backtrace.c
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/**
* Copyright (C) 2005 Brian Rogan <bcr6@cornell.edu>, IBM
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
**/
#include <linux/oprofile.h>
#include <linux/sched.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/compat.h>
#include <asm/oprofile_impl.h>
#define STACK_SP(STACK) *(STACK)
#define STACK_LR64(STACK) *((unsigned long *)(STACK) + 2)
#define STACK_LR32(STACK) *((unsigned int *)(STACK) + 1)
#ifdef CONFIG_PPC64
#define STACK_LR(STACK) STACK_LR64(STACK)
#else
#define STACK_LR(STACK) STACK_LR32(STACK)
#endif
static unsigned int user_getsp32(unsigned int sp, int is_first)
{
unsigned int stack_frame[2];
void __user *p = compat_ptr(sp);
if (!access_ok(VERIFY_READ, p, sizeof(stack_frame)))
return 0;
/*
* The most likely reason for this is that we returned -EFAULT,
* which means that we've done all that we can do from
* interrupt context.
*/
if (__copy_from_user_inatomic(stack_frame, p, sizeof(stack_frame)))
return 0;
if (!is_first)
oprofile_add_trace(STACK_LR32(stack_frame));
/*
* We do not enforce increasing stack addresses here because
* we may transition to a different stack, eg a signal handler.
*/
return STACK_SP(stack_frame);
}
#ifdef CONFIG_PPC64
static unsigned long user_getsp64(unsigned long sp, int is_first)
{
unsigned long stack_frame[3];
if (!access_ok(VERIFY_READ, (void __user *)sp, sizeof(stack_frame)))
return 0;
if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
sizeof(stack_frame)))
return 0;
if (!is_first)
oprofile_add_trace(STACK_LR64(stack_frame));
return STACK_SP(stack_frame);
}
#endif
static unsigned long kernel_getsp(unsigned long sp, int is_first)
{
unsigned long *stack_frame = (unsigned long *)sp;
if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
return 0;
if (!is_first)
oprofile_add_trace(STACK_LR(stack_frame));
/*
* We do not enforce increasing stack addresses here because
* we might be transitioning from an interrupt stack to a kernel
* stack. validate_sp() is designed to understand this, so just
* use it.
*/
return STACK_SP(stack_frame);
}
void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
{
unsigned long sp = regs->gpr[1];
int first_frame = 1;
/* We ditch the top stackframe so need to loop through an extra time */
depth += 1;
if (!user_mode(regs)) {
while (depth--) {
sp = kernel_getsp(sp, first_frame);
if (!sp)
break;
first_frame = 0;
}
} else {
pagefault_disable();
#ifdef CONFIG_PPC64
if (!is_32bit_task()) {
while (depth--) {
sp = user_getsp64(sp, first_frame);
if (!sp)
break;
first_frame = 0;
}
pagefault_enable();
return;
}
#endif
while (depth--) {
sp = user_getsp32(sp, first_frame);
if (!sp)
break;
first_frame = 0;
}
pagefault_enable();
}
}