SBI_PMU_HW_INSTRUCTIONS,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_CACHE_REFERENCES]	= {.hw_gen_event = {
+							SBI_PMU_HW_CACHE_REFERENCES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_CACHE_MISSES]		= {.hw_gen_event = {
+							SBI_PMU_HW_CACHE_MISSES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= {.hw_gen_event = {
+							SBI_PMU_HW_BRANCH_INSTRUCTIONS,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BRANCH_MISSES]		= {.hw_gen_event = {
+							SBI_PMU_HW_BRANCH_MISSES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_BUS_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_BUS_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= {.hw_gen_event = {
+							SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= {.hw_gen_event = {
+							SBI_PMU_HW_STALLED_CYCLES_BACKEND,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+	[PERF_COUNT_HW_REF_CPU_CYCLES]		= {.hw_gen_event = {
+							SBI_PMU_HW_REF_CPU_CYCLES,
+							SBI_PMU_EVENT_TYPE_HW, 0}},
+};
+
+#define C(x) PERF_COUNT_HW_CACHE_##x
+static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
+[PERF_COUNT_HW_CACHE_OP_MAX]
+[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
+	[C(L1D)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(L1I)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event =	{C(RESULT_ACCESS),
+					C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
+					C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(LL)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(DTLB)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(ITLB)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(BPU)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+	[C(NODE)] = {
+		[C(OP_READ)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_WRITE)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+		[C(OP_PREFETCH)] = {
+			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
+					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
+					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
+		},
+	},
+};
+
+static int pmu_sbi_ctr_get_width(int idx)
+{
+	return pmu_ctr_list[idx].width;
+}
+
+static int pmu_sbi_ctr_get_idx(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	struct sbiret ret;
+	int idx;
+	uint64_t cbase = 0;
+	uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
+	unsigned long cflags = 0;
+
+	/* retrieve the available counter index */
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
+			cflags, hwc->event_base, hwc->config, 0);
+	if (ret.error) {
+		pr_debug("Not able to find a counter for event %lx config %llx\n",
+			hwc->event_base, hwc->config);
+		return sbi_err_map_linux_errno(ret.error);
+	}
+
+	idx = ret.value;
+	if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
+		return -ENOENT;
+
+	/* Additional sanity check for the counter id */
+	if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
+		return idx;
+	else
+		return -ENOENT;
+}
+
+static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
+{
+
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	int idx = hwc->idx;
+
+	clear_bit(idx, cpuc->used_event_ctrs);
+}
+
+static int pmu_event_find_cache(u64 config)
+{
+	unsigned int cache_type, cache_op, cache_result, ret;
+
+	cache_type = (config >>  0) & 0xff;
+	if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+		return -EINVAL;
+
+	cache_op = (config >>  8) & 0xff;
+	if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
+		return -EINVAL;
+
+	cache_result = (config >> 16) & 0xff;
+	if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+		return -EINVAL;
+
+	ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
+
+	return ret;
+}
+
+static bool pmu_sbi_is_fw_event(struct perf_event *event)
+{
+	u32 type = event->attr.type;
+	u64 config = event->attr.config;
+
+	if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
+		return true;
+	else
+		return false;
+}
+
+static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
+{
+	u32 type = event->attr.type;
+	u64 config = event->attr.config;
+	int bSoftware;
+	u64 raw_config_val;
+	int ret;
+
+	switch (type) {
+	case PERF_TYPE_HARDWARE:
+		if (config >= PERF_COUNT_HW_MAX)
+			return -EINVAL;
+		ret = pmu_hw_event_map[event->attr.config].event_idx;
+		break;
+	case PERF_TYPE_HW_CACHE:
+		ret = pmu_event_find_cache(config);
+		break;
+	case PERF_TYPE_RAW:
+		/*
+		 * As per SBI specification, the upper 7 bits must be unused for
+		 * a raw event. Use the MSB (63b) to distinguish between hardware
+		 * raw event and firmware events.
+		 */
+		bSoftware = config >> 63;
+		raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
+		if (bSoftware) {
+			if (raw_config_val < SBI_PMU_FW_MAX)
+				ret = (raw_config_val & 0xFFFF) |
+				      (SBI_PMU_EVENT_TYPE_FW << 16);
+			else
+				return -EINVAL;
+		} else {
+			ret = RISCV_PMU_RAW_EVENT_IDX;
+			*econfig = raw_config_val;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static u64 pmu_sbi_ctr_read(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int idx = hwc->idx;
+	struct sbiret ret;
+	union sbi_pmu_ctr_info info;
+	u64 val = 0;
+
+	if (pmu_sbi_is_fw_event(event)) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
+				hwc->idx, 0, 0, 0, 0, 0);
+		if (!ret.error)
+			val = ret.value;
+	} else {
+		info = pmu_ctr_list[idx];
+		val = riscv_pmu_ctr_read_csr(info.csr);
+		if (IS_ENABLED(CONFIG_32BIT))
+			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
+	}
+
+	return val;
+}
+
+static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
+{
+	struct sbiret ret;
+	struct hw_perf_event *hwc = &event->hw;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
+			1, 1, ival, 0, 0);
+	if (ret.error)
+		pr_err("Starting counter idx %d failed with error %d\n",
+			hwc->idx, sbi_err_map_linux_errno(ret.error));
+}
+
+static void pmu_sbi_ctr_stop(struct perf_event *event)
+{
+	struct sbiret ret;
+	struct hw_perf_event *hwc = &event->hw;
+	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
+	unsigned long flag = 0;
+
+	if (cpuc->events[hwc->idx] == NULL)
+		flag = SBI_PMU_STOP_FLAG_RESET;
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
+	if (ret.error)
+		pr_err("Stopping counter idx %d failed with error %d\n",
+			hwc->idx, sbi_err_map_linux_errno(ret.error));
+}
+
+static int pmu_sbi_find_num_ctrs(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+
+static int pmu_sbi_get_ctrinfo(int nctr)
+{
+	struct sbiret ret;
+	int i, num_hw_ctr = 0, num_fw_ctr = 0;
+	union sbi_pmu_ctr_info cinfo;
+
+	pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
+	if (!pmu_ctr_list)
+		return -ENOMEM;
+
+	for (i = 0; i <= nctr; i++) {
+		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
+		if (ret.error)
+			/* The logical counter ids are not expected to be contiguous */
+			continue;
+		cinfo.value = ret.value;
+		if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
+			num_fw_ctr++;
+		else
+			num_hw_ctr++;
+		pmu_ctr_list[i].value = cinfo.value;
+	}
+
+	pr_info("There are %d firmware & %d hardware counters available\n",
+		num_fw_ctr, num_hw_ctr);
+
+	return 0;
+}
+
+static int pmu_sbi_starting_cpu(unsigned int cpu)
+{
+	/* Enable the access for TIME csr only from the user mode now */
+	csr_write(CSR_SCOUNTEREN, 0x2);
+
+	return 0;
+}
+
+static int pmu_sbi_dying_cpu(unsigned int cpu)
+{
+	/* Disable all counters access for user mode now */
+	csr_write(CSR_SCOUNTEREN, 0x0);
+
+	return 0;
+}
+
+
+static int pmu_sbi_device_probe(struct platform_device *pdev)
+{
+	struct riscv_pmu *pmu = NULL;
+	int num_counters;
+
+	pmu = riscv_pmu_alloc();
+	if (!pmu)
+		return -ENOMEM;
+
+	if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
+		sbi_probe_extension(SBI_EXT_PMU) <= 0) {
+		/* Fall back to the legacy implementation */
+		riscv_pmu_legacy_init(pmu);
+		return 0;
+	}
+
+	pr_info("SBI PMU extension is available\n");
+
+	num_counters = pmu_sbi_find_num_ctrs();
+	if (num_counters < 0) {
+		pr_err("SBI PMU extension doesn't provide any counters\n");
+		return -ENODEV;
+	}
+
+	/* cache all the information about counters now */
+	if (pmu_sbi_get_ctrinfo(num_counters))
+		return -ENODEV;
+
+	pmu->num_counters = num_counters;
+	pmu->ctr_start = pmu_sbi_ctr_start;
+	pmu->ctr_stop = pmu_sbi_ctr_stop;
+	pmu->event_map = pmu_sbi_event_map;
+	pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
+	pmu->ctr_get_width = pmu_sbi_ctr_get_width;
+	pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
+	pmu->ctr_read = pmu_sbi_ctr_read;
+
+	perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
+
+	cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
+			  "perf/riscv/pmu:starting",
+			  pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
+
+	return 0;
+}
+
+static struct platform_driver pmu_sbi_driver = {
+	.probe		= pmu_sbi_device_probe,
+	.driver		= {
+		.name	= RISCV_PMU_PDEV_NAME,
+	},
+};
+
+static int __init pmu_sbi_devinit(void)
+{
+	int ret;
+	struct platform_device *pdev;
+
+	ret = platform_driver_register(&pmu_sbi_driver);
+	if (ret)
+		return ret;
+
+	pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
+	if (IS_ERR(pdev)) {
+		platform_driver_unregister(&pmu_sbi_driver);
+		return PTR_ERR(pdev);
+	}
+
+	return ret;
+}
+device_initcall(pmu_sbi_devinit)
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 7/7] Documentation: riscv: Remove the old documentation
  2021-05-28 18:43 ` Atish Patra
@ 2021-05-28 18:44   ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The existing pmu documentation describes the limitation of perf infrastructure
in RISC-V ISA and limited feature set of perf in RISC-V.

However, SBI PMU extension and sscofpmf extension(ISA extension) allows to
implement most of the required features of perf. Remove the old documentation
which is not accurate anymore.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 Documentation/riscv/pmu.rst | 255 ------------------------------------
 1 file changed, 255 deletions(-)
 delete mode 100644 Documentation/riscv/pmu.rst

diff --git a/Documentation/riscv/pmu.rst b/Documentation/riscv/pmu.rst
deleted file mode 100644
index acb216b99c26..000000000000
--- a/Documentation/riscv/pmu.rst
+++ /dev/null
@@ -1,255 +0,0 @@
-===================================
-Supporting PMUs on RISC-V platforms
-===================================
-
-Alan Kao <alankao@andestech.com>, Mar 2018
-
-Introduction
-------------
-
-As of this writing, perf_event-related features mentioned in The RISC-V ISA
-Privileged Version 1.10 are as follows:
-(please check the manual for more details)
-
-* [m|s]counteren
-* mcycle[h], cycle[h]
-* minstret[h], instret[h]
-* mhpeventx, mhpcounterx[h]
-
-With such function set only, porting perf would require a lot of work, due to
-the lack of the following general architectural performance monitoring features:
-
-* Enabling/Disabling counters
-  Counters are just free-running all the time in our case.
-* Interrupt caused by counter overflow
-  No such feature in the spec.
-* Interrupt indicator
-  It is not possible to have many interrupt ports for all counters, so an
-  interrupt indicator is required for software to tell which counter has
-  just overflowed.
-* Writing to counters
-  There will be an SBI to support this since the kernel cannot modify the
-  counters [1].  Alternatively, some vendor considers to implement
-  hardware-extension for M-S-U model machines to write counters directly.
-
-This document aims to provide developers a quick guide on supporting their
-PMUs in the kernel.  The following sections briefly explain perf' mechanism
-and todos.
-
-You may check previous discussions here [1][2].  Also, it might be helpful
-to check the appendix for related kernel structures.
-
-
-1. Initialization
------------------
-
-*riscv_pmu* is a global pointer of type *struct riscv_pmu*, which contains
-various methods according to perf's internal convention and PMU-specific
-parameters.  One should declare such instance to represent the PMU.  By default,
-*riscv_pmu* points to a constant structure *riscv_base_pmu*, which has very
-basic support to a baseline QEMU model.
-
-Then he/she can either assign the instance's pointer to *riscv_pmu* so that
-the minimal and already-implemented logic can be leveraged, or invent his/her
-own *riscv_init_platform_pmu* implementation.
-
-In other words, existing sources of *riscv_base_pmu* merely provide a
-reference implementation.  Developers can flexibly decide how many parts they
-can leverage, and in the most extreme case, they can customize every function
-according to their needs.
-
-
-2. Event Initialization
------------------------
-
-When a user launches a perf command to monitor some events, it is first
-interpreted by the userspace perf tool into multiple *perf_event_open*
-system calls, and then each of them calls to the body of *event_init*
-member function that was assigned in the previous step.  In *riscv_base_pmu*'s
-case, it is *riscv_event_init*.
-
-The main purpose of this function is to translate the event provided by user
-into bitmap, so that HW-related control registers or counters can directly be
-manipulated.  The translation is based on the mappings and methods provided in
-*riscv_pmu*.
-
-Note that some features can be done in this stage as well:
-
-(1) interrupt setting, which is stated in the next section;
-(2) privilege level setting (user space only, kernel space only, both);
-(3) destructor setting.  Normally it is sufficient to apply *riscv_destroy_event*;
-(4) tweaks for non-sampling events, which will be utilized by functions such as
-    *perf_adjust_period*, usually something like the follows::
-
-      if (!is_sampling_event(event)) {
-              hwc->sample_period = x86_pmu.max_period;
-              hwc->last_period = hwc->sample_period;
-              local64_set(&hwc->period_left, hwc->sample_period);
-      }
-
-In the case of *riscv_base_pmu*, only (3) is provided for now.
-
-
-3. Interrupt
-------------
-
-3.1. Interrupt Initialization
-
-This often occurs at the beginning of the *event_init* method. In common
-practice, this should be a code segment like::
-
-  int x86_reserve_hardware(void)
-  {
-        int err = 0;
-
-        if (!atomic_inc_not_zero(&pmc_refcount)) {
-                mutex_lock(&pmc_reserve_mutex);
-                if (atomic_read(&pmc_refcount) == 0) {
-                        if (!reserve_pmc_hardware())
-                                err = -EBUSY;
-                        else
-                                reserve_ds_buffers();
-                }
-                if (!err)
-                        atomic_inc(&pmc_refcount);
-                mutex_unlock(&pmc_reserve_mutex);
-        }
-
-        return err;
-  }
-
-And the magic is in *reserve_pmc_hardware*, which usually does atomic
-operations to make implemented IRQ accessible from some global function pointer.
-*release_pmc_hardware* serves the opposite purpose, and it is used in event
-destructors mentioned in previous section.
-
-(Note: From the implementations in all the architectures, the *reserve/release*
-pair are always IRQ settings, so the *pmc_hardware* seems somehow misleading.
-It does NOT deal with the binding between an event and a physical counter,
-which will be introduced in the next section.)
-
-3.2. IRQ Structure
-
-Basically, a IRQ runs the following pseudo code::
-
-  for each hardware counter that triggered this overflow
-
-      get the event of this counter
-
-      // following two steps are defined as *read()*,
-      // check the section Reading/Writing Counters for details.
-      count the delta value since previous interrupt
-      update the event->count (# event occurs) by adding delta, and
-                 event->hw.period_left by subtracting delta
-
-      if the event overflows
-          sample data
-          set the counter appropriately for the next overflow
-
-          if the event overflows again
-              too frequently, throttle this event
-          fi
-      fi
-
-  end for
-
-However as of this writing, none of the RISC-V implementations have designed an
-interrupt for perf, so the details are to be completed in the future.
-
-4. Reading/Writing Counters
----------------------------
-
-They seem symmetric but perf treats them quite differently.  For reading, there
-is a *read* interface in *struct pmu*, but it serves more than just reading.
-According to the context, the *read* function not only reads the content of the
-counter (event->count), but also updates the left period to the next interrupt
-(event->hw.period_left).
-
-But the core of perf does not need direct write to counters.  Writing counters
-is hidden behind the abstraction of 1) *pmu->start*, literally start counting so one
-has to set the counter to a good value for the next interrupt; 2) inside the IRQ
-it should set the counter to the same resonable value.
-
-Reading is not a problem in RISC-V but writing would need some effort, since
-counters are not allowed to be written by S-mode.
-
-
-5. add()/del()/start()/stop()
------------------------------
-
-Basic idea: add()/del() adds/deletes events to/from a PMU, and start()/stop()
-starts/stop the counter of some event in the PMU.  All of them take the same
-arguments: *struct perf_event *event* and *int flag*.
-
-Consider perf as a state machine, then you will find that these functions serve
-as the state transition process between those states.
-Three states (event->hw.state) are defined:
-
-* PERF_HES_STOPPED:	the counter is stopped
-* PERF_HES_UPTODATE:	the event->count is up-to-date
-* PERF_HES_ARCH:	arch-dependent usage ... we don't need this for now
-
-A normal flow of these state transitions are as follows:
-
-* A user launches a perf event, resulting in calling to *event_init*.
-* When being context-switched in, *add* is called by the perf core, with a flag
-  PERF_EF_START, which means that the event should be started after it is added.
-  At this stage, a general event is bound to a physical counter, if any.
-  The state changes to PERF_HES_STOPPED and PERF_HES_UPTODATE, because it is now
-  stopped, and the (software) event count does not need updating.
-
-  - *start* is then called, and the counter is enabled.
-    With flag PERF_EF_RELOAD, it writes an appropriate value to the counter (check
-    previous section for detail).
-    Nothing is written if the flag does not contain PERF_EF_RELOAD.
-    The state now is reset to none, because it is neither stopped nor updated
-    (the counting already started)
-
-* When being context-switched out, *del* is called.  It then checks out all the
-  events in the PMU and calls *stop* to update their counts.
-
-  - *stop* is called by *del*
-    and the perf core with flag PERF_EF_UPDATE, and it often shares the same
-    subroutine as *read* with the same logic.
-    The state changes to PERF_HES_STOPPED and PERF_HES_UPTODATE, again.
-
-  - Life cycle of these two pairs: *add* and *del* are called repeatedly as
-    tasks switch in-and-out; *start* and *stop* is also called when the perf core
-    needs a quick stop-and-start, for instance, when the interrupt period is being
-    adjusted.
-
-Current implementation is sufficient for now and can be easily extended to
-features in the future.
-
-A. Related Structures
----------------------
-
-* struct pmu: include/linux/perf_event.h
-* struct riscv_pmu: arch/riscv/include/asm/perf_event.h
-
-  Both structures are designed to be read-only.
-
-  *struct pmu* defines some function pointer interfaces, and most of them take
-  *struct perf_event* as a main argument, dealing with perf events according to
-  perf's internal state machine (check kernel/events/core.c for details).
-
-  *struct riscv_pmu* defines PMU-specific parameters.  The naming follows the
-  convention of all other architectures.
-
-* struct perf_event: include/linux/perf_event.h
-* struct hw_perf_event
-
-  The generic structure that represents perf events, and the hardware-related
-  details.
-
-* struct riscv_hw_events: arch/riscv/include/asm/perf_event.h
-
-  The structure that holds the status of events, has two fixed members:
-  the number of events and the array of the events.
-
-References
-----------
-
-[1] https://github.com/riscv/riscv-linux/pull/124
-
-[2] https://groups.google.com/a/groups.riscv.org/forum/#!topic/sw-dev/f19TmCNP6yA
-- 
2.25.1


^ permalink raw reply	[flat|nested] 28+ messages in thread

* [RFC v2 7/7] Documentation: riscv: Remove the old documentation
@ 2021-05-28 18:44   ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-05-28 18:44 UTC (permalink / raw)
  To: linux-kernel
  Cc: Atish Patra, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

The existing pmu documentation describes the limitation of perf infrastructure
in RISC-V ISA and limited feature set of perf in RISC-V.

However, SBI PMU extension and sscofpmf extension(ISA extension) allows to
implement most of the required features of perf. Remove the old documentation
which is not accurate anymore.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
 Documentation/riscv/pmu.rst | 255 ------------------------------------
 1 file changed, 255 deletions(-)
 delete mode 100644 Documentation/riscv/pmu.rst

diff --git a/Documentation/riscv/pmu.rst b/Documentation/riscv/pmu.rst
deleted file mode 100644
index acb216b99c26..000000000000
--- a/Documentation/riscv/pmu.rst
+++ /dev/null
@@ -1,255 +0,0 @@
-===================================
-Supporting PMUs on RISC-V platforms
-===================================
-
-Alan Kao <alankao@andestech.com>, Mar 2018
-
-Introduction
-------------
-
-As of this writing, perf_event-related features mentioned in The RISC-V ISA
-Privileged Version 1.10 are as follows:
-(please check the manual for more details)
-
-* [m|s]counteren
-* mcycle[h], cycle[h]
-* minstret[h], instret[h]
-* mhpeventx, mhpcounterx[h]
-
-With such function set only, porting perf would require a lot of work, due to
-the lack of the following general architectural performance monitoring features:
-
-* Enabling/Disabling counters
-  Counters are just free-running all the time in our case.
-* Interrupt caused by counter overflow
-  No such feature in the spec.
-* Interrupt indicator
-  It is not possible to have many interrupt ports for all counters, so an
-  interrupt indicator is required for software to tell which counter has
-  just overflowed.
-* Writing to counters
-  There will be an SBI to support this since the kernel cannot modify the
-  counters [1].  Alternatively, some vendor considers to implement
-  hardware-extension for M-S-U model machines to write counters directly.
-
-This document aims to provide developers a quick guide on supporting their
-PMUs in the kernel.  The following sections briefly explain perf' mechanism
-and todos.
-
-You may check previous discussions here [1][2].  Also, it might be helpful
-to check the appendix for related kernel structures.
-
-
-1. Initialization
------------------
-
-*riscv_pmu* is a global pointer of type *struct riscv_pmu*, which contains
-various methods according to perf's internal convention and PMU-specific
-parameters.  One should declare such instance to represent the PMU.  By default,
-*riscv_pmu* points to a constant structure *riscv_base_pmu*, which has very
-basic support to a baseline QEMU model.
-
-Then he/she can either assign the instance's pointer to *riscv_pmu* so that
-the minimal and already-implemented logic can be leveraged, or invent his/her
-own *riscv_init_platform_pmu* implementation.
-
-In other words, existing sources of *riscv_base_pmu* merely provide a
-reference implementation.  Developers can flexibly decide how many parts they
-can leverage, and in the most extreme case, they can customize every function
-according to their needs.
-
-
-2. Event Initialization
------------------------
-
-When a user launches a perf command to monitor some events, it is first
-interpreted by the userspace perf tool into multiple *perf_event_open*
-system calls, and then each of them calls to the body of *event_init*
-member function that was assigned in the previous step.  In *riscv_base_pmu*'s
-case, it is *riscv_event_init*.
-
-The main purpose of this function is to translate the event provided by user
-into bitmap, so that HW-related control registers or counters can directly be
-manipulated.  The translation is based on the mappings and methods provided in
-*riscv_pmu*.
-
-Note that some features can be done in this stage as well:
-
-(1) interrupt setting, which is stated in the next section;
-(2) privilege level setting (user space only, kernel space only, both);
-(3) destructor setting.  Normally it is sufficient to apply *riscv_destroy_event*;
-(4) tweaks for non-sampling events, which will be utilized by functions such as
-    *perf_adjust_period*, usually something like the follows::
-
-      if (!is_sampling_event(event)) {
-              hwc->sample_period = x86_pmu.max_period;
-              hwc->last_period = hwc->sample_period;
-              local64_set(&hwc->period_left, hwc->sample_period);
-      }
-
-In the case of *riscv_base_pmu*, only (3) is provided for now.
-
-
-3. Interrupt
-------------
-
-3.1. Interrupt Initialization
-
-This often occurs at the beginning of the *event_init* method. In common
-practice, this should be a code segment like::
-
-  int x86_reserve_hardware(void)
-  {
-        int err = 0;
-
-        if (!atomic_inc_not_zero(&pmc_refcount)) {
-                mutex_lock(&pmc_reserve_mutex);
-                if (atomic_read(&pmc_refcount) == 0) {
-                        if (!reserve_pmc_hardware())
-                                err = -EBUSY;
-                        else
-                                reserve_ds_buffers();
-                }
-                if (!err)
-                        atomic_inc(&pmc_refcount);
-                mutex_unlock(&pmc_reserve_mutex);
-        }
-
-        return err;
-  }
-
-And the magic is in *reserve_pmc_hardware*, which usually does atomic
-operations to make implemented IRQ accessible from some global function pointer.
-*release_pmc_hardware* serves the opposite purpose, and it is used in event
-destructors mentioned in previous section.
-
-(Note: From the implementations in all the architectures, the *reserve/release*
-pair are always IRQ settings, so the *pmc_hardware* seems somehow misleading.
-It does NOT deal with the binding between an event and a physical counter,
-which will be introduced in the next section.)
-
-3.2. IRQ Structure
-
-Basically, a IRQ runs the following pseudo code::
-
-  for each hardware counter that triggered this overflow
-
-      get the event of this counter
-
-      // following two steps are defined as *read()*,
-      // check the section Reading/Writing Counters for details.
-      count the delta value since previous interrupt
-      update the event->count (# event occurs) by adding delta, and
-                 event->hw.period_left by subtracting delta
-
-      if the event overflows
-          sample data
-          set the counter appropriately for the next overflow
-
-          if the event overflows again
-              too frequently, throttle this event
-          fi
-      fi
-
-  end for
-
-However as of this writing, none of the RISC-V implementations have designed an
-interrupt for perf, so the details are to be completed in the future.
-
-4. Reading/Writing Counters
----------------------------
-
-They seem symmetric but perf treats them quite differently.  For reading, there
-is a *read* interface in *struct pmu*, but it serves more than just reading.
-According to the context, the *read* function not only reads the content of the
-counter (event->count), but also updates the left period to the next interrupt
-(event->hw.period_left).
-
-But the core of perf does not need direct write to counters.  Writing counters
-is hidden behind the abstraction of 1) *pmu->start*, literally start counting so one
-has to set the counter to a good value for the next interrupt; 2) inside the IRQ
-it should set the counter to the same resonable value.
-
-Reading is not a problem in RISC-V but writing would need some effort, since
-counters are not allowed to be written by S-mode.
-
-
-5. add()/del()/start()/stop()
------------------------------
-
-Basic idea: add()/del() adds/deletes events to/from a PMU, and start()/stop()
-starts/stop the counter of some event in the PMU.  All of them take the same
-arguments: *struct perf_event *event* and *int flag*.
-
-Consider perf as a state machine, then you will find that these functions serve
-as the state transition process between those states.
-Three states (event->hw.state) are defined:
-
-* PERF_HES_STOPPED:	the counter is stopped
-* PERF_HES_UPTODATE:	the event->count is up-to-date
-* PERF_HES_ARCH:	arch-dependent usage ... we don't need this for now
-
-A normal flow of these state transitions are as follows:
-
-* A user launches a perf event, resulting in calling to *event_init*.
-* When being context-switched in, *add* is called by the perf core, with a flag
-  PERF_EF_START, which means that the event should be started after it is added.
-  At this stage, a general event is bound to a physical counter, if any.
-  The state changes to PERF_HES_STOPPED and PERF_HES_UPTODATE, because it is now
-  stopped, and the (software) event count does not need updating.
-
-  - *start* is then called, and the counter is enabled.
-    With flag PERF_EF_RELOAD, it writes an appropriate value to the counter (check
-    previous section for detail).
-    Nothing is written if the flag does not contain PERF_EF_RELOAD.
-    The state now is reset to none, because it is neither stopped nor updated
-    (the counting already started)
-
-* When being context-switched out, *del* is called.  It then checks out all the
-  events in the PMU and calls *stop* to update their counts.
-
-  - *stop* is called by *del*
-    and the perf core with flag PERF_EF_UPDATE, and it often shares the same
-    subroutine as *read* with the same logic.
-    The state changes to PERF_HES_STOPPED and PERF_HES_UPTODATE, again.
-
-  - Life cycle of these two pairs: *add* and *del* are called repeatedly as
-    tasks switch in-and-out; *start* and *stop* is also called when the perf core
-    needs a quick stop-and-start, for instance, when the interrupt period is being
-    adjusted.
-
-Current implementation is sufficient for now and can be easily extended to
-features in the future.
-
-A. Related Structures
----------------------
-
-* struct pmu: include/linux/perf_event.h
-* struct riscv_pmu: arch/riscv/include/asm/perf_event.h
-
-  Both structures are designed to be read-only.
-
-  *struct pmu* defines some function pointer interfaces, and most of them take
-  *struct perf_event* as a main argument, dealing with perf events according to
-  perf's internal state machine (check kernel/events/core.c for details).
-
-  *struct riscv_pmu* defines PMU-specific parameters.  The naming follows the
-  convention of all other architectures.
-
-* struct perf_event: include/linux/perf_event.h
-* struct hw_perf_event
-
-  The generic structure that represents perf events, and the hardware-related
-  details.
-
-* struct riscv_hw_events: arch/riscv/include/asm/perf_event.h
-
-  The structure that holds the status of events, has two fixed members:
-  the number of events and the array of the events.
-
-References
-----------
-
-[1] https://github.com/riscv/riscv-linux/pull/124
-
-[2] https://groups.google.com/a/groups.riscv.org/forum/#!topic/sw-dev/f19TmCNP6yA
-- 
2.25.1


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
  2021-05-28 18:44   ` Atish Patra
@ 2021-06-01 13:10     ` Stanislaw Kardach
  -1 siblings, 0 replies; 28+ messages in thread
From: Stanislaw Kardach @ 2021-06-01 13:10 UTC (permalink / raw)
  To: Atish Patra
  Cc: linux-kernel, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> RISC-V SBI specification added a PMU extension that allows to configure
> /start/stop any pmu counter. The RISC-V perf can use most of the generic
> perf features except interrupt overflow and event filtering based on
> privilege mode which will be added in future.
> 
> It also allows to monitor a handful of firmware counters that can provide
> insights into firmware activity during a performance analysis.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  drivers/perf/Kconfig         |   8 +
>  drivers/perf/Makefile        |   1 +
>  drivers/perf/riscv_pmu.c     |   2 +
>  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
>  4 files changed, 548 insertions(+)
>  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 1546a487d970..2acb5feaab35 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
>  	  implementation on RISC-V based systems. This only allows counting
>  	  of cycle/instruction counter and will be removed in future.
>  
> +config RISCV_PMU_SBI
> +	depends on RISCV_PMU
> +	bool "RISC-V PMU based on SBI PMU extension"
> +	default y
> +	help
> +	  Say y if you want to use the CPU performance monitor
> +	  using SBI PMU extension on RISC-V based systems.
> +
>  config ARM_PMU_ACPI
>  	depends on ARM_PMU && ACPI
>  	def_bool y
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index e8aa666a9d28..7bcac4b5a983 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
>  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
>  ifeq ($(CONFIG_RISCV_PMU), y)
>  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
>  endif
>  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
>  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> index c184aa50134d..596af3a40948 100644
> --- a/drivers/perf/riscv_pmu.c
> +++ b/drivers/perf/riscv_pmu.c
> @@ -15,6 +15,8 @@
>  #include <linux/printk.h>
>  #include <linux/smp.h>
>  
> +#include <asm/sbi.h>
> +
>  static unsigned long csr_read_num(int csr_num)
>  {
>  #define switchcase_csr_read(__csr_num, __val)		{\
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> new file mode 100644
> index 000000000000..80dd1de428c4
> --- /dev/null
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -0,0 +1,537 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * RISC-V performance counter support.
> + *
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + *
> + * This code is based on ARM perf event code which is in turn based on
> + * sparc64 and x86 code.
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include <linux/perf/riscv_pmu.h>
> +#include <linux/platform_device.h>
> +
> +#include <asm/sbi.h>
> +
> +union sbi_pmu_ctr_info {
> +	unsigned long value;
> +	struct {
> +		unsigned long csr:12;
> +		unsigned long width:6;
> +#if __riscv_xlen == 32
> +		unsigned long reserved:13;
> +#else
> +		unsigned long reserved:45;
> +#endif
> +		unsigned long type:1;
> +	};
> +};
> +
> +/**
> + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> + * per_cpu in case of harts with different pmu counters
> + */
> +static union sbi_pmu_ctr_info *pmu_ctr_list;
> +
> +struct pmu_event_data {
> +	union {
> +		union {
> +			struct hw_gen_event {
> +				uint32_t event_code:16;
> +				uint32_t event_type:4;
> +				uint32_t reserved:12;
> +			} hw_gen_event;
> +			struct hw_cache_event {
> +				uint32_t result_id:1;
> +				uint32_t op_id:2;
> +				uint32_t cache_id:13;
> +				uint32_t event_type:4;
> +				uint32_t reserved:12;
> +			} hw_cache_event;
> +		};
> +		uint32_t event_idx;
> +	};
> +};
> +
> +static const struct pmu_event_data pmu_hw_event_map[] = {
> +	[PERF_COUNT_HW_CPU_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_CPU_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_INSTRUCTIONS]		= {.hw_gen_event = {
> +							SBI_PMU_HW_INSTRUCTIONS,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_CACHE_REFERENCES]	= {.hw_gen_event = {
> +							SBI_PMU_HW_CACHE_REFERENCES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_CACHE_MISSES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_CACHE_MISSES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= {.hw_gen_event = {
> +							SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BRANCH_MISSES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_BRANCH_MISSES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BUS_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_BUS_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= {.hw_gen_event = {
> +							SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= {.hw_gen_event = {
> +							SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_REF_CPU_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_REF_CPU_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +};
> +
> +#define C(x) PERF_COUNT_HW_CACHE_##x
> +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> +[PERF_COUNT_HW_CACHE_OP_MAX]
> +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> +	[C(L1D)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(L1I)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event =	{C(RESULT_ACCESS),
> +					C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> +					C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(LL)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(DTLB)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(ITLB)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(BPU)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(NODE)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +};
> +
> +static int pmu_sbi_ctr_get_width(int idx)
> +{
> +	return pmu_ctr_list[idx].width;
> +}
> +
> +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	struct sbiret ret;
> +	int idx;
> +	uint64_t cbase = 0;
> +	uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> +	unsigned long cflags = 0;
> +
> +	/* retrieve the available counter index */
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> +			cflags, hwc->event_base, hwc->config, 0);
> +	if (ret.error) {
> +		pr_debug("Not able to find a counter for event %lx config %llx\n",
> +			hwc->event_base, hwc->config);
> +		return sbi_err_map_linux_errno(ret.error);
> +	}
> +
> +	idx = ret.value;
> +	if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> +		return -ENOENT;
> +
> +	/* Additional sanity check for the counter id */
> +	if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> +		return idx;
> +	else
> +		return -ENOENT;
> +}
> +
> +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> +{
> +
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	int idx = hwc->idx;
> +
> +	clear_bit(idx, cpuc->used_event_ctrs);
> +}
> +
> +static int pmu_event_find_cache(u64 config)
> +{
> +	unsigned int cache_type, cache_op, cache_result, ret;
> +
> +	cache_type = (config >>  0) & 0xff;
> +	if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> +		return -EINVAL;
> +
> +	cache_op = (config >>  8) & 0xff;
> +	if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> +		return -EINVAL;
> +
> +	cache_result = (config >> 16) & 0xff;
> +	if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> +		return -EINVAL;
> +
> +	ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> +
> +	return ret;
> +}
> +
> +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> +{
> +	u32 type = event->attr.type;
> +	u64 config = event->attr.config;
> +
> +	if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> +		return true;
> +	else
> +		return false;
> +}
> +
> +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> +{
> +	u32 type = event->attr.type;
> +	u64 config = event->attr.config;
> +	int bSoftware;
> +	u64 raw_config_val;
> +	int ret;
> +
> +	switch (type) {
> +	case PERF_TYPE_HARDWARE:
> +		if (config >= PERF_COUNT_HW_MAX)
> +			return -EINVAL;
> +		ret = pmu_hw_event_map[event->attr.config].event_idx;
> +		break;
> +	case PERF_TYPE_HW_CACHE:
> +		ret = pmu_event_find_cache(config);
> +		break;
> +	case PERF_TYPE_RAW:
> +		/*
> +		 * As per SBI specification, the upper 7 bits must be unused for
> +		 * a raw event. Use the MSB (63b) to distinguish between hardware
> +		 * raw event and firmware events.
> +		 */
> +		bSoftware = config >> 63;
> +		raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> +		if (bSoftware) {
> +			if (raw_config_val < SBI_PMU_FW_MAX)
> +				ret = (raw_config_val & 0xFFFF) |
> +				      (SBI_PMU_EVENT_TYPE_FW << 16);
> +			else
> +				return -EINVAL;
> +		} else {
> +			ret = RISCV_PMU_RAW_EVENT_IDX;
> +			*econfig = raw_config_val;
> +		}
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	int idx = hwc->idx;
> +	struct sbiret ret;
> +	union sbi_pmu_ctr_info info;
> +	u64 val = 0;
> +
> +	if (pmu_sbi_is_fw_event(event)) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> +				hwc->idx, 0, 0, 0, 0, 0);
> +		if (!ret.error)
> +			val = ret.value;
> +	} else {
> +		info = pmu_ctr_list[idx];
> +		val = riscv_pmu_ctr_read_csr(info.csr);
> +		if (IS_ENABLED(CONFIG_32BIT))
> +			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> +	}
> +
> +	return val;
> +}
> +
> +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> +{
> +	struct sbiret ret;
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> +			1, 1, ival, 0, 0);
> +	if (ret.error)
> +		pr_err("Starting counter idx %d failed with error %d\n",
> +			hwc->idx, sbi_err_map_linux_errno(ret.error));
> +}
> +
> +static void pmu_sbi_ctr_stop(struct perf_event *event)
> +{
> +	struct sbiret ret;
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	unsigned long flag = 0;
> +
> +	if (cpuc->events[hwc->idx] == NULL)
> +		flag = SBI_PMU_STOP_FLAG_RESET;
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> +	if (ret.error)
> +		pr_err("Stopping counter idx %d failed with error %d\n",
> +			hwc->idx, sbi_err_map_linux_errno(ret.error));
> +}
> +
> +static int pmu_sbi_find_num_ctrs(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> +	if (!ret.error)
> +		return ret.value;
> +	else
> +		return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static int pmu_sbi_get_ctrinfo(int nctr)
> +{
> +	struct sbiret ret;
> +	int i, num_hw_ctr = 0, num_fw_ctr = 0;
> +	union sbi_pmu_ctr_info cinfo;
> +
> +	pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> +	if (!pmu_ctr_list)
> +		return -ENOMEM;
> +
> +	for (i = 0; i <= nctr; i++) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> +		if (ret.error)
> +			/* The logical counter ids are not expected to be contiguous */
> +			continue;
> +		cinfo.value = ret.value;
> +		if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> +			num_fw_ctr++;
> +		else
> +			num_hw_ctr++;
> +		pmu_ctr_list[i].value = cinfo.value;
> +	}
> +
> +	pr_info("There are %d firmware & %d hardware counters available\n",
> +		num_fw_ctr, num_hw_ctr);
> +
> +	return 0;
> +}
> +
> +static int pmu_sbi_starting_cpu(unsigned int cpu)
> +{
> +	/* Enable the access for TIME csr only from the user mode now */
> +	csr_write(CSR_SCOUNTEREN, 0x2);
Would it be possible to also enable CYCLE csr here (and I guess same
would propagate to mcounteren logic in the opensbi patches)? Are there
any security concerns in allowing applications to read it directly?

It would be useful given that the frequency of TIME is not fixed in spec
and it may not be enough for a rdtsc-like counter. In such cases CYCLE
csr might be useful to userspace applications (i.e. DPDK) with obvious
limitations such as gating via WFI or value changes when using perf.

For context: there was a similar situation with arm64 at the point of
DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
not its frequency which usually was ~100MHz. The PMU cycle counter
(PMCCNTR) was by default disabled for read from userspace (EL0). This
required DPDK folks to create a kernel module to enable the PMCCNTR in
userspace so that they could implement high-resolution rte_rdtsc() call.
This got fixed in Armv8.6-A which specified the timer counter frequency
to be 1GHz.

If the CYCLE csr remains S-mode private, I will have to effectively
resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
Alternatively perhaps a sysfs knob or driver parameter could be added to
enable the CYCLE csr in U-mode?
> +
> +	return 0;
> +}
> +
> +static int pmu_sbi_dying_cpu(unsigned int cpu)
> +{
> +	/* Disable all counters access for user mode now */
> +	csr_write(CSR_SCOUNTEREN, 0x0);
> +
> +	return 0;
> +}
> +
> +
> +static int pmu_sbi_device_probe(struct platform_device *pdev)
> +{
> +	struct riscv_pmu *pmu = NULL;
> +	int num_counters;
> +
> +	pmu = riscv_pmu_alloc();
> +	if (!pmu)
> +		return -ENOMEM;
> +
> +	if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> +		sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> +		/* Fall back to the legacy implementation */
> +		riscv_pmu_legacy_init(pmu);
> +		return 0;
> +	}
> +
> +	pr_info("SBI PMU extension is available\n");
> +
> +	num_counters = pmu_sbi_find_num_ctrs();
> +	if (num_counters < 0) {
> +		pr_err("SBI PMU extension doesn't provide any counters\n");
> +		return -ENODEV;
> +	}
> +
> +	/* cache all the information about counters now */
> +	if (pmu_sbi_get_ctrinfo(num_counters))
> +		return -ENODEV;
> +
> +	pmu->num_counters = num_counters;
> +	pmu->ctr_start = pmu_sbi_ctr_start;
> +	pmu->ctr_stop = pmu_sbi_ctr_stop;
> +	pmu->event_map = pmu_sbi_event_map;
> +	pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> +	pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> +	pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> +	pmu->ctr_read = pmu_sbi_ctr_read;
> +
> +	perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> +
> +	cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> +			  "perf/riscv/pmu:starting",
> +			  pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver pmu_sbi_driver = {
> +	.probe		= pmu_sbi_device_probe,
> +	.driver		= {
> +		.name	= RISCV_PMU_PDEV_NAME,
> +	},
> +};
> +
> +static int __init pmu_sbi_devinit(void)
> +{
> +	int ret;
> +	struct platform_device *pdev;
> +
> +	ret = platform_driver_register(&pmu_sbi_driver);
> +	if (ret)
> +		return ret;
> +
> +	pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> +	if (IS_ERR(pdev)) {
> +		platform_driver_unregister(&pmu_sbi_driver);
> +		return PTR_ERR(pdev);
> +	}
> +
> +	return ret;
> +}
> +device_initcall(pmu_sbi_devinit)
> -- 
> 2.25.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

-- 
Best Regards,
Stanislaw Kardach

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
@ 2021-06-01 13:10     ` Stanislaw Kardach
  0 siblings, 0 replies; 28+ messages in thread
From: Stanislaw Kardach @ 2021-06-01 13:10 UTC (permalink / raw)
  To: Atish Patra
  Cc: linux-kernel, Anup Patel, bpf, Daniel Lezcano, Guo Ren,
	Heinrich Schuchardt, Kefeng Wang, linux-doc, linux-perf-users,
	linux-riscv, Nick Kossifidis, Palmer Dabbelt, Paul Walmsley,
	Alan Kao, Nick Hu, Vincent Chen

On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> RISC-V SBI specification added a PMU extension that allows to configure
> /start/stop any pmu counter. The RISC-V perf can use most of the generic
> perf features except interrupt overflow and event filtering based on
> privilege mode which will be added in future.
> 
> It also allows to monitor a handful of firmware counters that can provide
> insights into firmware activity during a performance analysis.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  drivers/perf/Kconfig         |   8 +
>  drivers/perf/Makefile        |   1 +
>  drivers/perf/riscv_pmu.c     |   2 +
>  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
>  4 files changed, 548 insertions(+)
>  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 1546a487d970..2acb5feaab35 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
>  	  implementation on RISC-V based systems. This only allows counting
>  	  of cycle/instruction counter and will be removed in future.
>  
> +config RISCV_PMU_SBI
> +	depends on RISCV_PMU
> +	bool "RISC-V PMU based on SBI PMU extension"
> +	default y
> +	help
> +	  Say y if you want to use the CPU performance monitor
> +	  using SBI PMU extension on RISC-V based systems.
> +
>  config ARM_PMU_ACPI
>  	depends on ARM_PMU && ACPI
>  	def_bool y
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index e8aa666a9d28..7bcac4b5a983 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
>  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
>  ifeq ($(CONFIG_RISCV_PMU), y)
>  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
>  endif
>  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
>  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> index c184aa50134d..596af3a40948 100644
> --- a/drivers/perf/riscv_pmu.c
> +++ b/drivers/perf/riscv_pmu.c
> @@ -15,6 +15,8 @@
>  #include <linux/printk.h>
>  #include <linux/smp.h>
>  
> +#include <asm/sbi.h>
> +
>  static unsigned long csr_read_num(int csr_num)
>  {
>  #define switchcase_csr_read(__csr_num, __val)		{\
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> new file mode 100644
> index 000000000000..80dd1de428c4
> --- /dev/null
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -0,0 +1,537 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * RISC-V performance counter support.
> + *
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + *
> + * This code is based on ARM perf event code which is in turn based on
> + * sparc64 and x86 code.
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include <linux/perf/riscv_pmu.h>
> +#include <linux/platform_device.h>
> +
> +#include <asm/sbi.h>
> +
> +union sbi_pmu_ctr_info {
> +	unsigned long value;
> +	struct {
> +		unsigned long csr:12;
> +		unsigned long width:6;
> +#if __riscv_xlen == 32
> +		unsigned long reserved:13;
> +#else
> +		unsigned long reserved:45;
> +#endif
> +		unsigned long type:1;
> +	};
> +};
> +
> +/**
> + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> + * per_cpu in case of harts with different pmu counters
> + */
> +static union sbi_pmu_ctr_info *pmu_ctr_list;
> +
> +struct pmu_event_data {
> +	union {
> +		union {
> +			struct hw_gen_event {
> +				uint32_t event_code:16;
> +				uint32_t event_type:4;
> +				uint32_t reserved:12;
> +			} hw_gen_event;
> +			struct hw_cache_event {
> +				uint32_t result_id:1;
> +				uint32_t op_id:2;
> +				uint32_t cache_id:13;
> +				uint32_t event_type:4;
> +				uint32_t reserved:12;
> +			} hw_cache_event;
> +		};
> +		uint32_t event_idx;
> +	};
> +};
> +
> +static const struct pmu_event_data pmu_hw_event_map[] = {
> +	[PERF_COUNT_HW_CPU_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_CPU_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_INSTRUCTIONS]		= {.hw_gen_event = {
> +							SBI_PMU_HW_INSTRUCTIONS,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_CACHE_REFERENCES]	= {.hw_gen_event = {
> +							SBI_PMU_HW_CACHE_REFERENCES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_CACHE_MISSES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_CACHE_MISSES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BRANCH_INSTRUCTIONS]	= {.hw_gen_event = {
> +							SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BRANCH_MISSES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_BRANCH_MISSES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_BUS_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_BUS_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_STALLED_CYCLES_FRONTEND]	= {.hw_gen_event = {
> +							SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_STALLED_CYCLES_BACKEND]	= {.hw_gen_event = {
> +							SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +	[PERF_COUNT_HW_REF_CPU_CYCLES]		= {.hw_gen_event = {
> +							SBI_PMU_HW_REF_CPU_CYCLES,
> +							SBI_PMU_EVENT_TYPE_HW, 0}},
> +};
> +
> +#define C(x) PERF_COUNT_HW_CACHE_##x
> +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> +[PERF_COUNT_HW_CACHE_OP_MAX]
> +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> +	[C(L1D)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(L1I)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event =	{C(RESULT_ACCESS),
> +					C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> +					C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(LL)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(DTLB)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(ITLB)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(BPU)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +	[C(NODE)] = {
> +		[C(OP_READ)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_WRITE)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +		[C(OP_PREFETCH)] = {
> +			[C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> +					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +			[C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> +					C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> +		},
> +	},
> +};
> +
> +static int pmu_sbi_ctr_get_width(int idx)
> +{
> +	return pmu_ctr_list[idx].width;
> +}
> +
> +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	struct sbiret ret;
> +	int idx;
> +	uint64_t cbase = 0;
> +	uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> +	unsigned long cflags = 0;
> +
> +	/* retrieve the available counter index */
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> +			cflags, hwc->event_base, hwc->config, 0);
> +	if (ret.error) {
> +		pr_debug("Not able to find a counter for event %lx config %llx\n",
> +			hwc->event_base, hwc->config);
> +		return sbi_err_map_linux_errno(ret.error);
> +	}
> +
> +	idx = ret.value;
> +	if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> +		return -ENOENT;
> +
> +	/* Additional sanity check for the counter id */
> +	if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> +		return idx;
> +	else
> +		return -ENOENT;
> +}
> +
> +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> +{
> +
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	int idx = hwc->idx;
> +
> +	clear_bit(idx, cpuc->used_event_ctrs);
> +}
> +
> +static int pmu_event_find_cache(u64 config)
> +{
> +	unsigned int cache_type, cache_op, cache_result, ret;
> +
> +	cache_type = (config >>  0) & 0xff;
> +	if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> +		return -EINVAL;
> +
> +	cache_op = (config >>  8) & 0xff;
> +	if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> +		return -EINVAL;
> +
> +	cache_result = (config >> 16) & 0xff;
> +	if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> +		return -EINVAL;
> +
> +	ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> +
> +	return ret;
> +}
> +
> +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> +{
> +	u32 type = event->attr.type;
> +	u64 config = event->attr.config;
> +
> +	if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> +		return true;
> +	else
> +		return false;
> +}
> +
> +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> +{
> +	u32 type = event->attr.type;
> +	u64 config = event->attr.config;
> +	int bSoftware;
> +	u64 raw_config_val;
> +	int ret;
> +
> +	switch (type) {
> +	case PERF_TYPE_HARDWARE:
> +		if (config >= PERF_COUNT_HW_MAX)
> +			return -EINVAL;
> +		ret = pmu_hw_event_map[event->attr.config].event_idx;
> +		break;
> +	case PERF_TYPE_HW_CACHE:
> +		ret = pmu_event_find_cache(config);
> +		break;
> +	case PERF_TYPE_RAW:
> +		/*
> +		 * As per SBI specification, the upper 7 bits must be unused for
> +		 * a raw event. Use the MSB (63b) to distinguish between hardware
> +		 * raw event and firmware events.
> +		 */
> +		bSoftware = config >> 63;
> +		raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> +		if (bSoftware) {
> +			if (raw_config_val < SBI_PMU_FW_MAX)
> +				ret = (raw_config_val & 0xFFFF) |
> +				      (SBI_PMU_EVENT_TYPE_FW << 16);
> +			else
> +				return -EINVAL;
> +		} else {
> +			ret = RISCV_PMU_RAW_EVENT_IDX;
> +			*econfig = raw_config_val;
> +		}
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	int idx = hwc->idx;
> +	struct sbiret ret;
> +	union sbi_pmu_ctr_info info;
> +	u64 val = 0;
> +
> +	if (pmu_sbi_is_fw_event(event)) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> +				hwc->idx, 0, 0, 0, 0, 0);
> +		if (!ret.error)
> +			val = ret.value;
> +	} else {
> +		info = pmu_ctr_list[idx];
> +		val = riscv_pmu_ctr_read_csr(info.csr);
> +		if (IS_ENABLED(CONFIG_32BIT))
> +			val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> +	}
> +
> +	return val;
> +}
> +
> +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> +{
> +	struct sbiret ret;
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> +			1, 1, ival, 0, 0);
> +	if (ret.error)
> +		pr_err("Starting counter idx %d failed with error %d\n",
> +			hwc->idx, sbi_err_map_linux_errno(ret.error));
> +}
> +
> +static void pmu_sbi_ctr_stop(struct perf_event *event)
> +{
> +	struct sbiret ret;
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> +	struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> +	unsigned long flag = 0;
> +
> +	if (cpuc->events[hwc->idx] == NULL)
> +		flag = SBI_PMU_STOP_FLAG_RESET;
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> +	if (ret.error)
> +		pr_err("Stopping counter idx %d failed with error %d\n",
> +			hwc->idx, sbi_err_map_linux_errno(ret.error));
> +}
> +
> +static int pmu_sbi_find_num_ctrs(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> +	if (!ret.error)
> +		return ret.value;
> +	else
> +		return sbi_err_map_linux_errno(ret.error);
> +}
> +
> +static int pmu_sbi_get_ctrinfo(int nctr)
> +{
> +	struct sbiret ret;
> +	int i, num_hw_ctr = 0, num_fw_ctr = 0;
> +	union sbi_pmu_ctr_info cinfo;
> +
> +	pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> +	if (!pmu_ctr_list)
> +		return -ENOMEM;
> +
> +	for (i = 0; i <= nctr; i++) {
> +		ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> +		if (ret.error)
> +			/* The logical counter ids are not expected to be contiguous */
> +			continue;
> +		cinfo.value = ret.value;
> +		if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> +			num_fw_ctr++;
> +		else
> +			num_hw_ctr++;
> +		pmu_ctr_list[i].value = cinfo.value;
> +	}
> +
> +	pr_info("There are %d firmware & %d hardware counters available\n",
> +		num_fw_ctr, num_hw_ctr);
> +
> +	return 0;
> +}
> +
> +static int pmu_sbi_starting_cpu(unsigned int cpu)
> +{
> +	/* Enable the access for TIME csr only from the user mode now */
> +	csr_write(CSR_SCOUNTEREN, 0x2);
Would it be possible to also enable CYCLE csr here (and I guess same
would propagate to mcounteren logic in the opensbi patches)? Are there
any security concerns in allowing applications to read it directly?

It would be useful given that the frequency of TIME is not fixed in spec
and it may not be enough for a rdtsc-like counter. In such cases CYCLE
csr might be useful to userspace applications (i.e. DPDK) with obvious
limitations such as gating via WFI or value changes when using perf.

For context: there was a similar situation with arm64 at the point of
DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
not its frequency which usually was ~100MHz. The PMU cycle counter
(PMCCNTR) was by default disabled for read from userspace (EL0). This
required DPDK folks to create a kernel module to enable the PMCCNTR in
userspace so that they could implement high-resolution rte_rdtsc() call.
This got fixed in Armv8.6-A which specified the timer counter frequency
to be 1GHz.

If the CYCLE csr remains S-mode private, I will have to effectively
resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
Alternatively perhaps a sysfs knob or driver parameter could be added to
enable the CYCLE csr in U-mode?
> +
> +	return 0;
> +}
> +
> +static int pmu_sbi_dying_cpu(unsigned int cpu)
> +{
> +	/* Disable all counters access for user mode now */
> +	csr_write(CSR_SCOUNTEREN, 0x0);
> +
> +	return 0;
> +}
> +
> +
> +static int pmu_sbi_device_probe(struct platform_device *pdev)
> +{
> +	struct riscv_pmu *pmu = NULL;
> +	int num_counters;
> +
> +	pmu = riscv_pmu_alloc();
> +	if (!pmu)
> +		return -ENOMEM;
> +
> +	if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> +		sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> +		/* Fall back to the legacy implementation */
> +		riscv_pmu_legacy_init(pmu);
> +		return 0;
> +	}
> +
> +	pr_info("SBI PMU extension is available\n");
> +
> +	num_counters = pmu_sbi_find_num_ctrs();
> +	if (num_counters < 0) {
> +		pr_err("SBI PMU extension doesn't provide any counters\n");
> +		return -ENODEV;
> +	}
> +
> +	/* cache all the information about counters now */
> +	if (pmu_sbi_get_ctrinfo(num_counters))
> +		return -ENODEV;
> +
> +	pmu->num_counters = num_counters;
> +	pmu->ctr_start = pmu_sbi_ctr_start;
> +	pmu->ctr_stop = pmu_sbi_ctr_stop;
> +	pmu->event_map = pmu_sbi_event_map;
> +	pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> +	pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> +	pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> +	pmu->ctr_read = pmu_sbi_ctr_read;
> +
> +	perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> +
> +	cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> +			  "perf/riscv/pmu:starting",
> +			  pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver pmu_sbi_driver = {
> +	.probe		= pmu_sbi_device_probe,
> +	.driver		= {
> +		.name	= RISCV_PMU_PDEV_NAME,
> +	},
> +};
> +
> +static int __init pmu_sbi_devinit(void)
> +{
> +	int ret;
> +	struct platform_device *pdev;
> +
> +	ret = platform_driver_register(&pmu_sbi_driver);
> +	if (ret)
> +		return ret;
> +
> +	pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> +	if (IS_ERR(pdev)) {
> +		platform_driver_unregister(&pmu_sbi_driver);
> +		return PTR_ERR(pdev);
> +	}
> +
> +	return ret;
> +}
> +device_initcall(pmu_sbi_devinit)
> -- 
> 2.25.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

-- 
Best Regards,
Stanislaw Kardach

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
  2021-06-01 13:10     ` Stanislaw Kardach
@ 2021-06-01 15:48       ` Anup Patel
  -1 siblings, 0 replies; 28+ messages in thread
From: Anup Patel @ 2021-06-01 15:48 UTC (permalink / raw)
  To: Stanislaw Kardach
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
>
> On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > RISC-V SBI specification added a PMU extension that allows to configure
> > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > perf features except interrupt overflow and event filtering based on
> > privilege mode which will be added in future.
> >
> > It also allows to monitor a handful of firmware counters that can provide
> > insights into firmware activity during a performance analysis.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> >  drivers/perf/Kconfig         |   8 +
> >  drivers/perf/Makefile        |   1 +
> >  drivers/perf/riscv_pmu.c     |   2 +
> >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> >  4 files changed, 548 insertions(+)
> >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> >
> > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > index 1546a487d970..2acb5feaab35 100644
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> >         implementation on RISC-V based systems. This only allows counting
> >         of cycle/instruction counter and will be removed in future.
> >
> > +config RISCV_PMU_SBI
> > +     depends on RISCV_PMU
> > +     bool "RISC-V PMU based on SBI PMU extension"
> > +     default y
> > +     help
> > +       Say y if you want to use the CPU performance monitor
> > +       using SBI PMU extension on RISC-V based systems.
> > +
> >  config ARM_PMU_ACPI
> >       depends on ARM_PMU && ACPI
> >       def_bool y
> > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > index e8aa666a9d28..7bcac4b5a983 100644
> > --- a/drivers/perf/Makefile
> > +++ b/drivers/perf/Makefile
> > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> >  ifeq ($(CONFIG_RISCV_PMU), y)
> >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> >  endif
> >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > index c184aa50134d..596af3a40948 100644
> > --- a/drivers/perf/riscv_pmu.c
> > +++ b/drivers/perf/riscv_pmu.c
> > @@ -15,6 +15,8 @@
> >  #include <linux/printk.h>
> >  #include <linux/smp.h>
> >
> > +#include <asm/sbi.h>
> > +
> >  static unsigned long csr_read_num(int csr_num)
> >  {
> >  #define switchcase_csr_read(__csr_num, __val)                {\
> > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > new file mode 100644
> > index 000000000000..80dd1de428c4
> > --- /dev/null
> > +++ b/drivers/perf/riscv_pmu_sbi.c
> > @@ -0,0 +1,537 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * RISC-V performance counter support.
> > + *
> > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > + *
> > + * This code is based on ARM perf event code which is in turn based on
> > + * sparc64 and x86 code.
> > + */
> > +
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/perf/riscv_pmu.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <asm/sbi.h>
> > +
> > +union sbi_pmu_ctr_info {
> > +     unsigned long value;
> > +     struct {
> > +             unsigned long csr:12;
> > +             unsigned long width:6;
> > +#if __riscv_xlen == 32
> > +             unsigned long reserved:13;
> > +#else
> > +             unsigned long reserved:45;
> > +#endif
> > +             unsigned long type:1;
> > +     };
> > +};
> > +
> > +/**
> > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > + * per_cpu in case of harts with different pmu counters
> > + */
> > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > +
> > +struct pmu_event_data {
> > +     union {
> > +             union {
> > +                     struct hw_gen_event {
> > +                             uint32_t event_code:16;
> > +                             uint32_t event_type:4;
> > +                             uint32_t reserved:12;
> > +                     } hw_gen_event;
> > +                     struct hw_cache_event {
> > +                             uint32_t result_id:1;
> > +                             uint32_t op_id:2;
> > +                             uint32_t cache_id:13;
> > +                             uint32_t event_type:4;
> > +                             uint32_t reserved:12;
> > +                     } hw_cache_event;
> > +             };
> > +             uint32_t event_idx;
> > +     };
> > +};
> > +
> > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +};
> > +
> > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > +     [C(L1D)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(L1I)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(LL)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(DTLB)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(ITLB)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(BPU)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(NODE)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +};
> > +
> > +static int pmu_sbi_ctr_get_width(int idx)
> > +{
> > +     return pmu_ctr_list[idx].width;
> > +}
> > +
> > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > +{
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     struct sbiret ret;
> > +     int idx;
> > +     uint64_t cbase = 0;
> > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > +     unsigned long cflags = 0;
> > +
> > +     /* retrieve the available counter index */
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > +                     cflags, hwc->event_base, hwc->config, 0);
> > +     if (ret.error) {
> > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > +                     hwc->event_base, hwc->config);
> > +             return sbi_err_map_linux_errno(ret.error);
> > +     }
> > +
> > +     idx = ret.value;
> > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > +             return -ENOENT;
> > +
> > +     /* Additional sanity check for the counter id */
> > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > +             return idx;
> > +     else
> > +             return -ENOENT;
> > +}
> > +
> > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > +{
> > +
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     int idx = hwc->idx;
> > +
> > +     clear_bit(idx, cpuc->used_event_ctrs);
> > +}
> > +
> > +static int pmu_event_find_cache(u64 config)
> > +{
> > +     unsigned int cache_type, cache_op, cache_result, ret;
> > +
> > +     cache_type = (config >>  0) & 0xff;
> > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > +             return -EINVAL;
> > +
> > +     cache_op = (config >>  8) & 0xff;
> > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > +             return -EINVAL;
> > +
> > +     cache_result = (config >> 16) & 0xff;
> > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > +             return -EINVAL;
> > +
> > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > +
> > +     return ret;
> > +}
> > +
> > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > +{
> > +     u32 type = event->attr.type;
> > +     u64 config = event->attr.config;
> > +
> > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > +             return true;
> > +     else
> > +             return false;
> > +}
> > +
> > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > +{
> > +     u32 type = event->attr.type;
> > +     u64 config = event->attr.config;
> > +     int bSoftware;
> > +     u64 raw_config_val;
> > +     int ret;
> > +
> > +     switch (type) {
> > +     case PERF_TYPE_HARDWARE:
> > +             if (config >= PERF_COUNT_HW_MAX)
> > +                     return -EINVAL;
> > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > +             break;
> > +     case PERF_TYPE_HW_CACHE:
> > +             ret = pmu_event_find_cache(config);
> > +             break;
> > +     case PERF_TYPE_RAW:
> > +             /*
> > +              * As per SBI specification, the upper 7 bits must be unused for
> > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > +              * raw event and firmware events.
> > +              */
> > +             bSoftware = config >> 63;
> > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > +             if (bSoftware) {
> > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > +                             ret = (raw_config_val & 0xFFFF) |
> > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > +                     else
> > +                             return -EINVAL;
> > +             } else {
> > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > +                     *econfig = raw_config_val;
> > +             }
> > +             break;
> > +     default:
> > +             ret = -EINVAL;
> > +             break;
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > +{
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     int idx = hwc->idx;
> > +     struct sbiret ret;
> > +     union sbi_pmu_ctr_info info;
> > +     u64 val = 0;
> > +
> > +     if (pmu_sbi_is_fw_event(event)) {
> > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > +                             hwc->idx, 0, 0, 0, 0, 0);
> > +             if (!ret.error)
> > +                     val = ret.value;
> > +     } else {
> > +             info = pmu_ctr_list[idx];
> > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > +             if (IS_ENABLED(CONFIG_32BIT))
> > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > +     }
> > +
> > +     return val;
> > +}
> > +
> > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > +{
> > +     struct sbiret ret;
> > +     struct hw_perf_event *hwc = &event->hw;
> > +
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > +                     1, 1, ival, 0, 0);
> > +     if (ret.error)
> > +             pr_err("Starting counter idx %d failed with error %d\n",
> > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > +}
> > +
> > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > +{
> > +     struct sbiret ret;
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     unsigned long flag = 0;
> > +
> > +     if (cpuc->events[hwc->idx] == NULL)
> > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > +     if (ret.error)
> > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > +}
> > +
> > +static int pmu_sbi_find_num_ctrs(void)
> > +{
> > +     struct sbiret ret;
> > +
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > +     if (!ret.error)
> > +             return ret.value;
> > +     else
> > +             return sbi_err_map_linux_errno(ret.error);
> > +}
> > +
> > +static int pmu_sbi_get_ctrinfo(int nctr)
> > +{
> > +     struct sbiret ret;
> > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > +     union sbi_pmu_ctr_info cinfo;
> > +
> > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > +     if (!pmu_ctr_list)
> > +             return -ENOMEM;
> > +
> > +     for (i = 0; i <= nctr; i++) {
> > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > +             if (ret.error)
> > +                     /* The logical counter ids are not expected to be contiguous */
> > +                     continue;
> > +             cinfo.value = ret.value;
> > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > +                     num_fw_ctr++;
> > +             else
> > +                     num_hw_ctr++;
> > +             pmu_ctr_list[i].value = cinfo.value;
> > +     }
> > +
> > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > +             num_fw_ctr, num_hw_ctr);
> > +
> > +     return 0;
> > +}
> > +
> > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > +{
> > +     /* Enable the access for TIME csr only from the user mode now */
> > +     csr_write(CSR_SCOUNTEREN, 0x2);
> Would it be possible to also enable CYCLE csr here (and I guess same
> would propagate to mcounteren logic in the opensbi patches)? Are there
> any security concerns in allowing applications to read it directly?

If CYCLE csr is always enabled then a process can get cycle count of
all process and underlying kernel. This means process A can now
estimate code path taken by process B based on observing variations
in CYCLE csr values. This certainly seems like a back-door channel
being opened up.

Ideally, a process should only see CPU cycles consumed by the
process itself. Same rationale applies to Guest/VM as well.

>
> It would be useful given that the frequency of TIME is not fixed in spec
> and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> csr might be useful to userspace applications (i.e. DPDK) with obvious
> limitations such as gating via WFI or value changes when using perf.

CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
is same as CPU frequency and RISC-V platforms might support
CPU frequency scaling as well in which case CYCLE csr frequency
can change at runtime.

On other hand, it is much simpler to expose timer frequency to
user space via procfs or sysfs. In fact, RISC-V platform will always
have fixed frequency for TIME csr irrespective to underlying CPU
frequency.

>
> For context: there was a similar situation with arm64 at the point of
> DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> not its frequency which usually was ~100MHz. The PMU cycle counter
> (PMCCNTR) was by default disabled for read from userspace (EL0). This
> required DPDK folks to create a kernel module to enable the PMCCNTR in
> userspace so that they could implement high-resolution rte_rdtsc() call.
> This got fixed in Armv8.6-A which specified the timer counter frequency
> to be 1GHz.
>
> If the CYCLE csr remains S-mode private, I will have to effectively
> resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> Alternatively perhaps a sysfs knob or driver parameter could be added to
> enable the CYCLE csr in U-mode?

Before we think about sysfs knob or driver parameter, I would suggest
you to explore approaches of knowing timer frequency in DPDK.

Regards,
Anup

> > +
> > +     return 0;
> > +}
> > +
> > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > +{
> > +     /* Disable all counters access for user mode now */
> > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > +
> > +     return 0;
> > +}
> > +
> > +
> > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > +{
> > +     struct riscv_pmu *pmu = NULL;
> > +     int num_counters;
> > +
> > +     pmu = riscv_pmu_alloc();
> > +     if (!pmu)
> > +             return -ENOMEM;
> > +
> > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > +             /* Fall back to the legacy implementation */
> > +             riscv_pmu_legacy_init(pmu);
> > +             return 0;
> > +     }
> > +
> > +     pr_info("SBI PMU extension is available\n");
> > +
> > +     num_counters = pmu_sbi_find_num_ctrs();
> > +     if (num_counters < 0) {
> > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     /* cache all the information about counters now */
> > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > +             return -ENODEV;
> > +
> > +     pmu->num_counters = num_counters;
> > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > +     pmu->event_map = pmu_sbi_event_map;
> > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > +
> > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > +
> > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > +                       "perf/riscv/pmu:starting",
> > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > +
> > +     return 0;
> > +}
> > +
> > +static struct platform_driver pmu_sbi_driver = {
> > +     .probe          = pmu_sbi_device_probe,
> > +     .driver         = {
> > +             .name   = RISCV_PMU_PDEV_NAME,
> > +     },
> > +};
> > +
> > +static int __init pmu_sbi_devinit(void)
> > +{
> > +     int ret;
> > +     struct platform_device *pdev;
> > +
> > +     ret = platform_driver_register(&pmu_sbi_driver);
> > +     if (ret)
> > +             return ret;
> > +
> > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > +     if (IS_ERR(pdev)) {
> > +             platform_driver_unregister(&pmu_sbi_driver);
> > +             return PTR_ERR(pdev);
> > +     }
> > +
> > +     return ret;
> > +}
> > +device_initcall(pmu_sbi_devinit)
> > --
> > 2.25.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
> --
> Best Regards,
> Stanislaw Kardach

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
@ 2021-06-01 15:48       ` Anup Patel
  0 siblings, 0 replies; 28+ messages in thread
From: Anup Patel @ 2021-06-01 15:48 UTC (permalink / raw)
  To: Stanislaw Kardach
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
>
> On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > RISC-V SBI specification added a PMU extension that allows to configure
> > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > perf features except interrupt overflow and event filtering based on
> > privilege mode which will be added in future.
> >
> > It also allows to monitor a handful of firmware counters that can provide
> > insights into firmware activity during a performance analysis.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> >  drivers/perf/Kconfig         |   8 +
> >  drivers/perf/Makefile        |   1 +
> >  drivers/perf/riscv_pmu.c     |   2 +
> >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> >  4 files changed, 548 insertions(+)
> >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> >
> > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > index 1546a487d970..2acb5feaab35 100644
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> >         implementation on RISC-V based systems. This only allows counting
> >         of cycle/instruction counter and will be removed in future.
> >
> > +config RISCV_PMU_SBI
> > +     depends on RISCV_PMU
> > +     bool "RISC-V PMU based on SBI PMU extension"
> > +     default y
> > +     help
> > +       Say y if you want to use the CPU performance monitor
> > +       using SBI PMU extension on RISC-V based systems.
> > +
> >  config ARM_PMU_ACPI
> >       depends on ARM_PMU && ACPI
> >       def_bool y
> > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > index e8aa666a9d28..7bcac4b5a983 100644
> > --- a/drivers/perf/Makefile
> > +++ b/drivers/perf/Makefile
> > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> >  ifeq ($(CONFIG_RISCV_PMU), y)
> >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> >  endif
> >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > index c184aa50134d..596af3a40948 100644
> > --- a/drivers/perf/riscv_pmu.c
> > +++ b/drivers/perf/riscv_pmu.c
> > @@ -15,6 +15,8 @@
> >  #include <linux/printk.h>
> >  #include <linux/smp.h>
> >
> > +#include <asm/sbi.h>
> > +
> >  static unsigned long csr_read_num(int csr_num)
> >  {
> >  #define switchcase_csr_read(__csr_num, __val)                {\
> > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > new file mode 100644
> > index 000000000000..80dd1de428c4
> > --- /dev/null
> > +++ b/drivers/perf/riscv_pmu_sbi.c
> > @@ -0,0 +1,537 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * RISC-V performance counter support.
> > + *
> > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > + *
> > + * This code is based on ARM perf event code which is in turn based on
> > + * sparc64 and x86 code.
> > + */
> > +
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/perf/riscv_pmu.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <asm/sbi.h>
> > +
> > +union sbi_pmu_ctr_info {
> > +     unsigned long value;
> > +     struct {
> > +             unsigned long csr:12;
> > +             unsigned long width:6;
> > +#if __riscv_xlen == 32
> > +             unsigned long reserved:13;
> > +#else
> > +             unsigned long reserved:45;
> > +#endif
> > +             unsigned long type:1;
> > +     };
> > +};
> > +
> > +/**
> > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > + * per_cpu in case of harts with different pmu counters
> > + */
> > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > +
> > +struct pmu_event_data {
> > +     union {
> > +             union {
> > +                     struct hw_gen_event {
> > +                             uint32_t event_code:16;
> > +                             uint32_t event_type:4;
> > +                             uint32_t reserved:12;
> > +                     } hw_gen_event;
> > +                     struct hw_cache_event {
> > +                             uint32_t result_id:1;
> > +                             uint32_t op_id:2;
> > +                             uint32_t cache_id:13;
> > +                             uint32_t event_type:4;
> > +                             uint32_t reserved:12;
> > +                     } hw_cache_event;
> > +             };
> > +             uint32_t event_idx;
> > +     };
> > +};
> > +
> > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > +};
> > +
> > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > +     [C(L1D)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(L1I)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(LL)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(DTLB)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(ITLB)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(BPU)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +     [C(NODE)] = {
> > +             [C(OP_READ)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_WRITE)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +             [C(OP_PREFETCH)] = {
> > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > +             },
> > +     },
> > +};
> > +
> > +static int pmu_sbi_ctr_get_width(int idx)
> > +{
> > +     return pmu_ctr_list[idx].width;
> > +}
> > +
> > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > +{
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     struct sbiret ret;
> > +     int idx;
> > +     uint64_t cbase = 0;
> > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > +     unsigned long cflags = 0;
> > +
> > +     /* retrieve the available counter index */
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > +                     cflags, hwc->event_base, hwc->config, 0);
> > +     if (ret.error) {
> > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > +                     hwc->event_base, hwc->config);
> > +             return sbi_err_map_linux_errno(ret.error);
> > +     }
> > +
> > +     idx = ret.value;
> > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > +             return -ENOENT;
> > +
> > +     /* Additional sanity check for the counter id */
> > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > +             return idx;
> > +     else
> > +             return -ENOENT;
> > +}
> > +
> > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > +{
> > +
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     int idx = hwc->idx;
> > +
> > +     clear_bit(idx, cpuc->used_event_ctrs);
> > +}
> > +
> > +static int pmu_event_find_cache(u64 config)
> > +{
> > +     unsigned int cache_type, cache_op, cache_result, ret;
> > +
> > +     cache_type = (config >>  0) & 0xff;
> > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > +             return -EINVAL;
> > +
> > +     cache_op = (config >>  8) & 0xff;
> > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > +             return -EINVAL;
> > +
> > +     cache_result = (config >> 16) & 0xff;
> > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > +             return -EINVAL;
> > +
> > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > +
> > +     return ret;
> > +}
> > +
> > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > +{
> > +     u32 type = event->attr.type;
> > +     u64 config = event->attr.config;
> > +
> > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > +             return true;
> > +     else
> > +             return false;
> > +}
> > +
> > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > +{
> > +     u32 type = event->attr.type;
> > +     u64 config = event->attr.config;
> > +     int bSoftware;
> > +     u64 raw_config_val;
> > +     int ret;
> > +
> > +     switch (type) {
> > +     case PERF_TYPE_HARDWARE:
> > +             if (config >= PERF_COUNT_HW_MAX)
> > +                     return -EINVAL;
> > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > +             break;
> > +     case PERF_TYPE_HW_CACHE:
> > +             ret = pmu_event_find_cache(config);
> > +             break;
> > +     case PERF_TYPE_RAW:
> > +             /*
> > +              * As per SBI specification, the upper 7 bits must be unused for
> > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > +              * raw event and firmware events.
> > +              */
> > +             bSoftware = config >> 63;
> > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > +             if (bSoftware) {
> > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > +                             ret = (raw_config_val & 0xFFFF) |
> > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > +                     else
> > +                             return -EINVAL;
> > +             } else {
> > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > +                     *econfig = raw_config_val;
> > +             }
> > +             break;
> > +     default:
> > +             ret = -EINVAL;
> > +             break;
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > +{
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     int idx = hwc->idx;
> > +     struct sbiret ret;
> > +     union sbi_pmu_ctr_info info;
> > +     u64 val = 0;
> > +
> > +     if (pmu_sbi_is_fw_event(event)) {
> > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > +                             hwc->idx, 0, 0, 0, 0, 0);
> > +             if (!ret.error)
> > +                     val = ret.value;
> > +     } else {
> > +             info = pmu_ctr_list[idx];
> > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > +             if (IS_ENABLED(CONFIG_32BIT))
> > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > +     }
> > +
> > +     return val;
> > +}
> > +
> > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > +{
> > +     struct sbiret ret;
> > +     struct hw_perf_event *hwc = &event->hw;
> > +
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > +                     1, 1, ival, 0, 0);
> > +     if (ret.error)
> > +             pr_err("Starting counter idx %d failed with error %d\n",
> > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > +}
> > +
> > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > +{
> > +     struct sbiret ret;
> > +     struct hw_perf_event *hwc = &event->hw;
> > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > +     unsigned long flag = 0;
> > +
> > +     if (cpuc->events[hwc->idx] == NULL)
> > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > +     if (ret.error)
> > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > +}
> > +
> > +static int pmu_sbi_find_num_ctrs(void)
> > +{
> > +     struct sbiret ret;
> > +
> > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > +     if (!ret.error)
> > +             return ret.value;
> > +     else
> > +             return sbi_err_map_linux_errno(ret.error);
> > +}
> > +
> > +static int pmu_sbi_get_ctrinfo(int nctr)
> > +{
> > +     struct sbiret ret;
> > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > +     union sbi_pmu_ctr_info cinfo;
> > +
> > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > +     if (!pmu_ctr_list)
> > +             return -ENOMEM;
> > +
> > +     for (i = 0; i <= nctr; i++) {
> > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > +             if (ret.error)
> > +                     /* The logical counter ids are not expected to be contiguous */
> > +                     continue;
> > +             cinfo.value = ret.value;
> > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > +                     num_fw_ctr++;
> > +             else
> > +                     num_hw_ctr++;
> > +             pmu_ctr_list[i].value = cinfo.value;
> > +     }
> > +
> > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > +             num_fw_ctr, num_hw_ctr);
> > +
> > +     return 0;
> > +}
> > +
> > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > +{
> > +     /* Enable the access for TIME csr only from the user mode now */
> > +     csr_write(CSR_SCOUNTEREN, 0x2);
> Would it be possible to also enable CYCLE csr here (and I guess same
> would propagate to mcounteren logic in the opensbi patches)? Are there
> any security concerns in allowing applications to read it directly?

If CYCLE csr is always enabled then a process can get cycle count of
all process and underlying kernel. This means process A can now
estimate code path taken by process B based on observing variations
in CYCLE csr values. This certainly seems like a back-door channel
being opened up.

Ideally, a process should only see CPU cycles consumed by the
process itself. Same rationale applies to Guest/VM as well.

>
> It would be useful given that the frequency of TIME is not fixed in spec
> and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> csr might be useful to userspace applications (i.e. DPDK) with obvious
> limitations such as gating via WFI or value changes when using perf.

CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
is same as CPU frequency and RISC-V platforms might support
CPU frequency scaling as well in which case CYCLE csr frequency
can change at runtime.

On other hand, it is much simpler to expose timer frequency to
user space via procfs or sysfs. In fact, RISC-V platform will always
have fixed frequency for TIME csr irrespective to underlying CPU
frequency.

>
> For context: there was a similar situation with arm64 at the point of
> DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> not its frequency which usually was ~100MHz. The PMU cycle counter
> (PMCCNTR) was by default disabled for read from userspace (EL0). This
> required DPDK folks to create a kernel module to enable the PMCCNTR in
> userspace so that they could implement high-resolution rte_rdtsc() call.
> This got fixed in Armv8.6-A which specified the timer counter frequency
> to be 1GHz.
>
> If the CYCLE csr remains S-mode private, I will have to effectively
> resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> Alternatively perhaps a sysfs knob or driver parameter could be added to
> enable the CYCLE csr in U-mode?

Before we think about sysfs knob or driver parameter, I would suggest
you to explore approaches of knowing timer frequency in DPDK.

Regards,
Anup

> > +
> > +     return 0;
> > +}
> > +
> > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > +{
> > +     /* Disable all counters access for user mode now */
> > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > +
> > +     return 0;
> > +}
> > +
> > +
> > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > +{
> > +     struct riscv_pmu *pmu = NULL;
> > +     int num_counters;
> > +
> > +     pmu = riscv_pmu_alloc();
> > +     if (!pmu)
> > +             return -ENOMEM;
> > +
> > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > +             /* Fall back to the legacy implementation */
> > +             riscv_pmu_legacy_init(pmu);
> > +             return 0;
> > +     }
> > +
> > +     pr_info("SBI PMU extension is available\n");
> > +
> > +     num_counters = pmu_sbi_find_num_ctrs();
> > +     if (num_counters < 0) {
> > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     /* cache all the information about counters now */
> > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > +             return -ENODEV;
> > +
> > +     pmu->num_counters = num_counters;
> > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > +     pmu->event_map = pmu_sbi_event_map;
> > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > +
> > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > +
> > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > +                       "perf/riscv/pmu:starting",
> > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > +
> > +     return 0;
> > +}
> > +
> > +static struct platform_driver pmu_sbi_driver = {
> > +     .probe          = pmu_sbi_device_probe,
> > +     .driver         = {
> > +             .name   = RISCV_PMU_PDEV_NAME,
> > +     },
> > +};
> > +
> > +static int __init pmu_sbi_devinit(void)
> > +{
> > +     int ret;
> > +     struct platform_device *pdev;
> > +
> > +     ret = platform_driver_register(&pmu_sbi_driver);
> > +     if (ret)
> > +             return ret;
> > +
> > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > +     if (IS_ERR(pdev)) {
> > +             platform_driver_unregister(&pmu_sbi_driver);
> > +             return PTR_ERR(pdev);
> > +     }
> > +
> > +     return ret;
> > +}
> > +device_initcall(pmu_sbi_devinit)
> > --
> > 2.25.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
> --
> Best Regards,
> Stanislaw Kardach

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
  2021-06-01 15:48       ` Anup Patel
@ 2021-06-01 15:57         ` Anup Patel
  -1 siblings, 0 replies; 28+ messages in thread
From: Anup Patel @ 2021-06-01 15:57 UTC (permalink / raw)
  To: Stanislaw Kardach
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 1, 2021 at 9:18 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
> >
> > On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > > RISC-V SBI specification added a PMU extension that allows to configure
> > > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > > perf features except interrupt overflow and event filtering based on
> > > privilege mode which will be added in future.
> > >
> > > It also allows to monitor a handful of firmware counters that can provide
> > > insights into firmware activity during a performance analysis.
> > >
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > ---
> > >  drivers/perf/Kconfig         |   8 +
> > >  drivers/perf/Makefile        |   1 +
> > >  drivers/perf/riscv_pmu.c     |   2 +
> > >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> > >  4 files changed, 548 insertions(+)
> > >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> > >
> > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > > index 1546a487d970..2acb5feaab35 100644
> > > --- a/drivers/perf/Kconfig
> > > +++ b/drivers/perf/Kconfig
> > > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> > >         implementation on RISC-V based systems. This only allows counting
> > >         of cycle/instruction counter and will be removed in future.
> > >
> > > +config RISCV_PMU_SBI
> > > +     depends on RISCV_PMU
> > > +     bool "RISC-V PMU based on SBI PMU extension"
> > > +     default y
> > > +     help
> > > +       Say y if you want to use the CPU performance monitor
> > > +       using SBI PMU extension on RISC-V based systems.
> > > +
> > >  config ARM_PMU_ACPI
> > >       depends on ARM_PMU && ACPI
> > >       def_bool y
> > > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > > index e8aa666a9d28..7bcac4b5a983 100644
> > > --- a/drivers/perf/Makefile
> > > +++ b/drivers/perf/Makefile
> > > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> > >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> > >  ifeq ($(CONFIG_RISCV_PMU), y)
> > >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> > >  endif
> > >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> > >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > > index c184aa50134d..596af3a40948 100644
> > > --- a/drivers/perf/riscv_pmu.c
> > > +++ b/drivers/perf/riscv_pmu.c
> > > @@ -15,6 +15,8 @@
> > >  #include <linux/printk.h>
> > >  #include <linux/smp.h>
> > >
> > > +#include <asm/sbi.h>
> > > +
> > >  static unsigned long csr_read_num(int csr_num)
> > >  {
> > >  #define switchcase_csr_read(__csr_num, __val)                {\
> > > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > > new file mode 100644
> > > index 000000000000..80dd1de428c4
> > > --- /dev/null
> > > +++ b/drivers/perf/riscv_pmu_sbi.c
> > > @@ -0,0 +1,537 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * RISC-V performance counter support.
> > > + *
> > > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > > + *
> > > + * This code is based on ARM perf event code which is in turn based on
> > > + * sparc64 and x86 code.
> > > + */
> > > +
> > > +#include <linux/mod_devicetable.h>
> > > +#include <linux/perf/riscv_pmu.h>
> > > +#include <linux/platform_device.h>
> > > +
> > > +#include <asm/sbi.h>
> > > +
> > > +union sbi_pmu_ctr_info {
> > > +     unsigned long value;
> > > +     struct {
> > > +             unsigned long csr:12;
> > > +             unsigned long width:6;
> > > +#if __riscv_xlen == 32
> > > +             unsigned long reserved:13;
> > > +#else
> > > +             unsigned long reserved:45;
> > > +#endif
> > > +             unsigned long type:1;
> > > +     };
> > > +};
> > > +
> > > +/**
> > > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > > + * per_cpu in case of harts with different pmu counters
> > > + */
> > > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > > +
> > > +struct pmu_event_data {
> > > +     union {
> > > +             union {
> > > +                     struct hw_gen_event {
> > > +                             uint32_t event_code:16;
> > > +                             uint32_t event_type:4;
> > > +                             uint32_t reserved:12;
> > > +                     } hw_gen_event;
> > > +                     struct hw_cache_event {
> > > +                             uint32_t result_id:1;
> > > +                             uint32_t op_id:2;
> > > +                             uint32_t cache_id:13;
> > > +                             uint32_t event_type:4;
> > > +                             uint32_t reserved:12;
> > > +                     } hw_cache_event;
> > > +             };
> > > +             uint32_t event_idx;
> > > +     };
> > > +};
> > > +
> > > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +};
> > > +
> > > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > > +     [C(L1D)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(L1I)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(LL)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(DTLB)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(ITLB)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(BPU)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(NODE)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +};
> > > +
> > > +static int pmu_sbi_ctr_get_width(int idx)
> > > +{
> > > +     return pmu_ctr_list[idx].width;
> > > +}
> > > +
> > > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > > +{
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     struct sbiret ret;
> > > +     int idx;
> > > +     uint64_t cbase = 0;
> > > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > > +     unsigned long cflags = 0;
> > > +
> > > +     /* retrieve the available counter index */
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > > +                     cflags, hwc->event_base, hwc->config, 0);
> > > +     if (ret.error) {
> > > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > > +                     hwc->event_base, hwc->config);
> > > +             return sbi_err_map_linux_errno(ret.error);
> > > +     }
> > > +
> > > +     idx = ret.value;
> > > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > > +             return -ENOENT;
> > > +
> > > +     /* Additional sanity check for the counter id */
> > > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > > +             return idx;
> > > +     else
> > > +             return -ENOENT;
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > > +{
> > > +
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     int idx = hwc->idx;
> > > +
> > > +     clear_bit(idx, cpuc->used_event_ctrs);
> > > +}
> > > +
> > > +static int pmu_event_find_cache(u64 config)
> > > +{
> > > +     unsigned int cache_type, cache_op, cache_result, ret;
> > > +
> > > +     cache_type = (config >>  0) & 0xff;
> > > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     cache_op = (config >>  8) & 0xff;
> > > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     cache_result = (config >> 16) & 0xff;
> > > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > > +{
> > > +     u32 type = event->attr.type;
> > > +     u64 config = event->attr.config;
> > > +
> > > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > > +             return true;
> > > +     else
> > > +             return false;
> > > +}
> > > +
> > > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > > +{
> > > +     u32 type = event->attr.type;
> > > +     u64 config = event->attr.config;
> > > +     int bSoftware;
> > > +     u64 raw_config_val;
> > > +     int ret;
> > > +
> > > +     switch (type) {
> > > +     case PERF_TYPE_HARDWARE:
> > > +             if (config >= PERF_COUNT_HW_MAX)
> > > +                     return -EINVAL;
> > > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > > +             break;
> > > +     case PERF_TYPE_HW_CACHE:
> > > +             ret = pmu_event_find_cache(config);
> > > +             break;
> > > +     case PERF_TYPE_RAW:
> > > +             /*
> > > +              * As per SBI specification, the upper 7 bits must be unused for
> > > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > > +              * raw event and firmware events.
> > > +              */
> > > +             bSoftware = config >> 63;
> > > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > > +             if (bSoftware) {
> > > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > > +                             ret = (raw_config_val & 0xFFFF) |
> > > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > > +                     else
> > > +                             return -EINVAL;
> > > +             } else {
> > > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > > +                     *econfig = raw_config_val;
> > > +             }
> > > +             break;
> > > +     default:
> > > +             ret = -EINVAL;
> > > +             break;
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > > +{
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     int idx = hwc->idx;
> > > +     struct sbiret ret;
> > > +     union sbi_pmu_ctr_info info;
> > > +     u64 val = 0;
> > > +
> > > +     if (pmu_sbi_is_fw_event(event)) {
> > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > > +                             hwc->idx, 0, 0, 0, 0, 0);
> > > +             if (!ret.error)
> > > +                     val = ret.value;
> > > +     } else {
> > > +             info = pmu_ctr_list[idx];
> > > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > > +             if (IS_ENABLED(CONFIG_32BIT))
> > > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > > +     }
> > > +
> > > +     return val;
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > > +{
> > > +     struct sbiret ret;
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > > +                     1, 1, ival, 0, 0);
> > > +     if (ret.error)
> > > +             pr_err("Starting counter idx %d failed with error %d\n",
> > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > > +{
> > > +     struct sbiret ret;
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     unsigned long flag = 0;
> > > +
> > > +     if (cpuc->events[hwc->idx] == NULL)
> > > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > > +     if (ret.error)
> > > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > +}
> > > +
> > > +static int pmu_sbi_find_num_ctrs(void)
> > > +{
> > > +     struct sbiret ret;
> > > +
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > > +     if (!ret.error)
> > > +             return ret.value;
> > > +     else
> > > +             return sbi_err_map_linux_errno(ret.error);
> > > +}
> > > +
> > > +static int pmu_sbi_get_ctrinfo(int nctr)
> > > +{
> > > +     struct sbiret ret;
> > > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > > +     union sbi_pmu_ctr_info cinfo;
> > > +
> > > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > > +     if (!pmu_ctr_list)
> > > +             return -ENOMEM;
> > > +
> > > +     for (i = 0; i <= nctr; i++) {
> > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > > +             if (ret.error)
> > > +                     /* The logical counter ids are not expected to be contiguous */
> > > +                     continue;
> > > +             cinfo.value = ret.value;
> > > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > > +                     num_fw_ctr++;
> > > +             else
> > > +                     num_hw_ctr++;
> > > +             pmu_ctr_list[i].value = cinfo.value;
> > > +     }
> > > +
> > > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > > +             num_fw_ctr, num_hw_ctr);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > > +{
> > > +     /* Enable the access for TIME csr only from the user mode now */
> > > +     csr_write(CSR_SCOUNTEREN, 0x2);
> > Would it be possible to also enable CYCLE csr here (and I guess same
> > would propagate to mcounteren logic in the opensbi patches)? Are there
> > any security concerns in allowing applications to read it directly?
>
> If CYCLE csr is always enabled then a process can get cycle count of
> all process and underlying kernel. This means process A can now
> estimate code path taken by process B based on observing variations
> in CYCLE csr values. This certainly seems like a back-door channel
> being opened up.
>
> Ideally, a process should only see CPU cycles consumed by the
> process itself. Same rationale applies to Guest/VM as well.
>
> >
> > It would be useful given that the frequency of TIME is not fixed in spec
> > and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> > csr might be useful to userspace applications (i.e. DPDK) with obvious
> > limitations such as gating via WFI or value changes when using perf.
>
> CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
> is same as CPU frequency and RISC-V platforms might support
> CPU frequency scaling as well in which case CYCLE csr frequency
> can change at runtime.
>
> On other hand, it is much simpler to expose timer frequency to
> user space via procfs or sysfs. In fact, RISC-V platform will always
> have fixed frequency for TIME csr irrespective to underlying CPU
> frequency.
>
> >
> > For context: there was a similar situation with arm64 at the point of
> > DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> > not its frequency which usually was ~100MHz. The PMU cycle counter
> > (PMCCNTR) was by default disabled for read from userspace (EL0). This
> > required DPDK folks to create a kernel module to enable the PMCCNTR in
> > userspace so that they could implement high-resolution rte_rdtsc() call.
> > This got fixed in Armv8.6-A which specified the timer counter frequency
> > to be 1GHz.
> >
> > If the CYCLE csr remains S-mode private, I will have to effectively
> > resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> > Alternatively perhaps a sysfs knob or driver parameter could be added to
> > enable the CYCLE csr in U-mode?
>
> Before we think about sysfs knob or driver parameter, I would suggest
> you to explore approaches of knowing timer frequency in DPDK.

If device tree is exposed via procfs then you can know the TIME csr
frequency by reading:
/proc/device-tree/cpus/timebase-frequency

Regards,
Anup

>
> Regards,
> Anup
>
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > > +{
> > > +     /* Disable all counters access for user mode now */
> > > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +
> > > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > > +{
> > > +     struct riscv_pmu *pmu = NULL;
> > > +     int num_counters;
> > > +
> > > +     pmu = riscv_pmu_alloc();
> > > +     if (!pmu)
> > > +             return -ENOMEM;
> > > +
> > > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > > +             /* Fall back to the legacy implementation */
> > > +             riscv_pmu_legacy_init(pmu);
> > > +             return 0;
> > > +     }
> > > +
> > > +     pr_info("SBI PMU extension is available\n");
> > > +
> > > +     num_counters = pmu_sbi_find_num_ctrs();
> > > +     if (num_counters < 0) {
> > > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > > +             return -ENODEV;
> > > +     }
> > > +
> > > +     /* cache all the information about counters now */
> > > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > > +             return -ENODEV;
> > > +
> > > +     pmu->num_counters = num_counters;
> > > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > > +     pmu->event_map = pmu_sbi_event_map;
> > > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > > +
> > > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > > +
> > > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > > +                       "perf/riscv/pmu:starting",
> > > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static struct platform_driver pmu_sbi_driver = {
> > > +     .probe          = pmu_sbi_device_probe,
> > > +     .driver         = {
> > > +             .name   = RISCV_PMU_PDEV_NAME,
> > > +     },
> > > +};
> > > +
> > > +static int __init pmu_sbi_devinit(void)
> > > +{
> > > +     int ret;
> > > +     struct platform_device *pdev;
> > > +
> > > +     ret = platform_driver_register(&pmu_sbi_driver);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > > +     if (IS_ERR(pdev)) {
> > > +             platform_driver_unregister(&pmu_sbi_driver);
> > > +             return PTR_ERR(pdev);
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +device_initcall(pmu_sbi_devinit)
> > > --
> > > 2.25.1
> > >
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> > --
> > Best Regards,
> > Stanislaw Kardach

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
@ 2021-06-01 15:57         ` Anup Patel
  0 siblings, 0 replies; 28+ messages in thread
From: Anup Patel @ 2021-06-01 15:57 UTC (permalink / raw)
  To: Stanislaw Kardach
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 1, 2021 at 9:18 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
> >
> > On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > > RISC-V SBI specification added a PMU extension that allows to configure
> > > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > > perf features except interrupt overflow and event filtering based on
> > > privilege mode which will be added in future.
> > >
> > > It also allows to monitor a handful of firmware counters that can provide
> > > insights into firmware activity during a performance analysis.
> > >
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > ---
> > >  drivers/perf/Kconfig         |   8 +
> > >  drivers/perf/Makefile        |   1 +
> > >  drivers/perf/riscv_pmu.c     |   2 +
> > >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> > >  4 files changed, 548 insertions(+)
> > >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> > >
> > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > > index 1546a487d970..2acb5feaab35 100644
> > > --- a/drivers/perf/Kconfig
> > > +++ b/drivers/perf/Kconfig
> > > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> > >         implementation on RISC-V based systems. This only allows counting
> > >         of cycle/instruction counter and will be removed in future.
> > >
> > > +config RISCV_PMU_SBI
> > > +     depends on RISCV_PMU
> > > +     bool "RISC-V PMU based on SBI PMU extension"
> > > +     default y
> > > +     help
> > > +       Say y if you want to use the CPU performance monitor
> > > +       using SBI PMU extension on RISC-V based systems.
> > > +
> > >  config ARM_PMU_ACPI
> > >       depends on ARM_PMU && ACPI
> > >       def_bool y
> > > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > > index e8aa666a9d28..7bcac4b5a983 100644
> > > --- a/drivers/perf/Makefile
> > > +++ b/drivers/perf/Makefile
> > > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> > >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> > >  ifeq ($(CONFIG_RISCV_PMU), y)
> > >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> > >  endif
> > >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> > >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > > index c184aa50134d..596af3a40948 100644
> > > --- a/drivers/perf/riscv_pmu.c
> > > +++ b/drivers/perf/riscv_pmu.c
> > > @@ -15,6 +15,8 @@
> > >  #include <linux/printk.h>
> > >  #include <linux/smp.h>
> > >
> > > +#include <asm/sbi.h>
> > > +
> > >  static unsigned long csr_read_num(int csr_num)
> > >  {
> > >  #define switchcase_csr_read(__csr_num, __val)                {\
> > > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > > new file mode 100644
> > > index 000000000000..80dd1de428c4
> > > --- /dev/null
> > > +++ b/drivers/perf/riscv_pmu_sbi.c
> > > @@ -0,0 +1,537 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * RISC-V performance counter support.
> > > + *
> > > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > > + *
> > > + * This code is based on ARM perf event code which is in turn based on
> > > + * sparc64 and x86 code.
> > > + */
> > > +
> > > +#include <linux/mod_devicetable.h>
> > > +#include <linux/perf/riscv_pmu.h>
> > > +#include <linux/platform_device.h>
> > > +
> > > +#include <asm/sbi.h>
> > > +
> > > +union sbi_pmu_ctr_info {
> > > +     unsigned long value;
> > > +     struct {
> > > +             unsigned long csr:12;
> > > +             unsigned long width:6;
> > > +#if __riscv_xlen == 32
> > > +             unsigned long reserved:13;
> > > +#else
> > > +             unsigned long reserved:45;
> > > +#endif
> > > +             unsigned long type:1;
> > > +     };
> > > +};
> > > +
> > > +/**
> > > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > > + * per_cpu in case of harts with different pmu counters
> > > + */
> > > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > > +
> > > +struct pmu_event_data {
> > > +     union {
> > > +             union {
> > > +                     struct hw_gen_event {
> > > +                             uint32_t event_code:16;
> > > +                             uint32_t event_type:4;
> > > +                             uint32_t reserved:12;
> > > +                     } hw_gen_event;
> > > +                     struct hw_cache_event {
> > > +                             uint32_t result_id:1;
> > > +                             uint32_t op_id:2;
> > > +                             uint32_t cache_id:13;
> > > +                             uint32_t event_type:4;
> > > +                             uint32_t reserved:12;
> > > +                     } hw_cache_event;
> > > +             };
> > > +             uint32_t event_idx;
> > > +     };
> > > +};
> > > +
> > > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > +};
> > > +
> > > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > > +     [C(L1D)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(L1I)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(LL)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(DTLB)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(ITLB)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(BPU)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +     [C(NODE)] = {
> > > +             [C(OP_READ)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_WRITE)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +             [C(OP_PREFETCH)] = {
> > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > +             },
> > > +     },
> > > +};
> > > +
> > > +static int pmu_sbi_ctr_get_width(int idx)
> > > +{
> > > +     return pmu_ctr_list[idx].width;
> > > +}
> > > +
> > > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > > +{
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     struct sbiret ret;
> > > +     int idx;
> > > +     uint64_t cbase = 0;
> > > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > > +     unsigned long cflags = 0;
> > > +
> > > +     /* retrieve the available counter index */
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > > +                     cflags, hwc->event_base, hwc->config, 0);
> > > +     if (ret.error) {
> > > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > > +                     hwc->event_base, hwc->config);
> > > +             return sbi_err_map_linux_errno(ret.error);
> > > +     }
> > > +
> > > +     idx = ret.value;
> > > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > > +             return -ENOENT;
> > > +
> > > +     /* Additional sanity check for the counter id */
> > > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > > +             return idx;
> > > +     else
> > > +             return -ENOENT;
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > > +{
> > > +
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     int idx = hwc->idx;
> > > +
> > > +     clear_bit(idx, cpuc->used_event_ctrs);
> > > +}
> > > +
> > > +static int pmu_event_find_cache(u64 config)
> > > +{
> > > +     unsigned int cache_type, cache_op, cache_result, ret;
> > > +
> > > +     cache_type = (config >>  0) & 0xff;
> > > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     cache_op = (config >>  8) & 0xff;
> > > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     cache_result = (config >> 16) & 0xff;
> > > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > > +             return -EINVAL;
> > > +
> > > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > > +{
> > > +     u32 type = event->attr.type;
> > > +     u64 config = event->attr.config;
> > > +
> > > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > > +             return true;
> > > +     else
> > > +             return false;
> > > +}
> > > +
> > > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > > +{
> > > +     u32 type = event->attr.type;
> > > +     u64 config = event->attr.config;
> > > +     int bSoftware;
> > > +     u64 raw_config_val;
> > > +     int ret;
> > > +
> > > +     switch (type) {
> > > +     case PERF_TYPE_HARDWARE:
> > > +             if (config >= PERF_COUNT_HW_MAX)
> > > +                     return -EINVAL;
> > > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > > +             break;
> > > +     case PERF_TYPE_HW_CACHE:
> > > +             ret = pmu_event_find_cache(config);
> > > +             break;
> > > +     case PERF_TYPE_RAW:
> > > +             /*
> > > +              * As per SBI specification, the upper 7 bits must be unused for
> > > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > > +              * raw event and firmware events.
> > > +              */
> > > +             bSoftware = config >> 63;
> > > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > > +             if (bSoftware) {
> > > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > > +                             ret = (raw_config_val & 0xFFFF) |
> > > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > > +                     else
> > > +                             return -EINVAL;
> > > +             } else {
> > > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > > +                     *econfig = raw_config_val;
> > > +             }
> > > +             break;
> > > +     default:
> > > +             ret = -EINVAL;
> > > +             break;
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > > +{
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     int idx = hwc->idx;
> > > +     struct sbiret ret;
> > > +     union sbi_pmu_ctr_info info;
> > > +     u64 val = 0;
> > > +
> > > +     if (pmu_sbi_is_fw_event(event)) {
> > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > > +                             hwc->idx, 0, 0, 0, 0, 0);
> > > +             if (!ret.error)
> > > +                     val = ret.value;
> > > +     } else {
> > > +             info = pmu_ctr_list[idx];
> > > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > > +             if (IS_ENABLED(CONFIG_32BIT))
> > > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > > +     }
> > > +
> > > +     return val;
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > > +{
> > > +     struct sbiret ret;
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > > +                     1, 1, ival, 0, 0);
> > > +     if (ret.error)
> > > +             pr_err("Starting counter idx %d failed with error %d\n",
> > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > +}
> > > +
> > > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > > +{
> > > +     struct sbiret ret;
> > > +     struct hw_perf_event *hwc = &event->hw;
> > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > +     unsigned long flag = 0;
> > > +
> > > +     if (cpuc->events[hwc->idx] == NULL)
> > > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > > +     if (ret.error)
> > > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > +}
> > > +
> > > +static int pmu_sbi_find_num_ctrs(void)
> > > +{
> > > +     struct sbiret ret;
> > > +
> > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > > +     if (!ret.error)
> > > +             return ret.value;
> > > +     else
> > > +             return sbi_err_map_linux_errno(ret.error);
> > > +}
> > > +
> > > +static int pmu_sbi_get_ctrinfo(int nctr)
> > > +{
> > > +     struct sbiret ret;
> > > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > > +     union sbi_pmu_ctr_info cinfo;
> > > +
> > > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > > +     if (!pmu_ctr_list)
> > > +             return -ENOMEM;
> > > +
> > > +     for (i = 0; i <= nctr; i++) {
> > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > > +             if (ret.error)
> > > +                     /* The logical counter ids are not expected to be contiguous */
> > > +                     continue;
> > > +             cinfo.value = ret.value;
> > > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > > +                     num_fw_ctr++;
> > > +             else
> > > +                     num_hw_ctr++;
> > > +             pmu_ctr_list[i].value = cinfo.value;
> > > +     }
> > > +
> > > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > > +             num_fw_ctr, num_hw_ctr);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > > +{
> > > +     /* Enable the access for TIME csr only from the user mode now */
> > > +     csr_write(CSR_SCOUNTEREN, 0x2);
> > Would it be possible to also enable CYCLE csr here (and I guess same
> > would propagate to mcounteren logic in the opensbi patches)? Are there
> > any security concerns in allowing applications to read it directly?
>
> If CYCLE csr is always enabled then a process can get cycle count of
> all process and underlying kernel. This means process A can now
> estimate code path taken by process B based on observing variations
> in CYCLE csr values. This certainly seems like a back-door channel
> being opened up.
>
> Ideally, a process should only see CPU cycles consumed by the
> process itself. Same rationale applies to Guest/VM as well.
>
> >
> > It would be useful given that the frequency of TIME is not fixed in spec
> > and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> > csr might be useful to userspace applications (i.e. DPDK) with obvious
> > limitations such as gating via WFI or value changes when using perf.
>
> CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
> is same as CPU frequency and RISC-V platforms might support
> CPU frequency scaling as well in which case CYCLE csr frequency
> can change at runtime.
>
> On other hand, it is much simpler to expose timer frequency to
> user space via procfs or sysfs. In fact, RISC-V platform will always
> have fixed frequency for TIME csr irrespective to underlying CPU
> frequency.
>
> >
> > For context: there was a similar situation with arm64 at the point of
> > DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> > not its frequency which usually was ~100MHz. The PMU cycle counter
> > (PMCCNTR) was by default disabled for read from userspace (EL0). This
> > required DPDK folks to create a kernel module to enable the PMCCNTR in
> > userspace so that they could implement high-resolution rte_rdtsc() call.
> > This got fixed in Armv8.6-A which specified the timer counter frequency
> > to be 1GHz.
> >
> > If the CYCLE csr remains S-mode private, I will have to effectively
> > resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> > Alternatively perhaps a sysfs knob or driver parameter could be added to
> > enable the CYCLE csr in U-mode?
>
> Before we think about sysfs knob or driver parameter, I would suggest
> you to explore approaches of knowing timer frequency in DPDK.

If device tree is exposed via procfs then you can know the TIME csr
frequency by reading:
/proc/device-tree/cpus/timebase-frequency

Regards,
Anup

>
> Regards,
> Anup
>
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > > +{
> > > +     /* Disable all counters access for user mode now */
> > > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +
> > > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > > +{
> > > +     struct riscv_pmu *pmu = NULL;
> > > +     int num_counters;
> > > +
> > > +     pmu = riscv_pmu_alloc();
> > > +     if (!pmu)
> > > +             return -ENOMEM;
> > > +
> > > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > > +             /* Fall back to the legacy implementation */
> > > +             riscv_pmu_legacy_init(pmu);
> > > +             return 0;
> > > +     }
> > > +
> > > +     pr_info("SBI PMU extension is available\n");
> > > +
> > > +     num_counters = pmu_sbi_find_num_ctrs();
> > > +     if (num_counters < 0) {
> > > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > > +             return -ENODEV;
> > > +     }
> > > +
> > > +     /* cache all the information about counters now */
> > > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > > +             return -ENODEV;
> > > +
> > > +     pmu->num_counters = num_counters;
> > > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > > +     pmu->event_map = pmu_sbi_event_map;
> > > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > > +
> > > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > > +
> > > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > > +                       "perf/riscv/pmu:starting",
> > > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static struct platform_driver pmu_sbi_driver = {
> > > +     .probe          = pmu_sbi_device_probe,
> > > +     .driver         = {
> > > +             .name   = RISCV_PMU_PDEV_NAME,
> > > +     },
> > > +};
> > > +
> > > +static int __init pmu_sbi_devinit(void)
> > > +{
> > > +     int ret;
> > > +     struct platform_device *pdev;
> > > +
> > > +     ret = platform_driver_register(&pmu_sbi_driver);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > > +     if (IS_ERR(pdev)) {
> > > +             platform_driver_unregister(&pmu_sbi_driver);
> > > +             return PTR_ERR(pdev);
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +device_initcall(pmu_sbi_devinit)
> > > --
> > > 2.25.1
> > >
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> > --
> > Best Regards,
> > Stanislaw Kardach

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
  2021-06-01 15:57         ` Anup Patel
@ 2021-06-01 17:08           ` Stanislaw Kardach
  -1 siblings, 0 replies; 28+ messages in thread
From: Stanislaw Kardach @ 2021-06-01 17:08 UTC (permalink / raw)
  To: Anup Patel
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 01, 2021 at 09:27:50PM +0530, Anup Patel wrote:
> On Tue, Jun 1, 2021 at 9:18 PM Anup Patel <anup@brainfault.org> wrote:
> >
> > On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
> > >
> > > On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > > > RISC-V SBI specification added a PMU extension that allows to configure
> > > > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > > > perf features except interrupt overflow and event filtering based on
> > > > privilege mode which will be added in future.
> > > >
> > > > It also allows to monitor a handful of firmware counters that can provide
> > > > insights into firmware activity during a performance analysis.
> > > >
> > > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > > ---
> > > >  drivers/perf/Kconfig         |   8 +
> > > >  drivers/perf/Makefile        |   1 +
> > > >  drivers/perf/riscv_pmu.c     |   2 +
> > > >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> > > >  4 files changed, 548 insertions(+)
> > > >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> > > >
> > > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > > > index 1546a487d970..2acb5feaab35 100644
> > > > --- a/drivers/perf/Kconfig
> > > > +++ b/drivers/perf/Kconfig
> > > > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> > > >         implementation on RISC-V based systems. This only allows counting
> > > >         of cycle/instruction counter and will be removed in future.
> > > >
> > > > +config RISCV_PMU_SBI
> > > > +     depends on RISCV_PMU
> > > > +     bool "RISC-V PMU based on SBI PMU extension"
> > > > +     default y
> > > > +     help
> > > > +       Say y if you want to use the CPU performance monitor
> > > > +       using SBI PMU extension on RISC-V based systems.
> > > > +
> > > >  config ARM_PMU_ACPI
> > > >       depends on ARM_PMU && ACPI
> > > >       def_bool y
> > > > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > > > index e8aa666a9d28..7bcac4b5a983 100644
> > > > --- a/drivers/perf/Makefile
> > > > +++ b/drivers/perf/Makefile
> > > > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> > > >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> > > >  ifeq ($(CONFIG_RISCV_PMU), y)
> > > >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > > > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> > > >  endif
> > > >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> > > >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > > > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > > > index c184aa50134d..596af3a40948 100644
> > > > --- a/drivers/perf/riscv_pmu.c
> > > > +++ b/drivers/perf/riscv_pmu.c
> > > > @@ -15,6 +15,8 @@
> > > >  #include <linux/printk.h>
> > > >  #include <linux/smp.h>
> > > >
> > > > +#include <asm/sbi.h>
> > > > +
> > > >  static unsigned long csr_read_num(int csr_num)
> > > >  {
> > > >  #define switchcase_csr_read(__csr_num, __val)                {\
> > > > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > > > new file mode 100644
> > > > index 000000000000..80dd1de428c4
> > > > --- /dev/null
> > > > +++ b/drivers/perf/riscv_pmu_sbi.c
> > > > @@ -0,0 +1,537 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * RISC-V performance counter support.
> > > > + *
> > > > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > > > + *
> > > > + * This code is based on ARM perf event code which is in turn based on
> > > > + * sparc64 and x86 code.
> > > > + */
> > > > +
> > > > +#include <linux/mod_devicetable.h>
> > > > +#include <linux/perf/riscv_pmu.h>
> > > > +#include <linux/platform_device.h>
> > > > +
> > > > +#include <asm/sbi.h>
> > > > +
> > > > +union sbi_pmu_ctr_info {
> > > > +     unsigned long value;
> > > > +     struct {
> > > > +             unsigned long csr:12;
> > > > +             unsigned long width:6;
> > > > +#if __riscv_xlen == 32
> > > > +             unsigned long reserved:13;
> > > > +#else
> > > > +             unsigned long reserved:45;
> > > > +#endif
> > > > +             unsigned long type:1;
> > > > +     };
> > > > +};
> > > > +
> > > > +/**
> > > > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > > > + * per_cpu in case of harts with different pmu counters
> > > > + */
> > > > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > > > +
> > > > +struct pmu_event_data {
> > > > +     union {
> > > > +             union {
> > > > +                     struct hw_gen_event {
> > > > +                             uint32_t event_code:16;
> > > > +                             uint32_t event_type:4;
> > > > +                             uint32_t reserved:12;
> > > > +                     } hw_gen_event;
> > > > +                     struct hw_cache_event {
> > > > +                             uint32_t result_id:1;
> > > > +                             uint32_t op_id:2;
> > > > +                             uint32_t cache_id:13;
> > > > +                             uint32_t event_type:4;
> > > > +                             uint32_t reserved:12;
> > > > +                     } hw_cache_event;
> > > > +             };
> > > > +             uint32_t event_idx;
> > > > +     };
> > > > +};
> > > > +
> > > > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > > > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +};
> > > > +
> > > > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > > > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > > > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > > > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > > > +     [C(L1D)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(L1I)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > > > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(LL)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(DTLB)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(ITLB)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(BPU)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(NODE)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +};
> > > > +
> > > > +static int pmu_sbi_ctr_get_width(int idx)
> > > > +{
> > > > +     return pmu_ctr_list[idx].width;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > > > +{
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     struct sbiret ret;
> > > > +     int idx;
> > > > +     uint64_t cbase = 0;
> > > > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > > > +     unsigned long cflags = 0;
> > > > +
> > > > +     /* retrieve the available counter index */
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > > > +                     cflags, hwc->event_base, hwc->config, 0);
> > > > +     if (ret.error) {
> > > > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > > > +                     hwc->event_base, hwc->config);
> > > > +             return sbi_err_map_linux_errno(ret.error);
> > > > +     }
> > > > +
> > > > +     idx = ret.value;
> > > > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > > > +             return -ENOENT;
> > > > +
> > > > +     /* Additional sanity check for the counter id */
> > > > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > > > +             return idx;
> > > > +     else
> > > > +             return -ENOENT;
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > > > +{
> > > > +
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     int idx = hwc->idx;
> > > > +
> > > > +     clear_bit(idx, cpuc->used_event_ctrs);
> > > > +}
> > > > +
> > > > +static int pmu_event_find_cache(u64 config)
> > > > +{
> > > > +     unsigned int cache_type, cache_op, cache_result, ret;
> > > > +
> > > > +     cache_type = (config >>  0) & 0xff;
> > > > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     cache_op = (config >>  8) & 0xff;
> > > > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     cache_result = (config >> 16) & 0xff;
> > > > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +
> > > > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > > > +{
> > > > +     u32 type = event->attr.type;
> > > > +     u64 config = event->attr.config;
> > > > +
> > > > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > > > +             return true;
> > > > +     else
> > > > +             return false;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > > > +{
> > > > +     u32 type = event->attr.type;
> > > > +     u64 config = event->attr.config;
> > > > +     int bSoftware;
> > > > +     u64 raw_config_val;
> > > > +     int ret;
> > > > +
> > > > +     switch (type) {
> > > > +     case PERF_TYPE_HARDWARE:
> > > > +             if (config >= PERF_COUNT_HW_MAX)
> > > > +                     return -EINVAL;
> > > > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > > > +             break;
> > > > +     case PERF_TYPE_HW_CACHE:
> > > > +             ret = pmu_event_find_cache(config);
> > > > +             break;
> > > > +     case PERF_TYPE_RAW:
> > > > +             /*
> > > > +              * As per SBI specification, the upper 7 bits must be unused for
> > > > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > > > +              * raw event and firmware events.
> > > > +              */
> > > > +             bSoftware = config >> 63;
> > > > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > > > +             if (bSoftware) {
> > > > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > > > +                             ret = (raw_config_val & 0xFFFF) |
> > > > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > > > +                     else
> > > > +                             return -EINVAL;
> > > > +             } else {
> > > > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > > > +                     *econfig = raw_config_val;
> > > > +             }
> > > > +             break;
> > > > +     default:
> > > > +             ret = -EINVAL;
> > > > +             break;
> > > > +     }
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +
> > > > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > > > +{
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     int idx = hwc->idx;
> > > > +     struct sbiret ret;
> > > > +     union sbi_pmu_ctr_info info;
> > > > +     u64 val = 0;
> > > > +
> > > > +     if (pmu_sbi_is_fw_event(event)) {
> > > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > > > +                             hwc->idx, 0, 0, 0, 0, 0);
> > > > +             if (!ret.error)
> > > > +                     val = ret.value;
> > > > +     } else {
> > > > +             info = pmu_ctr_list[idx];
> > > > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > > > +             if (IS_ENABLED(CONFIG_32BIT))
> > > > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > > > +     }
> > > > +
> > > > +     return val;
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > > > +                     1, 1, ival, 0, 0);
> > > > +     if (ret.error)
> > > > +             pr_err("Starting counter idx %d failed with error %d\n",
> > > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     unsigned long flag = 0;
> > > > +
> > > > +     if (cpuc->events[hwc->idx] == NULL)
> > > > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > > > +     if (ret.error)
> > > > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > > +}
> > > > +
> > > > +static int pmu_sbi_find_num_ctrs(void)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > > > +     if (!ret.error)
> > > > +             return ret.value;
> > > > +     else
> > > > +             return sbi_err_map_linux_errno(ret.error);
> > > > +}
> > > > +
> > > > +static int pmu_sbi_get_ctrinfo(int nctr)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > > > +     union sbi_pmu_ctr_info cinfo;
> > > > +
> > > > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > > > +     if (!pmu_ctr_list)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     for (i = 0; i <= nctr; i++) {
> > > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > > > +             if (ret.error)
> > > > +                     /* The logical counter ids are not expected to be contiguous */
> > > > +                     continue;
> > > > +             cinfo.value = ret.value;
> > > > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > > > +                     num_fw_ctr++;
> > > > +             else
> > > > +                     num_hw_ctr++;
> > > > +             pmu_ctr_list[i].value = cinfo.value;
> > > > +     }
> > > > +
> > > > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > > > +             num_fw_ctr, num_hw_ctr);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > > > +{
> > > > +     /* Enable the access for TIME csr only from the user mode now */
> > > > +     csr_write(CSR_SCOUNTEREN, 0x2);
> > > Would it be possible to also enable CYCLE csr here (and I guess same
> > > would propagate to mcounteren logic in the opensbi patches)? Are there
> > > any security concerns in allowing applications to read it directly?
> >
> > If CYCLE csr is always enabled then a process can get cycle count of
> > all process and underlying kernel. This means process A can now
> > estimate code path taken by process B based on observing variations
> > in CYCLE csr values. This certainly seems like a back-door channel
> > being opened up.
> >
> > Ideally, a process should only see CPU cycles consumed by the
> > process itself. Same rationale applies to Guest/VM as well.
That makes sense, the default-on sounds like a bad idea.
> >
> > >
> > > It would be useful given that the frequency of TIME is not fixed in spec
> > > and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> > > csr might be useful to userspace applications (i.e. DPDK) with obvious
> > > limitations such as gating via WFI or value changes when using perf.
> >
> > CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
> > is same as CPU frequency and RISC-V platforms might support
> > CPU frequency scaling as well in which case CYCLE csr frequency
> > can change at runtime.
Correct. Same pronlrmd applied to arm64 arch and their cycle counter.
However for a 10GbE link the time budget for a single packet is 67ns
(~14e9 packets/second). So one can't do any accurate performance
measurements with 100MHz timer.
In those cases frequency scaling was usually disabled, 1 thread per core
only and context switches limited to a minimum, so cycle counter was
usable.
Once energy saving awareness kicked in, it wasn't, hence why Armv8.6-A
mandated a 1GHz timer counter. We don't have that in RISC-V, so hence
I'm talking about optionaly exposing CYCLE to U-mode.
> >
> > On other hand, it is much simpler to expose timer frequency to
> > user space via procfs or sysfs. In fact, RISC-V platform will always
> > have fixed frequency for TIME csr irrespective to underlying CPU
> > frequency.
As you have mentioned, it already is via FDT. If UEFI ever comes into
picture this will have to either revert back to a register or maybe part
of /proc/cpuinfo.

In general time-measurement scenarios TIME is enough. For high
performance scenarios (see above) 1MHz or even 100MHz is not enough.
Ideal solution would be to have a high-resolution TIME, however on
platforms that don't have it, there will be a need for a work-around and
I expect people will just use custom modules. Same as they did on arm64.

My intention here is just to point out a scenario that will come
eventually. Unless RISC-V spec mandates high-resolution counter or it
becomes a de-facto standard among platform implementers.
> >
> > >
> > > For context: there was a similar situation with arm64 at the point of
> > > DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> > > not its frequency which usually was ~100MHz. The PMU cycle counter
> > > (PMCCNTR) was by default disabled for read from userspace (EL0). This
> > > required DPDK folks to create a kernel module to enable the PMCCNTR in
> > > userspace so that they could implement high-resolution rte_rdtsc() call.
> > > This got fixed in Armv8.6-A which specified the timer counter frequency
> > > to be 1GHz.
> > >
> > > If the CYCLE csr remains S-mode private, I will have to effectively
> > > resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> > > Alternatively perhaps a sysfs knob or driver parameter could be added to
> > > enable the CYCLE csr in U-mode?
> >
> > Before we think about sysfs knob or driver parameter, I would suggest
> > you to explore approaches of knowing timer frequency in DPDK.
> 
> If device tree is exposed via procfs then you can know the TIME csr
> frequency by reading:
> /proc/device-tree/cpus/timebase-frequency
> 
> Regards,
> Anup
> 
> >
> > Regards,
> > Anup
> >
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > > > +{
> > > > +     /* Disable all counters access for user mode now */
> > > > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +
> > > > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > > > +{
> > > > +     struct riscv_pmu *pmu = NULL;
> > > > +     int num_counters;
> > > > +
> > > > +     pmu = riscv_pmu_alloc();
> > > > +     if (!pmu)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > > > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > > > +             /* Fall back to the legacy implementation */
> > > > +             riscv_pmu_legacy_init(pmu);
> > > > +             return 0;
> > > > +     }
> > > > +
> > > > +     pr_info("SBI PMU extension is available\n");
> > > > +
> > > > +     num_counters = pmu_sbi_find_num_ctrs();
> > > > +     if (num_counters < 0) {
> > > > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > > > +             return -ENODEV;
> > > > +     }
> > > > +
> > > > +     /* cache all the information about counters now */
> > > > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > > > +             return -ENODEV;
> > > > +
> > > > +     pmu->num_counters = num_counters;
> > > > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > > > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > > > +     pmu->event_map = pmu_sbi_event_map;
> > > > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > > > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > > > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > > > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > > > +
> > > > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > > > +
> > > > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > > > +                       "perf/riscv/pmu:starting",
> > > > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static struct platform_driver pmu_sbi_driver = {
> > > > +     .probe          = pmu_sbi_device_probe,
> > > > +     .driver         = {
> > > > +             .name   = RISCV_PMU_PDEV_NAME,
> > > > +     },
> > > > +};
> > > > +
> > > > +static int __init pmu_sbi_devinit(void)
> > > > +{
> > > > +     int ret;
> > > > +     struct platform_device *pdev;
> > > > +
> > > > +     ret = platform_driver_register(&pmu_sbi_driver);
> > > > +     if (ret)
> > > > +             return ret;
> > > > +
> > > > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > > > +     if (IS_ERR(pdev)) {
> > > > +             platform_driver_unregister(&pmu_sbi_driver);
> > > > +             return PTR_ERR(pdev);
> > > > +     }
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +device_initcall(pmu_sbi_devinit)
> > > > --
> > > > 2.25.1
> > > >
> > > >
> > > > _______________________________________________
> > > > linux-riscv mailing list
> > > > linux-riscv@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> > >
> > > --
> > > Best Regards,
> > > Stanislaw Kardach

-- 
Best Regards,
Stanislaw Kardach

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension
@ 2021-06-01 17:08           ` Stanislaw Kardach
  0 siblings, 0 replies; 28+ messages in thread
From: Stanislaw Kardach @ 2021-06-01 17:08 UTC (permalink / raw)
  To: Anup Patel
  Cc: Atish Patra, linux-kernel@vger.kernel.org List, Anup Patel, bpf,
	Daniel Lezcano, Guo Ren, Heinrich Schuchardt, Kefeng Wang,
	linux-doc, linux-perf-users, linux-riscv, Nick Kossifidis,
	Palmer Dabbelt, Paul Walmsley, Alan Kao, Nick Hu, Vincent Chen

On Tue, Jun 01, 2021 at 09:27:50PM +0530, Anup Patel wrote:
> On Tue, Jun 1, 2021 at 9:18 PM Anup Patel <anup@brainfault.org> wrote:
> >
> > On Tue, Jun 1, 2021 at 6:40 PM Stanislaw Kardach <kda@semihalf.com> wrote:
> > >
> > > On Fri, May 28, 2021 at 11:44:04AM -0700, Atish Patra wrote:
> > > > RISC-V SBI specification added a PMU extension that allows to configure
> > > > /start/stop any pmu counter. The RISC-V perf can use most of the generic
> > > > perf features except interrupt overflow and event filtering based on
> > > > privilege mode which will be added in future.
> > > >
> > > > It also allows to monitor a handful of firmware counters that can provide
> > > > insights into firmware activity during a performance analysis.
> > > >
> > > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > > ---
> > > >  drivers/perf/Kconfig         |   8 +
> > > >  drivers/perf/Makefile        |   1 +
> > > >  drivers/perf/riscv_pmu.c     |   2 +
> > > >  drivers/perf/riscv_pmu_sbi.c | 537 +++++++++++++++++++++++++++++++++++
> > > >  4 files changed, 548 insertions(+)
> > > >  create mode 100644 drivers/perf/riscv_pmu_sbi.c
> > > >
> > > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > > > index 1546a487d970..2acb5feaab35 100644
> > > > --- a/drivers/perf/Kconfig
> > > > +++ b/drivers/perf/Kconfig
> > > > @@ -73,6 +73,14 @@ config RISCV_PMU_LEGACY
> > > >         implementation on RISC-V based systems. This only allows counting
> > > >         of cycle/instruction counter and will be removed in future.
> > > >
> > > > +config RISCV_PMU_SBI
> > > > +     depends on RISCV_PMU
> > > > +     bool "RISC-V PMU based on SBI PMU extension"
> > > > +     default y
> > > > +     help
> > > > +       Say y if you want to use the CPU performance monitor
> > > > +       using SBI PMU extension on RISC-V based systems.
> > > > +
> > > >  config ARM_PMU_ACPI
> > > >       depends on ARM_PMU && ACPI
> > > >       def_bool y
> > > > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > > > index e8aa666a9d28..7bcac4b5a983 100644
> > > > --- a/drivers/perf/Makefile
> > > > +++ b/drivers/perf/Makefile
> > > > @@ -13,6 +13,7 @@ obj-$(CONFIG_QCOM_L3_PMU) += qcom_l3_pmu.o
> > > >  obj-$(CONFIG_RISCV_PMU) += riscv_pmu.o
> > > >  ifeq ($(CONFIG_RISCV_PMU), y)
> > > >  obj-$(CONFIG_RISCV_PMU_LEGACY) += riscv_pmu_legacy.o
> > > > +obj-$(CONFIG_RISCV_PMU_SBI) += riscv_pmu_sbi.o
> > > >  endif
> > > >  obj-$(CONFIG_THUNDERX2_PMU) += thunderx2_pmu.o
> > > >  obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
> > > > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > > > index c184aa50134d..596af3a40948 100644
> > > > --- a/drivers/perf/riscv_pmu.c
> > > > +++ b/drivers/perf/riscv_pmu.c
> > > > @@ -15,6 +15,8 @@
> > > >  #include <linux/printk.h>
> > > >  #include <linux/smp.h>
> > > >
> > > > +#include <asm/sbi.h>
> > > > +
> > > >  static unsigned long csr_read_num(int csr_num)
> > > >  {
> > > >  #define switchcase_csr_read(__csr_num, __val)                {\
> > > > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > > > new file mode 100644
> > > > index 000000000000..80dd1de428c4
> > > > --- /dev/null
> > > > +++ b/drivers/perf/riscv_pmu_sbi.c
> > > > @@ -0,0 +1,537 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * RISC-V performance counter support.
> > > > + *
> > > > + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> > > > + *
> > > > + * This code is based on ARM perf event code which is in turn based on
> > > > + * sparc64 and x86 code.
> > > > + */
> > > > +
> > > > +#include <linux/mod_devicetable.h>
> > > > +#include <linux/perf/riscv_pmu.h>
> > > > +#include <linux/platform_device.h>
> > > > +
> > > > +#include <asm/sbi.h>
> > > > +
> > > > +union sbi_pmu_ctr_info {
> > > > +     unsigned long value;
> > > > +     struct {
> > > > +             unsigned long csr:12;
> > > > +             unsigned long width:6;
> > > > +#if __riscv_xlen == 32
> > > > +             unsigned long reserved:13;
> > > > +#else
> > > > +             unsigned long reserved:45;
> > > > +#endif
> > > > +             unsigned long type:1;
> > > > +     };
> > > > +};
> > > > +
> > > > +/**
> > > > + * RISC-V doesn't have hetergenous harts yet. This need to be part of
> > > > + * per_cpu in case of harts with different pmu counters
> > > > + */
> > > > +static union sbi_pmu_ctr_info *pmu_ctr_list;
> > > > +
> > > > +struct pmu_event_data {
> > > > +     union {
> > > > +             union {
> > > > +                     struct hw_gen_event {
> > > > +                             uint32_t event_code:16;
> > > > +                             uint32_t event_type:4;
> > > > +                             uint32_t reserved:12;
> > > > +                     } hw_gen_event;
> > > > +                     struct hw_cache_event {
> > > > +                             uint32_t result_id:1;
> > > > +                             uint32_t op_id:2;
> > > > +                             uint32_t cache_id:13;
> > > > +                             uint32_t event_type:4;
> > > > +                             uint32_t reserved:12;
> > > > +                     } hw_cache_event;
> > > > +             };
> > > > +             uint32_t event_idx;
> > > > +     };
> > > > +};
> > > > +
> > > > +static const struct pmu_event_data pmu_hw_event_map[] = {
> > > > +     [PERF_COUNT_HW_CPU_CYCLES]              = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CPU_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_INSTRUCTIONS]            = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_INSTRUCTIONS,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_CACHE_REFERENCES]        = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CACHE_REFERENCES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_CACHE_MISSES]            = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_CACHE_MISSES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BRANCH_INSTRUCTIONS,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BRANCH_MISSES]           = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BRANCH_MISSES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_BUS_CYCLES]              = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_BUS_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_STALLED_CYCLES_FRONTEND,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_STALLED_CYCLES_BACKEND,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +     [PERF_COUNT_HW_REF_CPU_CYCLES]          = {.hw_gen_event = {
> > > > +                                                     SBI_PMU_HW_REF_CPU_CYCLES,
> > > > +                                                     SBI_PMU_EVENT_TYPE_HW, 0}},
> > > > +};
> > > > +
> > > > +#define C(x) PERF_COUNT_HW_CACHE_##x
> > > > +static const struct pmu_event_data pmu_cache_event_map[PERF_COUNT_HW_CACHE_MAX]
> > > > +[PERF_COUNT_HW_CACHE_OP_MAX]
> > > > +[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
> > > > +     [C(L1D)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(L1D), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(L1I)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS), C(OP_READ),
> > > > +                                     C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(L1I), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(LL)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(LL), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(DTLB)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(DTLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(ITLB)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(ITLB), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(BPU)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(BPU), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +     [C(NODE)] = {
> > > > +             [C(OP_READ)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_READ), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_WRITE)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_WRITE), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +             [C(OP_PREFETCH)] = {
> > > > +                     [C(RESULT_ACCESS)] = {.hw_cache_event = {C(RESULT_ACCESS),
> > > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +                     [C(RESULT_MISS)] = {.hw_cache_event = {C(RESULT_MISS),
> > > > +                                     C(OP_PREFETCH), C(NODE), SBI_PMU_EVENT_TYPE_CACHE, 0}},
> > > > +             },
> > > > +     },
> > > > +};
> > > > +
> > > > +static int pmu_sbi_ctr_get_width(int idx)
> > > > +{
> > > > +     return pmu_ctr_list[idx].width;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > > > +{
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     struct sbiret ret;
> > > > +     int idx;
> > > > +     uint64_t cbase = 0;
> > > > +     uint64_t cmask = GENMASK_ULL(rvpmu->num_counters - 1, 0);
> > > > +     unsigned long cflags = 0;
> > > > +
> > > > +     /* retrieve the available counter index */
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_CFG_MATCH, cbase, cmask,
> > > > +                     cflags, hwc->event_base, hwc->config, 0);
> > > > +     if (ret.error) {
> > > > +             pr_debug("Not able to find a counter for event %lx config %llx\n",
> > > > +                     hwc->event_base, hwc->config);
> > > > +             return sbi_err_map_linux_errno(ret.error);
> > > > +     }
> > > > +
> > > > +     idx = ret.value;
> > > > +     if (idx >= rvpmu->num_counters || !pmu_ctr_list[idx].value)
> > > > +             return -ENOENT;
> > > > +
> > > > +     /* Additional sanity check for the counter id */
> > > > +     if (!test_and_set_bit(idx, cpuc->used_event_ctrs))
> > > > +             return idx;
> > > > +     else
> > > > +             return -ENOENT;
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_clear_idx(struct perf_event *event)
> > > > +{
> > > > +
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     int idx = hwc->idx;
> > > > +
> > > > +     clear_bit(idx, cpuc->used_event_ctrs);
> > > > +}
> > > > +
> > > > +static int pmu_event_find_cache(u64 config)
> > > > +{
> > > > +     unsigned int cache_type, cache_op, cache_result, ret;
> > > > +
> > > > +     cache_type = (config >>  0) & 0xff;
> > > > +     if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     cache_op = (config >>  8) & 0xff;
> > > > +     if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     cache_result = (config >> 16) & 0xff;
> > > > +     if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
> > > > +             return -EINVAL;
> > > > +
> > > > +     ret = pmu_cache_event_map[cache_type][cache_op][cache_result].event_idx;
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +
> > > > +static bool pmu_sbi_is_fw_event(struct perf_event *event)
> > > > +{
> > > > +     u32 type = event->attr.type;
> > > > +     u64 config = event->attr.config;
> > > > +
> > > > +     if ((type == PERF_TYPE_RAW) && ((config >> 63) == 1))
> > > > +             return true;
> > > > +     else
> > > > +             return false;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
> > > > +{
> > > > +     u32 type = event->attr.type;
> > > > +     u64 config = event->attr.config;
> > > > +     int bSoftware;
> > > > +     u64 raw_config_val;
> > > > +     int ret;
> > > > +
> > > > +     switch (type) {
> > > > +     case PERF_TYPE_HARDWARE:
> > > > +             if (config >= PERF_COUNT_HW_MAX)
> > > > +                     return -EINVAL;
> > > > +             ret = pmu_hw_event_map[event->attr.config].event_idx;
> > > > +             break;
> > > > +     case PERF_TYPE_HW_CACHE:
> > > > +             ret = pmu_event_find_cache(config);
> > > > +             break;
> > > > +     case PERF_TYPE_RAW:
> > > > +             /*
> > > > +              * As per SBI specification, the upper 7 bits must be unused for
> > > > +              * a raw event. Use the MSB (63b) to distinguish between hardware
> > > > +              * raw event and firmware events.
> > > > +              */
> > > > +             bSoftware = config >> 63;
> > > > +             raw_config_val = config & RISCV_PMU_RAW_EVENT_MASK;
> > > > +             if (bSoftware) {
> > > > +                     if (raw_config_val < SBI_PMU_FW_MAX)
> > > > +                             ret = (raw_config_val & 0xFFFF) |
> > > > +                                   (SBI_PMU_EVENT_TYPE_FW << 16);
> > > > +                     else
> > > > +                             return -EINVAL;
> > > > +             } else {
> > > > +                     ret = RISCV_PMU_RAW_EVENT_IDX;
> > > > +                     *econfig = raw_config_val;
> > > > +             }
> > > > +             break;
> > > > +     default:
> > > > +             ret = -EINVAL;
> > > > +             break;
> > > > +     }
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +
> > > > +static u64 pmu_sbi_ctr_read(struct perf_event *event)
> > > > +{
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     int idx = hwc->idx;
> > > > +     struct sbiret ret;
> > > > +     union sbi_pmu_ctr_info info;
> > > > +     u64 val = 0;
> > > > +
> > > > +     if (pmu_sbi_is_fw_event(event)) {
> > > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_FW_READ,
> > > > +                             hwc->idx, 0, 0, 0, 0, 0);
> > > > +             if (!ret.error)
> > > > +                     val = ret.value;
> > > > +     } else {
> > > > +             info = pmu_ctr_list[idx];
> > > > +             val = riscv_pmu_ctr_read_csr(info.csr);
> > > > +             if (IS_ENABLED(CONFIG_32BIT))
> > > > +                     val = ((u64)riscv_pmu_ctr_read_csr(info.csr + 0x80)) << 32 | val;
> > > > +     }
> > > > +
> > > > +     return val;
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_START, hwc->idx,
> > > > +                     1, 1, ival, 0, 0);
> > > > +     if (ret.error)
> > > > +             pr_err("Starting counter idx %d failed with error %d\n",
> > > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > > +}
> > > > +
> > > > +static void pmu_sbi_ctr_stop(struct perf_event *event)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     struct hw_perf_event *hwc = &event->hw;
> > > > +     struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> > > > +     struct cpu_hw_events *cpuc = this_cpu_ptr(rvpmu->hw_events);
> > > > +     unsigned long flag = 0;
> > > > +
> > > > +     if (cpuc->events[hwc->idx] == NULL)
> > > > +             flag = SBI_PMU_STOP_FLAG_RESET;
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0);
> > > > +     if (ret.error)
> > > > +             pr_err("Stopping counter idx %d failed with error %d\n",
> > > > +                     hwc->idx, sbi_err_map_linux_errno(ret.error));
> > > > +}
> > > > +
> > > > +static int pmu_sbi_find_num_ctrs(void)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +
> > > > +     ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_NUM_COUNTERS, 0, 0, 0, 0, 0, 0);
> > > > +     if (!ret.error)
> > > > +             return ret.value;
> > > > +     else
> > > > +             return sbi_err_map_linux_errno(ret.error);
> > > > +}
> > > > +
> > > > +static int pmu_sbi_get_ctrinfo(int nctr)
> > > > +{
> > > > +     struct sbiret ret;
> > > > +     int i, num_hw_ctr = 0, num_fw_ctr = 0;
> > > > +     union sbi_pmu_ctr_info cinfo;
> > > > +
> > > > +     pmu_ctr_list = kzalloc(sizeof(*pmu_ctr_list) * nctr, GFP_KERNEL);
> > > > +     if (!pmu_ctr_list)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     for (i = 0; i <= nctr; i++) {
> > > > +             ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_GET_INFO, i, 0, 0, 0, 0, 0);
> > > > +             if (ret.error)
> > > > +                     /* The logical counter ids are not expected to be contiguous */
> > > > +                     continue;
> > > > +             cinfo.value = ret.value;
> > > > +             if (cinfo.type == SBI_PMU_CTR_TYPE_FW)
> > > > +                     num_fw_ctr++;
> > > > +             else
> > > > +                     num_hw_ctr++;
> > > > +             pmu_ctr_list[i].value = cinfo.value;
> > > > +     }
> > > > +
> > > > +     pr_info("There are %d firmware & %d hardware counters available\n",
> > > > +             num_fw_ctr, num_hw_ctr);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_starting_cpu(unsigned int cpu)
> > > > +{
> > > > +     /* Enable the access for TIME csr only from the user mode now */
> > > > +     csr_write(CSR_SCOUNTEREN, 0x2);
> > > Would it be possible to also enable CYCLE csr here (and I guess same
> > > would propagate to mcounteren logic in the opensbi patches)? Are there
> > > any security concerns in allowing applications to read it directly?
> >
> > If CYCLE csr is always enabled then a process can get cycle count of
> > all process and underlying kernel. This means process A can now
> > estimate code path taken by process B based on observing variations
> > in CYCLE csr values. This certainly seems like a back-door channel
> > being opened up.
> >
> > Ideally, a process should only see CPU cycles consumed by the
> > process itself. Same rationale applies to Guest/VM as well.
That makes sense, the default-on sounds like a bad idea.
> >
> > >
> > > It would be useful given that the frequency of TIME is not fixed in spec
> > > and it may not be enough for a rdtsc-like counter. In such cases CYCLE
> > > csr might be useful to userspace applications (i.e. DPDK) with obvious
> > > limitations such as gating via WFI or value changes when using perf.
> >
> > CYCLE csr frequency is also not fixed. In fact, CYCLE csr frequency
> > is same as CPU frequency and RISC-V platforms might support
> > CPU frequency scaling as well in which case CYCLE csr frequency
> > can change at runtime.
Correct. Same pronlrmd applied to arm64 arch and their cycle counter.
However for a 10GbE link the time budget for a single packet is 67ns
(~14e9 packets/second). So one can't do any accurate performance
measurements with 100MHz timer.
In those cases frequency scaling was usually disabled, 1 thread per core
only and context switches limited to a minimum, so cycle counter was
usable.
Once energy saving awareness kicked in, it wasn't, hence why Armv8.6-A
mandated a 1GHz timer counter. We don't have that in RISC-V, so hence
I'm talking about optionaly exposing CYCLE to U-mode.
> >
> > On other hand, it is much simpler to expose timer frequency to
> > user space via procfs or sysfs. In fact, RISC-V platform will always
> > have fixed frequency for TIME csr irrespective to underlying CPU
> > frequency.
As you have mentioned, it already is via FDT. If UEFI ever comes into
picture this will have to either revert back to a register or maybe part
of /proc/cpuinfo.

In general time-measurement scenarios TIME is enough. For high
performance scenarios (see above) 1MHz or even 100MHz is not enough.
Ideal solution would be to have a high-resolution TIME, however on
platforms that don't have it, there will be a need for a work-around and
I expect people will just use custom modules. Same as they did on arm64.

My intention here is just to point out a scenario that will come
eventually. Unless RISC-V spec mandates high-resolution counter or it
becomes a de-facto standard among platform implementers.
> >
> > >
> > > For context: there was a similar situation with arm64 at the point of
> > > DPDK port to that arch. Armv7-A standardized their timer (CNTVCT) but
> > > not its frequency which usually was ~100MHz. The PMU cycle counter
> > > (PMCCNTR) was by default disabled for read from userspace (EL0). This
> > > required DPDK folks to create a kernel module to enable the PMCCNTR in
> > > userspace so that they could implement high-resolution rte_rdtsc() call.
> > > This got fixed in Armv8.6-A which specified the timer counter frequency
> > > to be 1GHz.
> > >
> > > If the CYCLE csr remains S-mode private, I will have to effectively
> > > resort to the same kernel-module trick as arm64 in the RISC-V DPDK port.
> > > Alternatively perhaps a sysfs knob or driver parameter could be added to
> > > enable the CYCLE csr in U-mode?
> >
> > Before we think about sysfs knob or driver parameter, I would suggest
> > you to explore approaches of knowing timer frequency in DPDK.
> 
> If device tree is exposed via procfs then you can know the TIME csr
> frequency by reading:
> /proc/device-tree/cpus/timebase-frequency
> 
> Regards,
> Anup
> 
> >
> > Regards,
> > Anup
> >
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static int pmu_sbi_dying_cpu(unsigned int cpu)
> > > > +{
> > > > +     /* Disable all counters access for user mode now */
> > > > +     csr_write(CSR_SCOUNTEREN, 0x0);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +
> > > > +static int pmu_sbi_device_probe(struct platform_device *pdev)
> > > > +{
> > > > +     struct riscv_pmu *pmu = NULL;
> > > > +     int num_counters;
> > > > +
> > > > +     pmu = riscv_pmu_alloc();
> > > > +     if (!pmu)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     if (((sbi_major_version() == 0) && (sbi_minor_version() < 3)) ||
> > > > +             sbi_probe_extension(SBI_EXT_PMU) <= 0) {
> > > > +             /* Fall back to the legacy implementation */
> > > > +             riscv_pmu_legacy_init(pmu);
> > > > +             return 0;
> > > > +     }
> > > > +
> > > > +     pr_info("SBI PMU extension is available\n");
> > > > +
> > > > +     num_counters = pmu_sbi_find_num_ctrs();
> > > > +     if (num_counters < 0) {
> > > > +             pr_err("SBI PMU extension doesn't provide any counters\n");
> > > > +             return -ENODEV;
> > > > +     }
> > > > +
> > > > +     /* cache all the information about counters now */
> > > > +     if (pmu_sbi_get_ctrinfo(num_counters))
> > > > +             return -ENODEV;
> > > > +
> > > > +     pmu->num_counters = num_counters;
> > > > +     pmu->ctr_start = pmu_sbi_ctr_start;
> > > > +     pmu->ctr_stop = pmu_sbi_ctr_stop;
> > > > +     pmu->event_map = pmu_sbi_event_map;
> > > > +     pmu->ctr_get_idx = pmu_sbi_ctr_get_idx;
> > > > +     pmu->ctr_get_width = pmu_sbi_ctr_get_width;
> > > > +     pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> > > > +     pmu->ctr_read = pmu_sbi_ctr_read;
> > > > +
> > > > +     perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
> > > > +
> > > > +     cpuhp_setup_state(CPUHP_AP_PERF_RISCV_STARTING,
> > > > +                       "perf/riscv/pmu:starting",
> > > > +                       pmu_sbi_starting_cpu, pmu_sbi_dying_cpu);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +static struct platform_driver pmu_sbi_driver = {
> > > > +     .probe          = pmu_sbi_device_probe,
> > > > +     .driver         = {
> > > > +             .name   = RISCV_PMU_PDEV_NAME,
> > > > +     },
> > > > +};
> > > > +
> > > > +static int __init pmu_sbi_devinit(void)
> > > > +{
> > > > +     int ret;
> > > > +     struct platform_device *pdev;
> > > > +
> > > > +     ret = platform_driver_register(&pmu_sbi_driver);
> > > > +     if (ret)
> > > > +             return ret;
> > > > +
> > > > +     pdev = platform_device_register_simple(RISCV_PMU_PDEV_NAME, -1, NULL, 0);
> > > > +     if (IS_ERR(pdev)) {
> > > > +             platform_driver_unregister(&pmu_sbi_driver);
> > > > +             return PTR_ERR(pdev);
> > > > +     }
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +device_initcall(pmu_sbi_devinit)
> > > > --
> > > > 2.25.1
> > > >
> > > >
> > > > _______________________________________________
> > > > linux-riscv mailing list
> > > > linux-riscv@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> > >
> > > --
> > > Best Regards,
> > > Stanislaw Kardach

-- 
Best Regards,
Stanislaw Kardach

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Not compiling with CONFIG_BPF_SYSCALL enabled
  2021-05-28 18:43   ` Atish Patra
@ 2021-09-01 10:36     ` Nikita Shubin
  -1 siblings, 0 replies; 28+ messages in thread
From: Nikita Shubin @ 2021-09-01 10:36 UTC (permalink / raw)
  To: atish.patra
  Cc: alankao, anup.patel, bpf, daniel.lezcano, guoren, linux-doc,
	linux-kernel, linux-perf-users, linux-riscv, mick, nickhu,
	palmer, paul.walmsley, vincent.chen, wangkefeng.wang,
	xypron.glpk

Hello, Atish.

The above series won't compile with CONFIG_BPF_SYSCALL set:

linux/kernel/events/core.c:9912:18: error: assignment to 
'bpf_user_pt_regs_t *' {aka 'struct user_regs_struct *'} 
from incompatible pointer type 'struct pt_regs *' 
[-Werror=incompatible-pointer-types]
 9912 |         ctx.regs = perf_arch_bpf_user_pt_regs(regs);

Just informing you - hope this is helpful.

Yours,
Nikita Shubin


^ permalink raw reply	[flat|nested] 28+ messages in thread

* Not compiling with CONFIG_BPF_SYSCALL enabled
@ 2021-09-01 10:36     ` Nikita Shubin
  0 siblings, 0 replies; 28+ messages in thread
From: Nikita Shubin @ 2021-09-01 10:36 UTC (permalink / raw)
  To: atish.patra
  Cc: alankao, anup.patel, bpf, daniel.lezcano, guoren, linux-doc,
	linux-kernel, linux-perf-users, linux-riscv, mick, nickhu,
	palmer, paul.walmsley, vincent.chen, wangkefeng.wang,
	xypron.glpk

Hello, Atish.

The above series won't compile with CONFIG_BPF_SYSCALL set:

linux/kernel/events/core.c:9912:18: error: assignment to 
'bpf_user_pt_regs_t *' {aka 'struct user_regs_struct *'} 
from incompatible pointer type 'struct pt_regs *' 
[-Werror=incompatible-pointer-types]
 9912 |         ctx.regs = perf_arch_bpf_user_pt_regs(regs);

Just informing you - hope this is helpful.

Yours,
Nikita Shubin


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: Not compiling with CONFIG_BPF_SYSCALL enabled
  2021-09-01 10:36     ` Nikita Shubin
@ 2021-09-01 15:45       ` Atish Patra
  -1 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-09-01 15:45 UTC (permalink / raw)
  To: nikita.shubin
  Cc: mick, wangkefeng.wang, vincent.chen, palmer, linux-kernel,
	linux-perf-users, paul.walmsley, alankao, nickhu, daniel.lezcano,
	guoren, linux-doc, Anup Patel, bpf, xypron.glpk, linux-riscv

On Wed, 2021-09-01 at 13:36 +0300, Nikita Shubin wrote:
> Hello, Atish.
> 
> The above series won't compile with CONFIG_BPF_SYSCALL set:
> 
> linux/kernel/events/core.c:9912:18: error: assignment to 
> 'bpf_user_pt_regs_t *' {aka 'struct user_regs_struct *'} 
> from incompatible pointer type 'struct pt_regs *' 
> [-Werror=incompatible-pointer-types]
>  9912 |         ctx.regs = perf_arch_bpf_user_pt_regs(regs);
> 
> Just informing you - hope this is helpful.

Thanks for reporting this. I am spinning the v3 of this series. I will
take look.

> 
> Yours,
> Nikita Shubin
> 

-- 
Regards,
Atish

^ permalink raw reply	[flat|nested] 28+ messages in thread

* Re: Not compiling with CONFIG_BPF_SYSCALL enabled
@ 2021-09-01 15:45       ` Atish Patra
  0 siblings, 0 replies; 28+ messages in thread
From: Atish Patra @ 2021-09-01 15:45 UTC (permalink / raw)
  To: nikita.shubin
  Cc: mick, wangkefeng.wang, vincent.chen, palmer, linux-kernel,
	linux-perf-users, paul.walmsley, alankao, nickhu, daniel.lezcano,
	guoren, linux-doc, Anup Patel, bpf, xypron.glpk, linux-riscv

On Wed, 2021-09-01 at 13:36 +0300, Nikita Shubin wrote:
> Hello, Atish.
> 
> The above series won't compile with CONFIG_BPF_SYSCALL set:
> 
> linux/kernel/events/core.c:9912:18: error: assignment to 
> 'bpf_user_pt_regs_t *' {aka 'struct user_regs_struct *'} 
> from incompatible pointer type 'struct pt_regs *' 
> [-Werror=incompatible-pointer-types]
>  9912 |         ctx.regs = perf_arch_bpf_user_pt_regs(regs);
> 
> Just informing you - hope this is helpful.

Thanks for reporting this. I am spinning the v3 of this series. I will
take look.

> 
> Yours,
> Nikita Shubin
> 

-- 
Regards,
Atish
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 28+ messages in thread

end of thread, other threads:[~2021-09-01 15:45 UTC | newest]

Thread overview: 28+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-28 18:43 [RFC v2 0/7] Improve RISC-V Perf support using SBI PMU extension Atish Patra
2021-05-28 18:43 ` Atish Patra
2021-05-28 18:43 ` [RFC v2 1/7] RISC-V: Remove the current perf implementation Atish Patra
2021-05-28 18:43   ` Atish Patra
2021-09-01 10:36   ` Not compiling with CONFIG_BPF_SYSCALL enabled Nikita Shubin
2021-09-01 10:36     ` Nikita Shubin
2021-09-01 15:45     ` Atish Patra
2021-09-01 15:45       ` Atish Patra
2021-05-28 18:44 ` [RFC v2 2/7] RISC-V: Add CSR encodings for all HPMCOUNTERS Atish Patra
2021-05-28 18:44   ` Atish Patra
2021-05-28 18:44 ` [RFC v2 3/7] RISC-V: Add a perf core library for pmu drivers Atish Patra
2021-05-28 18:44   ` Atish Patra
2021-05-28 18:44 ` [RFC v2 4/7] RISC-V: Add a simple platform driver for RISC-V legacy perf Atish Patra
2021-05-28 18:44   ` Atish Patra
2021-05-28 18:44 ` [RFC v2 5/7] RISC-V: Add RISC-V SBI PMU extension definitions Atish Patra
2021-05-28 18:44   ` Atish Patra
2021-05-28 18:44 ` [RFC v2 6/7] RISC-V: Add perf platform driver based on SBI PMU extension Atish Patra
2021-05-28 18:44   ` Atish Patra
2021-06-01 13:10   ` Stanislaw Kardach
2021-06-01 13:10     ` Stanislaw Kardach
2021-06-01 15:48     ` Anup Patel
2021-06-01 15:48       ` Anup Patel
2021-06-01 15:57       ` Anup Patel
2021-06-01 15:57         ` Anup Patel
2021-06-01 17:08         ` Stanislaw Kardach
2021-06-01 17:08           ` Stanislaw Kardach
2021-05-28 18:44 ` [RFC v2 7/7] Documentation: riscv: Remove the old documentation Atish Patra
2021-05-28 18:44   ` Atish Patra

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.