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/*
* drivers/misc/tegra-profiler/backtrace.c
*
* Copyright (c) 2013, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <asm-generic/uaccess.h>
#include <linux/tegra_profiler.h>
#include "backtrace.h"
#define QUADD_USER_SPACE_MIN_ADDR 0x8000
static inline void
quadd_callchain_store(struct quadd_callchain *callchain_data, u32 ip)
{
if (callchain_data->nr < QUADD_MAX_STACK_DEPTH) {
/* pr_debug("[%d] Add entry: %#llx\n",
callchain_data->nr, ip); */
callchain_data->callchain[callchain_data->nr++] = ip;
}
}
static int
check_vma_address(unsigned long addr, struct vm_area_struct *vma)
{
unsigned long start, end, length;
if (vma) {
start = vma->vm_start;
end = vma->vm_end;
length = end - start;
if (length > sizeof(unsigned long) &&
addr >= start && addr <= end - sizeof(unsigned long))
return 0;
}
return -EINVAL;
}
static unsigned long __user *
user_backtrace(unsigned long __user *tail,
struct quadd_callchain *callchain_data,
struct vm_area_struct *stack_vma)
{
unsigned long value, value_lr = 0, value_fp = 0;
unsigned long __user *fp_prev = NULL;
if (check_vma_address((unsigned long)tail, stack_vma))
return NULL;
if (__copy_from_user_inatomic(&value, tail, sizeof(unsigned long)))
return NULL;
if (!check_vma_address(value, stack_vma)) {
/* clang's frame */
value_fp = value;
if (check_vma_address((unsigned long)(tail + 1), stack_vma))
return NULL;
if (__copy_from_user_inatomic(&value_lr, tail + 1,
sizeof(unsigned long)))
return NULL;
} else {
/* gcc's frame */
if (__copy_from_user_inatomic(&value_fp, tail - 1,
sizeof(unsigned long)))
return NULL;
if (check_vma_address(value_fp, stack_vma))
return NULL;
value_lr = value;
}
fp_prev = (unsigned long __user *)value_fp;
if (value_lr < QUADD_USER_SPACE_MIN_ADDR)
return NULL;
quadd_callchain_store(callchain_data, value_lr);
if (fp_prev <= tail)
return NULL;
return fp_prev;
}
unsigned int
quadd_get_user_callchain(struct pt_regs *regs,
struct quadd_callchain *callchain_data)
{
unsigned long fp, sp, pc, reg;
struct vm_area_struct *vma, *vma_pc;
unsigned long __user *tail = NULL;
struct mm_struct *mm = current->mm;
callchain_data->nr = 0;
if (!regs || !user_mode(regs) || !mm)
return 0;
if (thumb_mode(regs))
return 0;
fp = regs->ARM_fp;
sp = regs->ARM_sp;
pc = regs->ARM_pc;
if (fp == 0 || fp < sp || fp & 0x3)
return 0;
vma = find_vma(mm, sp);
if (check_vma_address(fp, vma))
return 0;
if (__copy_from_user_inatomic(®, (unsigned long __user *)fp,
sizeof(unsigned long)))
return 0;
if (reg > fp &&
!check_vma_address(reg, vma)) {
unsigned long value;
int read_lr = 0;
if (!check_vma_address(fp + sizeof(unsigned long), vma)) {
if (__copy_from_user_inatomic(
&value,
(unsigned long __user *)fp + 1,
sizeof(unsigned long)))
return 0;
vma_pc = find_vma(mm, pc);
read_lr = 1;
}
if (!read_lr || check_vma_address(value, vma_pc)) {
/* gcc: fp --> short frame tail (fp) */
if (regs->ARM_lr < QUADD_USER_SPACE_MIN_ADDR)
return 0;
quadd_callchain_store(callchain_data, regs->ARM_lr);
tail = (unsigned long __user *)reg;
}
}
if (!tail)
tail = (unsigned long __user *)fp;
while (tail && !((unsigned long)tail & 0x3))
tail = user_backtrace(tail, callchain_data, vma);
return callchain_data->nr;
}
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