More libbacktrace fixes.
Included in minor fix ups is the addition of a warning macro to replace
all of the ALOGW calls.
Fix a race where multiple threads could be attempting to unwind the threads
of the current process at the same time.
Bug: 8410085
Change-Id: I02a65dc778dde690e5f95fc8ff069a32d0832fd1
diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index eca1c3d..17d9e1d 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -72,10 +72,8 @@
return impl_->Unwind(num_ignore_frames);
}
-__BEGIN_DECLS
-extern char* __cxa_demangle (const char* mangled, char* buf, size_t* len,
- int* status);
-__END_DECLS
+extern "C" char* __cxa_demangle(const char* mangled, char* buf, size_t* len,
+ int* status);
std::string Backtrace::GetFunctionName(uintptr_t pc, uintptr_t* offset) {
std::string func_name = impl_->GetFunctionNameRaw(pc, offset);
@@ -97,7 +95,7 @@
bool Backtrace::VerifyReadWordArgs(uintptr_t ptr, uint32_t* out_value) {
if (ptr & 3) {
- ALOGW("Backtrace::verifyReadWordArgs: invalid pointer %p", (void*)ptr);
+ BACK_LOGW("invalid pointer %p", (void*)ptr);
*out_value = (uint32_t)-1;
return false;
}
@@ -172,7 +170,7 @@
*out_value = *reinterpret_cast<uint32_t*>(ptr);
return true;
} else {
- ALOGW("BacktraceCurrent::readWord: pointer %p not in a readbale map", reinterpret_cast<void*>(ptr));
+ BACK_LOGW("pointer %p not in a readable map", reinterpret_cast<void*>(ptr));
*out_value = static_cast<uint32_t>(-1);
return false;
}
@@ -198,7 +196,7 @@
}
#if defined(__APPLE__)
- ALOGW("BacktracePtrace::readWord: MacOS does not support reading from another pid.\n");
+ BACK_LOGW("MacOS does not support reading from another pid.");
return false;
#else
// ptrace() returns -1 and sets errno when the operation fails.
@@ -206,8 +204,8 @@
errno = 0;
*out_value = ptrace(PTRACE_PEEKTEXT, Tid(), reinterpret_cast<void*>(ptr), NULL);
if (*out_value == static_cast<uint32_t>(-1) && errno) {
- ALOGW("BacktracePtrace::readWord: invalid pointer 0x%08x reading from tid %d, "
- "ptrace() errno=%d", ptr, Tid(), errno);
+ BACK_LOGW("invalid pointer %p reading from tid %d, ptrace() strerror(errno)=%s",
+ reinterpret_cast<void*>(ptr), Tid(), strerror(errno));
return false;
}
return true;
@@ -295,11 +293,8 @@
const backtrace_context_t* context, size_t frame_num, char* buf,
size_t buf_size) {
if (buf_size == 0 || buf == NULL) {
- ALOGW("backtrace_format_frame_data: bad call buf %p buf_size %zu\n",
- buf, buf_size);
- return;
- }
- if (context->data) {
+ BACK_LOGW("bad call buf %p buf_size %zu", buf, buf_size);
+ } else if (context->data) {
Backtrace* backtrace = reinterpret_cast<Backtrace*>(context->data);
std::string line = backtrace->FormatFrameData(frame_num);
if (line.size() > buf_size) {
diff --git a/libbacktrace/Backtrace.h b/libbacktrace/Backtrace.h
index b89bc89..00f0a10 100644
--- a/libbacktrace/Backtrace.h
+++ b/libbacktrace/Backtrace.h
@@ -21,6 +21,10 @@
#include <sys/types.h>
+// Macro to log the function name along with the warning message.
+#define BACK_LOGW(format, ...) \
+ ALOGW("%s: " format, __PRETTY_FUNCTION__, ##__VA_ARGS__)
+
class BacktraceImpl {
public:
virtual ~BacktraceImpl() { }
diff --git a/libbacktrace/BacktraceThread.cpp b/libbacktrace/BacktraceThread.cpp
index 6c3641e..8e664c4 100644
--- a/libbacktrace/BacktraceThread.cpp
+++ b/libbacktrace/BacktraceThread.cpp
@@ -31,55 +31,55 @@
// ThreadEntry implementation.
//-------------------------------------------------------------------------
static ThreadEntry* g_list = NULL;
-static pthread_mutex_t g_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t g_entry_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t g_sigaction_mutex = PTHREAD_MUTEX_INITIALIZER;
ThreadEntry::ThreadEntry(
BacktraceThreadInterface* intf, pid_t pid, pid_t tid, size_t num_ignore_frames)
- : thread_intf_(intf), pid_(pid), tid_(tid), next_(NULL), prev_(NULL),
- state_(STATE_WAITING), num_ignore_frames_(num_ignore_frames) {
+ : thread_intf(intf), pid(pid), tid(tid), next(NULL), prev(NULL),
+ state(STATE_WAITING), num_ignore_frames(num_ignore_frames) {
}
ThreadEntry::~ThreadEntry() {
- pthread_mutex_lock(&g_mutex);
+ pthread_mutex_lock(&g_entry_mutex);
if (g_list == this) {
- g_list = next_;
+ g_list = next;
} else {
- if (next_) {
- next_->prev_ = prev_;
+ if (next) {
+ next->prev = prev;
}
- prev_->next_ = next_;
+ prev->next = next;
}
- pthread_mutex_unlock(&g_mutex);
+ pthread_mutex_unlock(&g_entry_mutex);
- next_ = NULL;
- prev_ = NULL;
+ next = NULL;
+ prev = NULL;
}
ThreadEntry* ThreadEntry::AddThreadToUnwind(
BacktraceThreadInterface* intf, pid_t pid, pid_t tid, size_t num_ignore_frames) {
ThreadEntry* entry = new ThreadEntry(intf, pid, tid, num_ignore_frames);
- pthread_mutex_lock(&g_mutex);
+ pthread_mutex_lock(&g_entry_mutex);
ThreadEntry* cur_entry = g_list;
while (cur_entry != NULL) {
if (cur_entry->Match(pid, tid)) {
// There is already an entry for this pid/tid, this is bad.
- ALOGW("%s::%s(): Entry for pid %d tid %d already exists.\n",
- __FILE__, __FUNCTION__, pid, tid);
+ BACK_LOGW("Entry for pid %d tid %d already exists.", pid, tid);
- pthread_mutex_unlock(&g_mutex);
+ pthread_mutex_unlock(&g_entry_mutex);
return NULL;
}
- cur_entry = cur_entry->next_;
+ cur_entry = cur_entry->next;
}
// Add the entry to the list.
- entry->next_ = g_list;
+ entry->next = g_list;
if (g_list) {
- g_list->prev_ = entry;
+ g_list->prev = entry;
}
g_list = entry;
- pthread_mutex_unlock(&g_mutex);
+ pthread_mutex_unlock(&g_entry_mutex);
return entry;
}
@@ -89,7 +89,7 @@
//-------------------------------------------------------------------------
static void SignalHandler(int n __attribute__((unused)), siginfo_t* siginfo,
void* sigcontext) {
- if (pthread_mutex_lock(&g_mutex) == 0) {
+ if (pthread_mutex_lock(&g_entry_mutex) == 0) {
pid_t pid = getpid();
pid_t tid = gettid();
ThreadEntry* cur_entry = g_list;
@@ -97,20 +97,19 @@
if (cur_entry->Match(pid, tid)) {
break;
}
- cur_entry = cur_entry->next_;
+ cur_entry = cur_entry->next;
}
- pthread_mutex_unlock(&g_mutex);
+ pthread_mutex_unlock(&g_entry_mutex);
if (!cur_entry) {
- ALOGW("%s::%s(): Unable to find pid %d tid %d information\n",
- __FILE__, __FUNCTION__, pid, tid);
+ BACK_LOGW("Unable to find pid %d tid %d information", pid, tid);
return;
}
- if (android_atomic_acquire_cas(STATE_WAITING, STATE_DUMPING, &cur_entry->state_) == 0) {
- cur_entry->thread_intf_->ThreadUnwind(siginfo, sigcontext,
- cur_entry->num_ignore_frames_);
+ if (android_atomic_acquire_cas(STATE_WAITING, STATE_DUMPING, &cur_entry->state) == 0) {
+ cur_entry->thread_intf->ThreadUnwind(siginfo, sigcontext,
+ cur_entry->num_ignore_frames);
}
- android_atomic_release_store(STATE_DONE, &cur_entry->state_);
+ android_atomic_release_store(STATE_DONE, &cur_entry->state);
}
}
@@ -143,18 +142,18 @@
}
bool BacktraceThread::TriggerUnwindOnThread(ThreadEntry* entry) {
- entry->state_ = STATE_WAITING;
+ entry->state = STATE_WAITING;
if (tgkill(Pid(), Tid(), SIGURG) != 0) {
- ALOGW("%s::%s(): tgkill failed %s\n", __FILE__, __FUNCTION__, strerror(errno));
+ BACK_LOGW("tgkill failed %s", strerror(errno));
return false;
}
- // Allow up to a second for the dump to occur.
- int wait_millis = 1000;
+ // Allow up to ten seconds for the dump to start.
+ int wait_millis = 10000;
int32_t state;
while (true) {
- state = android_atomic_acquire_load(&entry->state_);
+ state = android_atomic_acquire_load(&entry->state);
if (state != STATE_WAITING) {
break;
}
@@ -167,24 +166,22 @@
bool cancelled = false;
if (state == STATE_WAITING) {
- if (android_atomic_acquire_cas(state, STATE_CANCEL, &entry->state_) == 0) {
- ALOGW("%s::%s(): Cancelled dump of thread %d\n", __FILE__, __FUNCTION__,
- entry->tid_);
+ if (android_atomic_acquire_cas(state, STATE_CANCEL, &entry->state) == 0) {
+ BACK_LOGW("Cancelled dump of thread %d", entry->tid);
state = STATE_CANCEL;
cancelled = true;
} else {
- state = android_atomic_acquire_load(&entry->state_);
+ state = android_atomic_acquire_load(&entry->state);
}
}
- // Wait for at most one minute for the dump to finish.
- wait_millis = 60000;
- while (android_atomic_acquire_load(&entry->state_) != STATE_DONE) {
+ // Wait for at most ten seconds for the cancel or dump to finish.
+ wait_millis = 10000;
+ while (android_atomic_acquire_load(&entry->state) != STATE_DONE) {
if (wait_millis--) {
usleep(1000);
} else {
- ALOGW("%s::%s(): Didn't finish thread unwind in 60 seconds.\n",
- __FILE__, __FUNCTION__);
+ BACK_LOGW("Didn't finish thread unwind in 60 seconds.");
break;
}
}
@@ -202,17 +199,24 @@
return false;
}
+ // Prevent multiple threads trying to set the trigger action on different
+ // threads at the same time.
bool retval = false;
- struct sigaction act, oldact;
- memset(&act, 0, sizeof(act));
- act.sa_sigaction = SignalHandler;
- act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
- sigemptyset(&act.sa_mask);
- if (sigaction(SIGURG, &act, &oldact) == 0) {
- retval = TriggerUnwindOnThread(entry);
- sigaction(SIGURG, &oldact, NULL);
+ if (pthread_mutex_lock(&g_sigaction_mutex) == 0) {
+ struct sigaction act, oldact;
+ memset(&act, 0, sizeof(act));
+ act.sa_sigaction = SignalHandler;
+ act.sa_flags = SA_RESTART | SA_SIGINFO | SA_ONSTACK;
+ sigemptyset(&act.sa_mask);
+ if (sigaction(SIGURG, &act, &oldact) == 0) {
+ retval = TriggerUnwindOnThread(entry);
+ sigaction(SIGURG, &oldact, NULL);
+ } else {
+ BACK_LOGW("sigaction failed %s", strerror(errno));
+ }
+ pthread_mutex_unlock(&g_sigaction_mutex);
} else {
- ALOGW("%s::%s(): sigaction failed %s\n", __FILE__, __FUNCTION__, strerror(errno));
+ BACK_LOGW("unable to acquire sigaction mutex.");
}
if (retval) {
diff --git a/libbacktrace/BacktraceThread.h b/libbacktrace/BacktraceThread.h
index afea771..8ed1122 100644
--- a/libbacktrace/BacktraceThread.h
+++ b/libbacktrace/BacktraceThread.h
@@ -32,26 +32,25 @@
class BacktraceThreadInterface;
-class ThreadEntry {
-public:
+struct ThreadEntry {
ThreadEntry(
BacktraceThreadInterface* impl, pid_t pid, pid_t tid,
size_t num_ignore_frames);
~ThreadEntry();
- bool Match(pid_t pid, pid_t tid) { return (pid == pid_ && tid == tid_); }
+ bool Match(pid_t chk_pid, pid_t chk_tid) { return (chk_pid == pid && chk_tid == tid); }
static ThreadEntry* AddThreadToUnwind(
BacktraceThreadInterface* thread_intf, pid_t pid, pid_t tid,
size_t num_ignored_frames);
- BacktraceThreadInterface* thread_intf_;
- pid_t pid_;
- pid_t tid_;
- ThreadEntry* next_;
- ThreadEntry* prev_;
- int32_t state_;
- int num_ignore_frames_;
+ BacktraceThreadInterface* thread_intf;
+ pid_t pid;
+ pid_t tid;
+ ThreadEntry* next;
+ ThreadEntry* prev;
+ int32_t state;
+ int num_ignore_frames;
};
// Interface class that does not contain any local storage, only defines
diff --git a/libbacktrace/Corkscrew.cpp b/libbacktrace/Corkscrew.cpp
index 8ba1e80..9daa752 100644
--- a/libbacktrace/Corkscrew.cpp
+++ b/libbacktrace/Corkscrew.cpp
@@ -37,7 +37,7 @@
bool CorkscrewCommon::GenerateFrameData(
backtrace_frame_t* cork_frames, ssize_t num_frames) {
if (num_frames < 0) {
- ALOGW("CorkscrewCommon::GenerateFrameData: libcorkscrew unwind failed.\n");
+ BACK_LOGW("libcorkscrew unwind failed.");
return false;
}
@@ -184,7 +184,7 @@
}
//-------------------------------------------------------------------------
-// C++ object createion functions.
+// C++ object creation functions.
//-------------------------------------------------------------------------
Backtrace* CreateCurrentObj() {
return new BacktraceCurrent(new CorkscrewCurrent());
diff --git a/libbacktrace/UnwindCurrent.cpp b/libbacktrace/UnwindCurrent.cpp
index 0280e93..d4ba68f 100644
--- a/libbacktrace/UnwindCurrent.cpp
+++ b/libbacktrace/UnwindCurrent.cpp
@@ -27,9 +27,9 @@
#include "UnwindCurrent.h"
+// Define the ucontext_t structures needed for each supported arch.
#if defined(__arm__)
- #if !defined(__BIONIC_HAVE_UCONTEXT_T)
- // The Current version of the Android <signal.h> doesn't define ucontext_t.
+ // The current version of the <signal.h> doesn't define ucontext_t.
#include <asm/sigcontext.h> // Ensure 'struct sigcontext' is defined.
// Machine context at the time a signal was raised.
@@ -40,8 +40,19 @@
struct sigcontext uc_mcontext;
uint32_t uc_sigmask;
} ucontext_t;
- #endif // !__BIONIC_HAVE_UCONTEXT_T
-#endif // defined(__arm__)
+#elif defined(__mips__)
+ typedef struct ucontext {
+ uint32_t sp;
+ uint32_t ra;
+ uint32_t pc;
+ } ucontext_t;
+#elif defined(__i386__)
+ #include <asm/sigcontext.h>
+ #include <asm/ucontext.h>
+ typedef struct ucontext ucontext_t;
+#else
+ #error Unsupported architecture.
+#endif
//-------------------------------------------------------------------------
// UnwindCurrent functions.
@@ -55,7 +66,7 @@
bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
int ret = unw_getcontext(&context_);
if (ret < 0) {
- ALOGW("UnwindCurrent::Unwind: unw_getcontext failed %d\n", ret);
+ BACK_LOGW("unw_getcontext failed %d", ret);
return false;
}
return UnwindFromContext(num_ignore_frames, true);
@@ -81,7 +92,7 @@
unw_cursor_t* cursor = new unw_cursor_t;
int ret = unw_init_local(cursor, &context_);
if (ret < 0) {
- ALOGW("UnwindCurrent::UnwindWithContext: unw_init_local failed %d\n", ret);
+ BACK_LOGW("unw_init_local failed %d", ret);
return false;
}
@@ -89,13 +100,13 @@
unw_word_t pc;
ret = unw_get_reg(cursor, UNW_REG_IP, &pc);
if (ret < 0) {
- ALOGW("UnwindCurrent::UnwindWithContext: Failed to read IP %d\n", ret);
+ BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(cursor, UNW_REG_SP, &sp);
if (ret < 0) {
- ALOGW("UnwindCurrent::UnwindWithContext: Failed to read SP %d\n", ret);
+ BACK_LOGW("Failed to read SP %d", ret);
break;
}
@@ -142,10 +153,9 @@
void UnwindCurrent::ExtractContext(void* sigcontext) {
unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
-
-#if defined(__arm__)
const ucontext_t* uc = reinterpret_cast<const ucontext_t*>(sigcontext);
+#if defined(__arm__)
context->regs[0] = uc->uc_mcontext.arm_r0;
context->regs[1] = uc->uc_mcontext.arm_r1;
context->regs[2] = uc->uc_mcontext.arm_r2;
@@ -162,28 +172,11 @@
context->regs[13] = uc->uc_mcontext.arm_sp;
context->regs[14] = uc->uc_mcontext.arm_lr;
context->regs[15] = uc->uc_mcontext.arm_pc;
-
#elif defined(__mips__)
-
- typedef struct ucontext {
- uint32_t sp;
- uint32_t ra;
- uint32_t pc;
- } ucontext_t;
-
- const ucontext_t* uc = (const ucontext_t*)sigcontext;
-
context->uc_mcontext.sp = uc->sp;
context->uc_mcontext.pc = uc->pc;
context->uc_mcontext.ra = uc->ra;
-#elif defined(__x86__)
-
- #include <asm/sigcontext.h>
- #include <asm/ucontext.h>
- typedef struct ucontext ucontext_t;
-
- const ucontext_t* uc = (const ucontext_t*)sigcontext;
-
+#elif defined(__i386__)
context->uc_mcontext.gregs[REG_EBP] = uc->uc_mcontext.gregs[REG_EBP];
context->uc_mcontext.gregs[REG_ESP] = uc->uc_mcontext.gregs[REG_ESP];
context->uc_mcontext.gregs[REG_EIP] = uc->uc_mcontext.gregs[REG_EIP];
diff --git a/libbacktrace/UnwindPtrace.cpp b/libbacktrace/UnwindPtrace.cpp
index 628caa0..a734a24 100644
--- a/libbacktrace/UnwindPtrace.cpp
+++ b/libbacktrace/UnwindPtrace.cpp
@@ -45,13 +45,13 @@
bool UnwindPtrace::Unwind(size_t num_ignore_frames) {
addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
if (!addr_space_) {
- ALOGW("UnwindPtrace::Unwind: unw_create_addr_space failed.\n");
+ BACK_LOGW("unw_create_addr_space failed.");
return false;
}
upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(backtrace_obj_->Tid()));
if (!upt_info_) {
- ALOGW("UnwindPtrace::Unwind: Failed to create upt info.\n");
+ BACK_LOGW("Failed to create upt info.");
return false;
}
@@ -61,7 +61,7 @@
unw_cursor_t cursor;
int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
if (ret < 0) {
- ALOGW("UnwindPtrace::Unwind: unw_init_remote failed %d\n", ret);
+ BACK_LOGW("unw_init_remote failed %d", ret);
return false;
}
@@ -69,13 +69,13 @@
unw_word_t pc;
ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
if (ret < 0) {
- ALOGW("UnwindPtrace::Unwind: Failed to read IP %d\n", ret);
+ BACK_LOGW("Failed to read IP %d", ret);
break;
}
unw_word_t sp;
ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
if (ret < 0) {
- ALOGW("UnwindPtrace::Unwind: Failed to read SP %d\n", ret);
+ BACK_LOGW("Failed to read SP %d", ret);
break;
}