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Commit e0ab2322 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Display the map offset for each frame. 

The dlopen of a shared library in an apk results in large map offsets.
Unfortunately, the current way that the frame data is printed, it's
impossible to tell what the relative pc is relative to. With the
addition of the offset, it's possible to figure out what the relative
pc actually references.

Bug: 23348999
Change-Id: Ia51b669ea3f810158cfd0d71d9ae89bf9a3170d3
parent 29c12755

libbacktrace/Backtrace.cpp

+5 −0
Original line number Diff line number Diff line
@@ -102,6 +102,11 @@ std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) { 
  uintptr_t relative_pc = BacktraceMap::GetRelativePc(frame->map, frame->pc);



  std::string line(StringPrintf("#%02zu pc %" PRIPTR "  %s", frame->num, relative_pc, map_name));

  // Special handling for non-zero offset maps, we need to print that

  // information.

  if (frame->map.offset != 0) {

    line += " (offset " + StringPrintf("0x%" PRIxPTR, frame->map.offset) + ")";

  }

  if (!frame->func_name.empty()) {

    line += " (" + frame->func_name;

    if (frame->func_offset) {

libbacktrace/backtrace_test.cpp

+9 −0
Original line number Diff line number Diff line
@@ -823,6 +823,15 @@ TEST(libbacktrace, format_test) { 
  EXPECT_EQ("#01 pc 00000000123456dc  MapFake (ProcFake+645)",

#else

  EXPECT_EQ("#01 pc 123456dc  MapFake (ProcFake+645)",

#endif

            backtrace->FormatFrameData(&frame));



  // Check a non-zero map offset.

  frame.map.offset = 0x1000;

#if defined(__LP64__)

  EXPECT_EQ("#01 pc 00000000123456dc  MapFake (offset 0x1000) (ProcFake+645)",

#else

  EXPECT_EQ("#01 pc 123456dc  MapFake (offset 0x1000) (ProcFake+645)",

#endif

            backtrace->FormatFrameData(&frame));

}