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/*
* SH specific backtracing code for oprofile
*
* Copyright 2007 STMicroelectronics Ltd.
*
* Author: Dave Peverley <dpeverley@mpc-data.co.uk>
*
* Based on ARM oprofile backtrace code by Richard Purdie and in turn, i386
* oprofile backtrace code by John Levon, David Smith
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/oprofile.h>
#include <linux/sched.h>
#include <linux/kallsyms.h>
#include <linux/mm.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
#include <asm/sections.h>
/* Limit to stop backtracing too far. */
static int backtrace_limit = 20;
static unsigned long *
user_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
{
unsigned long buf_stack;
/* Also check accessibility of address */
if (!access_ok(VERIFY_READ, stackaddr, sizeof(unsigned long)))
return NULL;
if (__copy_from_user_inatomic(&buf_stack, stackaddr, sizeof(unsigned long)))
return NULL;
/* Quick paranoia check */
if (buf_stack & 3)
return NULL;
oprofile_add_trace(buf_stack);
stackaddr++;
return stackaddr;
}
/*
* | | /\ Higher addresses
* | |
* --------------- stack base (address of current_thread_info)
* | thread info |
* . .
* | stack |
* --------------- saved regs->regs[15] value if valid
* . .
* --------------- struct pt_regs stored on stack (struct pt_regs *)
* | |
* . .
* | |
* --------------- ???
* | |
* | | \/ Lower addresses
*
* Thus, &pt_regs <-> stack base restricts the valid(ish) fp values
*/
static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
{
unsigned long stack = (unsigned long)regs;
unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
}
static unsigned long *
kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
{
unsigned long addr;
/*
* If not a valid kernel address, keep going till we find one
* or the SP stops being a valid address.
*/
do {
addr = *stackaddr++;
oprofile_add_trace(addr);
} while (valid_kernel_stack(stackaddr, regs));
return stackaddr;
}
void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
{
unsigned long *stackaddr;
/*
* Paranoia - clip max depth as we could get lost in the weeds.
*/
if (depth > backtrace_limit)
depth = backtrace_limit;
stackaddr = (unsigned long *)regs->regs[15];
if (!user_mode(regs)) {
while (depth-- && valid_kernel_stack(stackaddr, regs))
stackaddr = kernel_backtrace(stackaddr, regs);
return;
}
while (depth-- && (stackaddr != NULL))
stackaddr = user_backtrace(stackaddr, regs);
}
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