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/*
* Copyright (C) 2017 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.
*/
#include <errno.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <unistd.h>
#include <memory>
#include <vector>
#include <benchmark/benchmark.h>
#include <backtrace/Backtrace.h>
#define AT_COMMON_SIZES Arg(1)->Arg(4)->Arg(8)->Arg(16)->Arg(100)->Arg(200)->Arg(500)->Arg(1024)
static void Attach(pid_t pid) {
if (ptrace(PTRACE_ATTACH, pid, 0, 0) == -1) {
perror("Failed to attach");
abort();
}
siginfo_t si;
// Wait for up to 5 seconds.
for (size_t i = 0; i < 5000; i++) {
if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si) == 0) {
return;
}
usleep(1000);
}
printf("Remote process failed to stop in five seconds.\n");
abort();
}
class ScopedPidReaper {
public:
ScopedPidReaper(pid_t pid) : pid_(pid) {}
~ScopedPidReaper() {
kill(pid_, SIGKILL);
waitpid(pid_, nullptr, 0);
}
private:
pid_t pid_;
};
static size_t ProcessVmRead(pid_t pid, uint64_t remote_src, void* dst, size_t len) {
struct iovec dst_iov = {
.iov_base = dst, .iov_len = len,
};
struct iovec src_iov = {
.iov_base = reinterpret_cast<void*>(remote_src), .iov_len = len,
};
ssize_t rc = process_vm_readv(pid, &dst_iov, 1, &src_iov, 1, 0);
return rc == -1 ? 0 : rc;
}
static bool PtraceReadLong(pid_t pid, uint64_t addr, long* value) {
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*value = ptrace(PTRACE_PEEKTEXT, pid, reinterpret_cast<void*>(addr), nullptr);
if (*value == -1 && errno) {
return false;
}
return true;
}
static size_t PtraceRead(pid_t pid, uint64_t addr, void* dst, size_t bytes) {
size_t bytes_read = 0;
long data;
for (size_t i = 0; i < bytes / sizeof(long); i++) {
if (!PtraceReadLong(pid, addr, &data)) {
return bytes_read;
}
memcpy(dst, &data, sizeof(long));
dst = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(dst) + sizeof(long));
addr += sizeof(long);
bytes_read += sizeof(long);
}
size_t left_over = bytes & (sizeof(long) - 1);
if (left_over) {
if (!PtraceReadLong(pid, addr, &data)) {
return bytes_read;
}
memcpy(dst, &data, left_over);
bytes_read += left_over;
}
return bytes_read;
}
static void CreateRemoteProcess(size_t size, void** map, pid_t* pid) {
*map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (*map == MAP_FAILED) {
perror("Can't allocate memory");
abort();
}
memset(*map, 0xaa, size);
if ((*pid = fork()) == 0) {
for (volatile int i = 0;; i++)
;
exit(1);
}
if (*pid < 0) {
perror("Failed to fork");
abort();
}
Attach(*pid);
// Don't need this map in the current process any more.
munmap(*map, size);
}
static void BM_read_with_ptrace(benchmark::State& state) {
void* map;
pid_t pid;
CreateRemoteProcess(state.range(0), &map, &pid);
ScopedPidReaper reap(pid);
std::vector<uint8_t> read_buffer(state.range(0));
uint64_t addr = reinterpret_cast<uint64_t>(map);
while (state.KeepRunning()) {
if (PtraceRead(pid, addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) {
printf("Unexpected bad read.\n");
abort();
}
}
ptrace(PTRACE_DETACH, pid, 0, 0);
}
BENCHMARK(BM_read_with_ptrace)->AT_COMMON_SIZES;
static void BM_read_with_process_vm_read(benchmark::State& state) {
void* map;
pid_t pid;
CreateRemoteProcess(state.range(0), &map, &pid);
ScopedPidReaper reap(pid);
std::vector<uint8_t> read_buffer(state.range(0));
uint64_t addr = reinterpret_cast<uint64_t>(map);
while (state.KeepRunning()) {
if (ProcessVmRead(pid, addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) {
printf("Unexpected bad read.\n");
abort();
}
}
ptrace(PTRACE_DETACH, pid, 0, 0);
}
BENCHMARK(BM_read_with_process_vm_read)->AT_COMMON_SIZES;
static void BM_read_with_backtrace_object(benchmark::State& state) {
void* map;
pid_t pid;
CreateRemoteProcess(state.range(0), &map, &pid);
ScopedPidReaper reap(pid);
std::unique_ptr<Backtrace> backtrace(Backtrace::Create(pid, BACKTRACE_CURRENT_THREAD));
if (backtrace.get() == nullptr) {
printf("Failed to create backtrace.\n");
abort();
}
uint64_t addr = reinterpret_cast<uint64_t>(map);
std::vector<uint8_t> read_buffer(state.range(0));
while (state.KeepRunning()) {
if (backtrace->Read(addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) {
printf("Unexpected bad read.\n");
abort();
}
}
ptrace(PTRACE_DETACH, pid, 0, 0);
}
BENCHMARK(BM_read_with_backtrace_object)->AT_COMMON_SIZES;
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