145 lines
3.6 KiB
C
145 lines
3.6 KiB
C
/*
|
|
* Arm specific backtracing code for oprofile
|
|
*
|
|
* Copyright 2005 Openedhand Ltd.
|
|
*
|
|
* Author: Richard Purdie <rpurdie@openedhand.com>
|
|
*
|
|
* Based on 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/mm.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
|
|
/*
|
|
* The registers we're interested in are at the end of the variable
|
|
* length saved register structure. The fp points at the end of this
|
|
* structure so the address of this struct is:
|
|
* (struct frame_tail *)(xxx->fp)-1
|
|
*/
|
|
struct frame_tail {
|
|
struct frame_tail *fp;
|
|
unsigned long sp;
|
|
unsigned long lr;
|
|
} __attribute__((packed));
|
|
|
|
|
|
#ifdef CONFIG_FRAME_POINTER
|
|
static struct frame_tail* kernel_backtrace(struct frame_tail *tail)
|
|
{
|
|
oprofile_add_trace(tail->lr);
|
|
|
|
/* frame pointers should strictly progress back up the stack
|
|
* (towards higher addresses) */
|
|
if (tail >= tail->fp)
|
|
return NULL;
|
|
|
|
return tail->fp-1;
|
|
}
|
|
#endif
|
|
|
|
static struct frame_tail* user_backtrace(struct frame_tail *tail)
|
|
{
|
|
struct frame_tail buftail;
|
|
|
|
/* hardware pte might not be valid due to dirty/accessed bit emulation
|
|
* so we use copy_from_user and benefit from exception fixups */
|
|
if (copy_from_user(&buftail, tail, sizeof(struct frame_tail)))
|
|
return NULL;
|
|
|
|
oprofile_add_trace(buftail.lr);
|
|
|
|
/* frame pointers should strictly progress back up the stack
|
|
* (towards higher addresses) */
|
|
if (tail >= buftail.fp)
|
|
return NULL;
|
|
|
|
return buftail.fp-1;
|
|
}
|
|
|
|
/* Compare two addresses and see if they're on the same page */
|
|
#define CMP_ADDR_EQUAL(x,y,offset) ((((unsigned long) x) >> PAGE_SHIFT) \
|
|
== ((((unsigned long) y) + offset) >> PAGE_SHIFT))
|
|
|
|
/* check that the page(s) containing the frame tail are present */
|
|
static int pages_present(struct frame_tail *tail)
|
|
{
|
|
struct mm_struct * mm = current->mm;
|
|
|
|
if (!check_user_page_readable(mm, (unsigned long)tail))
|
|
return 0;
|
|
|
|
if (CMP_ADDR_EQUAL(tail, tail, 8))
|
|
return 1;
|
|
|
|
if (!check_user_page_readable(mm, ((unsigned long)tail) + 8))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* | | /\ Higher addresses
|
|
* | |
|
|
* --------------- stack base (address of current_thread_info)
|
|
* | thread info |
|
|
* . .
|
|
* | stack |
|
|
* --------------- saved regs->ARM_fp value if valid (frame_tail address)
|
|
* . .
|
|
* --------------- struct pt_regs stored on stack (struct pt_regs *)
|
|
* | |
|
|
* . .
|
|
* | |
|
|
* --------------- %esp
|
|
* | |
|
|
* | | \/ Lower addresses
|
|
*
|
|
* Thus, &pt_regs <-> stack base restricts the valid(ish) fp values
|
|
*/
|
|
static int valid_kernel_stack(struct frame_tail *tail, struct pt_regs *regs)
|
|
{
|
|
unsigned long tailaddr = (unsigned long)tail;
|
|
unsigned long stack = (unsigned long)regs;
|
|
unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
|
|
|
|
return (tailaddr > stack) && (tailaddr < stack_base);
|
|
}
|
|
|
|
void arm_backtrace(struct pt_regs * const regs, unsigned int depth)
|
|
{
|
|
struct frame_tail *tail;
|
|
unsigned long last_address = 0;
|
|
|
|
tail = ((struct frame_tail *) regs->ARM_fp) - 1;
|
|
|
|
if (!user_mode(regs)) {
|
|
|
|
#ifdef CONFIG_FRAME_POINTER
|
|
while (depth-- && tail && valid_kernel_stack(tail, regs)) {
|
|
tail = kernel_backtrace(tail);
|
|
}
|
|
#endif
|
|
return;
|
|
}
|
|
|
|
while (depth-- && tail && !((unsigned long) tail & 3)) {
|
|
if ((!CMP_ADDR_EQUAL(last_address, tail, 0)
|
|
|| !CMP_ADDR_EQUAL(last_address, tail, 8))
|
|
&& !pages_present(tail))
|
|
return;
|
|
last_address = (unsigned long) tail;
|
|
tail = user_backtrace(tail);
|
|
}
|
|
}
|
|
|