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Commit c56a4994 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Only skip frames for local unwinds. 

When doing a remote unwind, and there is a crash in the unwind stack
code or in libbacktrace, the old version would skip those frames.
This makes debugging crashes in those libraries a bit difficult.

Bug: 68820611

Test: Ran unit tests.
Test: kill -3 a zygote process and verify no frames in
Test: libunwindstack.so/libbacktrace.so.
Test: Forced a crash in libunwindstack.so and verified the tombstone
Test: contains the full crash.
Change-Id: I297e5b3775c87c0dddf57ebb423bd72ba1baf193
parent 0d323c12

libbacktrace/UnwindStack.cpp

+6 −5
Original line number Diff line number Diff line
@@ -44,13 +44,13 @@ 
#include "UnwindStackMap.h"



bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,

                       std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames) {

  std::vector<std::string> skip_names{"libunwindstack.so", "libbacktrace.so"};

                       std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,

                       std::vector<std::string>* skip_names) {

  UnwindStackMap* stack_map = reinterpret_cast<UnwindStackMap*>(back_map);

  auto process_memory = stack_map->process_memory();

  unwindstack::Unwinder unwinder(MAX_BACKTRACE_FRAMES + num_ignore_frames, stack_map->stack_maps(),

                                 regs, stack_map->process_memory());

  unwinder.Unwind(&skip_names, &stack_map->GetSuffixesToIgnore());

  unwinder.Unwind(skip_names, &stack_map->GetSuffixesToIgnore());



  if (num_ignore_frames >= unwinder.NumFrames()) {

    frames->resize(0);
@@ -104,7 +104,8 @@ bool UnwindStackCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* 
  }



  error_ = BACKTRACE_UNWIND_NO_ERROR;

  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames);

  std::vector<std::string> skip_names{"libunwindstack.so", "libbacktrace.so"};

  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, &skip_names);

}



UnwindStackPtrace::UnwindStackPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
@@ -124,5 +125,5 @@ bool UnwindStackPtrace::Unwind(size_t num_ignore_frames, ucontext_t* context) { 
  }



  error_ = BACKTRACE_UNWIND_NO_ERROR;

  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames);

  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, nullptr);

}

libbacktrace/include/backtrace/Backtrace.h

+2 −1
Original line number Diff line number Diff line
@@ -109,7 +109,8 @@ public: 
  virtual bool Unwind(size_t num_ignore_frames, ucontext_t* context = NULL) = 0;



  static bool Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,

                     std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames);

                     std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,

                     std::vector<std::string>* skip_names);



  // Get the function name and offset into the function given the pc.

  // If the string is empty, then no valid function name was found,