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x86: improve the 32 bit Frame Pointer backtracer to also use the traditional backtrace 

The 32 bit Frame Pointer backtracer code checks if the EBP is valid
to do a backtrace; however currently on a failure it just gives up
and prints nothing. That's not very nice; we can do better and still
print a decent backtrace.

This patch changes the backtracer to use the regular backtracing algorithm
at the same time as the EBP backtracer; the EBP backtracer is basically
used to figure out which part of the backtrace are reliable vs those
which are likely to be noise.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Arjan van de Ven 2008-01-30 13:33:07 +01:00 committed by Ingo Molnar
parent bc850d6b37
commit e9d4efddbe
1 changed files with 20 additions and 24 deletions
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44
arch/x86/kernel/traps_32.c
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@ -118,36 +118,32 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
#ifdef CONFIG_FRAME_POINTER
struct stack_frame *frame = (struct stack_frame *)bp;
while (valid_stack_ptr(tinfo, frame, sizeof(*frame))) {
struct stack_frame *next;
unsigned long addr;
addr = frame->return_address;
if (__kernel_text_address(addr))
ops->address(data, addr, 1);
/*
* break out of recursive entries (such as
* end_of_stack_stop_unwind_function). Also,
* we can never allow a frame pointer to
* move downwards!
*/
next = frame->next_frame;
bp = (unsigned long) next;
if (next <= frame)
break;
frame = next;
}
#else
/*
* if EBP is "deeper" into the stack than the actual stack pointer,
* we need to rewind the stack pointer a little to start at the
* first stack frame, but only if EBP is in this stack frame.
*/
if (stack > (unsigned long *) bp
&& valid_stack_ptr(tinfo, frame, sizeof(*frame)))
stack = (unsigned long *) bp;
while (valid_stack_ptr(tinfo, stack, sizeof(*stack))) {
unsigned long addr;
addr = *stack++;
if (__kernel_text_address(addr))
ops->address(data, addr, 1);
addr = *stack;
if (__kernel_text_address(addr)) {
if ((unsigned long) stack == bp + 4) {
ops->address(data, addr, 1);
frame = frame->next_frame;
bp = (unsigned long) frame;
} else {
ops->address(data, addr, 0);
}
}
stack++;
}
#endif
return bp;
}