[PATCH v2 0/4] ARC: handle DSP presence in HW

[PATCH v2 0/4] ARC: handle DSP presence in HW

[Eugeniy Paltsev]

Arc processors may have DSP extension which is optional.
In this patch series we:
* Handle issues caused by DSP extension presence in HW
* Add optional support for DSP-enabled applications in
  userspace (with optional AGU extension support)

Changes v1->v2:
 * use r10:r11 register pair as a scratch for ASM code instead of
   r58:r59
 * reset DSP_CTRL to value suitable for kernel also in case of
   DSP for userspcae enabled
 * Use "Ir" instead of "I" parameter modifier to inline ASM
   to give compiler wiggle room.
 * Save / restore ACC0_GLO, ACC0_GHI only in case of context
   switch
 * Don't define additional options in headers to not introduce
   explicit include dependencies
 * Mode DSP config check to DSP code itself
 * Minor fixes

Eugeniy Paltsev (4):
  ARC: add helpers to sanitize config options
  ARC: handle DSP presence in HW
  ARC: add support for DSP-enabled userspace applications
  ARC: allow userspace DSP applications to use AGU extensions

 arch/arc/Kconfig                   |  50 +++++++++-
 arch/arc/include/asm/arcregs.h     |  26 +++++
 arch/arc/include/asm/asserts.h     |  34 +++++++
 arch/arc/include/asm/dsp-impl.h    | 150 +++++++++++++++++++++++++++++
 arch/arc/include/asm/dsp.h         |  29 ++++++
 arch/arc/include/asm/entry-arcv2.h |   6 ++
 arch/arc/include/asm/processor.h   |   4 +
 arch/arc/include/asm/ptrace.h      |   3 +
 arch/arc/include/asm/switch_to.h   |   2 +
 arch/arc/kernel/asm-offsets.c      |   4 +
 arch/arc/kernel/head.S             |   4 +
 arch/arc/kernel/setup.c            |  34 ++++---
 12 files changed, 332 insertions(+), 14 deletions(-)
 create mode 100644 arch/arc/include/asm/asserts.h
 create mode 100644 arch/arc/include/asm/dsp-impl.h
 create mode 100644 arch/arc/include/asm/dsp.h

-- 
2.21.1

[PATCH v2 1/4] ARC: add helpers to sanitize config options

[Eugeniy Paltsev]

We'll use this macro in coming patches extensively.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 arch/arc/include/asm/asserts.h | 24 ++++++++++++++++++++++++
 arch/arc/kernel/setup.c        | 25 ++++++++++++-------------
 2 files changed, 36 insertions(+), 13 deletions(-)
 create mode 100644 arch/arc/include/asm/asserts.h

diff --git a/arch/arc/include/asm/asserts.h b/arch/arc/include/asm/asserts.h
new file mode 100644
index 000000000000..3314efbeb528
--- /dev/null
+++ b/arch/arc/include/asm/asserts.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+ */
+#ifndef __ASM_ARC_ASSERTS_H
+#define __ASM_ARC_ASSERTS_H
+
+/* Helpers to sanitize config options. */
+
+void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena);
+
+/*
+ * Check required config option:
+ *  - panic in case of OPT enabled but corresponding HW absent.
+ *  - warn in case of OPT disabled but corresponding HW exists.
+*/
+#define CHK_OPT_STRICT(opt_name, hw_exists)				\
+({									\
+	chk_opt_strict(#opt_name, hw_exists, IS_ENABLED(opt_name));	\
+})
+
+#endif /* __ASM_ARC_ASSERTS_H */
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index aa41af6ef4ac..820c0cfb0702 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -19,6 +19,7 @@
 #include <uapi/linux/mount.h>
 #include <asm/sections.h>
 #include <asm/arcregs.h>
+#include <asm/asserts.h>
 #include <asm/tlb.h>
 #include <asm/setup.h>
 #include <asm/page.h>
@@ -389,11 +390,18 @@ static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
 	return buf;
 }
 
+void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena)
+{
+	if (hw_exists && !opt_ena)
+		pr_warn(" ! Enable %s for working apps\n", opt_name);
+	else if (!hw_exists && opt_ena)
+		panic("Disable %s, hardware NOT present\n", opt_name);
+}
+
 static void arc_chk_core_config(void)
 {
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
-	int saved = 0, present = 0;
-	char *opt_nm = NULL;
+	int present = 0;
 
 	if (!cpu->extn.timer0)
 		panic("Timer0 is not present!\n");
@@ -425,23 +433,14 @@ static void arc_chk_core_config(void)
 	 */
 
 	if (is_isa_arcompact()) {
-		opt_nm = "CONFIG_ARC_FPU_SAVE_RESTORE";
-		saved = IS_ENABLED(CONFIG_ARC_FPU_SAVE_RESTORE);
-
 		/* only DPDP checked since SP has no arch visible regs */
 		present = cpu->extn.fpu_dp;
+		CHK_OPT_STRICT(CONFIG_ARC_FPU_SAVE_RESTORE, present);
 	} else {
-		opt_nm = "CONFIG_ARC_HAS_ACCL_REGS";
-		saved = IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS);
-
 		/* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
 		present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
+		CHK_OPT_STRICT(CONFIG_ARC_HAS_ACCL_REGS, present);
 	}
-
-	if (present && !saved)
-		pr_warn("Enable %s for working apps\n", opt_nm);
-	else if (!present && saved)
-		panic("Disable %s, hardware NOT present\n", opt_nm);
 }
 
 /*
-- 
2.21.1

[PATCH v2 2/4] ARC: handle DSP presence in HW

[Eugeniy Paltsev]

In case of DSP extension presence in HW some instructions
(related to integer multiply, multiply-accumulate, and divide
operation) executes on this DSP execution unit. So their
execution will depend on dsp configuration register (DSP_CTRL)

As we want these instructions to execute the same way regardless
of DSP presence we need to set DSP_CTRL properly. However this
register can be modified bu any usersace app therefore any
usersace may break kernel execution.

Fix that by configure DSP_CTRL in CPU early code and in IRQs
entries.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 arch/arc/Kconfig                   | 29 +++++++++++++++-
 arch/arc/include/asm/arcregs.h     | 12 +++++++
 arch/arc/include/asm/dsp-impl.h    | 54 ++++++++++++++++++++++++++++++
 arch/arc/include/asm/entry-arcv2.h |  3 ++
 arch/arc/kernel/head.S             |  4 +++
 arch/arc/kernel/setup.c            |  3 ++
 6 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 arch/arc/include/asm/dsp-impl.h

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 7124ab82dfa3..55432a8fc20d 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -401,13 +401,40 @@ config ARC_HAS_DIV_REM
 	default y
 
 config ARC_HAS_ACCL_REGS
-	bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6)"
+	bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6 and/or DSP)"
 	default y
 	help
 	  Depending on the configuration, CPU can contain accumulator reg-pair
 	  (also referred to as r58:r59). These can also be used by gcc as GPR so
 	  kernel needs to save/restore per process
 
+config ARC_DSP_HANDLED
+	def_bool n
+
+choice
+	prompt "DSP support"
+	default ARC_DSP_NONE
+	help
+	  Depending on the configuration, CPU can contain DSP registers
+	  (ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_CTRL, DSP_FFT_CTRL).
+	  Bellow is options describing how to handle these registers in
+	  interrupt entry / exit and in context switch.
+
+config ARC_DSP_NONE
+	bool "No DSP extension presence in HW"
+	help
+	  No DSP extension presence in HW
+
+config ARC_DSP_KERNEL
+	bool "DSP extension in HW, no support for userspace"
+	select ARC_HAS_ACCL_REGS
+	select ARC_DSP_HANDLED
+	help
+	  DSP extension presence in HW, no support for DSP-enabled userspace
+	  applications. We don't save / restore DSP registers and only do
+	  some minimal preparations so userspace won't be able to break kernel
+endchoice
+
 config ARC_IRQ_NO_AUTOSAVE
 	bool "Disable hardware autosave regfile on interrupts"
 	default n
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index f7e432448e4b..135f6ec08a69 100644
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -118,6 +118,18 @@
 #define ARC_AUX_DPFP_2H         0x304
 #define ARC_AUX_DPFP_STAT       0x305
 
+/*
+ * DSP-related registers
+ */
+#define ARC_AUX_DSP_BUILD	0x7A
+#define ARC_AUX_ACC0_LO		0x580
+#define ARC_AUX_ACC0_GLO	0x581
+#define ARC_AUX_ACC0_HI		0x582
+#define ARC_AUX_ACC0_GHI	0x583
+#define ARC_AUX_DSP_BFLY0	0x598
+#define ARC_AUX_DSP_CTRL	0x59F
+#define ARC_AUX_DSP_FFT_CTRL	0x59E
+
 #ifndef __ASSEMBLY__
 
 #include <soc/arc/aux.h>
diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
new file mode 100644
index 000000000000..606620383eca
--- /dev/null
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+ */
+#ifndef __ASM_ARC_DSP_IMPL_H
+#define __ASM_ARC_DSP_IMPL_H
+
+#define DSP_CTRL_DISABLED_ALL		0
+
+#ifdef __ASSEMBLY__
+
+/* clobbers r5 register */
+.macro DSP_EARLY_INIT
+	lr	r5, [ARC_AUX_DSP_BUILD]
+	bmsk	r5, r5, 7
+	breq    r5, 0, 1f
+	mov	r5, DSP_CTRL_DISABLED_ALL
+	sr	r5, [ARC_AUX_DSP_CTRL]
+1:
+.endm
+
+/* clobbers r10, r11 registers pair */
+.macro DSP_SAVE_REGFILE_IRQ
+#if defined(CONFIG_ARC_DSP_KERNEL)
+	/*
+	 * Drop any changes to DSP_CTRL made by userspace so userspace won't be
+	 * able to break kernel - reset it to DSP_CTRL_DISABLED_ALL value
+	 */
+	mov	r10, DSP_CTRL_DISABLED_ALL
+	sr	r10, [ARC_AUX_DSP_CTRL]
+#endif /* ARC_DSP_KERNEL */
+.endm
+
+#else /* __ASEMBLY__ */
+
+#include <asm/asserts.h>
+
+static inline bool dsp_exist(void)
+{
+	struct bcr_generic bcr;
+
+	READ_BCR(ARC_AUX_DSP_BUILD, bcr);
+	return !!bcr.ver;
+}
+
+static inline void dsp_config_check(void)
+{
+	CHK_OPT_STRICT(CONFIG_ARC_DSP_HANDLED, dsp_exist());
+}
+
+#endif /* __ASEMBLY__ */
+#endif /* __ASM_ARC_DSP_IMPL_H */
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 0b8b63d0bec1..dd6aa18b51ca 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -4,6 +4,7 @@
 #define __ASM_ARC_ENTRY_ARCV2_H
 
 #include <asm/asm-offsets.h>
+#include <asm/dsp-impl.h>
 #include <asm/irqflags-arcv2.h>
 #include <asm/thread_info.h>	/* For THREAD_SIZE */
 
@@ -165,6 +166,8 @@
 	ST2	r58, r59, PT_r58
 #endif
 
+	/* clobbers r10, r11 registers pair */
+	DSP_SAVE_REGFILE_IRQ
 .endm
 
 /*------------------------------------------------------------------------*/
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 6f41265f6250..6eb23f1545ee 100644
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -14,6 +14,7 @@
 #include <asm/entry.h>
 #include <asm/arcregs.h>
 #include <asm/cache.h>
+#include <asm/dsp-impl.h>
 #include <asm/irqflags.h>
 
 .macro CPU_EARLY_SETUP
@@ -59,6 +60,9 @@
 #endif
 	kflag	r5
 #endif
+	; Config DSP_CTRL properly, so kernel may use integer multiply,
+	; multiply-accumulate, and divide operations
+	DSP_EARLY_INIT
 .endm
 
 	.section .init.text, "ax",@progbits
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 820c0cfb0702..1ed1528d9045 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -27,6 +27,7 @@
 #include <asm/unwind.h>
 #include <asm/mach_desc.h>
 #include <asm/smp.h>
+#include <asm/dsp-impl.h>
 
 #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
 
@@ -440,6 +441,8 @@ static void arc_chk_core_config(void)
 		/* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
 		present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
 		CHK_OPT_STRICT(CONFIG_ARC_HAS_ACCL_REGS, present);
+
+		dsp_config_check();
 	}
 }
 
-- 
2.21.1

[PATCH v2 3/4] ARC: add support for DSP-enabled userspace applications

[Eugeniy Paltsev]

To be able to run DSP-enabled userspace applications we need to
save and restore following DSP-related registers:
At IRQ/exception entry/exit:
 * DSP_CTRL (save it and reset to value suitable for kernel)
 * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair)
At context switch:
 * ACC0_GLO, ACC0_GHI
 * DSP_BFLY0, DSP_FFT_CTRL

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 arch/arc/Kconfig                   | 12 +++++
 arch/arc/include/asm/arcregs.h     |  2 +
 arch/arc/include/asm/dsp-impl.h    | 74 +++++++++++++++++++++++++++++-
 arch/arc/include/asm/dsp.h         | 24 ++++++++++
 arch/arc/include/asm/entry-arcv2.h |  3 ++
 arch/arc/include/asm/processor.h   |  4 ++
 arch/arc/include/asm/ptrace.h      |  3 ++
 arch/arc/include/asm/switch_to.h   |  2 +
 arch/arc/kernel/asm-offsets.c      |  4 ++
 9 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 arch/arc/include/asm/dsp.h

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 55432a8fc20d..eb3bcb206882 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -411,6 +411,9 @@ config ARC_HAS_ACCL_REGS
 config ARC_DSP_HANDLED
 	def_bool n
 
+config ARC_DSP_SAVE_RESTORE_REGS
+	def_bool n
+
 choice
 	prompt "DSP support"
 	default ARC_DSP_NONE
@@ -433,6 +436,15 @@ config ARC_DSP_KERNEL
 	  DSP extension presence in HW, no support for DSP-enabled userspace
 	  applications. We don't save / restore DSP registers and only do
 	  some minimal preparations so userspace won't be able to break kernel
+
+config ARC_DSP_USERSPACE
+	bool "Support DSP for userspace apps"
+	select ARC_HAS_ACCL_REGS
+	select ARC_DSP_HANDLED
+	select ARC_DSP_SAVE_RESTORE_REGS
+	help
+	  DSP extension presence in HW, support save / restore DSP registers to
+	  run DSP-enabled userspace applications
 endchoice
 
 config ARC_IRQ_NO_AUTOSAVE
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index 135f6ec08a69..aee1ee263065 100644
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -120,6 +120,8 @@
 
 /*
  * DSP-related registers
+ * Registers names must correspond to dsp_callee_regs structure fields names
+ * for automatic offset calculation in DSP_AUX_SAVE_RESTORE macros.
  */
 #define ARC_AUX_DSP_BUILD	0x7A
 #define ARC_AUX_ACC0_LO		0x580
diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
index 606620383eca..8380f7bede81 100644
--- a/arch/arc/include/asm/dsp-impl.h
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -7,6 +7,8 @@
 #ifndef __ASM_ARC_DSP_IMPL_H
 #define __ASM_ARC_DSP_IMPL_H
 
+#include <asm/dsp.h>
+
 #define DSP_CTRL_DISABLED_ALL		0
 
 #ifdef __ASSEMBLY__
@@ -30,12 +32,82 @@
 	 */
 	mov	r10, DSP_CTRL_DISABLED_ALL
 	sr	r10, [ARC_AUX_DSP_CTRL]
-#endif /* ARC_DSP_KERNEL */
+
+#elif defined(CONFIG_ARC_DSP_SAVE_RESTORE_REGS)
+	/*
+	 * Save DSP_CTRL register and reset it to value suitable for kernel
+	 * (DSP_CTRL_DISABLED_ALL)
+	 */
+	mov	r10, DSP_CTRL_DISABLED_ALL
+	aex	r10, [ARC_AUX_DSP_CTRL]
+	st	r10, [sp, PT_DSP_CTRL]
+
+#endif
+.endm
+
+/* clobbers r10, r11 registers pair */
+.macro DSP_RESTORE_REGFILE_IRQ
+#if defined(CONFIG_ARC_DSP_SAVE_RESTORE_REGS)
+	ld	r10, [sp, PT_DSP_CTRL]
+	sr	r10, [ARC_AUX_DSP_CTRL]
+
+#endif
 .endm
 
 #else /* __ASEMBLY__ */
 
+#include <linux/sched.h>
 #include <asm/asserts.h>
+#include <asm/switch_to.h>
+
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+
+/*
+ * As we save new and restore old AUX register value in the same place we
+ * can optimize a bit and use AEX instruction (swap contents of an auxiliary
+ * register with a core register) instead of LR + SR pair.
+ */
+#define AUX_SAVE_RESTORE(_saveto, _readfrom, _offt, _aux)		\
+do {									\
+	long unsigned int _scratch;					\
+									\
+	__asm__ __volatile__(						\
+		"ld	%0, [%2, %4]			\n"		\
+		"aex	%0, [%3]			\n"		\
+		"st	%0, [%1, %4]			\n"		\
+		:							\
+		  "=&r" (_scratch)	/* must be early clobber */	\
+		:							\
+		   "r" (_saveto),					\
+		   "r" (_readfrom),					\
+		   "Ir" (_aux),						\
+		   "Ir" (_offt)						\
+		:							\
+		  "memory"						\
+	);								\
+} while (0)
+
+#define DSP_AUX_SAVE_RESTORE(_saveto, _readfrom, _aux)			\
+	AUX_SAVE_RESTORE(_saveto, _readfrom,				\
+		offsetof(struct dsp_callee_regs, _aux),			\
+		ARC_AUX_##_aux)
+
+static inline void dsp_save_restore(struct task_struct *prev,
+					struct task_struct *next)
+{
+	long unsigned int *saveto = &prev->thread.dsp.ACC0_GLO;
+	long unsigned int *readfrom = &next->thread.dsp.ACC0_GLO;
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, ACC0_GLO);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, ACC0_GHI);
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_BFLY0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_FFT_CTRL);
+}
+
+#else /* !CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
+#define dsp_save_restore(p, n)
+#endif /* CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
 
 static inline bool dsp_exist(void)
 {
diff --git a/arch/arc/include/asm/dsp.h b/arch/arc/include/asm/dsp.h
new file mode 100644
index 000000000000..b016f4d2a09f
--- /dev/null
+++ b/arch/arc/include/asm/dsp.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Author: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+ */
+#ifndef __ASM_ARC_DSP_H
+#define __ASM_ARC_DSP_H
+
+#ifndef __ASSEMBLY__
+
+/*
+ * DSP-related saved registers - need to be saved only when you are
+ * scheduled out.
+ * structure fields name must correspond to aux register defenitions for
+ * automatic offset calculation in DSP_AUX_SAVE_RESTORE macros
+ */
+struct dsp_callee_regs {
+	unsigned long ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_FFT_CTRL;
+};
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_ARC_DSP_H */
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index dd6aa18b51ca..ae0aa5323be1 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -192,6 +192,9 @@
 	ld	r25, [sp, PT_user_r25]
 #endif
 
+	/* clobbers r10, r11 registers pair */
+	DSP_RESTORE_REGFILE_IRQ
+
 #ifdef CONFIG_ARC_HAS_ACCL_REGS
 	LD2	r58, r59, PT_r58
 #endif
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index ec532d1e0725..0fcea5bad343 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -14,6 +14,7 @@
 #ifndef __ASSEMBLY__
 
 #include <asm/ptrace.h>
+#include <asm/dsp.h>
 #include <asm/fpu.h>
 
 #ifdef CONFIG_ARC_PLAT_EZNPS
@@ -31,6 +32,9 @@ struct thread_struct {
 	unsigned long ksp;	/* kernel mode stack pointer */
 	unsigned long callee_reg;	/* pointer to callee regs */
 	unsigned long fault_address;	/* dbls as brkpt holder as well */
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+	struct dsp_callee_regs dsp;
+#endif
 #ifdef CONFIG_ARC_FPU_SAVE_RESTORE
 	struct arc_fpu fpu;
 #endif
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index ba9854ef39e8..2fdb87addadc 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -91,6 +91,9 @@ struct pt_regs {
 #ifdef CONFIG_ARC_HAS_ACCL_REGS
 	unsigned long r58, r59;	/* ACCL/ACCH used by FPU / DSP MPY */
 #endif
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+	unsigned long DSP_CTRL;
+#endif
 
 	/*------- Below list auto saved by h/w -----------*/
 	unsigned long r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, r11;
diff --git a/arch/arc/include/asm/switch_to.h b/arch/arc/include/asm/switch_to.h
index aadf65b2b56c..4a3d67989d19 100644
--- a/arch/arc/include/asm/switch_to.h
+++ b/arch/arc/include/asm/switch_to.h
@@ -9,6 +9,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/sched.h>
+#include <asm/dsp-impl.h>
 #include <asm/fpu.h>
 
 #ifdef CONFIG_ARC_PLAT_EZNPS
@@ -24,6 +25,7 @@ struct task_struct *__switch_to(struct task_struct *p, struct task_struct *n);
 #define switch_to(prev, next, last)	\
 do {					\
 	ARC_EZNPS_DP_PREV(prev, next);	\
+	dsp_save_restore(prev, next);	\
 	fpu_save_restore(prev, next);	\
 	last = __switch_to(prev, next);\
 	mb();				\
diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c
index c783bcd35eb8..0e884036ab74 100644
--- a/arch/arc/kernel/asm-offsets.c
+++ b/arch/arc/kernel/asm-offsets.c
@@ -12,6 +12,7 @@
 #include <asm/hardirq.h>
 #include <asm/page.h>
 
+
 int main(void)
 {
 	DEFINE(TASK_THREAD, offsetof(struct task_struct, thread));
@@ -75,6 +76,9 @@ int main(void)
 	OFFSET(PT_r58, pt_regs, r58);
 	OFFSET(PT_r59, pt_regs, r59);
 #endif
+#ifdef CONFIG_ARC_DSP_SAVE_RESTORE_REGS
+	OFFSET(PT_DSP_CTRL, pt_regs, DSP_CTRL);
+#endif
 
 	return 0;
 }
-- 
2.21.1

[PATCH v2 4/4] ARC: allow userspace DSP applications to use AGU extensions

[Eugeniy Paltsev]

To be able to run DSP-enabled userspace applications with AGU
(address generation unit) extensions we additionally need to
save and restore following registers at context switch:
 * AGU_AP*
 * AGU_OS*
 * AGU_MOD*

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 arch/arc/Kconfig                |  9 +++++++++
 arch/arc/include/asm/arcregs.h  | 12 ++++++++++++
 arch/arc/include/asm/asserts.h  | 10 ++++++++++
 arch/arc/include/asm/dsp-impl.h | 24 ++++++++++++++++++++++++
 arch/arc/include/asm/dsp.h      |  5 +++++
 arch/arc/kernel/setup.c         |  6 ++++++
 6 files changed, 66 insertions(+)

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index eb3bcb206882..ff306246d0f8 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -445,6 +445,15 @@ config ARC_DSP_USERSPACE
 	help
 	  DSP extension presence in HW, support save / restore DSP registers to
 	  run DSP-enabled userspace applications
+
+config ARC_DSP_AGU_USERSPACE
+	bool "Support DSP with AGU for userspace apps"
+	select ARC_HAS_ACCL_REGS
+	select ARC_DSP_HANDLED
+	select ARC_DSP_SAVE_RESTORE_REGS
+	help
+	  DSP and AGU extensions presence in HW, support save / restore DSP
+	  and AGU registers to run DSP-enabled userspace applications
 endchoice
 
 config ARC_IRQ_NO_AUTOSAVE
diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index aee1ee263065..2162023195c5 100644
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -132,6 +132,18 @@
 #define ARC_AUX_DSP_CTRL	0x59F
 #define ARC_AUX_DSP_FFT_CTRL	0x59E
 
+#define ARC_AUX_AGU_BUILD	0xCC
+#define ARC_AUX_AGU_AP0		0x5C0
+#define ARC_AUX_AGU_AP1		0x5C1
+#define ARC_AUX_AGU_AP2		0x5C2
+#define ARC_AUX_AGU_AP3		0x5C3
+#define ARC_AUX_AGU_OS0		0x5D0
+#define ARC_AUX_AGU_OS1		0x5D1
+#define ARC_AUX_AGU_MOD0	0x5E0
+#define ARC_AUX_AGU_MOD1	0x5E1
+#define ARC_AUX_AGU_MOD2	0x5E2
+#define ARC_AUX_AGU_MOD3	0x5E3
+
 #ifndef __ASSEMBLY__
 
 #include <soc/arc/aux.h>
diff --git a/arch/arc/include/asm/asserts.h b/arch/arc/include/asm/asserts.h
index 3314efbeb528..108f33be6aa5 100644
--- a/arch/arc/include/asm/asserts.h
+++ b/arch/arc/include/asm/asserts.h
@@ -10,6 +10,7 @@
 /* Helpers to sanitize config options. */
 
 void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena);
+void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena);
 
 /*
  * Check required config option:
@@ -21,4 +22,13 @@ void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena);
 	chk_opt_strict(#opt_name, hw_exists, IS_ENABLED(opt_name));	\
 })
 
+/*
+ * Check optional config option:
+ *  - panic in case of OPT enabled but corresponding HW absent.
+*/
+#define CHK_OPT_WEAK(opt_name, hw_exists)				\
+({									\
+	chk_opt_weak(#opt_name, hw_exists, IS_ENABLED(opt_name));	\
+})
+
 #endif /* __ASM_ARC_ASSERTS_H */
diff --git a/arch/arc/include/asm/dsp-impl.h b/arch/arc/include/asm/dsp-impl.h
index 8380f7bede81..e1aa212ca6eb 100644
--- a/arch/arc/include/asm/dsp-impl.h
+++ b/arch/arc/include/asm/dsp-impl.h
@@ -103,6 +103,21 @@ static inline void dsp_save_restore(struct task_struct *prev,
 
 	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_BFLY0);
 	DSP_AUX_SAVE_RESTORE(saveto, readfrom, DSP_FFT_CTRL);
+
+#ifdef CONFIG_ARC_DSP_AGU_USERSPACE
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP1);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP2);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_AP3);
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_OS0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_OS1);
+
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD0);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD1);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD2);
+	DSP_AUX_SAVE_RESTORE(saveto, readfrom, AGU_MOD3);
+#endif /* CONFIG_ARC_DSP_AGU_USERSPACE */
 }
 
 #else /* !CONFIG_ARC_DSP_SAVE_RESTORE_REGS */
@@ -117,9 +132,18 @@ static inline bool dsp_exist(void)
 	return !!bcr.ver;
 }
 
+static inline bool agu_exist(void)
+{
+	struct bcr_generic bcr;
+
+	READ_BCR(ARC_AUX_AGU_BUILD, bcr);
+	return !!bcr.ver;
+}
+
 static inline void dsp_config_check(void)
 {
 	CHK_OPT_STRICT(CONFIG_ARC_DSP_HANDLED, dsp_exist());
+	CHK_OPT_WEAK(CONFIG_ARC_DSP_AGU_USERSPACE, agu_exist());
 }
 
 #endif /* __ASEMBLY__ */
diff --git a/arch/arc/include/asm/dsp.h b/arch/arc/include/asm/dsp.h
index b016f4d2a09f..202c78e56704 100644
--- a/arch/arc/include/asm/dsp.h
+++ b/arch/arc/include/asm/dsp.h
@@ -17,6 +17,11 @@
  */
 struct dsp_callee_regs {
 	unsigned long ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_FFT_CTRL;
+#ifdef CONFIG_ARC_DSP_AGU_USERSPACE
+	unsigned long AGU_AP0, AGU_AP1, AGU_AP2, AGU_AP3;
+	unsigned long AGU_OS0, AGU_OS1;
+	unsigned long AGU_MOD0, AGU_MOD1, AGU_MOD2, AGU_MOD3;
+#endif
 };
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 1ed1528d9045..b2b1cb645d9e 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -399,6 +399,12 @@ void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena)
 		panic("Disable %s, hardware NOT present\n", opt_name);
 }
 
+void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena)
+{
+	if (!hw_exists && opt_ena)
+		panic("Disable %s, hardware NOT present\n", opt_name);
+}
+
 static void arc_chk_core_config(void)
 {
 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
-- 
2.21.1

Re: [PATCH v2 1/4] ARC: add helpers to sanitize config options

[Vineet Gupta]

On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
> We'll use this macro in coming patches extensively.
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

LGTM !

Acked-by: Vineet Gupta <vgupta@synopsys.com>

Re: [PATCH v2 2/4] ARC: handle DSP presence in HW

[Vineet Gupta]

On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
> In case of DSP extension presence in HW some instructions
> (related to integer multiply, multiply-accumulate, and divide
> operation) executes on this DSP execution unit. So their
> execution will depend on dsp configuration register (DSP_CTRL)
> 
> As we want these instructions to execute the same way regardless
> of DSP presence we need to set DSP_CTRL properly. However this
> register can be modified bu any usersace app therefore any
> usersace may break kernel execution.
> 
> Fix that by configure DSP_CTRL in CPU early code and in IRQs
> entries.

How about below ....

"When DSP extensions are present, some of the regular integer instructions such as
DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in
DSP_CTRL aux register. This register is writable by userspace and thus can
potentially affect corresponding instructions in kernel code, intentionally or
otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and
every entry to kernel.

Do note that for this config we simply zero out the DSP_CTRL reg assuming
userspace doesn't really care about DSP. The next patch caters to the DSP aware
userspace which this actually saved/restored upon kernel entry."



> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
>  arch/arc/Kconfig                   | 29 +++++++++++++++-
>  arch/arc/include/asm/arcregs.h     | 12 +++++++
>  arch/arc/include/asm/dsp-impl.h    | 54 ++++++++++++++++++++++++++++++
>  arch/arc/include/asm/entry-arcv2.h |  3 ++
>  arch/arc/kernel/head.S             |  4 +++
>  arch/arc/kernel/setup.c            |  3 ++
>  6 files changed, 104 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arc/include/asm/dsp-impl.h
> 
> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
> index 7124ab82dfa3..55432a8fc20d 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -401,13 +401,40 @@ config ARC_HAS_DIV_REM
>  	default y
>  
>  config ARC_HAS_ACCL_REGS
> -	bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6)"
> +	bool "Reg Pair ACCL:ACCH (FPU and/or MPY > 6 and/or DSP)"
>  	default y
>  	help
>  	  Depending on the configuration, CPU can contain accumulator reg-pair
>  	  (also referred to as r58:r59). These can also be used by gcc as GPR so
>  	  kernel needs to save/restore per process
>  
> +config ARC_DSP_HANDLED
> +	def_bool n
> +
> +choice
> +	prompt "DSP support"
> +	default ARC_DSP_NONE
> +	help
> +	  Depending on the configuration, CPU can contain DSP registers
> +	  (ACC0_GLO, ACC0_GHI, DSP_BFLY0, DSP_CTRL, DSP_FFT_CTRL).
> +	  Bellow is options describing how to handle these registers in

typo: Below

Looks good otherwise. No need to respin just for this.

Reviewed-by: Vineet Gupta <vgupta@synopsys.com>

Re: [PATCH v2 2/4] ARC: handle DSP presence in HW

[Eugeniy Paltsev]

>From: Vineet Gupta <vgupta@synopsys.com>
>Sent: Saturday, March 7, 2020 03:12
>To: Eugeniy Paltsev; linux-snps-arc@lists.infradead.org
>Cc: Alexey Brodkin; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH v2 2/4] ARC: handle DSP presence in HW
>
>On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
>> In case of DSP extension presence in HW some instructions
>> (related to integer multiply, multiply-accumulate, and divide
>> operation) executes on this DSP execution unit. So their
>> execution will depend on dsp configuration register (DSP_CTRL)
>>
>> As we want these instructions to execute the same way regardless
>> of DSP presence we need to set DSP_CTRL properly. However this
>> register can be modified bu any usersace app therefore any
>> usersace may break kernel execution.
>>
>> Fix that by configure DSP_CTRL in CPU early code and in IRQs
>> entries.
>
> How about below ....
> 
> "When DSP extensions are present, some of the regular integer instructions such as
> DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in
> DSP_CTRL aux register. This register is writable by userspace and thus can
> potentially affect corresponding instructions in kernel code, intentionally or
> otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and
> every entry to kernel.
> 
> Do note that for this config we simply zero out the DSP_CTRL reg assuming
> userspace doesn't really care about DSP. The next patch caters to the DSP aware
> userspace which this actually saved/restored upon kernel entry."
>From: Vineet Gupta <vgupta@synopsys.com>
>Sent: Saturday, March 7, 2020 03:12
>To: Eugeniy Paltsev; linux-snps-arc@lists.infradead.org
>Cc: Alexey Brodkin; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH v2 2/4] ARC: handle DSP presence in HW
>
>On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
>> In case of DSP extension presence in HW some instructions
>> (related to integer multiply, multiply-accumulate, and divide
>> operation) executes on this DSP execution unit. So their
>> execution will depend on dsp configuration register (DSP_CTRL)
>>
>> As we want these instructions to execute the same way regardless
>> of DSP presence we need to set DSP_CTRL properly. However this
>> register can be modified bu any usersace app therefore any
>> usersace may break kernel execution.
>>
>> Fix that by configure DSP_CTRL in CPU early code and in IRQs
>> entries.
>
> How about below ....

> 
> "When DSP extensions are present, some of the regular integer instructions such as
> DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in
> DSP_CTRL aux register. This register is writable by userspace and thus can
> potentially affect corresponding instructions in kernel code, intentionally or
> otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and
> every entry to kernel.
> 
> Do note that for this config we simply zero out the DSP_CTRL reg assuming
> userspace doesn't really care about DSP. The next patch caters to the DSP aware
> userspace which this actually saved/restored upon kernel entry."

Re: [PATCH v2 2/4] ARC: handle DSP presence in HW

[Eugeniy Paltsev]

>From: Vineet Gupta <vgupta@synopsys.com>
>Sent: Saturday, March 7, 2020 03:12
>To: Eugeniy Paltsev; linux-snps-arc@lists.infradead.org
>Cc: Alexey Brodkin; linux-kernel@vger.kernel.org
>Subject: Re: [PATCH v2 2/4] ARC: handle DSP presence in HW
>
>On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
>> In case of DSP extension presence in HW some instructions
>> (related to integer multiply, multiply-accumulate, and divide
>> operation) executes on this DSP execution unit. So their
>> execution will depend on dsp configuration register (DSP_CTRL)
>>
>> As we want these instructions to execute the same way regardless
>> of DSP presence we need to set DSP_CTRL properly. However this
>> register can be modified bu any usersace app therefore any
>> usersace may break kernel execution.
>>
>> Fix that by configure DSP_CTRL in CPU early code and in IRQs
>> entries.
>
> How about below ....

Good description, ACK.

> "When DSP extensions are present, some of the regular integer instructions such as
> DIV, MACD etc are executed in the DSP unit with semantics alterable by flags in
> DSP_CTRL aux register. This register is writable by userspace and thus can
> potentially affect corresponding instructions in kernel code, intentionally or
> otherwise. So safegaurd kernel by effectively disabling DSP_CTRL upon bootup and
> every entry to kernel.
> 
> Do note that for this config we simply zero out the DSP_CTRL reg assuming
> userspace doesn't really care about DSP. The next patch caters to the DSP aware
> userspace which this actually saved/restored upon kernel entry."

Re: [PATCH v2 3/4] ARC: add support for DSP-enabled userspace applications

[Vineet Gupta]

On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
> To be able to run DSP-enabled userspace applications we need to
> save and restore following DSP-related registers:
> At IRQ/exception entry/exit:
>  * DSP_CTRL (save it and reset to value suitable for kernel)
>  * ACC0_LO, ACC0_HI (we already save them as r58, r59 pair)
> At context switch:
>  * ACC0_GLO, ACC0_GHI
>  * DSP_BFLY0, DSP_FFT_CTRL
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

Acked-by: Vineet Gupta <vgupta@synopsys.com>

Re: [PATCH v2 4/4] ARC: allow userspace DSP applications to use AGU extensions

[Vineet Gupta]

On 3/5/20 12:02 PM, Eugeniy Paltsev wrote:
> To be able to run DSP-enabled userspace applications with AGU
> (address generation unit) extensions we additionally need to
> save and restore following registers at context switch:
>  * AGU_AP*
>  * AGU_OS*
>  * AGU_MOD*
> 
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>

Acked-by: Vineet Gupta <vgupta@synopsys.com>