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* Copyright (C) 2011 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
* Backtracing functions for x86.
#define LOG_TAG "Corkscrew"
//#define LOG_NDEBUG 0
#include "../backtrace-arch.h"
#include "../backtrace-helper.h"
#include <corkscrew/ptrace.h>
#include <stdlib.h>
#include <signal.h>
#include <stdbool.h>
#include <limits.h>
#include <errno.h>
#include <sys/ptrace.h>
#include <sys/exec_elf.h>
#include <cutils/log.h>
/* Machine context at the time a signal was raised. */
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
struct sigcontext {
uint32_t gs;
uint32_t fs;
uint32_t es;
uint32_t ds;
uint32_t edi;
uint32_t esi;
uint32_t ebp;
uint32_t esp;
uint32_t ebx;
uint32_t edx;
uint32_t ecx;
uint32_t eax;
uint32_t trapno;
uint32_t err;
uint32_t eip;
uint32_t cs;
uint32_t efl;
uint32_t uesp;
uint32_t ss;
void* fpregs;
uint32_t oldmask;
uint32_t cr2;
} uc_mcontext;
uint32_t uc_sigmask;
} ucontext_t;
/* Unwind state. */
typedef struct {
uint32_t ebp;
uint32_t eip;
uint32_t esp;
} unwind_state_t;
uintptr_t rewind_pc_arch(const memory_t* memory, uintptr_t pc) {
// TODO: Implement for x86.
return pc;
static ssize_t unwind_backtrace_common(const memory_t* memory,
const map_info_t* map_info_list,
unwind_state_t* state, backtrace_frame_t* backtrace,
size_t ignore_depth, size_t max_depth) {
size_t ignored_frames = 0;
size_t returned_frames = 0;
for (size_t index = 0; state->ebp && returned_frames < max_depth; index++) {
backtrace_frame_t* frame = add_backtrace_entry(
index ? rewind_pc_arch(memory, state->eip) : state->eip,
backtrace, ignore_depth, max_depth,
&ignored_frames, &returned_frames);
uint32_t next_esp = state->ebp + 8;
if (frame) {
frame->stack_top = state->esp;
if (state->esp < next_esp) {
frame->stack_size = next_esp - state->esp;
state->esp = next_esp;
if (!try_get_word(memory, state->ebp + 4, &state->eip)
|| !try_get_word(memory, state->ebp, &state->ebp)
|| !state->eip) {
return returned_frames;
ssize_t unwind_backtrace_signal_arch(siginfo_t* siginfo, void* sigcontext,
const map_info_t* map_info_list,
backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
const ucontext_t* uc = (const ucontext_t*)sigcontext;
unwind_state_t state;
state.ebp = uc->uc_mcontext.ebp;
state.eip = uc->uc_mcontext.eip;
state.esp = uc->uc_mcontext.esp;
memory_t memory;
init_memory(&memory, map_info_list);
return unwind_backtrace_common(&memory, map_info_list,
&state, backtrace, ignore_depth, max_depth);
ssize_t unwind_backtrace_ptrace_arch(pid_t tid, const ptrace_context_t* context,
backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
pt_regs_x86_t regs;
if (ptrace(PTRACE_GETREGS, tid, 0, &regs)) {
return -1;
unwind_state_t state;
state.ebp = regs.ebp;
state.eip = regs.eip;
state.esp = regs.esp;
memory_t memory;
init_memory_ptrace(&memory, tid);
return unwind_backtrace_common(&memory, context->map_info_list,
&state, backtrace, ignore_depth, max_depth);