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[ARM] 5382/1: unwind: Reorganise the stacktrace support

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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>
This commit is contained in:
Catalin Marinas
2009-02-11 13:07:53 +01:00
committed by Russell King
parent 67a94c23bb
commit 2d7c11bfc9
7 changed files with 109 additions and 59 deletions
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86
arch/arm/kernel/stacktrace.c
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@@ -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 @@ static int save_trace(struct stackframe *frame, void *d)
{
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 @@ static int save_trace(struct stackframe *frame, void *d)
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 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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;
}