linux-kernel - [PATCH v3 1/3] MIPS: Add user stack and registers to perf.

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Date:	Fri, 1 Apr 2016 10:56:55 +0200
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	David Daney <david.daney@...ium.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Paul Burton <paul.burton@...tec.com>,
	James Hogan <james.hogan@...tec.com>,
	Matt Redfearn <matt.redfearn@...tec.com>,
	Qais Yousef <qais.yousef@...tec.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Jiri Olsa <jolsa@...hat.com>, Wang Nan <wangnan0@...wei.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/3] MIPS: Add user stack and registers to perf.

From: David Daney <david.daney@...ium.com>

This allows for extracting off-line stack traces from user-space code
in the perf tool.

[ralf@...ux-mips.org: Add perf_get_regs_user() which is required after
88a7c26af8da (perf: >> Move task_pt_regs sampling into arch code).]

Signed-off-by: David Daney <david.daney@...ium.com>
Cc: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
---
 arch/mips/Kconfig                      |  2 +
 arch/mips/include/uapi/asm/perf_regs.h | 41 +++++++++++++++++++++
 arch/mips/kernel/Makefile              |  2 +-
 arch/mips/kernel/perf_regs.c           | 67 ++++++++++++++++++++++++++++++++++
 4 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 arch/mips/include/uapi/asm/perf_regs.h
 create mode 100644 arch/mips/kernel/perf_regs.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 35d92a1..6051f58 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -11,6 +11,8 @@ config MIPS
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_PERF_EVENTS
+	select HAVE_PERF_REGS
+	select HAVE_PERF_USER_STACK_DUMP
 	select PERF_USE_VMALLOC
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/mips/include/uapi/asm/perf_regs.h b/arch/mips/include/uapi/asm/perf_regs.h
new file mode 100644
index 0000000..9577af5
--- /dev/null
+++ b/arch/mips/include/uapi/asm/perf_regs.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_MIPS_PERF_REGS_H
+#define _ASM_MIPS_PERF_REGS_H
+
+enum perf_event_mips_regs {
+	PERF_REG_MIPS_PC,
+	PERF_REG_MIPS_R1,
+	PERF_REG_MIPS_R2,
+	PERF_REG_MIPS_R3,
+	PERF_REG_MIPS_R4,
+	PERF_REG_MIPS_R5,
+	PERF_REG_MIPS_R6,
+	PERF_REG_MIPS_R7,
+	PERF_REG_MIPS_R8,
+	PERF_REG_MIPS_R9,
+	PERF_REG_MIPS_R10,
+	PERF_REG_MIPS_R11,
+	PERF_REG_MIPS_R12,
+	PERF_REG_MIPS_R13,
+	PERF_REG_MIPS_R14,
+	PERF_REG_MIPS_R15,
+	PERF_REG_MIPS_R16,
+	PERF_REG_MIPS_R17,
+	PERF_REG_MIPS_R18,
+	PERF_REG_MIPS_R19,
+	PERF_REG_MIPS_R20,
+	PERF_REG_MIPS_R21,
+	PERF_REG_MIPS_R22,
+	PERF_REG_MIPS_R23,
+	PERF_REG_MIPS_R24,
+	PERF_REG_MIPS_R25,
+	/*
+	 * 26 and 27 are k0 and k1, they are always clobbered thus not
+	 * stored.
+	 */
+	PERF_REG_MIPS_R28,
+	PERF_REG_MIPS_R29,
+	PERF_REG_MIPS_R30,
+	PERF_REG_MIPS_R31,
+	PERF_REG_MIPS_MAX = PERF_REG_MIPS_R31 + 1,
+};
+#endif /* _ASM_MIPS_PERF_REGS_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 6a24628..1cdf1e9 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -97,7 +97,7 @@ CFLAGS_cpu-bugs64.o	= $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/n
 
 obj-$(CONFIG_HAVE_STD_PC_SERIAL_PORT)	+= 8250-platform.o
 
-obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o
+obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_regs.o
 obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event_mipsxx.o
 
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
diff --git a/arch/mips/kernel/perf_regs.c b/arch/mips/kernel/perf_regs.c
new file mode 100644
index 0000000..65bb25c
--- /dev/null
+++ b/arch/mips/kernel/perf_regs.c
@@ -0,0 +1,67 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Some parts derived from x86 version of this file.
+ *
+ * Copyright (C) 2013 Cavium, Inc.
+ */
+
+#include <linux/perf_event.h>
+
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_32BIT
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+	return PERF_SAMPLE_REGS_ABI_32;
+}
+#else /* Must be CONFIG_64BIT */
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+	if (test_tsk_thread_flag(tsk, TIF_32BIT_REGS))
+		return PERF_SAMPLE_REGS_ABI_32;
+	else
+		return PERF_SAMPLE_REGS_ABI_64;
+}
+#endif /* CONFIG_32BIT */
+
+int perf_reg_validate(u64 mask)
+{
+	if (!mask)
+		return -EINVAL;
+	if (mask & ~((1ull << PERF_REG_MIPS_MAX) - 1))
+		return -EINVAL;
+	return 0;
+}
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	long v;
+
+	switch (idx) {
+	case PERF_REG_MIPS_PC:
+		v = regs->cp0_epc;
+		break;
+	case PERF_REG_MIPS_R1 ... PERF_REG_MIPS_R25:
+		v = regs->regs[idx - PERF_REG_MIPS_R1 + 1];
+		break;
+	case PERF_REG_MIPS_R28 ... PERF_REG_MIPS_R31:
+		v = regs->regs[idx - PERF_REG_MIPS_R28 + 28];
+		break;
+
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	return (s64)v; /* Sign extend if 32-bit. */
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+	struct pt_regs *regs, struct pt_regs *regs_user_copy)
+{
+	regs_user->regs = task_pt_regs(current);
+	regs_user->abi = perf_reg_abi(current);
+}
-- 
2.5.5