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/*
* arch/i386/kernel/stacktrace.c
*
* Stack trace management functions
*
* Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*/
#include <linux/sched.h>
#include <linux/stacktrace.h>
static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
{
return p > (void *)tinfo &&
p < (void *)tinfo + THREAD_SIZE - 3;
}
/*
* Save stack-backtrace addresses into a stack_trace buffer:
*/
static inline unsigned long
save_context_stack(struct stack_trace *trace, unsigned int skip,
struct thread_info *tinfo, unsigned long *stack,
unsigned long ebp)
{
unsigned long addr;
#ifdef CONFIG_FRAME_POINTER
while (valid_stack_ptr(tinfo, (void *)ebp)) {
addr = *(unsigned long *)(ebp + 4);
if (!skip)
trace->entries[trace->nr_entries++] = addr;
else
skip--;
if (trace->nr_entries >= trace->max_entries)
break;
/*
* break out of recursive entries (such as
* end_of_stack_stop_unwind_function):
*/
if (ebp == *(unsigned long *)ebp)
break;
ebp = *(unsigned long *)ebp;
}
#else
while (valid_stack_ptr(tinfo, stack)) {
addr = *stack++;
if (__kernel_text_address(addr)) {
if (!skip)
trace->entries[trace->nr_entries++] = addr;
else
skip--;
if (trace->nr_entries >= trace->max_entries)
break;
}
}
#endif
return ebp;
}
/*
* Save stack-backtrace addresses into a stack_trace buffer.
* If all_contexts is set, all contexts (hardirq, softirq and process)
* are saved. If not set then only the current context is saved.
*/
void save_stack_trace(struct stack_trace *trace,
struct task_struct *task, int all_contexts,
unsigned int skip)
{
unsigned long ebp;
unsigned long *stack = &ebp;
WARN_ON(trace->nr_entries || !trace->max_entries);
if (!task || task == current) {
/* Grab ebp right from our regs: */
asm ("movl %%ebp, %0" : "=r" (ebp));
} else {
/* ebp is the last reg pushed by switch_to(): */
ebp = *(unsigned long *) task->thread.esp;
}
while (1) {
struct thread_info *context = (struct thread_info *)
((unsigned long)stack & (~(THREAD_SIZE - 1)));
ebp = save_context_stack(trace, skip, context, stack, ebp);
stack = (unsigned long *)context->previous_esp;
if (!all_contexts || !stack ||
trace->nr_entries >= trace->max_entries)
break;
trace->entries[trace->nr_entries++] = ULONG_MAX;
if (trace->nr_entries >= trace->max_entries)
break;
}
}
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