[ARM] 5382/1: unwind: Reorganise the stacktrace support
This patch changes the walk_stacktrace and its callers for easier
integration of stack unwinding. The arch/arm/kernel/stacktrace.h file is
also moved to arch/arm/include/asm/stacktrace.h.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h
new file mode 100644
index 0000000..4d0a164
--- /dev/null
+++ b/arch/arm/include/asm/stacktrace.h
@@ -0,0 +1,15 @@
+#ifndef __ASM_STACKTRACE_H
+#define __ASM_STACKTRACE_H
+
+struct stackframe {
+ unsigned long fp;
+ unsigned long sp;
+ unsigned long lr;
+ unsigned long pc;
+};
+
+extern int unwind_frame(struct stackframe *frame);
+extern void walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data);
+
+#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index b9dc8a8..4f88482 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -99,6 +99,8 @@
#define thread_saved_pc(tsk) \
((unsigned long)(task_thread_info(tsk)->cpu_context.pc))
+#define thread_saved_sp(tsk) \
+ ((unsigned long)(task_thread_info(tsk)->cpu_context.sp))
#define thread_saved_fp(tsk) \
((unsigned long)(task_thread_info(tsk)->cpu_context.fp))
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index d3ea6fa..af377c7 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -34,6 +34,7 @@
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/thread_notify.h>
+#include <asm/stacktrace.h>
#include <asm/mach/time.h>
static const char *processor_modes[] = {
@@ -372,23 +373,21 @@
unsigned long get_wchan(struct task_struct *p)
{
- unsigned long fp, lr;
- unsigned long stack_start, stack_end;
+ struct stackframe frame;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
- stack_start = (unsigned long)end_of_stack(p);
- stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
-
- fp = thread_saved_fp(p);
+ frame.fp = thread_saved_fp(p);
+ frame.sp = thread_saved_sp(p);
+ frame.lr = 0; /* recovered from the stack */
+ frame.pc = thread_saved_pc(p);
do {
- if (fp < stack_start || fp > stack_end)
+ int ret = unwind_frame(&frame);
+ if (ret < 0)
return 0;
- lr = ((unsigned long *)fp)[-1];
- if (!in_sched_functions(lr))
- return lr;
- fp = *(unsigned long *) (fp - 12);
+ if (!in_sched_functions(frame.pc))
+ return frame.pc;
} while (count ++ < 16);
return 0;
}
diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index fc650f6..9f444e5 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -2,34 +2,59 @@
#include <linux/sched.h>
#include <linux/stacktrace.h>
-#include "stacktrace.h"
+#include <asm/stacktrace.h>
-int walk_stackframe(unsigned long fp, unsigned long low, unsigned long high,
- int (*fn)(struct stackframe *, void *), void *data)
+#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
+/*
+ * Unwind the current stack frame and store the new register values in the
+ * structure passed as argument. Unwinding is equivalent to a function return,
+ * hence the new PC value rather than LR should be used for backtrace.
+ *
+ * With framepointer enabled, a simple function prologue looks like this:
+ * mov ip, sp
+ * stmdb sp!, {fp, ip, lr, pc}
+ * sub fp, ip, #4
+ *
+ * A simple function epilogue looks like this:
+ * ldm sp, {fp, sp, pc}
+ *
+ * Note that with framepointer enabled, even the leaf functions have the same
+ * prologue and epilogue, therefore we can ignore the LR value in this case.
+ */
+int unwind_frame(struct stackframe *frame)
{
- struct stackframe *frame;
+ unsigned long high, low;
+ unsigned long fp = frame->fp;
- do {
- /*
- * Check current frame pointer is within bounds
- */
- if (fp < (low + 12) || fp + 4 >= high)
- break;
+ /* only go to a higher address on the stack */
+ low = frame->sp;
+ high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE;
- frame = (struct stackframe *)(fp - 12);
+ /* check current frame pointer is within bounds */
+ if (fp < (low + 12) || fp + 4 >= high)
+ return -EINVAL;
+
+ /* restore the registers from the stack frame */
+ frame->fp = *(unsigned long *)(fp - 12);
+ frame->sp = *(unsigned long *)(fp - 8);
+ frame->pc = *(unsigned long *)(fp - 4);
+
+ return 0;
+}
+#endif
+
+void walk_stackframe(struct stackframe *frame,
+ int (*fn)(struct stackframe *, void *), void *data)
+{
+ while (1) {
+ int ret;
if (fn(frame, data))
break;
-
- /*
- * Update the low bound - the next frame must always
- * be at a higher address than the current frame.
- */
- low = fp + 4;
- fp = frame->fp;
- } while (fp);
-
- return 0;
+ ret = unwind_frame(frame);
+ if (ret < 0)
+ break;
+ }
}
EXPORT_SYMBOL(walk_stackframe);
@@ -44,7 +69,7 @@
{
struct stack_trace_data *data = d;
struct stack_trace *trace = data->trace;
- unsigned long addr = frame->lr;
+ unsigned long addr = frame->pc;
if (data->no_sched_functions && in_sched_functions(addr))
return 0;
@@ -61,11 +86,10 @@
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
struct stack_trace_data data;
- unsigned long fp, base;
+ struct stackframe frame;
data.trace = trace;
data.skip = trace->skip;
- base = (unsigned long)task_stack_page(tsk);
if (tsk != current) {
#ifdef CONFIG_SMP
@@ -76,14 +100,22 @@
BUG();
#else
data.no_sched_functions = 1;
- fp = thread_saved_fp(tsk);
+ frame.fp = thread_saved_fp(tsk);
+ frame.sp = thread_saved_sp(tsk);
+ frame.lr = 0; /* recovered from the stack */
+ frame.pc = thread_saved_pc(tsk);
#endif
} else {
+ register unsigned long current_sp asm ("sp");
+
data.no_sched_functions = 0;
- asm("mov %0, fp" : "=r" (fp));
+ frame.fp = (unsigned long)__builtin_frame_address(0);
+ frame.sp = current_sp;
+ frame.lr = (unsigned long)__builtin_return_address(0);
+ frame.pc = (unsigned long)save_stack_trace_tsk;
}
- walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data);
+ walk_stackframe(&frame, save_trace, &data);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
diff --git a/arch/arm/kernel/stacktrace.h b/arch/arm/kernel/stacktrace.h
deleted file mode 100644
index e9fd20cb..0000000
--- a/arch/arm/kernel/stacktrace.h
+++ /dev/null
@@ -1,9 +0,0 @@
-struct stackframe {
- unsigned long fp;
- unsigned long sp;
- unsigned long lr;
- unsigned long pc;
-};
-
-int walk_stackframe(unsigned long fp, unsigned long low, unsigned long high,
- int (*fn)(struct stackframe *, void *), void *data);
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index c68b44a..4cdc4a0 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -33,6 +33,7 @@
#include <asm/leds.h>
#include <asm/thread_info.h>
+#include <asm/stacktrace.h>
#include <asm/mach/time.h>
/*
@@ -55,14 +56,22 @@
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
- unsigned long fp, pc = instruction_pointer(regs);
+ struct stackframe frame;
- if (in_lock_functions(pc)) {
- fp = regs->ARM_fp;
- pc = ((unsigned long *)fp)[-1];
- }
+ if (!in_lock_functions(regs->ARM_pc))
+ return regs->ARM_pc;
- return pc;
+ frame.fp = regs->ARM_fp;
+ frame.sp = regs->ARM_sp;
+ frame.lr = regs->ARM_lr;
+ frame.pc = regs->ARM_pc;
+ do {
+ int ret = unwind_frame(&frame);
+ if (ret < 0)
+ return 0;
+ } while (in_lock_functions(frame.pc));
+
+ return frame.pc;
}
EXPORT_SYMBOL(profile_pc);
#endif
diff --git a/arch/arm/oprofile/backtrace.c b/arch/arm/oprofile/backtrace.c
index cefc21c..d805a52 100644
--- a/arch/arm/oprofile/backtrace.c
+++ b/arch/arm/oprofile/backtrace.c
@@ -18,15 +18,14 @@
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <asm/ptrace.h>
-
-#include "../kernel/stacktrace.h"
+#include <asm/stacktrace.h>
static int report_trace(struct stackframe *frame, void *d)
{
unsigned int *depth = d;
if (*depth) {
- oprofile_add_trace(frame->lr);
+ oprofile_add_trace(frame->pc);
(*depth)--;
}
@@ -70,9 +69,12 @@
struct frame_tail *tail = ((struct frame_tail *) regs->ARM_fp) - 1;
if (!user_mode(regs)) {
- unsigned long base = ((unsigned long)regs) & ~(THREAD_SIZE - 1);
- walk_stackframe(regs->ARM_fp, base, base + THREAD_SIZE,
- report_trace, &depth);
+ struct stackframe frame;
+ frame.fp = regs->ARM_fp;
+ frame.sp = regs->ARM_sp;
+ frame.lr = regs->ARM_lr;
+ frame.pc = regs->ARM_pc;
+ walk_stackframe(&frame, report_trace, &depth);
return;
}