backtrace.c 1.9 KB
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/**
 * @file backtrace.c
 *
 * @remark Copyright 2002 OProfile authors
 * @remark Read the file COPYING
 *
 * @author John Levon
 * @author David Smith
 */

#include <linux/oprofile.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
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#include <asm/uaccess.h>
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#include <asm/stacktrace.h>
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static void backtrace_warning_symbol(void *data, char *msg,
				     unsigned long symbol)
{
	/* Ignore warnings */
}
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static void backtrace_warning(void *data, char *msg)
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{
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	/* Ignore warnings */
}
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static int backtrace_stack(void *data, char *name)
{
	/* Yes, we want all stacks */
	return 0;
}
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static void backtrace_address(void *data, unsigned long addr, int reliable)
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{
	unsigned int *depth = data;

	if ((*depth)--)
		oprofile_add_trace(addr);
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}

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static struct stacktrace_ops backtrace_ops = {
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	.warning	= backtrace_warning,
	.warning_symbol	= backtrace_warning_symbol,
	.stack		= backtrace_stack,
	.address	= backtrace_address,
	.walk_stack	= print_context_stack,
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};

struct frame_head {
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	struct frame_head *bp;
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	unsigned long ret;
} __attribute__((packed));

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static struct frame_head *dump_user_backtrace(struct frame_head *head)
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{
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	struct frame_head bufhead[2];
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	/* Also check accessibility of one struct frame_head beyond */
	if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
		return NULL;
	if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
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		return NULL;

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	oprofile_add_trace(bufhead[0].ret);
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	/* frame pointers should strictly progress back up the stack
	 * (towards higher addresses) */
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	if (head >= bufhead[0].bp)
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		return NULL;
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	return bufhead[0].bp;
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}

void
x86_backtrace(struct pt_regs * const regs, unsigned int depth)
{
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	struct frame_head *head = (struct frame_head *)frame_pointer(regs);
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	if (!user_mode_vm(regs)) {
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		unsigned long stack = kernel_stack_pointer(regs);
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		if (depth)
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			dump_trace(NULL, regs, (unsigned long *)stack, 0,
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				   &backtrace_ops, &depth);
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		return;
	}

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	while (depth-- && head)
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		head = dump_user_backtrace(head);
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}