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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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "Corkscrew"
//#define LOG_NDEBUG 0
#include "ptrace-arch.h"
#include <corkscrew/ptrace.h>
#include <errno.h>
#include <sys/ptrace.h>
#include <cutils/log.h>
static const uint32_t ELF_MAGIC = 0x464C457f; // "ELF\0177"
#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif
#ifndef PAGE_MASK
#define PAGE_MASK (~(PAGE_SIZE - 1))
#endif
bool try_get_word(pid_t tid, uintptr_t ptr, uint32_t* out_value) {
if (ptr & 3) {
LOGV("try_get_word: invalid pointer 0x%08x", ptr);
*out_value = 0;
return false;
}
if (tid < 0) {
#if 0 /*unreliable, unclear whether this is safe from a signal handler context*/
// Determine whether the pointer is likely to be valid before dereferencing it.
unsigned char vec[1];
while (mincore((void*)(ptr & PAGE_MASK), sizeof(uint32_t), vec)) {
if (errno != EAGAIN && errno != EINTR) {
LOGV("try_get_word: invalid pointer 0x%08x, mincore() errno=%d", ptr, errno);
*out_value = 0;
return false;
}
}
#endif
*out_value = *(uint32_t*)ptr;
return true;
} else {
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, tid, (void*)ptr, NULL);
if (*out_value == 0xffffffffL && errno) {
LOGV("try_get_word: invalid pointer 0x%08x, ptrace() errno=%d", ptr, errno);
*out_value = 0;
return false;
}
return true;
}
}
static void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) {
if (mi->is_executable) {
uint32_t elf_magic;
if (try_get_word(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) {
map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t));
if (data) {
mi->data = data;
if (mi->name[0]) {
data->symbol_table = load_symbol_table(mi->name);
}
#ifdef CORKSCREW_HAVE_ARCH
load_ptrace_map_info_data_arch(pid, mi, data);
#endif
}
}
}
}
ptrace_context_t* load_ptrace_context(pid_t pid) {
ptrace_context_t* context =
(ptrace_context_t*)calloc(1, sizeof(ptrace_context_t));
if (context) {
context->map_info_list = load_map_info_list(pid);
for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
load_ptrace_map_info_data(pid, mi);
}
}
return context;
}
static void free_ptrace_map_info_data(map_info_t* mi) {
map_info_data_t* data = (map_info_data_t*)mi->data;
if (data) {
if (data->symbol_table) {
free_symbol_table(data->symbol_table);
}
#ifdef CORKSCREW_HAVE_ARCH
free_ptrace_map_info_data_arch(mi, data);
#endif
free(data);
mi->data = NULL;
}
}
void free_ptrace_context(ptrace_context_t* context) {
for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
free_ptrace_map_info_data(mi);
}
free_map_info_list(context->map_info_list);
}
void find_symbol_ptrace(const ptrace_context_t* context,
uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) {
const map_info_t* mi = find_map_info(context->map_info_list, addr);
const symbol_t* symbol = NULL;
if (mi) {
const map_info_data_t* data = (const map_info_data_t*)mi->data;
if (data && data->symbol_table) {
symbol = find_symbol(data->symbol_table, addr - mi->start);
}
}
*out_map_info = mi;
*out_symbol = symbol;
}
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