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/*
* Copyright (C) 2015 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.
*/
#if __linux__
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#endif
#include "jni.h"
#include <backtrace/Backtrace.h>
#include "base/logging.h"
#include "base/macros.h"
#include "gc/heap.h"
#include "gc/space/image_space.h"
#include "oat_file.h"
#include "utils.h"
namespace art {
// For testing debuggerd. We do not have expected-death tests, so can't test this by default.
// Code for this is copied from SignalTest.
static constexpr bool kCauseSegfault = false;
char* go_away_compiler_cfi = nullptr;
static void CauseSegfault() {
#if defined(__arm__) || defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
// On supported architectures we cause a real SEGV.
*go_away_compiler_cfi = 'a';
#else
// On other architectures we simulate SEGV.
kill(getpid(), SIGSEGV);
#endif
}
extern "C" JNIEXPORT jboolean JNICALL Java_Main_sleep(JNIEnv*, jobject, jint, jboolean, jdouble) {
// Keep pausing.
for (;;) {
pause();
}
}
// Helper to look for a sequence in the stack trace.
#if __linux__
static bool CheckStack(Backtrace* bt, const std::vector<std::string>& seq) {
size_t cur_search_index = 0; // The currently active index in seq.
CHECK_GT(seq.size(), 0U);
for (Backtrace::const_iterator it = bt->begin(); it != bt->end(); ++it) {
if (BacktraceMap::IsValid(it->map)) {
LOG(INFO) << "Got " << it->func_name << ", looking for " << seq[cur_search_index];
if (it->func_name == seq[cur_search_index]) {
cur_search_index++;
if (cur_search_index == seq.size()) {
return true;
}
}
}
}
printf("Can not find %s in backtrace:\n", seq[cur_search_index].c_str());
for (Backtrace::const_iterator it = bt->begin(); it != bt->end(); ++it) {
if (BacktraceMap::IsValid(it->map)) {
printf(" %s\n", it->func_name.c_str());
}
}
return false;
}
#endif
// Currently we have to fall back to our own loader for the boot image when it's compiled PIC
// because its base is zero. Thus in-process unwinding through it won't work. This is a helper
// detecting this.
#if __linux__
static bool IsPicImage() {
gc::space::ImageSpace* image_space = Runtime::Current()->GetHeap()->GetImageSpace();
CHECK(image_space != nullptr); // We should be running with an image.
const OatFile* oat_file = image_space->GetOatFile();
CHECK(oat_file != nullptr); // We should have an oat file to go with the image.
return oat_file->IsPic();
}
#endif
extern "C" JNIEXPORT jboolean JNICALL Java_Main_unwindInProcess(JNIEnv*, jobject, jint, jboolean) {
#if __linux__
if (IsPicImage()) {
LOG(INFO) << "Image is pic, in-process unwinding check bypassed.";
return JNI_TRUE;
}
// TODO: What to do on Valgrind?
std::unique_ptr<Backtrace> bt(Backtrace::Create(BACKTRACE_CURRENT_PROCESS, GetTid()));
if (!bt->Unwind(0, nullptr)) {
printf("Can not unwind in process.\n");
return JNI_FALSE;
} else if (bt->NumFrames() == 0) {
printf("No frames for unwind in process.\n");
return JNI_FALSE;
}
// We cannot really parse an exact stack, as the optimizing compiler may inline some functions.
// This is also risky, as deduping might play a trick on us, so the test needs to make sure that
// only unique functions are being expected.
std::vector<std::string> seq = {
"Java_Main_unwindInProcess", // This function.
"boolean Main.unwindInProcess(int, boolean)", // The corresponding Java native method frame.
"int java.util.Arrays.binarySearch(java.lang.Object[], int, int, java.lang.Object, java.util.Comparator)", // Framework method.
"void Main.main(java.lang.String[])" // The Java entry method.
};
bool result = CheckStack(bt.get(), seq);
if (!kCauseSegfault) {
return result ? JNI_TRUE : JNI_FALSE;
} else {
LOG(INFO) << "Result of check-stack: " << result;
}
#endif
if (kCauseSegfault) {
CauseSegfault();
}
return JNI_FALSE;
}
#if __linux__
static constexpr int kSleepTimeMicroseconds = 50000; // 0.05 seconds
static constexpr int kMaxTotalSleepTimeMicroseconds = 1000000; // 1 second
// Wait for a sigstop. This code is copied from libbacktrace.
int wait_for_sigstop(pid_t tid, int* total_sleep_time_usec, bool* detach_failed ATTRIBUTE_UNUSED) {
for (;;) {
int status;
pid_t n = TEMP_FAILURE_RETRY(waitpid(tid, &status, __WALL | WNOHANG));
if (n == -1) {
PLOG(WARNING) << "waitpid failed: tid " << tid;
break;
} else if (n == tid) {
if (WIFSTOPPED(status)) {
return WSTOPSIG(status);
} else {
PLOG(ERROR) << "unexpected waitpid response: n=" << n << ", status=" << std::hex << status;
break;
}
}
if (*total_sleep_time_usec > kMaxTotalSleepTimeMicroseconds) {
PLOG(WARNING) << "timed out waiting for stop signal: tid=" << tid;
break;
}
usleep(kSleepTimeMicroseconds);
*total_sleep_time_usec += kSleepTimeMicroseconds;
}
return -1;
}
#endif
extern "C" JNIEXPORT jboolean JNICALL Java_Main_unwindOtherProcess(JNIEnv*, jobject, jint pid_int) {
#if __linux__
// TODO: What to do on Valgrind?
pid_t pid = static_cast<pid_t>(pid_int);
// OK, this is painful. debuggerd uses ptrace to unwind other processes.
if (ptrace(PTRACE_ATTACH, pid, 0, 0)) {
// Were not able to attach, bad.
printf("Failed to attach to other process.\n");
PLOG(ERROR) << "Failed to attach.";
kill(pid, SIGKILL);
return JNI_FALSE;
}
kill(pid, SIGSTOP);
bool detach_failed = false;
int total_sleep_time_usec = 0;
int signal = wait_for_sigstop(pid, &total_sleep_time_usec, &detach_failed);
if (signal == -1) {
LOG(WARNING) << "wait_for_sigstop failed.";
}
std::unique_ptr<Backtrace> bt(Backtrace::Create(pid, BACKTRACE_CURRENT_THREAD));
bool result = true;
if (!bt->Unwind(0, nullptr)) {
printf("Can not unwind other process.\n");
result = false;
} else if (bt->NumFrames() == 0) {
printf("No frames for unwind of other process.\n");
result = false;
}
if (result) {
// See comment in unwindInProcess for non-exact stack matching.
std::vector<std::string> seq = {
// "Java_Main_sleep", // The sleep function being executed in the
// other runtime.
// Note: For some reason, the name isn't
// resolved, so don't look for it right now.
"boolean Main.sleep(int, boolean, double)", // The corresponding Java native method frame.
"int java.util.Arrays.binarySearch(java.lang.Object[], int, int, java.lang.Object, java.util.Comparator)", // Framework method.
"void Main.main(java.lang.String[])" // The Java entry method.
};
result = CheckStack(bt.get(), seq);
}
if (ptrace(PTRACE_DETACH, pid, 0, 0) != 0) {
PLOG(ERROR) << "Detach failed";
}
// Kill the other process once we are done with it.
kill(pid, SIGKILL);
return result ? JNI_TRUE : JNI_FALSE;
#else
return JNI_FALSE;
#endif
}
} // namespace art