Rewrite unwind thread handling.
This new version doesn't require any specialized thread
implementation, it uses the Current implementation to do its job.
In addition, it runs much faster when multiple threads are trying
to unwind at the same time since the global signal lock is held for
only a small amount of time. Even running through the threads one at
a time should be faster since it no longer requires two passes through
the unwound stacks.
The new code now allows multiple simultaneous unwinds of the
same thread.
Finally, add the ability to unwind from a ucontext_t passed in. This
functionality doesn't work for remote unwinds yet.
Change-Id: I4d181d7ca5ffd2acfd1686e668e6d21e36b425cb
diff --git a/libbacktrace/UnwindCurrent.cpp b/libbacktrace/UnwindCurrent.cpp
index 67d372a..e5f7c3d 100755
--- a/libbacktrace/UnwindCurrent.cpp
+++ b/libbacktrace/UnwindCurrent.cpp
@@ -24,6 +24,7 @@
#include <libunwind.h>
#include "BacktraceLog.h"
+#include "BacktraceThread.h"
#include "UnwindCurrent.h"
#include "UnwindMap.h"
@@ -36,15 +37,45 @@
UnwindCurrent::~UnwindCurrent() {
}
-bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
- int ret = unw_getcontext(&context_);
- if (ret < 0) {
- BACK_LOGW("unw_getcontext failed %d", ret);
- return false;
+bool UnwindCurrent::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
+ if (!ucontext) {
+ int ret = unw_getcontext(&context_);
+ if (ret < 0) {
+ BACK_LOGW("unw_getcontext failed %d", ret);
+ return false;
+ }
+ }
+ else {
+ GetUnwContextFromUcontext(ucontext);
}
return UnwindFromContext(num_ignore_frames, false);
}
+void UnwindCurrent::GetUnwContextFromUcontext(const ucontext_t* ucontext) {
+ unw_tdep_context_t* unw_context = reinterpret_cast<unw_tdep_context_t*>(&context_);
+
+#if defined(__arm__)
+ unw_context->regs[0] = ucontext->uc_mcontext.arm_r0;
+ unw_context->regs[1] = ucontext->uc_mcontext.arm_r1;
+ unw_context->regs[2] = ucontext->uc_mcontext.arm_r2;
+ unw_context->regs[3] = ucontext->uc_mcontext.arm_r3;
+ unw_context->regs[4] = ucontext->uc_mcontext.arm_r4;
+ unw_context->regs[5] = ucontext->uc_mcontext.arm_r5;
+ unw_context->regs[6] = ucontext->uc_mcontext.arm_r6;
+ unw_context->regs[7] = ucontext->uc_mcontext.arm_r7;
+ unw_context->regs[8] = ucontext->uc_mcontext.arm_r8;
+ unw_context->regs[9] = ucontext->uc_mcontext.arm_r9;
+ unw_context->regs[10] = ucontext->uc_mcontext.arm_r10;
+ unw_context->regs[11] = ucontext->uc_mcontext.arm_fp;
+ unw_context->regs[12] = ucontext->uc_mcontext.arm_ip;
+ unw_context->regs[13] = ucontext->uc_mcontext.arm_sp;
+ unw_context->regs[14] = ucontext->uc_mcontext.arm_lr;
+ unw_context->regs[15] = ucontext->uc_mcontext.arm_pc;
+#else
+ unw_context->uc_mcontext = ucontext->uc_mcontext;
+#endif
+}
+
std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
*offset = 0;
char buf[512];
@@ -122,47 +153,6 @@
return true;
}
-void UnwindCurrent::ExtractContext(void* sigcontext) {
- unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
- 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;
- context->regs[3] = uc->uc_mcontext.arm_r3;
- context->regs[4] = uc->uc_mcontext.arm_r4;
- context->regs[5] = uc->uc_mcontext.arm_r5;
- context->regs[6] = uc->uc_mcontext.arm_r6;
- context->regs[7] = uc->uc_mcontext.arm_r7;
- context->regs[8] = uc->uc_mcontext.arm_r8;
- context->regs[9] = uc->uc_mcontext.arm_r9;
- context->regs[10] = uc->uc_mcontext.arm_r10;
- context->regs[11] = uc->uc_mcontext.arm_fp;
- context->regs[12] = uc->uc_mcontext.arm_ip;
- context->regs[13] = uc->uc_mcontext.arm_sp;
- context->regs[14] = uc->uc_mcontext.arm_lr;
- context->regs[15] = uc->uc_mcontext.arm_pc;
-#else
- context->uc_mcontext = uc->uc_mcontext;
-#endif
-}
-
-//-------------------------------------------------------------------------
-// UnwindThread functions.
-//-------------------------------------------------------------------------
-UnwindThread::UnwindThread() {
-}
-
-UnwindThread::~UnwindThread() {
-}
-
-void UnwindThread::ThreadUnwind(
- siginfo_t* /*siginfo*/, void* sigcontext, size_t num_ignore_frames) {
- ExtractContext(sigcontext);
- UnwindFromContext(num_ignore_frames, true);
-}
-
//-------------------------------------------------------------------------
// C++ object creation function.
//-------------------------------------------------------------------------
@@ -171,6 +161,5 @@
}
Backtrace* CreateThreadObj(pid_t tid, BacktraceMap* map) {
- UnwindThread* thread_obj = new UnwindThread();
- return new BacktraceThread(thread_obj, thread_obj, tid, map);
+ return new BacktraceThread(new UnwindCurrent(), tid, map);
}