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/*
* arch/x86_64/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>
#include <asm/smp.h>
static inline int
in_range(unsigned long start, unsigned long addr, unsigned long end)
{
return addr >= start && addr <= end;
}
static unsigned long
get_stack_end(struct task_struct *task, unsigned long stack)
{
unsigned long stack_start, stack_end, flags;
int i, cpu;
/*
* The most common case is that we are in the task stack:
*/
stack_start = (unsigned long)task->thread_info;
stack_end = stack_start + THREAD_SIZE;
if (in_range(stack_start, stack, stack_end))
return stack_end;
/*
* We are in an interrupt if irqstackptr is set:
*/
raw_local_irq_save(flags);
cpu = safe_smp_processor_id();
stack_end = (unsigned long)cpu_pda(cpu)->irqstackptr;
if (stack_end) {
stack_start = stack_end & ~(IRQSTACKSIZE-1);
if (in_range(stack_start, stack, stack_end))
goto out_restore;
/*
* We get here if we are in an IRQ context but we
* are also in an exception stack.
*/
}
/*
* Iterate over all exception stacks, and figure out whether
* 'stack' is in one of them:
*/
for (i = 0; i < N_EXCEPTION_STACKS; i++) {
/*
* set 'end' to the end of the exception stack.
*/
stack_end = per_cpu(init_tss, cpu).ist[i];
stack_start = stack_end - EXCEPTION_STKSZ;
/*
* Is 'stack' above this exception frame's end?
* If yes then skip to the next frame.
*/
if (stack >= stack_end)
continue;
/*
* Is 'stack' above this exception frame's start address?
* If yes then we found the right frame.
*/
if (stack >= stack_start)
goto out_restore;
/*
* If this is a debug stack, and if it has a larger size than
* the usual exception stacks, then 'stack' might still
* be within the lower portion of the debug stack:
*/
#if DEBUG_STKSZ > EXCEPTION_STKSZ
if (i == DEBUG_STACK - 1 && stack >= stack_end - DEBUG_STKSZ) {
/*
* Black magic. A large debug stack is composed of
* multiple exception stack entries, which we
* iterate through now. Dont look:
*/
do {
stack_end -= EXCEPTION_STKSZ;
stack_start -= EXCEPTION_STKSZ;
} while (stack < stack_start);
goto out_restore;
}
#endif
}
/*
* Ok, 'stack' is not pointing to any of the system stacks.
*/
stack_end = 0;
out_restore:
raw_local_irq_restore(flags);
return stack_end;
}
/*
* Save stack-backtrace addresses into a stack_trace buffer:
*/
static inline unsigned long
save_context_stack(struct stack_trace *trace,
unsigned long stack, unsigned long stack_end)
{
int skip = trace->skip;
unsigned long addr;
#ifdef CONFIG_FRAME_POINTER
unsigned long prev_stack = 0;
while (in_range(prev_stack, stack, stack_end)) {
pr_debug("stack: %p\n", (void *)stack);
addr = (unsigned long)(((unsigned long *)stack)[1]);
pr_debug("addr: %p\n", (void *)addr);
if (!skip)
trace->entries[trace->nr_entries++] = addr-1;
else
skip--;
if (trace->nr_entries >= trace->max_entries)
break;
if (!addr)
return 0;
/*
* Stack frames must go forwards (otherwise a loop could
* happen if the stackframe is corrupted), so we move
* prev_stack forwards:
*/
prev_stack = stack;
stack = (unsigned long)(((unsigned long *)stack)[0]);
}
pr_debug("invalid: %p\n", (void *)stack);
#else
while (stack < stack_end) {
addr = ((unsigned long *)stack)[0];
stack += sizeof(long);
if (__kernel_text_address(addr)) {
if (!skip)
trace->entries[trace->nr_entries++] = addr-1;
else
skip--;
if (trace->nr_entries >= trace->max_entries)
break;
}
}
#endif
return stack;
}
#define MAX_STACKS 10
/*
* Save stack-backtrace addresses into a stack_trace buffer.
*/
void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
{
unsigned long stack = (unsigned long)&stack;
int i, nr_stacks = 0, stacks_done[MAX_STACKS];
WARN_ON(trace->nr_entries || !trace->max_entries);
if (!task)
task = current;
pr_debug("task: %p, ti: %p\n", task, task->thread_info);
if (!task || task == current) {
/* Grab rbp right from our regs: */
asm ("mov %%rbp, %0" : "=r" (stack));
pr_debug("rbp: %p\n", (void *)stack);
} else {
/* rbp is the last reg pushed by switch_to(): */
stack = task->thread.rsp;
pr_debug("other task rsp: %p\n", (void *)stack);
stack = (unsigned long)(((unsigned long *)stack)[0]);
pr_debug("other task rbp: %p\n", (void *)stack);
}
while (1) {
unsigned long stack_end = get_stack_end(task, stack);
pr_debug("stack: %p\n", (void *)stack);
pr_debug("stack end: %p\n", (void *)stack_end);
/*
* Invalid stack addres?
*/
if (!stack_end)
return;
/*
* Were we in this stack already? (recursion)
*/
for (i = 0; i < nr_stacks; i++)
if (stacks_done[i] == stack_end)
return;
stacks_done[nr_stacks] = stack_end;
stack = save_context_stack(trace, stack, stack_end);
if (!stack || trace->nr_entries >= trace->max_entries)
return;
trace->entries[trace->nr_entries++] = ULONG_MAX;
if (trace->nr_entries >= trace->max_entries)
return;
if (++nr_stacks >= MAX_STACKS)
return;
}
}
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