backtrace.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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
*/
#include <linux/oprofile.h>
#include <linux/sched.h>
#include <linux/kallsyms.h>
#include <linux/mm.h>
#include <asm/unwinder.h>
#include <asm/ptrace.h>
#include <linux/uaccess.h>
#include <asm/sections.h>
#include <asm/stacktrace.h>
static void backtrace_address(void *data, unsigned long addr, int reliable)
{
unsigned int *depth = data;
if ((*depth)--)
oprofile_add_trace(addr);
}
static struct stacktrace_ops backtrace_ops = {
.address = backtrace_address,
};
/* 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(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;
}
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 *)kernel_stack_pointer(regs);
if (!user_mode(regs)) {
if (depth)
unwind_stack(NULL, regs, stackaddr,
&backtrace_ops, &depth);
return;
}
while (depth-- && (stackaddr != NULL))
stackaddr = user_backtrace(stackaddr, regs);
}