279843e139
Modify BacktracePtrace::Read to use the process_vm_readv syscall instead of doing multiple ptrace calls. Test: Ran the backtrace unit tests on host and on x86_64 emulator. Change-Id: I24c2787f6713d8eb44312f3aa751d1f6d9d34719
92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <stdint.h>
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#include <string.h>
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#include <sys/uio.h>
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#include <sys/param.h>
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#include <sys/ptrace.h>
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#include <sys/types.h>
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#include <ucontext.h>
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#include <unistd.h>
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#include <backtrace/Backtrace.h>
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#include <backtrace/BacktraceMap.h>
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#include "BacktraceLog.h"
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#include "BacktracePtrace.h"
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#include "thread_utils.h"
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#if !defined(__APPLE__)
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static bool PtraceRead(pid_t tid, uintptr_t addr, word_t* out_value) {
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// ptrace() returns -1 and sets errno when the operation fails.
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// To disambiguate -1 from a valid result, we clear errno beforehand.
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errno = 0;
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*out_value = ptrace(PTRACE_PEEKTEXT, tid, reinterpret_cast<void*>(addr), nullptr);
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if (*out_value == static_cast<word_t>(-1) && errno) {
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return false;
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}
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return true;
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}
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#endif
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bool BacktracePtrace::ReadWord(uintptr_t ptr, word_t* out_value) {
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#if defined(__APPLE__)
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BACK_LOGW("MacOS does not support reading from another pid.");
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return false;
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#else
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if (!VerifyReadWordArgs(ptr, out_value)) {
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return false;
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}
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backtrace_map_t map;
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FillInMap(ptr, &map);
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if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
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return false;
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}
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return PtraceRead(Tid(), ptr, out_value);
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#endif
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}
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size_t BacktracePtrace::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
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#if defined(__APPLE__)
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BACK_LOGW("MacOS does not support reading from another pid.");
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return 0;
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#else
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backtrace_map_t map;
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FillInMap(addr, &map);
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if (!BacktraceMap::IsValid(map) || !(map.flags & PROT_READ)) {
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return 0;
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}
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bytes = MIN(map.end - addr, bytes);
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struct iovec local_io;
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local_io.iov_base = buffer;
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local_io.iov_len = bytes;
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struct iovec remote_io;
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remote_io.iov_base = reinterpret_cast<void*>(addr);
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remote_io.iov_len = bytes;
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ssize_t bytes_read = process_vm_readv(Tid(), &local_io, 1, &remote_io, 1, 0);
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if (bytes_read == -1) {
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return 0;
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}
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return static_cast<size_t>(bytes_read);
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#endif
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}
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