ARM: perf: Android backtracing for Perf

This patch changes default function stack format that Perf
profiler uses for backtracing. With this patch enabled Perf
profiler will use stack format of the Android OS for its
operation.

Bug 983412

Change-Id: Ic767533540111e3a79d5a00d1942e9512aff1a76
Signed-off-by: Igor Nabirushkin <inabirushkin@nvidia.com>
Reviewed-on: http://git-master/r/200210
(cherry picked from commit 9f47a70674ce651275780c34f3112d70ef56b467)
Reviewed-on: http://git-master/r/203347
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Thomas Cherry <tcherry@nvidia.com>
Tested-by: Ryan Bissell <rbissell@nvidia.com>

2 files changed, 333 insertions, 1 deletions

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index e19edc6f2d15..44d9e574db05 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -5,6 +5,7 @@
  *
  * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
  * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
+ * Copyright (c) 2012-2013, NVIDIA CORPORATION.  All rights reserved.
  *
  * This code is based on the sparc64 perf event code, which is in turn based
  * on the x86 code. Callchain code is based on the ARM OProfile backtrace
@@ -533,11 +534,18 @@ int armpmu_register(struct arm_pmu *armpmu, int type)
  *
  * This code has been adapted from the ARM OProfile support.
  */
+#ifndef CONFIG_PERF_ANDROID_BACKTRACE
 struct frame_tail {
 	struct frame_tail __user *fp;
 	unsigned long sp;
 	unsigned long lr;
-} __attribute__((packed));
+} __packed;
+#else
+struct frame_tail {
+	unsigned long fp;
+	unsigned long lr;
+} __packed;
+#endif
 
 /*
  * Get the return address for a single stackframe and return a pointer to the
@@ -557,6 +565,7 @@ user_backtrace(struct frame_tail __user *tail,
 
 	perf_callchain_store(entry, buftail.lr);
 
+#ifndef CONFIG_PERF_ANDROID_BACKTRACE
 	/*
 	 * Frame pointers should strictly progress back up the stack
 	 * (towards higher addresses).
@@ -565,8 +574,233 @@ user_backtrace(struct frame_tail __user *tail,
 		return NULL;
 
 	return buftail.fp - 1;
+#else
+	/*
+	 * Frame pointers should strictly progress back up the stack
+	 * (towards higher addresses).
+	 */
+	if ((unsigned long *)(tail + 1) >= (unsigned long *)buftail.fp)
+		return NULL;
+
+	return  (struct frame_tail *)(buftail.fp - sizeof(unsigned long));
+#endif
+}
+
+
+#ifdef CONFIG_PERF_ANDROID_BACKTRACE
+
+#define AB_USER_SPACE_MIN_ADDR	0x8000
+#define PERF_CALLCHAIN_CHECK_PROLOG_EPILOG 1
+
+#ifdef PERF_CALLCHAIN_CHECK_PROLOG_EPILOG
+
+enum regs {
+#ifdef CONFIG_THUMB2_KERNEL
+	FP = 7,
+#else
+	FP = 11,
+#endif
+	SP = 13,
+	LR = 14,
+	PC = 15
+};
+
+#define INSTR_MASK_STR_FP	0xffff0000
+#define INSTR_STR_FP		0xe52d0000
+
+#define INSTR_MASK_STMDB	0xffff0000
+#define INSTR_STMDB_SP		0xe92d0000
+
+#define INSTR_MASK_LDMIA	0x0fff0000
+#define INSTR_LDMIA_SP		0x08bd0000
+
+#define INSTR_MASK_ADD_RN_RD	0xfffff000
+#define INSTR_ADD_FP_SP		0xe28db000
+
+#define INSTR_MASK_BRANCH	0x0f000000
+#define INSTR_BRANCH		0x0a000000
+
+#define INSTR_MASK_BRANCH_L	0x0f000000
+#define INSTR_BRANCH_L		0x0b000000
+
+#define INSTR_MASK_BRANCH_X	0x0ffffff0
+#define INSTR_BRANCH_X		0x012fff10
+
+#define INSTR_MASK_BRANCH_LX	0x0ffffff0
+#define INSTR_BRANCH_LX		0x012fff30
+
+#define check_in_register_list(val, reg) \
+	(((val) & 0xffff) & (1 << (reg)))
+
+static inline int is_instr_push_with_fp(unsigned long instr)
+{
+	if ((instr & INSTR_MASK_STMDB) == INSTR_STMDB_SP) {
+		if (check_in_register_list(instr, SP) ||
+			check_in_register_list(instr, PC)) {
+			return -1;
+		}
+		if (check_in_register_list(instr, FP))
+			return 1;
+	}
+
+	if ((instr & INSTR_MASK_STR_FP) == INSTR_STR_FP)
+		return 1;
+
+	return 0;
+}
+
+static inline int is_instr_push_with_fp_lr(unsigned long instr)
+{
+	if ((instr & INSTR_MASK_STMDB) == INSTR_STMDB_SP) {
+		if (check_in_register_list(instr, SP) ||
+			check_in_register_list(instr, PC)) {
+			return -1;
+		}
+		if (check_in_register_list(instr, FP) &&
+			check_in_register_list(instr, LR)) {
+			return 1;
+		}
+	}
+	return 0;
+}
+
+#define is_instr_add_fp(instr) \
+	((((instr) & INSTR_MASK_ADD_RN_RD) == INSTR_ADD_FP_SP))
+
+#define is_instr_pop(instr) \
+	((((instr) & INSTR_MASK_LDMIA) == INSTR_LDMIA_SP))
+
+#define is_instr_pop_fp(instr) \
+	((((instr) & INSTR_MASK_LDMIA) == INSTR_LDMIA_SP) && \
+	check_in_register_list(instr, FP)) \
+
+#define is_instr_branch(instr) \
+	((((instr) & INSTR_MASK_BRANCH) == INSTR_BRANCH) || \
+	(((instr) & INSTR_MASK_BRANCH_L) == INSTR_BRANCH_L) || \
+	(((instr) & INSTR_MASK_BRANCH_X) == INSTR_BRANCH_X) || \
+	(((instr) & INSTR_MASK_BRANCH_LX) == INSTR_BRANCH_LX))
+
+enum {
+	INSTR_TYPE_PUSH_FP,
+	INSTR_TYPE_PUSH_FP_LR,
+	INSTR_TYPE_ADD_FP,
+	INSTR_TYPE_POP,
+	INSTR_TYPE_POP_FP,
+	INSTR_TYPE_BRANCH,
+	INSTR_TYPE_UNKNOWN,
+};
+
+#define MAX_CHECK_INSTR_LENGTH	5
+
+static unsigned long instr_before[MAX_CHECK_INSTR_LENGTH];
+static int instr_before_nr;
+
+static unsigned long instr_after[MAX_CHECK_INSTR_LENGTH];
+static int instr_after_nr;
+
+static int read_instructions(unsigned long *addr, int direction)
+{
+	int i, delta, type, nr_instr = 0;
+	unsigned long instr, *c_addr = addr;
+	unsigned long *instr_p;
+
+	if (direction) {
+		delta = 1;
+		instr_p = instr_after;
+	} else {
+		delta = -1;
+		instr_p = instr_before;
+	}
+
+	for (i = 0; i < MAX_CHECK_INSTR_LENGTH; i++) {
+		if (get_user(instr, c_addr))
+			return -1;
+
+		type = INSTR_TYPE_UNKNOWN;
+		if (is_instr_push_with_fp(instr))
+			type = INSTR_TYPE_PUSH_FP;
+		else if (is_instr_push_with_fp_lr(instr))
+			type = INSTR_TYPE_PUSH_FP_LR;
+		else if (is_instr_add_fp(instr))
+			type = INSTR_TYPE_ADD_FP;
+		else if (is_instr_pop_fp(instr))
+			type = INSTR_TYPE_POP_FP;
+		else if (is_instr_pop(instr))
+			type = INSTR_TYPE_POP;
+		else if (is_instr_branch(instr))
+			type = INSTR_TYPE_BRANCH;
+		else
+			type = INSTR_TYPE_UNKNOWN;
+
+		if (type != INSTR_TYPE_UNKNOWN)
+			instr_p[nr_instr++] = type;
+
+		c_addr += delta;
+	}
+
+	return nr_instr;
+}
+
+static int is_func_prologue_epilogue(unsigned long *addr)
+{
+	unsigned long instr_prev, instr_curr, instr_next;
+
+	instr_before_nr = 0;
+	instr_after_nr = 0;
+
+	if (get_user(instr_curr, addr))
+		return 1;
+
+	if (get_user(instr_prev, addr - 1))
+		return 1;
+
+	if (get_user(instr_next, addr + 1))
+		return 1;
+
+	if (is_instr_pop_fp(instr_curr))
+		return 0;
+
+	if (is_instr_push_with_fp(instr_curr) ||
+		is_instr_push_with_fp(instr_next) ||
+		is_instr_push_with_fp(instr_prev) ||
+		is_instr_add_fp(instr_curr) ||
+		is_instr_add_fp(instr_next) ||
+		is_instr_pop_fp(instr_prev)) {
+		return 1;
+	}
+
+	instr_before_nr = read_instructions(addr, 0);
+	if (instr_before_nr < 0)
+		return 1;
+
+	instr_after_nr = read_instructions(addr, 1);
+	if (instr_after_nr < 0)
+		return 1;
+
+	if (!instr_before_nr && !instr_after_nr)
+		return 0;
+
+	if (instr_before_nr) {
+		if (instr_before[0] == INSTR_TYPE_ADD_FP)
+			return 0;
+		else if (instr_before[0] == INSTR_TYPE_PUSH_FP)
+			return 1;
+	}
+
+	if (instr_after_nr) {
+		if (instr_after[0] == INSTR_TYPE_PUSH_FP)
+			return 1;
+		else if (instr_after[0] == INSTR_TYPE_ADD_FP)
+			return 1;
+	}
+
+	return 0;
 }
+#endif	/* PERF_CALLCHAIN_CHECK_PROLOG_EPILOG */
+
+#endif  /* CONFIG_PERF_ANDROID_BACKTRACE */
 
+#ifndef CONFIG_PERF_ANDROID_BACKTRACE
 void
 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
@@ -584,6 +818,90 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 	       tail && !((unsigned long)tail & 0x3))
 		tail = user_backtrace(tail, entry);
 }
+#else	/* CONFIG_PERF_ANDROID_BACKTRACE */
+static inline int
+perf_check_frame_address(unsigned long addr, struct vm_area_struct *vma)
+{
+	unsigned long start, end;
+
+	if (vma) {
+		start = vma->vm_start;
+		end = vma->vm_end;
+		if (addr >= start && addr <= end - 2 * sizeof(unsigned long))
+			return 0;
+	}
+	return -EINVAL;
+}
+
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+	struct frame_tail __user *tail;
+	unsigned long *fp, reg;
+	struct vm_area_struct *vma;
+	int pe_flag = 0;
+
+	if (thumb_mode(regs))
+		return;
+
+	fp = (unsigned long *)regs->ARM_fp;
+	if (!access_ok(VERIFY_READ, fp, sizeof(unsigned long)))
+		return;
+
+	vma = find_vma(current->mm, regs->ARM_sp);
+
+	if (fp < (unsigned long *)regs->ARM_sp)
+		return;
+
+	if (perf_check_frame_address((unsigned long)fp, vma))
+		return;
+
+	if (__copy_from_user_inatomic(&reg, fp, sizeof(unsigned long)))
+		return;
+
+#ifdef PERF_CALLCHAIN_CHECK_PROLOG_EPILOG
+	if (is_func_prologue_epilogue((unsigned long *)regs->ARM_pc))
+		pe_flag = 1;
+#endif
+
+	if (pe_flag) {
+		/* fp->prev frame tail (fp, lr) */
+		if (regs->ARM_lr < AB_USER_SPACE_MIN_ADDR)
+			return;
+		perf_callchain_store(entry, (unsigned long)regs->ARM_lr);
+		tail = (struct frame_tail *)(regs->ARM_fp
+			- sizeof(unsigned long));
+	} else {
+		if ((unsigned long *)reg > fp &&
+			!perf_check_frame_address(reg, vma)) {
+			/* fp->short frame tail (fp) */
+
+			if (regs->ARM_lr < AB_USER_SPACE_MIN_ADDR)
+				return;
+			perf_callchain_store(entry, regs->ARM_lr);
+			tail = (struct frame_tail *)(reg
+				- sizeof(unsigned long));
+		} else {
+			/* fp->current frame tail (fp, lr) */
+			tail = (struct frame_tail *)(regs->ARM_fp
+				- sizeof(unsigned long));
+		}
+	}
+
+	if ((unsigned long *)tail->fp <= fp ||
+		perf_check_frame_address(tail->fp, vma)) {
+		return;
+	}
+
+	while (tail && !((unsigned long)tail & 0x3)) {
+		if (perf_check_frame_address((unsigned long)tail, vma) ||
+			tail->lr < AB_USER_SPACE_MIN_ADDR) {
+			return;
+		}
+		tail = user_backtrace(tail, entry);
+	}
+}
+#endif	/* CONFIG_PERF_ANDROID_BACKTRACE */
 
 /*
  * Gets called by walk_stackframe() for every stackframe. This will be called
diff --git a/init/Kconfig b/init/Kconfig
index d6660c5b4d76..0486e886586a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1486,6 +1486,20 @@ config PERF_EVENTS
 
 	  Say Y if unsure.
 
+config PERF_ANDROID_BACKTRACE
+	default n
+	bool "Backtracing support for the Perf tool on Android"
+	depends on PERF_EVENTS
+	help
+	  This config changes default function stack format that Perf
+	  profiler uses for backtracing. With this config enabled Perf
+	  profiler will use stack format of the Android OS for its
+	  operation.
+
+	  Say Y only if this kernel will be used with Android OS.
+
+	  Say N if unsure.
+
 config DEBUG_PERF_USE_VMALLOC
 	default n
 	bool "Debug: use vmalloc to back perf mmap() buffers"