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* [PATCH v4 00/10] LoongArch: Add ftrace support
@ 2022-09-16  2:55 Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 01/10] LoongArch/ftrace: Add basic support Qing Zhang
                   ` (7 more replies)
  0 siblings, 8 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel

This patch series to support basic and dynamic ftrace.

1) -pg
Use `-pg` makes stub like a child function `void _mcount(void *ra)`.
Thus, it can be seen store RA and open stack before `call _mcount`.
Find `open stack` at first, and then find `store RA`.

2) -fpatchable-function-entry=2
The compiler has inserted 2 NOPs before the regular function prologue.
T series registers are available and safe because of LoongArch psABI.

At runtime, replace nop with bl to enable ftrace call and replace bl with
nop to disable ftrace call. The bl requires us to save the original RA value,
so here it saves RA at t0.
details are:

| Compiled   |       Disabled         |        Enabled         |
+------------+------------------------+------------------------+
| nop        | move     t0, ra        | move     t0, ra        |
| nop        | nop                    | bl      ftrace_caller  |
| func_body  | func_body              | func_body              |

The RA value will be recovered by ftrace_regs_entry, and restored into RA
before returning to the regular function prologue. When a function is not
being traced, the move t0, ra is not harmful.

performs a series of startup tests on ftrace and The test cases in selftests
has passed on LoongArch.

Changes in v2:
 - Remove patch "LoongArch: ftrace: Add CALLER_ADDRx macros" there are other
   better ways
 Suggested by Steve:
 - Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support (6/10)
 Suggested by Jinyang:
 - Change addu16id to lu12iw and Adjust module_finalize return value (7/10)
 - Use the "jr" pseudo-instruction where applicable (1/10)
 - Use the "la.pcrel" instead of "la" (3/10)

Changes in v3:
 Reported by Jeff: 
 - Fix unwind state when option func_stack_trace (10/10)

Changes in v4:
 - No comments. Just resend the series.
 - Rebased onto v6.0.0-rc4.

Qing Zhang (10):
  LoongArch/ftrace: Add basic support
  LoongArch/ftrace: Add recordmcount support
  LoongArch/ftrace: Add dynamic function tracer support
  LoongArch/ftrace: Add dynamic function graph tracer support
  LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support
  LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support
  LoongArch: modules/ftrace: Initialize PLT at load time
  LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
  LoongArch: Enable CONFIG_KALLSYMS_ALL and CONFIG_DEBUG_FS
  LoongArch/ftrace: Fix unwind state when option func_stack_trace

 arch/loongarch/Kconfig                     |   7 +
 arch/loongarch/Makefile                    |   5 +
 arch/loongarch/configs/loongson3_defconfig |   2 +
 arch/loongarch/include/asm/ftrace.h        |  61 +++++
 arch/loongarch/include/asm/inst.h          |  18 ++
 arch/loongarch/include/asm/module.h        |   5 +-
 arch/loongarch/include/asm/module.lds.h    |   1 +
 arch/loongarch/include/asm/unwind.h        |   3 +-
 arch/loongarch/kernel/Makefile             |  13 +
 arch/loongarch/kernel/entry_dyn.S          | 154 ++++++++++++
 arch/loongarch/kernel/ftrace.c             |  74 ++++++
 arch/loongarch/kernel/ftrace_dyn.c         | 264 +++++++++++++++++++++
 arch/loongarch/kernel/inst.c               | 127 ++++++++++
 arch/loongarch/kernel/mcount.S             |  94 ++++++++
 arch/loongarch/kernel/module-sections.c    |  11 +
 arch/loongarch/kernel/module.c             |  47 ++++
 arch/loongarch/kernel/unwind_guess.c       |   4 +-
 arch/loongarch/kernel/unwind_prologue.c    |  44 +++-
 scripts/recordmcount.c                     |  23 ++
 19 files changed, 947 insertions(+), 10 deletions(-)
 create mode 100644 arch/loongarch/include/asm/ftrace.h
 create mode 100644 arch/loongarch/kernel/entry_dyn.S
 create mode 100644 arch/loongarch/kernel/ftrace.c
 create mode 100644 arch/loongarch/kernel/ftrace_dyn.c
 create mode 100644 arch/loongarch/kernel/mcount.S

-- 
2.36.1


^ permalink raw reply	[flat|nested] 10+ messages in thread
* [PATCH v4 01/10] LoongArch/ftrace: Add basic support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-17  9:38   ` Huacai Chen
  2022-09-16  2:55 ` [PATCH v4 02/10] LoongArch/ftrace: Add recordmcount support Qing Zhang
                   ` (6 subsequent siblings)
  7 siblings, 1 reply; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel, Jinyang He

This patch contains basic ftrace support for LoongArch.
Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph
tracer (HAVE_FUNCTION_GRAPH_TRACER) are implemented following the
instructions in Documentation/trace/ftrace-design.txt.

Use `-pg` makes stub like a child function `void _mcount(void *ra)`.
Thus, it can be seen store RA and open stack before `call _mcount`.
Find `open stack` at first, and then find `store RA`

Note that the functions in both inst.c and time.c should not be
hooked with the compiler's -pg option: to prevent infinite self-
referencing for the former, and to ignore early setup stuff for the
latter.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/Kconfig              |  2 +
 arch/loongarch/Makefile             |  5 ++
 arch/loongarch/include/asm/ftrace.h | 18 ++++++
 arch/loongarch/kernel/Makefile      |  8 +++
 arch/loongarch/kernel/ftrace.c      | 74 +++++++++++++++++++++++
 arch/loongarch/kernel/mcount.S      | 94 +++++++++++++++++++++++++++++
 6 files changed, 201 insertions(+)
 create mode 100644 arch/loongarch/include/asm/ftrace.h
 create mode 100644 arch/loongarch/kernel/ftrace.c
 create mode 100644 arch/loongarch/kernel/mcount.S

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 9b1f2ab878e9..95eab9611191 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -90,6 +90,8 @@ config LOONGARCH
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
 	select HAVE_FAST_GUP
+        select HAVE_FUNCTION_GRAPH_TRACER
+        select HAVE_FUNCTION_TRACER
 	select HAVE_GENERIC_VDSO
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 69b39ba3a09d..1149a17dc04f 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -33,6 +33,11 @@ ifneq ($(SUBARCH),$(ARCH))
   endif
 endif
 
+ifdef CONFIG_DYNAMIC_FTRACE
+  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
+  CC_FLAGS_FTRACE := -fpatchable-function-entry=2
+endif
+
 ifdef CONFIG_64BIT
 ld-emul			= $(64bit-emul)
 cflags-y		+= -mabi=lp64s
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
new file mode 100644
index 000000000000..6a3e76234618
--- /dev/null
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _ASM_LOONGARCH_FTRACE_H
+#define _ASM_LOONGARCH_FTRACE_H
+
+#ifdef CONFIG_FUNCTION_TRACER
+#define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+#define mcount _mcount
+
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_FUNCTION_TRACER */
+#endif /* _ASM_LOONGARCH_FTRACE_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7225916dd378..7db7ab152f71 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -14,6 +14,14 @@ obj-$(CONFIG_EFI) 		+= efi.o
 
 obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
 
+ifdef CONFIG_FUNCTION_TRACER
+    obj-y += mcount.o ftrace.o
+    CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
+  CFLAGS_REMOVE_inst.o = $(CC_FLAGS_FTRACE)
+  CFLAGS_REMOVE_time.o = $(CC_FLAGS_FTRACE)
+  CFLAGS_REMOVE_perf_event.o = $(CC_FLAGS_FTRACE)
+endif
+
 obj-$(CONFIG_MODULES)		+= module.o module-sections.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
diff --git a/arch/loongarch/kernel/ftrace.c b/arch/loongarch/kernel/ftrace.c
new file mode 100644
index 000000000000..c8ddc5f11f32
--- /dev/null
+++ b/arch/loongarch/kernel/ftrace.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/uaccess.h>
+#include <linux/init.h>
+#include <linux/ftrace.h>
+#include <linux/syscalls.h>
+
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/cacheflush.h>
+#include <asm/inst.h>
+#include <asm/loongarch.h>
+#include <asm/syscall.h>
+#include <asm/unistd.h>
+
+#include <asm-generic/sections.h>
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+/*
+ * As `call _mcount` follows LoongArch psABI, ra-saved operation and
+ * stack operation can be found before this insn.
+ */
+
+static int ftrace_get_parent_ra_addr(unsigned long insn_addr, int *ra_off)
+{
+	union loongarch_instruction *insn;
+	int limit = 32;
+
+	insn = (union loongarch_instruction *)insn_addr;
+
+	do {
+		insn--;
+		limit--;
+
+		if (is_ra_save_ins(insn))
+			*ra_off = -((1 << 12) - insn->reg2i12_format.immediate);
+
+	} while (!is_stack_alloc_ins(insn) && limit);
+
+	if (!limit)
+		return -EINVAL;
+
+	return 0;
+}
+
+void prepare_ftrace_return(unsigned long self_addr,
+		unsigned long callsite_sp, unsigned long old)
+{
+	int ra_off;
+	unsigned long return_hooker = (unsigned long)&return_to_handler;
+
+	if (unlikely(ftrace_graph_is_dead()))
+		return;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	if (ftrace_get_parent_ra_addr(self_addr, &ra_off))
+		goto out;
+
+	if (!function_graph_enter(old, self_addr, 0, NULL))
+		*(unsigned long *)(callsite_sp + ra_off) = return_hooker;
+
+	return;
+
+out:
+	ftrace_graph_stop();
+	WARN_ON(1);
+}
+#endif	/* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/loongarch/kernel/mcount.S b/arch/loongarch/kernel/mcount.S
new file mode 100644
index 000000000000..3de7c2d7fd12
--- /dev/null
+++ b/arch/loongarch/kernel/mcount.S
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * LoongArch specific _mcount support
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <asm/export.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/ftrace.h>
+
+	.text
+
+#define MCOUNT_STACK_SIZE	(2 * SZREG)
+#define MCOUNT_S0_OFFSET	(0)
+#define MCOUNT_RA_OFFSET	(SZREG)
+
+	.macro MCOUNT_SAVE_REGS
+	PTR_ADDI sp, sp, -MCOUNT_STACK_SIZE
+	PTR_S	s0, sp, MCOUNT_S0_OFFSET
+	PTR_S	ra, sp, MCOUNT_RA_OFFSET
+	move	s0, a0
+	.endm
+
+	.macro MCOUNT_RESTORE_REGS
+	move	a0, s0
+	PTR_L	ra, sp, MCOUNT_RA_OFFSET
+	PTR_L	s0, sp, MCOUNT_S0_OFFSET
+	PTR_ADDI sp, sp, MCOUNT_STACK_SIZE
+	.endm
+
+
+SYM_FUNC_START(_mcount)
+	la.pcrel	t1, ftrace_stub
+	la.pcrel	t2, ftrace_trace_function	/* Prepare t2 for (1) */
+	PTR_L	t2, t2, 0
+	beq	t1, t2, fgraph_trace
+
+	MCOUNT_SAVE_REGS
+
+	move	a0, ra				/* arg0: self return address */
+	move	a1, s0				/* arg1: parent's return address */
+	jirl	ra, t2, 0			/* (1) call *ftrace_trace_function */
+
+	MCOUNT_RESTORE_REGS
+
+fgraph_trace:
+#ifdef	CONFIG_FUNCTION_GRAPH_TRACER
+	la.pcrel	t1, ftrace_stub
+	la.pcrel	t3, ftrace_graph_return
+	PTR_L	t3, t3, 0
+	bne	t1, t3, ftrace_graph_caller
+	la.pcrel	t1, ftrace_graph_entry_stub
+	la.pcrel	t3, ftrace_graph_entry
+	PTR_L	t3, t3, 0
+	bne	t1, t3, ftrace_graph_caller
+#endif
+
+	.globl ftrace_stub
+ftrace_stub:
+	jr	ra
+SYM_FUNC_END(_mcount)
+EXPORT_SYMBOL(_mcount)
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_FUNC_START(ftrace_graph_caller)
+	MCOUNT_SAVE_REGS
+
+	PTR_ADDI	a0, ra, -4			/* arg0: Callsite self return addr */
+	PTR_ADDI	a1, sp, MCOUNT_STACK_SIZE	/* arg1: Callsite sp */
+	move	a2, s0					/* arg2: Callsite parent ra */
+	bl	prepare_ftrace_return
+
+	MCOUNT_RESTORE_REGS
+	jr	ra
+SYM_FUNC_END(ftrace_graph_caller)
+
+SYM_FUNC_START(return_to_handler)
+	PTR_ADDI sp, sp, -2 * SZREG
+	PTR_S	a0, sp, 0
+	PTR_S	a1, sp, SZREG
+
+	bl	ftrace_return_to_handler
+
+	/* restore the real parent address: a0 -> ra */
+	move	ra, a0
+
+	PTR_L	a0, sp, 0
+	PTR_L	a1, sp, SZREG
+	PTR_ADDI	sp, sp, 2 * SZREG
+	jr	ra
+SYM_FUNC_END(return_to_handler)
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 02/10] LoongArch/ftrace: Add recordmcount support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 01/10] LoongArch/ftrace: Add basic support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 03/10] LoongArch/ftrace: Add dynamic function tracer support Qing Zhang
                   ` (5 subsequent siblings)
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel

Recordmcount utility under scripts is run, after compiling each object,
to find out all the locations of calling _mcount() and put them into
specific seciton named __mcount_loc.
Then linker collects all such information into a table in the kernel image
(between __start_mcount_loc and __stop_mcount_loc) for later use by ftrace.

This patch adds loongarch specific definitions to identify such locations.
On loongarch, only C version is used to build the kernel now that
CONFIG_HAVE_C_RECORDMCOUNT is on.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/Kconfig |  2 ++
 scripts/recordmcount.c | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 95eab9611191..eb964abcd3be 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -85,11 +85,13 @@ config LOONGARCH
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_CONTEXT_TRACKING_USER
+	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
 	select HAVE_FAST_GUP
+	select HAVE_FTRACE_MCOUNT_RECORD
         select HAVE_FUNCTION_GRAPH_TRACER
         select HAVE_FUNCTION_TRACER
 	select HAVE_GENERIC_VDSO
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index cce12e1971d8..ae42f9c5dc42 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -38,6 +38,13 @@
 #define R_AARCH64_ABS64	257
 #endif
 
+#ifndef EM_LOONGARCH
+#define EM_LOONGARCH		258
+#define R_LARCH_64		2
+#define R_LARCH_MARK_LA			20
+#define R_LARCH_SOP_PUSH_PLT_PCREL	29
+#endif
+
 #define R_ARM_PC24		1
 #define R_ARM_THM_CALL		10
 #define R_ARM_CALL		28
@@ -441,6 +448,17 @@ static int arm64_is_fake_mcount(Elf64_Rel const *rp)
 	return ELF64_R_TYPE(w8(rp->r_info)) != R_AARCH64_CALL26;
 }
 
+static int LARCH64_is_fake_mcount(Elf64_Rel const *rp)
+{
+	switch (ELF64_R_TYPE(w(rp->r_info))) {
+	case R_LARCH_MARK_LA:
+	case R_LARCH_SOP_PUSH_PLT_PCREL:
+		return 0;
+	}
+
+	return 1;
+}
+
 /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
  * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
  * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
@@ -558,6 +576,7 @@ static int do_file(char const *const fname)
 		break;
 	case EM_IA_64:	reltype = R_IA64_IMM64; break;
 	case EM_MIPS:	/* reltype: e_class    */ break;
+	case EM_LOONGARCH:	/* reltype: e_class    */ break;
 	case EM_PPC:	reltype = R_PPC_ADDR32; break;
 	case EM_PPC64:	reltype = R_PPC64_ADDR64; break;
 	case EM_S390:	/* reltype: e_class    */ break;
@@ -610,6 +629,10 @@ static int do_file(char const *const fname)
 			Elf64_r_info = MIPS64_r_info;
 			is_fake_mcount64 = MIPS64_is_fake_mcount;
 		}
+		if (w2(ghdr->e_machine) == EM_LOONGARCH) {
+			reltype = R_LARCH_64;
+			is_fake_mcount64 = LARCH64_is_fake_mcount;
+		}
 		if (do64(ghdr, fname, reltype) < 0)
 			goto out;
 		break;
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 03/10] LoongArch/ftrace: Add dynamic function tracer support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 01/10] LoongArch/ftrace: Add basic support Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 02/10] LoongArch/ftrace: Add recordmcount support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 04/10] LoongArch/ftrace: Add dynamic function graph " Qing Zhang
                   ` (4 subsequent siblings)
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel, Jinyang He

The compiler has inserted 2 NOPs before the regular function prologue.
T series registers are available and safe because of LoongArch psABI.

At runtime, replace nop with bl to enable ftrace call and replace bl with
nop to disable ftrace call. The bl requires us to save the original RA value,
so here it saves RA at t0.
details are:

| Compiled   |       Disabled         |        Enabled         |
+------------+------------------------+------------------------+
| nop        | move     t0, ra        | move     t0, ra        |
| nop        | nop                    | bl      ftrace_caller  |
| func_body  | func_body              | func_body              |

The RA value will be recovered by ftrace_regs_entry, and restored into RA
before returning to the regular function prologue. When a function is not
being traced, the move t0, ra is not harmful.

1) ftrace_make_call, ftrace_make_nop (in kernel/ftrace.c)
   The two functions turn each recorded call site of filtered functions
   into a call to ftrace_caller or nops.

2) ftracce_update_ftrace_func (in kernel/ftrace.c)
   turns the nops at ftrace_call into a call to a generic entry for
   function tracers.

3) ftrace_caller (in kernel/mcount-dyn.S)
   The entry where each _mcount call sites calls to once they are
   filtered to be traced.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/Kconfig              |   1 +
 arch/loongarch/include/asm/ftrace.h |  16 ++++
 arch/loongarch/include/asm/inst.h   |  15 ++++
 arch/loongarch/kernel/Makefile      |   5 ++
 arch/loongarch/kernel/entry_dyn.S   |  89 ++++++++++++++++++++++
 arch/loongarch/kernel/ftrace_dyn.c  | 111 ++++++++++++++++++++++++++++
 arch/loongarch/kernel/inst.c        |  92 +++++++++++++++++++++++
 7 files changed, 329 insertions(+)
 create mode 100644 arch/loongarch/kernel/entry_dyn.S
 create mode 100644 arch/loongarch/kernel/ftrace_dyn.c

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index eb964abcd3be..1d64c603e985 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -88,6 +88,7 @@ config LOONGARCH
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_DMA_CONTIGUOUS
+	select HAVE_DYNAMIC_FTRACE
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
 	select HAVE_FAST_GUP
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 6a3e76234618..76ca58767f4d 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -10,9 +10,25 @@
 #define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
 
 #ifndef __ASSEMBLY__
+#ifndef CONFIG_DYNAMIC_FTRACE
 extern void _mcount(void);
 #define mcount _mcount
+#endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+	return addr;
+}
+
+struct dyn_arch_ftrace {
+};
+
+struct dyn_ftrace;
+int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
+#define ftrace_init_nop ftrace_init_nop
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
 #endif /* _ASM_LOONGARCH_FTRACE_H */
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index fce1843ceebb..f4a12f872a71 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -10,6 +10,9 @@
 
 #define INSN_BREAK		0x002a0000
 
+#define INSN_NOP 0x03400000
+#define INSN_BREAK 0x002a0000
+
 #define ADDR_IMMMASK_LU52ID	0xFFF0000000000000
 #define ADDR_IMMMASK_LU32ID	0x000FFFFF00000000
 #define ADDR_IMMMASK_ADDU16ID	0x00000000FFFF0000
@@ -331,6 +334,18 @@ static inline bool is_stack_alloc_ins(union loongarch_instruction *ip)
 		is_imm12_negative(ip->reg2i12_format.immediate);
 }
 
+int larch_insn_read(void *addr, u32 *insnp);
+int larch_insn_write(void *addr, u32 insn);
+int larch_insn_patch_text(void *addr, u32 insn);
+
+u32 larch_insn_gen_nop(void);
+u32 larch_insn_gen_b(unsigned long pc, unsigned long dest);
+u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest);
+
+u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj,
+			enum loongarch_gpr rk);
+u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj);
+
 u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
 u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
 u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest);
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7db7ab152f71..b14f88cc42d0 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -15,8 +15,13 @@ obj-$(CONFIG_EFI) 		+= efi.o
 obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
 
 ifdef CONFIG_FUNCTION_TRACER
+  ifndef CONFIG_DYNAMIC_FTRACE
     obj-y += mcount.o ftrace.o
     CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
+  else
+    obj-y += entry_dyn.o ftrace_dyn.o
+    CFLAGS_REMOVE_ftrace_dyn.o = $(CC_FLAGS_FTRACE)
+  endif
   CFLAGS_REMOVE_inst.o = $(CC_FLAGS_FTRACE)
   CFLAGS_REMOVE_time.o = $(CC_FLAGS_FTRACE)
   CFLAGS_REMOVE_perf_event.o = $(CC_FLAGS_FTRACE)
diff --git a/arch/loongarch/kernel/entry_dyn.S b/arch/loongarch/kernel/entry_dyn.S
new file mode 100644
index 000000000000..205925bc3822
--- /dev/null
+++ b/arch/loongarch/kernel/entry_dyn.S
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <asm/export.h>
+#include <asm/regdef.h>
+#include <asm/stackframe.h>
+#include <asm/ftrace.h>
+
+	.text
+/*
+ * Due to -fpatchable-function-entry=2: the compiler inserted 2 NOPs before the
+ * regular C function prologue. When PC arrived here, the last 2 instructions
+ * as follows,
+ * 	move		t0, ra
+ * 	bl		callsite (for modules, callsite is a tramplione)
+ *
+ * modules tramplione as follows,
+ * 	lu12i.w		t1, callsite[31:12]
+ * 	lu32i.d		t1, callsite[51:32]
+ * 	lu52i.d		t1, t1, callsite[63:52]
+ * 	jirl		zero, t1, callsite[11:0] >> 2
+ *
+ * See arch/loongarch/kernel/ftrace_dyn.c for details. Here, pay attention to
+ * that the T series regs are available and safe because each C functions
+ * follows the LoongArch psABI well.
+ */
+
+	.macro  ftrace_regs_entry
+	PTR_ADDI sp, sp, -PT_SIZE
+	/* Save trace function ra at PT_ERA */
+	PTR_S	ra, sp, PT_ERA
+	/* Save parent ra at PT_R1(RA) */
+	PTR_S	t0, sp, PT_R1
+	PTR_S	a0, sp, PT_R4
+	PTR_S	a1, sp, PT_R5
+	PTR_S	a2, sp, PT_R6
+	PTR_S	a3, sp, PT_R7
+	PTR_S	a4, sp, PT_R8
+	PTR_S	a5, sp, PT_R9
+	PTR_S	a6, sp, PT_R10
+	PTR_S	a7, sp, PT_R11
+	PTR_S	fp, sp, PT_R22
+
+	PTR_ADDI t8, sp, PT_SIZE
+	PTR_S   t8, sp, PT_R3
+
+	.endm
+
+SYM_CODE_START(ftrace_caller)
+	ftrace_regs_entry
+	b	ftrace_common
+SYM_CODE_END(ftrace_caller)
+
+SYM_CODE_START(ftrace_common)
+	PTR_ADDI	a0, ra, -8	/* arg0: ip */
+	move		a1, t0		/* arg1: parent_ip */
+	la.pcrel	t1, function_trace_op
+	PTR_L		a2, t1, 0	/* arg2: op */
+	move		a3, sp		/* arg3: regs */
+	.globl ftrace_call
+ftrace_call:
+	bl		ftrace_stub
+/*
+ * As we didn't use S series regs in this assmembly code and all calls
+ * are C function which will save S series regs by themselves, there is
+ * no need to restore S series regs. The T series is available and safe
+ * at the callsite, so there is no need to restore the T series regs.
+ */
+ftrace_common_return:
+	PTR_L	a0, sp, PT_R4
+	PTR_L	a1, sp, PT_R5
+	PTR_L	a2, sp, PT_R6
+	PTR_L	a3, sp, PT_R7
+	PTR_L	a4, sp, PT_R8
+	PTR_L	a5, sp, PT_R9
+	PTR_L	a6, sp, PT_R10
+	PTR_L	a7, sp, PT_R11
+	PTR_L	fp, sp, PT_R22
+	PTR_L	ra, sp, PT_R1
+	PTR_L	t0, sp, PT_ERA
+	PTR_ADDI sp, sp, PT_SIZE
+	jr	t0
+SYM_CODE_END(ftrace_common)
+
+SYM_FUNC_START(ftrace_stub)
+	jr	ra
+SYM_FUNC_END(ftrace_stub)
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
new file mode 100644
index 000000000000..1f8955be8b64
--- /dev/null
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Based on arch/arm64/kernel/ftrace.c
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/ftrace.h>
+#include <linux/uaccess.h>
+
+#include <asm/inst.h>
+
+static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,
+			      bool validate)
+{
+	u32 replaced;
+
+	if (validate) {
+		if (larch_insn_read((void *)pc, &replaced))
+			return -EFAULT;
+
+		if (replaced != old)
+			return -EINVAL;
+	}
+
+	if (larch_insn_patch_text((void *)pc, new))
+		return -EPERM;
+
+	return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned long pc;
+	u32 new;
+
+	pc = (unsigned long)&ftrace_call;
+	new = larch_insn_gen_bl(pc, (unsigned long)func);
+
+	return ftrace_modify_code(pc, 0, new, false);
+}
+
+/*
+ * The compiler has inserted 2 NOPs before the regular function prologue.
+ * T series registers are available and safe because of LoongArch psABI.
+ *
+ * At runtime, replace nop with bl to enable ftrace call and replace bl with
+ * nop to disable ftrace call. The bl requires us to save the original RA value,
+ * so here it saves RA at t0.
+ * details are:
+ *
+ * | Compiled   |       Disabled         |        Enabled         |
+ * +------------+------------------------+------------------------+
+ * | nop        | move     t0, ra        | move     t0, ra        |
+ * | nop        | nop                    | bl      ftrace_caller  |
+ * | func_body  | func_body              | func_body              |
+ *
+ * The RA value will be recovered by ftrace_regs_entry, and restored into RA
+ * before returning to the regular function prologue. When a function is not
+ * being traced, the move t0, ra is not harmful.
+ */
+
+int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
+{
+	unsigned long pc;
+	u32 old, new;
+
+	pc = rec->ip;
+	old = larch_insn_gen_nop();
+	new = larch_insn_gen_move(LOONGARCH_GPR_T0, LOONGARCH_GPR_RA);
+
+	return ftrace_modify_code(pc, old, new, true);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned long pc;
+	u32 old, new;
+
+	pc = rec->ip + LOONGARCH_INSN_SIZE;
+
+	old = larch_insn_gen_nop();
+	new = larch_insn_gen_bl(pc, addr);
+
+	return ftrace_modify_code(pc, old, new, true);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+		    unsigned long addr)
+{
+	unsigned long pc;
+	u32 old, new;
+
+	pc = rec->ip + LOONGARCH_INSN_SIZE;
+
+	new = larch_insn_gen_nop();
+	old = larch_insn_gen_bl(pc, addr);
+
+	return ftrace_modify_code(pc, old, new, true);
+}
+
+void arch_ftrace_update_code(int command)
+{
+	command |= FTRACE_MAY_SLEEP;
+	ftrace_modify_all_code(command);
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+	return 0;
+}
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index b1df0ec34bd1..d62cdf4a9ffb 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -2,8 +2,83 @@
 /*
  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
  */
+#include <linux/sizes.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
 #include <asm/inst.h>
 
+static DEFINE_RAW_SPINLOCK(patch_lock);
+
+int larch_insn_read(void *addr, u32 *insnp)
+{
+	int ret;
+	u32 val;
+
+	ret = copy_from_kernel_nofault(&val, addr, LOONGARCH_INSN_SIZE);
+	if (!ret)
+		*insnp = val;
+
+	return ret;
+}
+
+int larch_insn_write(void *addr, u32 insn)
+{
+	int ret;
+	unsigned long flags = 0;
+
+	raw_spin_lock_irqsave(&patch_lock, flags);
+	ret = copy_to_kernel_nofault(addr, &insn, LOONGARCH_INSN_SIZE);
+	raw_spin_unlock_irqrestore(&patch_lock, flags);
+
+	return ret;
+}
+
+int larch_insn_patch_text(void *addr, u32 insn)
+{
+	int ret;
+	u32 *tp = addr;
+
+	if ((unsigned long)tp & 3)
+		return -EINVAL;
+
+	ret = larch_insn_write(tp, insn);
+	if (!ret)
+		flush_icache_range((unsigned long)tp,
+				   (unsigned long)tp + LOONGARCH_INSN_SIZE);
+
+	return ret;
+}
+
+u32 larch_insn_gen_nop(void)
+{
+	return INSN_NOP;
+}
+
+u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
+{
+	unsigned int immediate_l, immediate_h;
+	union loongarch_instruction insn;
+	long offset = dest - pc;
+
+	if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
+		pr_warn("The generated bl instruction is out of range.\n");
+		return INSN_BREAK;
+	}
+
+	offset >>= 2;
+
+	immediate_l = offset & 0xffff;
+	offset >>= 16;
+	immediate_h = offset & 0x3ff;
+
+	insn.reg0i26_format.opcode = bl_op;
+	insn.reg0i26_format.immediate_l = immediate_l;
+	insn.reg0i26_format.immediate_h = immediate_h;
+
+	return insn.word;
+}
+
 u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm)
 {
 	union loongarch_instruction insn;
@@ -38,3 +113,20 @@ u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned l
 
 	return insn.word;
 }
+
+u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj, enum loongarch_gpr rk)
+{
+	union loongarch_instruction insn;
+
+	insn.reg3_format.opcode = or_op;
+	insn.reg3_format.rd = rd;
+	insn.reg3_format.rj = rj;
+	insn.reg3_format.rk = rk;
+
+	return insn.word;
+}
+
+u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj)
+{
+	return larch_insn_gen_or(rd, rj, 0);
+}
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 04/10] LoongArch/ftrace: Add dynamic function graph tracer support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
                   ` (2 preceding siblings ...)
  2022-09-16  2:55 ` [PATCH v4 03/10] LoongArch/ftrace: Add dynamic function tracer support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 05/10] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Qing Zhang
                   ` (3 subsequent siblings)
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel, Jinyang He

Once the function_graph tracer is enabled, a filtered function has the
following call sequence:

1) ftracer_caller        ==> on/off by ftrace_make_call/ftrace_make_nop
2) ftrace_graph_caller
3) ftrace_graph_call     ==> on/off by ftrace_en/disable_ftrace_graph_caller
4) prepare_ftrace_return

Considering the following DYNAMIC_FTRACE_WITH_REGS feature, it would be
more extendable to have a ftrace_graph_caller function, instead of
calling prepare_ftrace_return directly in ftrace_caller.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/kernel/entry_dyn.S  | 33 ++++++++++++++++++++++
 arch/loongarch/kernel/ftrace_dyn.c | 45 ++++++++++++++++++++++++++++++
 arch/loongarch/kernel/inst.c       | 24 ++++++++++++++++
 3 files changed, 102 insertions(+)

diff --git a/arch/loongarch/kernel/entry_dyn.S b/arch/loongarch/kernel/entry_dyn.S
index 205925bc3822..0c12cc108e6f 100644
--- a/arch/loongarch/kernel/entry_dyn.S
+++ b/arch/loongarch/kernel/entry_dyn.S
@@ -62,6 +62,11 @@ SYM_CODE_START(ftrace_common)
 	.globl ftrace_call
 ftrace_call:
 	bl		ftrace_stub
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_call
+ftrace_graph_call:
+	nop				/* b ftrace_graph_caller */
+#endif
 /*
  * As we didn't use S series regs in this assmembly code and all calls
  * are C function which will save S series regs by themselves, there is
@@ -84,6 +89,34 @@ ftrace_common_return:
 	jr	t0
 SYM_CODE_END(ftrace_common)
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_CODE_START(ftrace_graph_caller)
+	PTR_L		a0, sp, PT_ERA
+	PTR_ADDI	a0, a0, -8	/* arg0: self_addr */
+	PTR_ADDI	a1, sp, PT_R1	/* arg1: parent */
+	bl		prepare_ftrace_return
+	b		ftrace_common_return
+SYM_CODE_END(ftrace_graph_caller)
+
+SYM_CODE_START(return_to_handler)
+	/* save return value regs */
+	PTR_ADDI 	sp, sp, -2 * SZREG
+	PTR_S		a0, sp, 0
+	PTR_S		a1, sp, SZREG
+
+	move		a0, zero	/* Has no check FP now. */
+	bl		ftrace_return_to_handler
+	move		ra, a0		/* parent ra */
+
+	/* restore return value regs */
+	PTR_L		a0, sp, 0
+	PTR_L		a1, sp, SZREG
+	PTR_ADDI 	sp, sp, 2 * SZREG
+
+	jr	ra
+SYM_CODE_END(return_to_handler)
+#endif
+
 SYM_FUNC_START(ftrace_stub)
 	jr	ra
 SYM_FUNC_END(ftrace_stub)
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 1f8955be8b64..3fe791b6783e 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -109,3 +109,48 @@ int __init ftrace_dyn_arch_init(void)
 {
 	return 0;
 }
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+extern void ftrace_graph_call(void);
+
+void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
+{
+	unsigned long return_hooker = (unsigned long)&return_to_handler;
+	unsigned long old;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	old = *parent;
+
+	if (!function_graph_enter(old, self_addr, 0, NULL))
+		*parent = return_hooker;
+}
+
+static int ftrace_modify_graph_caller(bool enable)
+{
+	unsigned long pc, func;
+	u32 branch, nop;
+
+	pc = (unsigned long)&ftrace_graph_call;
+	func = (unsigned long)&ftrace_graph_caller;
+
+	branch = larch_insn_gen_b(pc, func);
+	nop = larch_insn_gen_nop();
+
+	if (enable)
+		return ftrace_modify_code(pc, nop, branch, true);
+	else
+		return ftrace_modify_code(pc, branch, nop, true);
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_graph_caller(false);
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index d62cdf4a9ffb..2d2e942eb06a 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -55,6 +55,30 @@ u32 larch_insn_gen_nop(void)
 	return INSN_NOP;
 }
 
+u32 larch_insn_gen_b(unsigned long pc, unsigned long dest)
+{
+	unsigned int immediate_l, immediate_h;
+	union loongarch_instruction insn;
+	long offset = dest - pc;
+
+	if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
+		pr_warn("The generated b instruction is out of range.\n");
+		return INSN_BREAK;
+	}
+
+	offset >>= 2;
+
+	immediate_l = offset & 0xffff;
+	offset >>= 16;
+	immediate_h = offset & 0x3ff;
+
+	insn.reg0i26_format.opcode = b_op;
+	insn.reg0i26_format.immediate_l = immediate_l;
+	insn.reg0i26_format.immediate_h = immediate_h;
+
+	return insn.word;
+}
+
 u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
 {
 	unsigned int immediate_l, immediate_h;
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 05/10] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
                   ` (3 preceding siblings ...)
  2022-09-16  2:55 ` [PATCH v4 04/10] LoongArch/ftrace: Add dynamic function graph " Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 06/10] LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support Qing Zhang
                   ` (2 subsequent siblings)
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel, Jinyang He

This patch implements DYNAMIC_FTRACE_WITH_REGS on LoongArch, which allows
a traced function's arguments (and some other registers) to be captured
into a struct pt_regs, allowing these to be inspected and modified.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/Kconfig              |  1 +
 arch/loongarch/include/asm/ftrace.h |  3 +++
 arch/loongarch/kernel/entry_dyn.S   | 36 +++++++++++++++++++++++++++--
 arch/loongarch/kernel/ftrace_dyn.c  | 17 ++++++++++++++
 4 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 1d64c603e985..2f70f98b18be 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -89,6 +89,7 @@ config LOONGARCH
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
 	select HAVE_FAST_GUP
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 76ca58767f4d..a3f974a7a5ce 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -28,6 +28,9 @@ struct dyn_ftrace;
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #define ftrace_init_nop ftrace_init_nop
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+#endif
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
diff --git a/arch/loongarch/kernel/entry_dyn.S b/arch/loongarch/kernel/entry_dyn.S
index 0c12cc108e6f..02835186b463 100644
--- a/arch/loongarch/kernel/entry_dyn.S
+++ b/arch/loongarch/kernel/entry_dyn.S
@@ -27,7 +27,7 @@
  * follows the LoongArch psABI well.
  */
 
-	.macro  ftrace_regs_entry
+	.macro  ftrace_regs_entry allregs=0
 	PTR_ADDI sp, sp, -PT_SIZE
 	/* Save trace function ra at PT_ERA */
 	PTR_S	ra, sp, PT_ERA
@@ -43,16 +43,48 @@
 	PTR_S	a7, sp, PT_R11
 	PTR_S	fp, sp, PT_R22
 
+	.if \allregs
+	PTR_S	t0, sp, PT_R12
+	PTR_S	t1, sp, PT_R13
+	PTR_S	t2, sp, PT_R14
+	PTR_S	t3, sp, PT_R15
+	PTR_S	t4, sp, PT_R16
+	PTR_S	t5, sp, PT_R17
+	PTR_S	t6, sp, PT_R18
+	PTR_S	t7, sp, PT_R19
+	PTR_S	t8, sp, PT_R20
+	PTR_S	s0, sp, PT_R23
+	PTR_S	s1, sp, PT_R24
+	PTR_S	s2, sp, PT_R25
+	PTR_S	s3, sp, PT_R26
+	PTR_S	s4, sp, PT_R27
+	PTR_S	s5, sp, PT_R28
+	PTR_S	s6, sp, PT_R29
+	PTR_S	s7, sp, PT_R30
+	PTR_S	s8, sp, PT_R31
+	PTR_S	tp, sp, PT_R2
+	/* Clear it for later use as a flag sometimes. */
+	PTR_S	zero, sp, PT_R0
+	PTR_S	$r21, sp, PT_R21
+	.endif
+
 	PTR_ADDI t8, sp, PT_SIZE
 	PTR_S   t8, sp, PT_R3
 
 	.endm
 
 SYM_CODE_START(ftrace_caller)
-	ftrace_regs_entry
+	ftrace_regs_entry allregs=0
 	b	ftrace_common
 SYM_CODE_END(ftrace_caller)
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+SYM_CODE_START(ftrace_regs_caller)
+	ftrace_regs_entry allregs=1
+	b	ftrace_common
+SYM_CODE_END(ftrace_regs_caller)
+#endif
+
 SYM_CODE_START(ftrace_common)
 	PTR_ADDI	a0, ra, -8	/* arg0: ip */
 	move		a1, t0		/* arg1: parent_ip */
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 3fe791b6783e..ec3d951be50c 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -99,6 +99,23 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 	return ftrace_modify_code(pc, old, new, true);
 }
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+			unsigned long addr)
+{
+	unsigned long pc;
+	long offset;
+	u32 old, new;
+
+	pc = rec->ip + LOONGARCH_INSN_SIZE;
+
+	old = larch_insn_gen_bl(pc, old_addr);
+	new = larch_insn_gen_bl(pc, addr);
+
+	return ftrace_modify_code(pc, old, new, true);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
 void arch_ftrace_update_code(int command)
 {
 	command |= FTRACE_MAY_SLEEP;
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 06/10] LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
                   ` (4 preceding siblings ...)
  2022-09-16  2:55 ` [PATCH v4 05/10] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 07/10] LoongArch: modules/ftrace: Initialize PLT at load time Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 08/10] LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support Qing Zhang
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel

Allow for arguments to be passed in to ftrace_regs by default,
If this is set, then arguments and stack can be found from
the pt_regs.

1. HAVE_DYNAMIC_FTRACE_WITH_ARGS don't need special hook for graph
tracer entry point, but instead we can use graph_ops::func function
to install the return_hooker.
2. Livepatch requires this option in the future.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/Kconfig              |  1 +
 arch/loongarch/include/asm/ftrace.h | 17 +++++++++++++++++
 arch/loongarch/kernel/ftrace_dyn.c  | 12 ++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 2f70f98b18be..40bbc9a08969 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -89,6 +89,7 @@ config LOONGARCH
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
+	select HAVE_DYNAMIC_FTRACE_WITH_ARGS
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index a3f974a7a5ce..5cc13ae48164 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -15,6 +15,23 @@ extern void _mcount(void);
 #define mcount _mcount
 #endif
 
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+struct ftrace_ops;
+
+struct ftrace_regs {
+	struct pt_regs regs;
+};
+
+static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)
+{
+	return &fregs->regs;
+}
+
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs);
+#define ftrace_graph_func ftrace_graph_func
+#endif
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index ec3d951be50c..f538829312d7 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -144,6 +144,17 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
 		*parent = return_hooker;
 }
 
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	struct pt_regs *regs = &fregs->regs;
+	unsigned long *parent = (unsigned long *)&regs->regs[1];
+
+	prepare_ftrace_return(ip, (unsigned long *)parent);
+}
+#else
+
 static int ftrace_modify_graph_caller(bool enable)
 {
 	unsigned long pc, func;
@@ -170,4 +181,5 @@ int ftrace_disable_ftrace_graph_caller(void)
 {
 	return ftrace_modify_graph_caller(false);
 }
+#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 07/10] LoongArch: modules/ftrace: Initialize PLT at load time
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
                   ` (5 preceding siblings ...)
  2022-09-16  2:55 ` [PATCH v4 06/10] LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  2022-09-16  2:55 ` [PATCH v4 08/10] LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support Qing Zhang
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel

To Implement ftrace trampiones through plt entry.

Tested by forcing ftrace_make_call() to use the module PLT, and then
loading up a module after setting up ftrace with:

| echo ":mod:<module-name>" > set_ftrace_filter;
| echo function > current_tracer;
| modprobe <module-name>

Since FTRACE_ADDR/FTRACE_REGS_ADDR is only defined when CONFIG_DYNAMIC_FTRACE
is selected, we wrap its use along with most of module_init_ftrace_plt() with
ifdeffery rather than using IS_ENABLED().

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/include/asm/ftrace.h     |  4 ++
 arch/loongarch/include/asm/inst.h       |  3 +
 arch/loongarch/include/asm/module.h     |  5 +-
 arch/loongarch/include/asm/module.lds.h |  1 +
 arch/loongarch/kernel/ftrace_dyn.c      | 79 +++++++++++++++++++++++++
 arch/loongarch/kernel/inst.c            | 11 ++++
 arch/loongarch/kernel/module-sections.c | 11 ++++
 arch/loongarch/kernel/module.c          | 47 +++++++++++++++
 8 files changed, 160 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 5cc13ae48164..807226aad1c0 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -6,6 +6,10 @@
 #ifndef _ASM_LOONGARCH_FTRACE_H
 #define _ASM_LOONGARCH_FTRACE_H
 
+#define FTRACE_PLT_IDX		0
+#define FTRACE_REGS_PLT_IDX	1
+#define NR_FTRACE_PLTS		2
+
 #ifdef CONFIG_FUNCTION_TRACER
 #define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
 
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index f4a12f872a71..5a1aa977ae20 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -15,10 +15,12 @@
 
 #define ADDR_IMMMASK_LU52ID	0xFFF0000000000000
 #define ADDR_IMMMASK_LU32ID	0x000FFFFF00000000
+#define ADDR_IMMMASK_LU12IW	0x00000000FFFFF000
 #define ADDR_IMMMASK_ADDU16ID	0x00000000FFFF0000
 
 #define ADDR_IMMSHIFT_LU52ID	52
 #define ADDR_IMMSHIFT_LU32ID	32
+#define ADDR_IMMSHIFT_LU12IW	12
 #define ADDR_IMMSHIFT_ADDU16ID	16
 
 #define ADDR_IMM(addr, INSN)	((addr & ADDR_IMMMASK_##INSN) >> ADDR_IMMSHIFT_##INSN)
@@ -346,6 +348,7 @@ u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj,
 			enum loongarch_gpr rk);
 u32 larch_insn_gen_move(enum loongarch_gpr rd, enum loongarch_gpr rj);
 
+u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm);
 u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
 u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
 u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest);
diff --git a/arch/loongarch/include/asm/module.h b/arch/loongarch/include/asm/module.h
index b29b19a46f42..a311cfec2b23 100644
--- a/arch/loongarch/include/asm/module.h
+++ b/arch/loongarch/include/asm/module.h
@@ -20,6 +20,9 @@ struct mod_arch_specific {
 	struct mod_section got;
 	struct mod_section plt;
 	struct mod_section plt_idx;
+
+	/* for CONFIG_DYNAMIC_FTRACE */
+	struct plt_entry *ftrace_trampolines;
 };
 
 struct got_entry {
@@ -49,7 +52,7 @@ static inline struct plt_entry emit_plt_entry(unsigned long val)
 {
 	u32 lu12iw, lu32id, lu52id, jirl;
 
-	lu12iw = (lu12iw_op << 25 | (((val >> 12) & 0xfffff) << 5) | LOONGARCH_GPR_T1);
+	lu12iw = larch_insn_gen_lu12iw(LOONGARCH_GPR_T1, ADDR_IMM(val, LU12IW));
 	lu32id = larch_insn_gen_lu32id(LOONGARCH_GPR_T1, ADDR_IMM(val, LU32ID));
 	lu52id = larch_insn_gen_lu52id(LOONGARCH_GPR_T1, LOONGARCH_GPR_T1, ADDR_IMM(val, LU52ID));
 	jirl = larch_insn_gen_jirl(0, LOONGARCH_GPR_T1, 0, (val & 0xfff));
diff --git a/arch/loongarch/include/asm/module.lds.h b/arch/loongarch/include/asm/module.lds.h
index a3d1bc0fcc72..438f09d4ccf4 100644
--- a/arch/loongarch/include/asm/module.lds.h
+++ b/arch/loongarch/include/asm/module.lds.h
@@ -5,4 +5,5 @@ SECTIONS {
 	.got : { BYTE(0) }
 	.plt : { BYTE(0) }
 	.plt.idx : { BYTE(0) }
+	.ftrace_trampoline : { BYTE(0) }
 }
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index f538829312d7..dd37185d446e 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -9,6 +9,7 @@
 #include <linux/uaccess.h>
 
 #include <asm/inst.h>
+#include <asm/module.h>
 
 static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,
 			      bool validate)
@@ -72,12 +73,63 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
 	return ftrace_modify_code(pc, old, new, true);
 }
 
+static inline int __get_mod(struct module **mod, unsigned long addr)
+{
+	preempt_disable();
+	*mod = __module_text_address(addr);
+	preempt_enable();
+
+	if (WARN_ON(!(*mod)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
+{
+	struct plt_entry *plt = mod->arch.ftrace_trampolines;
+
+	if (addr == FTRACE_ADDR)
+		return &plt[FTRACE_PLT_IDX];
+	if (addr == FTRACE_REGS_ADDR &&
+			IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+		return &plt[FTRACE_REGS_PLT_IDX];
+
+	return NULL;
+}
+
+static unsigned long get_plt_addr(struct module *mod, unsigned long addr)
+{
+	struct plt_entry *plt;
+
+	plt = get_ftrace_plt(mod, addr);
+	if (!plt) {
+		pr_err("ftrace: no module PLT for %ps\n", (void *)addr);
+		return -EINVAL;
+	}
+
+	return (unsigned long)plt;
+}
+
 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned long pc;
+	long offset;
 	u32 old, new;
 
 	pc = rec->ip + LOONGARCH_INSN_SIZE;
+	offset = (long)pc - (long)addr;
+
+	if (offset < -SZ_128M || offset >= SZ_128M) {
+		int ret;
+		struct module *mod;
+
+		ret = __get_mod(&mod, pc);
+		if (ret)
+			return ret;
+
+		addr = get_plt_addr(mod, addr);
+	}
 
 	old = larch_insn_gen_nop();
 	new = larch_insn_gen_bl(pc, addr);
@@ -89,9 +141,22 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 		    unsigned long addr)
 {
 	unsigned long pc;
+	long offset;
 	u32 old, new;
 
 	pc = rec->ip + LOONGARCH_INSN_SIZE;
+	offset = (long)pc - (long)addr;
+
+	if (offset < -SZ_128M || offset >= SZ_128M) {
+		int ret;
+		struct module *mod;
+
+		ret = __get_mod(&mod, pc);
+		if (ret)
+			return ret;
+
+		addr = get_plt_addr(mod, addr);
+	}
 
 	new = larch_insn_gen_nop();
 	old = larch_insn_gen_bl(pc, addr);
@@ -108,6 +173,20 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 	u32 old, new;
 
 	pc = rec->ip + LOONGARCH_INSN_SIZE;
+	offset = (long)pc - (long)addr;
+
+	if (offset < -SZ_128M || offset >= SZ_128M) {
+		int ret;
+		struct module *mod;
+
+		ret = __get_mod(&mod, pc);
+		if (ret)
+			return ret;
+
+		addr = get_plt_addr(mod, addr);
+
+		old_addr = get_plt_addr(mod, old_addr);
+	}
 
 	old = larch_insn_gen_bl(pc, old_addr);
 	new = larch_insn_gen_bl(pc, addr);
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index 2d2e942eb06a..0d6bd7000ba6 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -103,6 +103,17 @@ u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
 	return insn.word;
 }
 
+u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm)
+{
+	union loongarch_instruction insn;
+
+	insn.reg1i20_format.opcode = lu12iw_op;
+	insn.reg1i20_format.rd = rd;
+	insn.reg1i20_format.immediate = imm;
+
+	return insn.word;
+}
+
 u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm)
 {
 	union loongarch_instruction insn;
diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c
index d296a70b758f..bd1a96691c98 100644
--- a/arch/loongarch/kernel/module-sections.c
+++ b/arch/loongarch/kernel/module-sections.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/elf.h>
+#include <linux/ftrace.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 
@@ -103,6 +104,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 			      char *secstrings, struct module *mod)
 {
 	unsigned int i, num_plts = 0, num_gots = 0;
+	Elf_Shdr *tramp = NULL;
 
 	/*
 	 * Find the empty .plt sections.
@@ -114,6 +116,8 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 			mod->arch.plt.shdr = sechdrs + i;
 		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
 			mod->arch.plt_idx.shdr = sechdrs + i;
+		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
+			tramp = sechdrs + i;
 	}
 
 	if (!mod->arch.got.shdr) {
@@ -166,5 +170,12 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 	mod->arch.plt_idx.num_entries = 0;
 	mod->arch.plt_idx.max_entries = num_plts;
 
+	if (tramp) {
+		tramp->sh_type = SHT_NOBITS;
+		tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
+		tramp->sh_addralign = __alignof__(struct plt_entry);
+		tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
+	}
+
 	return 0;
 }
diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 097595b2fc14..e036b1ebf98e 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -10,6 +10,7 @@
 
 #include <linux/moduleloader.h>
 #include <linux/elf.h>
+#include <linux/ftrace.h>
 #include <linux/mm.h>
 #include <linux/numa.h>
 #include <linux/vmalloc.h>
@@ -17,6 +18,7 @@
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <asm/inst.h>
 
 static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top)
 {
@@ -456,3 +458,48 @@ void *module_alloc(unsigned long size)
 	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
 			GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0));
 }
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+				    const char *name)
+{
+	const Elf_Shdr *s, *se;
+	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
+		if (strcmp(name, secstrs + s->sh_name) == 0)
+			return s;
+	}
+
+	return NULL;
+}
+#endif
+
+static int module_init_ftrace_plt(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+				  struct module *mod)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+	const Elf_Shdr *s;
+	struct plt_entry *ftrace_plts;
+
+	s = find_section(hdr, sechdrs, ".ftrace_trampoline");
+	if (!s)
+		return -ENOEXEC;
+
+	ftrace_plts = (void *)s->sh_addr;
+
+	ftrace_plts[FTRACE_PLT_IDX] = emit_plt_entry(FTRACE_ADDR);
+
+	if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+		ftrace_plts[FTRACE_REGS_PLT_IDX] = emit_plt_entry(FTRACE_REGS_ADDR);
+
+	mod->arch.ftrace_trampolines = ftrace_plts;
+#endif
+	return 0;
+}
+
+int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod)
+{
+	return module_init_ftrace_plt(hdr, sechdrs, mod);
+
+}
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* [PATCH v4 08/10] LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
  2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
                   ` (6 preceding siblings ...)
  2022-09-16  2:55 ` [PATCH v4 07/10] LoongArch: modules/ftrace: Initialize PLT at load time Qing Zhang
@ 2022-09-16  2:55 ` Qing Zhang
  7 siblings, 0 replies; 10+ messages in thread
From: Qing Zhang @ 2022-09-16  2:55 UTC (permalink / raw)
  To: Huacai Chen, Steven Rostedt, Ingo Molnar
  Cc: WANG Xuerui, loongarch, linux-kernel

Ftrace_graph_ret_addr can be called by stack unwinding code to convert
a found stack return address ('ret') to its original value, in case the
function graph tracer has modified it to be 'return_to_handler',If the
hasn't been modified, the unchanged value of 'ret' is returned.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
 arch/loongarch/include/asm/ftrace.h     |  3 +++
 arch/loongarch/include/asm/unwind.h     |  1 +
 arch/loongarch/kernel/ftrace_dyn.c      |  2 +-
 arch/loongarch/kernel/unwind_guess.c    |  4 +++-
 arch/loongarch/kernel/unwind_prologue.c | 11 +++++++++--
 5 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 807226aad1c0..2a676ece4857 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -10,6 +10,8 @@
 #define FTRACE_REGS_PLT_IDX	1
 #define NR_FTRACE_PLTS		2
 
+#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
+
 #ifdef CONFIG_FUNCTION_TRACER
 #define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
 
@@ -37,6 +39,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
 	return addr;
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index 6af4718bdf01..f66b07c3e6a1 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -21,6 +21,7 @@ struct unwind_state {
 	struct stack_info stack_info;
 	struct task_struct *task;
 	bool first, error;
+	int graph_idx;
 	unsigned long sp, pc, ra;
 };
 
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index dd37185d446e..b070ce225989 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -219,7 +219,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
 
 	old = *parent;
 
-	if (!function_graph_enter(old, self_addr, 0, NULL))
+	if (!function_graph_enter(old, self_addr, 0, parent))
 		*parent = return_hooker;
 }
 
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index 5afa6064d73e..229ba014cea0 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2022 Loongson Technology Corporation Limited
  */
+#include <linux/ftrace.h>
 #include <linux/kernel.h>
 
 #include <asm/unwind.h>
@@ -53,7 +54,8 @@ bool unwind_next_frame(struct unwind_state *state)
 		     state->sp < info->end;
 		     state->sp += sizeof(unsigned long)) {
 			addr = *(unsigned long *)(state->sp);
-
+			state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
 			if (__kernel_text_address(addr))
 				return true;
 		}
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index b206d9159205..f77f3b6f3f06 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2022 Loongson Technology Corporation Limited
  */
+#include <linux/ftrace.h>
 #include <linux/kallsyms.h>
 
 #include <asm/inst.h>
@@ -32,6 +33,8 @@ static bool unwind_by_guess(struct unwind_state *state)
 	     state->sp < info->end;
 	     state->sp += sizeof(unsigned long)) {
 		addr = *(unsigned long *)(state->sp);
+		state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+			addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
 		if (__kernel_text_address(addr))
 			return true;
 	}
@@ -146,8 +149,11 @@ bool unwind_next_frame(struct unwind_state *state)
 			break;
 
 		case UNWINDER_PROLOGUE:
-			if (unwind_by_prologue(state))
+			if (unwind_by_prologue(state)) {
+				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+					state->pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
 				return true;
+			}
 
 			if (info->type == STACK_TYPE_IRQ &&
 				info->end == state->sp) {
@@ -157,8 +163,9 @@ bool unwind_next_frame(struct unwind_state *state)
 				if (user_mode(regs) || !__kernel_text_address(pc))
 					return false;
 
-				state->pc = pc;
 				state->sp = regs->regs[3];
+				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+					pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
 				state->ra = regs->regs[1];
 				state->first = true;
 				get_stack_info(state->sp, state->task, info);
-- 
2.36.1


^ permalink raw reply related	[flat|nested] 10+ messages in thread
* Re: [PATCH v4 01/10] LoongArch/ftrace: Add basic support
  2022-09-16  2:55 ` [PATCH v4 01/10] LoongArch/ftrace: Add basic support Qing Zhang
@ 2022-09-17  9:38   ` Huacai Chen
  0 siblings, 0 replies; 10+ messages in thread
From: Huacai Chen @ 2022-09-17  9:38 UTC (permalink / raw)
  To: Qing Zhang
  Cc: Steven Rostedt, Ingo Molnar, WANG Xuerui, loongarch, LKML, Jinyang He

Hi, Qing,

On Fri, Sep 16, 2022 at 10:55 AM Qing Zhang <zhangqing@loongson.cn> wrote:
>
> This patch contains basic ftrace support for LoongArch.
> Specifically, function tracer (HAVE_FUNCTION_TRACER), function graph
> tracer (HAVE_FUNCTION_GRAPH_TRACER) are implemented following the
> instructions in Documentation/trace/ftrace-design.txt.
>
> Use `-pg` makes stub like a child function `void _mcount(void *ra)`.
> Thus, it can be seen store RA and open stack before `call _mcount`.
> Find `open stack` at first, and then find `store RA`
>
> Note that the functions in both inst.c and time.c should not be
> hooked with the compiler's -pg option: to prevent infinite self-
> referencing for the former, and to ignore early setup stuff for the
> latter.
>
> Co-developed-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
> ---
>  arch/loongarch/Kconfig              |  2 +
>  arch/loongarch/Makefile             |  5 ++
>  arch/loongarch/include/asm/ftrace.h | 18 ++++++
>  arch/loongarch/kernel/Makefile      |  8 +++
>  arch/loongarch/kernel/ftrace.c      | 74 +++++++++++++++++++++++
>  arch/loongarch/kernel/mcount.S      | 94 +++++++++++++++++++++++++++++
>  6 files changed, 201 insertions(+)
>  create mode 100644 arch/loongarch/include/asm/ftrace.h
>  create mode 100644 arch/loongarch/kernel/ftrace.c
>  create mode 100644 arch/loongarch/kernel/mcount.S
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 9b1f2ab878e9..95eab9611191 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -90,6 +90,8 @@ config LOONGARCH
>         select HAVE_EBPF_JIT
>         select HAVE_EXIT_THREAD
>         select HAVE_FAST_GUP
> +        select HAVE_FUNCTION_GRAPH_TRACER
> +        select HAVE_FUNCTION_TRACER
The indentation is obviously wrong here, and some other patches have
the same problem.


Huacai

>         select HAVE_GENERIC_VDSO
>         select HAVE_IOREMAP_PROT
>         select HAVE_IRQ_EXIT_ON_IRQ_STACK
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index 69b39ba3a09d..1149a17dc04f 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -33,6 +33,11 @@ ifneq ($(SUBARCH),$(ARCH))
>    endif
>  endif
>
> +ifdef CONFIG_DYNAMIC_FTRACE
> +  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
> +  CC_FLAGS_FTRACE := -fpatchable-function-entry=2
> +endif
> +
>  ifdef CONFIG_64BIT
>  ld-emul                        = $(64bit-emul)
>  cflags-y               += -mabi=lp64s
> diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
> new file mode 100644
> index 000000000000..6a3e76234618
> --- /dev/null
> +++ b/arch/loongarch/include/asm/ftrace.h
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _ASM_LOONGARCH_FTRACE_H
> +#define _ASM_LOONGARCH_FTRACE_H
> +
> +#ifdef CONFIG_FUNCTION_TRACER
> +#define MCOUNT_INSN_SIZE 4             /* sizeof mcount call */
> +
> +#ifndef __ASSEMBLY__
> +extern void _mcount(void);
> +#define mcount _mcount
> +
> +#endif /* __ASSEMBLY__ */
> +#endif /* CONFIG_FUNCTION_TRACER */
> +#endif /* _ASM_LOONGARCH_FTRACE_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 7225916dd378..7db7ab152f71 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -14,6 +14,14 @@ obj-$(CONFIG_EFI)            += efi.o
>
>  obj-$(CONFIG_CPU_HAS_FPU)      += fpu.o
>
> +ifdef CONFIG_FUNCTION_TRACER
> +    obj-y += mcount.o ftrace.o
> +    CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
> +  CFLAGS_REMOVE_inst.o = $(CC_FLAGS_FTRACE)
> +  CFLAGS_REMOVE_time.o = $(CC_FLAGS_FTRACE)
> +  CFLAGS_REMOVE_perf_event.o = $(CC_FLAGS_FTRACE)
> +endif
> +
>  obj-$(CONFIG_MODULES)          += module.o module-sections.o
>  obj-$(CONFIG_STACKTRACE)       += stacktrace.o
>
> diff --git a/arch/loongarch/kernel/ftrace.c b/arch/loongarch/kernel/ftrace.c
> new file mode 100644
> index 000000000000..c8ddc5f11f32
> --- /dev/null
> +++ b/arch/loongarch/kernel/ftrace.c
> @@ -0,0 +1,74 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/uaccess.h>
> +#include <linux/init.h>
> +#include <linux/ftrace.h>
> +#include <linux/syscalls.h>
> +
> +#include <asm/asm.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/cacheflush.h>
> +#include <asm/inst.h>
> +#include <asm/loongarch.h>
> +#include <asm/syscall.h>
> +#include <asm/unistd.h>
> +
> +#include <asm-generic/sections.h>
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +
> +/*
> + * As `call _mcount` follows LoongArch psABI, ra-saved operation and
> + * stack operation can be found before this insn.
> + */
> +
> +static int ftrace_get_parent_ra_addr(unsigned long insn_addr, int *ra_off)
> +{
> +       union loongarch_instruction *insn;
> +       int limit = 32;
> +
> +       insn = (union loongarch_instruction *)insn_addr;
> +
> +       do {
> +               insn--;
> +               limit--;
> +
> +               if (is_ra_save_ins(insn))
> +                       *ra_off = -((1 << 12) - insn->reg2i12_format.immediate);
> +
> +       } while (!is_stack_alloc_ins(insn) && limit);
> +
> +       if (!limit)
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
> +void prepare_ftrace_return(unsigned long self_addr,
> +               unsigned long callsite_sp, unsigned long old)
> +{
> +       int ra_off;
> +       unsigned long return_hooker = (unsigned long)&return_to_handler;
> +
> +       if (unlikely(ftrace_graph_is_dead()))
> +               return;
> +
> +       if (unlikely(atomic_read(&current->tracing_graph_pause)))
> +               return;
> +
> +       if (ftrace_get_parent_ra_addr(self_addr, &ra_off))
> +               goto out;
> +
> +       if (!function_graph_enter(old, self_addr, 0, NULL))
> +               *(unsigned long *)(callsite_sp + ra_off) = return_hooker;
> +
> +       return;
> +
> +out:
> +       ftrace_graph_stop();
> +       WARN_ON(1);
> +}
> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> diff --git a/arch/loongarch/kernel/mcount.S b/arch/loongarch/kernel/mcount.S
> new file mode 100644
> index 000000000000..3de7c2d7fd12
> --- /dev/null
> +++ b/arch/loongarch/kernel/mcount.S
> @@ -0,0 +1,94 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * LoongArch specific _mcount support
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <asm/export.h>
> +#include <asm/regdef.h>
> +#include <asm/stackframe.h>
> +#include <asm/ftrace.h>
> +
> +       .text
> +
> +#define MCOUNT_STACK_SIZE      (2 * SZREG)
> +#define MCOUNT_S0_OFFSET       (0)
> +#define MCOUNT_RA_OFFSET       (SZREG)
> +
> +       .macro MCOUNT_SAVE_REGS
> +       PTR_ADDI sp, sp, -MCOUNT_STACK_SIZE
> +       PTR_S   s0, sp, MCOUNT_S0_OFFSET
> +       PTR_S   ra, sp, MCOUNT_RA_OFFSET
> +       move    s0, a0
> +       .endm
> +
> +       .macro MCOUNT_RESTORE_REGS
> +       move    a0, s0
> +       PTR_L   ra, sp, MCOUNT_RA_OFFSET
> +       PTR_L   s0, sp, MCOUNT_S0_OFFSET
> +       PTR_ADDI sp, sp, MCOUNT_STACK_SIZE
> +       .endm
> +
> +
> +SYM_FUNC_START(_mcount)
> +       la.pcrel        t1, ftrace_stub
> +       la.pcrel        t2, ftrace_trace_function       /* Prepare t2 for (1) */
> +       PTR_L   t2, t2, 0
> +       beq     t1, t2, fgraph_trace
> +
> +       MCOUNT_SAVE_REGS
> +
> +       move    a0, ra                          /* arg0: self return address */
> +       move    a1, s0                          /* arg1: parent's return address */
> +       jirl    ra, t2, 0                       /* (1) call *ftrace_trace_function */
> +
> +       MCOUNT_RESTORE_REGS
> +
> +fgraph_trace:
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +       la.pcrel        t1, ftrace_stub
> +       la.pcrel        t3, ftrace_graph_return
> +       PTR_L   t3, t3, 0
> +       bne     t1, t3, ftrace_graph_caller
> +       la.pcrel        t1, ftrace_graph_entry_stub
> +       la.pcrel        t3, ftrace_graph_entry
> +       PTR_L   t3, t3, 0
> +       bne     t1, t3, ftrace_graph_caller
> +#endif
> +
> +       .globl ftrace_stub
> +ftrace_stub:
> +       jr      ra
> +SYM_FUNC_END(_mcount)
> +EXPORT_SYMBOL(_mcount)
> +
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> +SYM_FUNC_START(ftrace_graph_caller)
> +       MCOUNT_SAVE_REGS
> +
> +       PTR_ADDI        a0, ra, -4                      /* arg0: Callsite self return addr */
> +       PTR_ADDI        a1, sp, MCOUNT_STACK_SIZE       /* arg1: Callsite sp */
> +       move    a2, s0                                  /* arg2: Callsite parent ra */
> +       bl      prepare_ftrace_return
> +
> +       MCOUNT_RESTORE_REGS
> +       jr      ra
> +SYM_FUNC_END(ftrace_graph_caller)
> +
> +SYM_FUNC_START(return_to_handler)
> +       PTR_ADDI sp, sp, -2 * SZREG
> +       PTR_S   a0, sp, 0
> +       PTR_S   a1, sp, SZREG
> +
> +       bl      ftrace_return_to_handler
> +
> +       /* restore the real parent address: a0 -> ra */
> +       move    ra, a0
> +
> +       PTR_L   a0, sp, 0
> +       PTR_L   a1, sp, SZREG
> +       PTR_ADDI        sp, sp, 2 * SZREG
> +       jr      ra
> +SYM_FUNC_END(return_to_handler)
> +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> --
> 2.36.1
>

^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2022-09-17  9:38 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-16  2:55 [PATCH v4 00/10] LoongArch: Add ftrace support Qing Zhang
2022-09-16  2:55 ` [PATCH v4 01/10] LoongArch/ftrace: Add basic support Qing Zhang
2022-09-17  9:38   ` Huacai Chen
2022-09-16  2:55 ` [PATCH v4 02/10] LoongArch/ftrace: Add recordmcount support Qing Zhang
2022-09-16  2:55 ` [PATCH v4 03/10] LoongArch/ftrace: Add dynamic function tracer support Qing Zhang
2022-09-16  2:55 ` [PATCH v4 04/10] LoongArch/ftrace: Add dynamic function graph " Qing Zhang
2022-09-16  2:55 ` [PATCH v4 05/10] LoongArch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Qing Zhang
2022-09-16  2:55 ` [PATCH v4 06/10] LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support Qing Zhang
2022-09-16  2:55 ` [PATCH v4 07/10] LoongArch: modules/ftrace: Initialize PLT at load time Qing Zhang
2022-09-16  2:55 ` [PATCH v4 08/10] LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support Qing Zhang

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