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/*
* Copyright (C) 2018 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 <android/fdsan.h>
#include <bionic/malloc.h>
#include <inttypes.h>
#include <malloc.h>
#include <private/bionic_malloc_dispatch.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/system_properties.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <atomic>
#include <tuple>
#include "perfetto/base/build_config.h"
#include "perfetto/base/logging.h"
#include "perfetto/ext/base/no_destructor.h"
#include "perfetto/ext/base/unix_socket.h"
#include "perfetto/ext/base/utils.h"
#include "src/profiling/common/proc_utils.h"
#include "src/profiling/memory/client.h"
#include "src/profiling/memory/scoped_spinlock.h"
#include "src/profiling/memory/unhooked_allocator.h"
#include "src/profiling/memory/wire_protocol.h"
using perfetto::profiling::ScopedSpinlock;
using perfetto::profiling::UnhookedAllocator;
// This is so we can make an so that we can swap out with the existing
// libc_malloc_hooks.so
#ifndef HEAPPROFD_PREFIX
#define HEAPPROFD_PREFIX heapprofd
#endif
#define HEAPPROFD_ADD_PREFIX(name) \
PERFETTO_BUILDFLAG_CAT(HEAPPROFD_PREFIX, name)
#pragma GCC visibility push(default)
extern "C" {
bool HEAPPROFD_ADD_PREFIX(_initialize)(const MallocDispatch* malloc_dispatch,
bool* zygote_child,
const char* options);
void HEAPPROFD_ADD_PREFIX(_finalize)();
void HEAPPROFD_ADD_PREFIX(_dump_heap)(const char* file_name);
void HEAPPROFD_ADD_PREFIX(_get_malloc_leak_info)(uint8_t** info,
size_t* overall_size,
size_t* info_size,
size_t* total_memory,
size_t* backtrace_size);
bool HEAPPROFD_ADD_PREFIX(_write_malloc_leak_info)(FILE* fp);
ssize_t HEAPPROFD_ADD_PREFIX(_malloc_backtrace)(void* pointer,
uintptr_t* frames,
size_t frame_count);
void HEAPPROFD_ADD_PREFIX(_free_malloc_leak_info)(uint8_t* info);
size_t HEAPPROFD_ADD_PREFIX(_malloc_usable_size)(void* pointer);
void* HEAPPROFD_ADD_PREFIX(_malloc)(size_t size);
void HEAPPROFD_ADD_PREFIX(_free)(void* pointer);
void* HEAPPROFD_ADD_PREFIX(_aligned_alloc)(size_t alignment, size_t size);
void* HEAPPROFD_ADD_PREFIX(_memalign)(size_t alignment, size_t bytes);
void* HEAPPROFD_ADD_PREFIX(_realloc)(void* pointer, size_t bytes);
void* HEAPPROFD_ADD_PREFIX(_calloc)(size_t nmemb, size_t bytes);
struct mallinfo HEAPPROFD_ADD_PREFIX(_mallinfo)();
int HEAPPROFD_ADD_PREFIX(_mallopt)(int param, int value);
int HEAPPROFD_ADD_PREFIX(_malloc_info)(int options, FILE* fp);
int HEAPPROFD_ADD_PREFIX(_posix_memalign)(void** memptr,
size_t alignment,
size_t size);
int HEAPPROFD_ADD_PREFIX(_malloc_iterate)(uintptr_t base,
size_t size,
void (*callback)(uintptr_t base,
size_t size,
void* arg),
void* arg);
void HEAPPROFD_ADD_PREFIX(_malloc_disable)();
void HEAPPROFD_ADD_PREFIX(_malloc_enable)();
#if defined(HAVE_DEPRECATED_MALLOC_FUNCS)
void* HEAPPROFD_ADD_PREFIX(_pvalloc)(size_t bytes);
void* HEAPPROFD_ADD_PREFIX(_valloc)(size_t size);
#endif
}
#pragma GCC visibility pop
namespace {
// The real malloc function pointers we get in initialize. Set once in the first
// initialize invocation, and never changed afterwards. Because bionic does a
// release write after initialization and an acquire read to retrieve the hooked
// malloc functions, we can use relaxed memory mode for both writing and
// reading.
std::atomic<const MallocDispatch*> g_dispatch{nullptr};
// Holds the active profiling client. Is empty at the start, or after we've
// started shutting down a profiling session. Hook invocations take shared_ptr
// copies (ensuring that the client stays alive until no longer needed), and do
// nothing if this master pointer is empty.
//
// This shared_ptr itself is protected by g_client_lock. Note that shared_ptr
// handles are not thread-safe by themselves:
// https://en.cppreference.com/w/cpp/memory/shared_ptr/atomic
//
// To avoid on-destruction re-entrancy issues, this shared_ptr needs to be
// constructed with an allocator that uses the unhooked malloc & free functions.
// See UnhookedAllocator.
//
// NoDestructor<> wrapper is used to avoid destructing the shared_ptr at program
// exit. The rationale is:
// * Avoiding the atexit destructor racing against other threads that are
// possibly running within the hooks.
// * Making sure that atexit handlers running after this global's destructor
// can still safely enter the hooks.
perfetto::base::NoDestructor<std::shared_ptr<perfetto::profiling::Client>>
g_client;
// Protects g_client, and serves as an external lock for sampling decisions (see
// perfetto::profiling::Sampler).
//
// We rely on this atomic's destuction being a nop, as it is possible for the
// hooks to attempt to acquire the spinlock after its destructor should have run
// (technically a use-after-destruct scenario).
std::atomic<bool> g_client_lock{false};
constexpr char kHeapprofdBinPath[] = "/system/bin/heapprofd";
const MallocDispatch* GetDispatch() {
return g_dispatch.load(std::memory_order_relaxed);
}
int CloneWithoutSigchld() {
auto ret = clone(nullptr, nullptr, 0, nullptr);
if (ret == 0)
android_fdsan_set_error_level(ANDROID_FDSAN_ERROR_LEVEL_DISABLED);
return ret;
}
int ForklikeClone() {
auto ret = clone(nullptr, nullptr, SIGCHLD, nullptr);
if (ret == 0)
android_fdsan_set_error_level(ANDROID_FDSAN_ERROR_LEVEL_DISABLED);
return ret;
}
// Like daemon(), but using clone to avoid invoking pthread_atfork(3) handlers.
int Daemonize() {
switch (ForklikeClone()) {
case -1:
PERFETTO_PLOG("Daemonize.clone");
return -1;
break;
case 0:
break;
default:
_exit(0);
break;
}
if (setsid() == -1) {
PERFETTO_PLOG("Daemonize.setsid");
return -1;
}
// best effort chdir & fd close
chdir("/");
int fd = open("/dev/null", O_RDWR, 0);
if (fd != -1) {
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
close(fd);
}
return 0;
}
// Called only if |g_client_lock| acquisition fails, which shouldn't happen
// unless we're in a completely unexpected state (which we won't know how to
// recover from). Tries to abort (SIGABRT) the whole process to serve as an
// explicit indication of a bug.
//
// Doesn't use PERFETTO_FATAL as that is a single attempt to self-signal (in
// practice - SIGTRAP), while abort() tries to make sure the process has
// exited one way or another.
__attribute__((noreturn, noinline)) void AbortOnSpinlockTimeout() {
PERFETTO_ELOG(
"Timed out on the spinlock - something is horribly wrong. "
"Aborting whole process.");
abort();
}
std::string ReadSystemProperty(const char* key) {
std::string prop_value;
const prop_info* prop = __system_property_find(key);
if (!prop) {
return prop_value; // empty
}
__system_property_read_callback(
prop,
[](void* cookie, const char* name, const char* value, uint32_t) {
std::string* prop_value = reinterpret_cast<std::string*>(cookie);
*prop_value = value;
},
&prop_value);
return prop_value;
}
bool ShouldForkPrivateDaemon() {
std::string build_type = ReadSystemProperty("ro.build.type");
if (build_type.empty()) {
PERFETTO_ELOG(
"Cannot determine platform build type, proceeding in fork mode "
"profiling.");
return true;
}
// On development builds, we support both modes of profiling, depending on a
// system property.
if (build_type == "userdebug" || build_type == "eng") {
// Note: if renaming the property, also update system_property.cc
std::string mode = ReadSystemProperty("heapprofd.userdebug.mode");
return mode == "fork";
}
// User/other builds - always fork private profiler.
return true;
}
std::shared_ptr<perfetto::profiling::Client> CreateClientForCentralDaemon(
UnhookedAllocator<perfetto::profiling::Client> unhooked_allocator) {
PERFETTO_DLOG("Constructing client for central daemon.");
using perfetto::profiling::Client;
perfetto::base::Optional<perfetto::base::UnixSocketRaw> sock =
Client::ConnectToHeapprofd(perfetto::profiling::kHeapprofdSocketFile);
if (!sock) {
PERFETTO_ELOG("Failed to connect to %s.",
perfetto::profiling::kHeapprofdSocketFile);
return nullptr;
}
return Client::CreateAndHandshake(std::move(sock.value()),
unhooked_allocator);
}
std::shared_ptr<perfetto::profiling::Client> CreateClientAndPrivateDaemon(
UnhookedAllocator<perfetto::profiling::Client> unhooked_allocator) {
PERFETTO_DLOG("Setting up fork mode profiling.");
perfetto::base::UnixSocketRaw parent_sock;
perfetto::base::UnixSocketRaw child_sock;
std::tie(parent_sock, child_sock) = perfetto::base::UnixSocketRaw::CreatePair(
perfetto::base::SockFamily::kUnix, perfetto::base::SockType::kStream);
if (!parent_sock || !child_sock) {
PERFETTO_PLOG("Failed to create socketpair.");
return nullptr;
}
child_sock.RetainOnExec();
// Record own pid and cmdline, to pass down to the forked heapprofd.
pid_t target_pid = getpid();
std::string target_cmdline;
if (!perfetto::profiling::GetCmdlineForPID(target_pid, &target_cmdline)) {
target_cmdline = "failed-to-read-cmdline";
PERFETTO_ELOG(
"Failed to read own cmdline, proceeding as this might be a by-pid "
"profiling request (which will still work).");
}
// Prepare arguments for heapprofd.
std::string pid_arg =
std::string("--exclusive-for-pid=") + std::to_string(target_pid);
std::string cmd_arg =
std::string("--exclusive-for-cmdline=") + target_cmdline;
std::string fd_arg =
std::string("--inherit-socket-fd=") + std::to_string(child_sock.fd());
const char* argv[] = {kHeapprofdBinPath, pid_arg.c_str(), cmd_arg.c_str(),
fd_arg.c_str(), nullptr};
// Use fork-like clone to avoid invoking the host's pthread_atfork(3)
// handlers. Also avoid sending the current process a SIGCHILD to further
// reduce our interference.
pid_t clone_pid = CloneWithoutSigchld();
if (clone_pid == -1) {
PERFETTO_PLOG("Failed to clone.");
return nullptr;
}
if (clone_pid == 0) { // child
// Daemonize clones again, terminating the calling thread (i.e. the direct
// child of the original process). So the rest of this codepath will be
// executed in a new reparented process.
if (Daemonize() == -1) {
PERFETTO_PLOG("Daemonization failed.");
_exit(1);
}
execv(kHeapprofdBinPath, const_cast<char**>(argv));
PERFETTO_PLOG("Failed to execute private heapprofd.");
_exit(1);
} // else - parent continuing the client setup
child_sock.ReleaseFd().reset(); // close child socket's fd
if (!parent_sock.SetTxTimeout(perfetto::profiling::kClientSockTimeoutMs)) {
PERFETTO_PLOG("Failed to set socket transmit timeout.");
return nullptr;
}
if (!parent_sock.SetRxTimeout(perfetto::profiling::kClientSockTimeoutMs)) {
PERFETTO_PLOG("Failed to set socket receive timeout.");
return nullptr;
}
// Wait on the immediate child to exit (allow for ECHILD in the unlikely case
// we're in a process that has made its children unwaitable).
int unused = 0;
if (PERFETTO_EINTR(waitpid(clone_pid, &unused, __WCLONE)) == -1 &&
errno != ECHILD) {
PERFETTO_PLOG("Failed to waitpid on immediate child.");
return nullptr;
}
return perfetto::profiling::Client::CreateAndHandshake(std::move(parent_sock),
unhooked_allocator);
}
// Note: android_mallopt(M_RESET_HOOKS) is mutually exclusive with
// heapprofd_initialize. Concurrent calls get discarded, which might be our
// unpatching attempt if there is a concurrent re-initialization running due to
// a new signal.
//
// Note: g_client can be reset by heapprofd_initialize without calling this
// function.
void ShutdownLazy() {
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
if (!g_client.ref()) // other invocation already initiated shutdown
return;
// Clear primary shared pointer, such that later hook invocations become nops.
g_client.ref().reset();
if (!android_mallopt(M_RESET_HOOKS, nullptr, 0))
PERFETTO_PLOG("Unpatching heapprofd hooks failed.");
}
} // namespace
// Setup for the rest of profiling. The first time profiling is triggered in a
// process, this is called after this client library is dlopened, but before the
// rest of the hooks are patched in. However, as we support multiple profiling
// sessions within a process' lifetime, this function can also be legitimately
// called any number of times afterwards (note: bionic guarantees that at most
// one initialize call is active at a time).
//
// Note: if profiling is triggered at runtime, this runs on a dedicated pthread
// (which is safe to block). If profiling is triggered at startup, then this
// code runs synchronously.
bool HEAPPROFD_ADD_PREFIX(_initialize)(const MallocDispatch* malloc_dispatch,
bool*,
const char*) {
using ::perfetto::profiling::Client;
// Table of pointers to backing implementation.
g_dispatch.store(malloc_dispatch, std::memory_order_relaxed);
// TODO(fmayer): Check other destructions of client and make a decision
// whether we want to ban heap objects in the client or not.
std::shared_ptr<Client> old_client;
{
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
if (g_client.ref()) {
PERFETTO_LOG("Rejecting concurrent profiling initialization.");
return true; // success as we're in a valid state
}
old_client = g_client.ref();
g_client.ref().reset();
}
old_client.reset();
// The dispatch table never changes, so let the custom allocator retain the
// function pointers directly.
UnhookedAllocator<Client> unhooked_allocator(malloc_dispatch->malloc,
malloc_dispatch->free);
// These factory functions use heap objects, so we need to run them without
// the spinlock held.
std::shared_ptr<Client> client =
ShouldForkPrivateDaemon()
? CreateClientAndPrivateDaemon(unhooked_allocator)
: CreateClientForCentralDaemon(unhooked_allocator);
if (!client) {
PERFETTO_LOG("heapprofd_client not initialized, not installing hooks.");
return false;
}
PERFETTO_LOG("heapprofd_client initialized.");
{
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
// This cannot have been set in the meantime. There are never two concurrent
// calls to this function, as Bionic uses atomics to guard against that.
PERFETTO_DCHECK(g_client.ref() == nullptr);
g_client.ref() = std::move(client);
}
return true;
}
void HEAPPROFD_ADD_PREFIX(_finalize)() {
// At the time of writing, invoked only as an atexit handler. We don't have
// any specific action to take, and cleanup can be left to the OS.
}
// Decides whether an allocation with the given address and size needs to be
// sampled, and if so, records it. Performs the necessary synchronization (holds
// |g_client_lock| spinlock) while accessing the shared sampler, and obtaining a
// profiling client handle (shared_ptr).
//
// If the allocation is to be sampled, the recording is done without holding
// |g_client_lock|. The client handle is guaranteed to not be invalidated while
// the allocation is being recorded.
//
// If the attempt to record the allocation fails, initiates lazy shutdown of the
// client & hooks.
static void MaybeSampleAllocation(size_t size, void* addr) {
size_t sampled_alloc_sz = 0;
std::shared_ptr<perfetto::profiling::Client> client;
{
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
if (!g_client.ref()) // no active client (most likely shutting down)
return;
sampled_alloc_sz = g_client.ref()->GetSampleSizeLocked(size);
if (sampled_alloc_sz == 0) // not sampling
return;
client = g_client.ref(); // owning copy
} // unlock
if (!client->RecordMalloc(sampled_alloc_sz, size,
reinterpret_cast<uint64_t>(addr))) {
ShutdownLazy();
}
}
void* HEAPPROFD_ADD_PREFIX(_malloc)(size_t size) {
const MallocDispatch* dispatch = GetDispatch();
void* addr = dispatch->malloc(size);
MaybeSampleAllocation(size, addr);
return addr;
}
void* HEAPPROFD_ADD_PREFIX(_calloc)(size_t nmemb, size_t size) {
const MallocDispatch* dispatch = GetDispatch();
void* addr = dispatch->calloc(nmemb, size);
MaybeSampleAllocation(nmemb * size, addr);
return addr;
}
void* HEAPPROFD_ADD_PREFIX(_aligned_alloc)(size_t alignment, size_t size) {
const MallocDispatch* dispatch = GetDispatch();
void* addr = dispatch->aligned_alloc(alignment, size);
MaybeSampleAllocation(size, addr);
return addr;
}
void* HEAPPROFD_ADD_PREFIX(_memalign)(size_t alignment, size_t size) {
const MallocDispatch* dispatch = GetDispatch();
void* addr = dispatch->memalign(alignment, size);
MaybeSampleAllocation(size, addr);
return addr;
}
int HEAPPROFD_ADD_PREFIX(_posix_memalign)(void** memptr,
size_t alignment,
size_t size) {
const MallocDispatch* dispatch = GetDispatch();
int res = dispatch->posix_memalign(memptr, alignment, size);
if (res != 0)
return res;
MaybeSampleAllocation(size, *memptr);
return 0;
}
// Note: we record the free before calling the backing implementation to make
// sure that the address is not reused before we've processed the deallocation
// (which includes assigning a sequence id to it).
void HEAPPROFD_ADD_PREFIX(_free)(void* pointer) {
// free on a nullptr is valid but has no effect. Short circuit here, for
// various advantages:
// * More efficient
// * Notably printf calls free(nullptr) even when it is used in a way
// malloc-free way, as it unconditionally frees the pointer even if
// it was never written to.
// Short circuiting here makes it less likely to accidentally build
// infinite recursion.
if (pointer == nullptr)
return;
const MallocDispatch* dispatch = GetDispatch();
std::shared_ptr<perfetto::profiling::Client> client;
{
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
client = g_client.ref(); // owning copy (or empty)
}
if (client) {
if (!client->RecordFree(reinterpret_cast<uint64_t>(pointer)))
ShutdownLazy();
}
return dispatch->free(pointer);
}
// Approach to recording realloc: under the initial lock, get a safe copy of the
// client, and make the sampling decision in advance. Then record the
// deallocation, call the real realloc, and finally record the sample if one is
// necessary.
//
// As with the free, we record the deallocation before calling the backing
// implementation to make sure the address is still exclusive while we're
// processing it.
void* HEAPPROFD_ADD_PREFIX(_realloc)(void* pointer, size_t size) {
const MallocDispatch* dispatch = GetDispatch();
size_t sampled_alloc_sz = 0;
std::shared_ptr<perfetto::profiling::Client> client;
{
ScopedSpinlock s(&g_client_lock, ScopedSpinlock::Mode::Try);
if (PERFETTO_UNLIKELY(!s.locked()))
AbortOnSpinlockTimeout();
// If there is no active client, we still want to reach the backing realloc,
// so keep going.
if (g_client.ref()) {
client = g_client.ref(); // owning copy
sampled_alloc_sz = g_client.ref()->GetSampleSizeLocked(size);
}
} // unlock
if (client && pointer) {
if (!client->RecordFree(reinterpret_cast<uint64_t>(pointer)))
ShutdownLazy();
}
void* addr = dispatch->realloc(pointer, size);
if (size == 0 || sampled_alloc_sz == 0)
return addr;
// We do not reach this point without a valid client, because in that case
// sampled_alloc_sz == 0.
PERFETTO_DCHECK(client);
if (!client->RecordMalloc(sampled_alloc_sz, size,
reinterpret_cast<uint64_t>(addr))) {
ShutdownLazy();
}
return addr;
}
void HEAPPROFD_ADD_PREFIX(_dump_heap)(const char*) {}
void HEAPPROFD_ADD_PREFIX(
_get_malloc_leak_info)(uint8_t**, size_t*, size_t*, size_t*, size_t*) {}
bool HEAPPROFD_ADD_PREFIX(_write_malloc_leak_info)(FILE*) {
return false;
}
ssize_t HEAPPROFD_ADD_PREFIX(_malloc_backtrace)(void*, uintptr_t*, size_t) {
return -1;
}
void HEAPPROFD_ADD_PREFIX(_free_malloc_leak_info)(uint8_t*) {}
size_t HEAPPROFD_ADD_PREFIX(_malloc_usable_size)(void* pointer) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->malloc_usable_size(pointer);
}
struct mallinfo HEAPPROFD_ADD_PREFIX(_mallinfo)() {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->mallinfo();
}
int HEAPPROFD_ADD_PREFIX(_mallopt)(int param, int value) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->mallopt(param, value);
}
int HEAPPROFD_ADD_PREFIX(_malloc_info)(int options, FILE* fp) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->malloc_info(options, fp);
}
int HEAPPROFD_ADD_PREFIX(_malloc_iterate)(uintptr_t base,
size_t size,
void (*callback)(uintptr_t base,
size_t size,
void* arg),
void* arg) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->malloc_iterate(base, size, callback, arg);
}
void HEAPPROFD_ADD_PREFIX(_malloc_disable)() {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->malloc_disable();
}
void HEAPPROFD_ADD_PREFIX(_malloc_enable)() {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->malloc_enable();
}
#if defined(HAVE_DEPRECATED_MALLOC_FUNCS)
void* HEAPPROFD_ADD_PREFIX(_pvalloc)(size_t size) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->pvalloc(size);
}
void* HEAPPROFD_ADD_PREFIX(_valloc)(size_t size) {
const MallocDispatch* dispatch = GetDispatch();
return dispatch->valloc(size);
}
#endif