Commit graph

14 commits

Author SHA1 Message Date
Christopher Ferris
bf373edc3c Add caching of build id in MapInfo object.
Change the GetBuildID function to return a std::string.
Added benchmark to check how long it takes to get the build id from
a file versus an elf object.
Added a way to get an elf without passing in a valid process_memory and
added tests for this.

Test: New unit tests.
Change-Id: I3029019767e0181c758d611fe635bc1bf72d6e8e
2019-01-17 20:14:00 -08:00
Florian Mayer
da459e56f7 Read .note.gnu.build-id.
This will be used by heapprofd to allow us to correlate build ids with
memory leaks in libraries and binaries.

Test: m
Test: host libunwindstack_test
Test: run unwind_info against my phone's libc.so (32/64) and compare
      to readelf Build ID output.

Bug: 120186412

Change-Id: I3cefd6cce9a8733509bf35b7175eb0f967783477
2018-12-05 14:13:30 +00:00
Christopher Ferris
5acf069a7a Be permissive about badly formed elf files.
Here is the allowable issues with an elf file that will not result in an error:
- The program headers/section headers offset points to unreadable memory.
- Allow missing program header and/or section headers.
- Allow a symbol table section header to point to invalid symbol table values.

There is no real reason to require the elf file be perfect. Everything in
the code has sane defaults, so any missing information won't cause any
problems.

This gets rid of the warning that occurs any time an elf is loaded
from memory. In memory elf files never contain all of the section headers,
and do not contain the symbol table data.

Update tests to test these new cases.

Test: Builds and unit tests all pass.
Change-Id: Iaefe2cd6b6c965a01ed425a112d6afae339f3b78
2018-08-03 22:02:05 +00:00
Christopher Ferris
92acaac8c7 Refactor the DwarfSection classes.
Modify the code for the no header sections because it turns out that
it is not okay to assume that the fdes are non-overlapping. It's necessary
to read the fdes in order and match as you go.

Modify the code so that it only reads until it finds the given pc rather than
reading all of the cie/fde entries at once.

Rewrote the tests to verify the new behavior.

Bug: 68998033
Bug: 110235461

Test: Ran libbacktrace/libunwindstack unit tests.
Test: Unwind the mediaserver process on a walleye and verify it
Test: unwinds properly.

Change-Id: I7bb59d1db72c13fa34caa9735ec34c1a60e20ed2
2018-06-27 14:52:21 -07:00
Christopher Ferris
f882a38864 Fix ARM program header values used for exidx.
Before, I was using p_vaddr to get the offset into the elf file where
the exidx frame starts. I changed that to use p_offset since this already
has the load bias offset in it and some elf files do not set p_vaddr
properly.

Also, use p_filesz instead of p_memsz, since again, some elf files do
not set p_memsz to the same as p_filesz.

Bug: 110704153

Test: All libbacktrace/libunwindstack unit tests pass.
Test: Randomly unwind process on a walleye.
Test: Verified that this properly dumps and unwinds the shared
Test: library that sets p_vaddr and p_memsz differently.
Change-Id: Ic7b1e5d07439f4636fa02cd884a8727a5737372b
2018-06-22 16:48:02 -07:00
Christopher Ferris
4cc36d2b43 Fix handling of load bias values.
It turns out that for the dwarf information, if a FDE indicates it's pc
relative, then pc has to be incremented by the load bias. If not, then
it should not be incremented.

Previously, the code always subtracted load bias values from pcs, and assumed
that all fdes were incremented by load bias values. The new code actually
reads the fdes and adjusted the pcs in the fde and in the eh frame hdr so
that load bias values are already handled properly.

In addition, add dumping of arm exidx values in unwind_reg_info. This allowed
verifying that the debug frame in those elf files was being handled properly.

Added a new unit test that only has a debug frame that has a non-zero load
bias and has fde entries that do not have pc relative encoding.

Fix a couple of other small bugs.

Bug: 109824792

Test: All libbacktrace/libunwindstack unit tests pass.
Test: Ran ART 137-cfi test and 004-ThreadStress.
Test: Verify that displaying the fde start and end pc actually match the
Test: real data for fde that have pc relative set, and that don't.
Test: Verified that the unwind information for arm exidx matches the
Test: debug frame data.

Change-Id: I707555286b5cb05df9f25489e8c5ede753cfe0fb
2018-06-11 18:53:55 -07:00
Christopher Ferris
beae42bc7f Fix soname reading code.
The dynamic section contained an address, not an offset into the elf
file to indicate where the soname exists. Changed to use the strtab
entries in the section headers to map this address to the actual offset.

Refactor the soname test a bit to make it easier to verify the code.

Bug: 73499044

Test: Passes new unit tests.
Test: Ran unwind_info on the failing shared elf and verified the soinfo
Test: is correct.
Change-Id: I16ba148389bcb9aadd3566fb442dac27f89fe894
2018-02-15 17:57:13 -08:00
Christopher Ferris
150db124f3 Add ability to read jit gdb data.
Changes:
- New JitDebug class to handle all of the jit gdb interface.
- Add unit tests for all, along with new offline test using debug data.
- Add new Memory type called MemoryOfflineParts that has multiple
  MemoryOffline objects to support the offline test.
- Update the tools to use the JitDebug object.
- Modify libbacktrace to use the JitDebug, but only looking in libart.so
  and libartd.so.
- Change the Format32Bits to Is32Bit since it's more accurate and I use
  it in a different context where original name didn't make sense.
- Add a new function to find global variables in an elf file
  (GetGlobalVariable).
- Add a new function to determine if a pc is valid for this elf (IsValidPc).

Bug: 68396769

Test: Ran new unit tests. Added new offline test that uses jit debug data.
Test: Ran art test that generates jit data and verified a crash unwinds
Test: through the jit data.
Change-Id: I6e7ee2f5bab2242028a06feece156dff21c0a974
2018-01-12 11:18:42 -08:00
Christopher Ferris
c9dee84d81 Add support for only a .eh_frame.
Static executables only have a .eh_frame section and no .eh_frame_hdr
section. Add support for this by rearranging the class hierarchy and
creating a DwarfEhFrameWithHdr class and a DwarfEhFrame class to handle
the different cases.

Add new unit tests for DwarfEhFrame and for the new functionality.

Bug: 68820189

Test: Passes new unit tests, unwinds static executables.
Change-Id: I63d7cb8c52a686e96579a2266e18c0d06bbb6e63
2017-11-07 13:22:39 -08:00
Christopher Ferris
e69f470933 Multiple bugfixes, small restructuring.
- Move the load bias stored out of ElfInterface into Elf. For the compressed
  sections, the load bias was not the same as the data from the uncompressed
  section.
- Move the initialization of the compressed section into Init. It was too easy
  to forget to call the init of the compressed section.
- Do not automatically add in load bias to the pc before calling ElfInterface
  code. Do all of the pc manipulations in the Elf object.
- Change the interface GetFunctionName code to pass in the load_bias instead
  of modifying the pc inside the code.
- Modify the Step function to pass in the elf offset, not add it to the pc.
  It is necessary to have two different relative values when executing the
  Step: a pc that is relative to the beginning of the elf for the reading data
  the actual instructions when trying to determine if this is in a signal
  frame, and a pc that is relative to the map for finding the appropriate
  unwind information.
- Add a feature to Unwinder so that an unwind can be stopped if it ends up
  in map that has a specified suffix. This is so that the ART unwinding
  code doesn't require skipping the compressed section. Instead, stop at
  if trying to unwind through a known suffix code that means the code is
  in java code. This is important because the compressed section data is
  not only used by the jave compiled code, so that will continue to work.
- Fix tests for restructuring, add new tests for new functionality.

Test: Ran art test 137-cfi using new unwinder as default.
Test: Ran new unit tests.
Change-Id: I42e658c64c5e14f698ba34944a3043afac967884
2017-10-20 11:15:32 -07:00
Christopher Ferris
d226a51409 Make the library usable as a library.
- Add namespace unwindstack everywhere so that it's easier for other
  code to use the library.
- Move some of the header files into include/unwindstack so that they
  can be exposed.
- Modify the headers so that only a limited number need to be exposed.
- Update the tools to use the new headers.
- Add a GetLoadBias() call on the Elf object. This prevents the need
  to get the interface object out of the Elf object.
- Move the GetRelPc() call out of the Reg class, to the Elf class. It's
  not always the case that a Reg object will be around when you want to
  get a relative pc. The tests for this moved to ElfTest.cpp.

Bug: 23762183

Test: Unit tests pass.
Change-Id: Iac609dac1dd90ed83d1a1e24ff2579c96c023bc3
2017-07-14 12:20:23 -07:00
Christopher Ferris
8098b1c378 Add section parsing and function name handling.
Add the code to parse the Elf section headers.

Add the plumbing through of all the symbol handling code.

Add tests for all of this new functionality.

Bug: 23762183

Test: Pass new unit tests.
Change-Id: Ie2d90cbb3d7653c53251dbcf34d9e5d241278377
2017-06-23 10:51:28 -07:00
Christopher Ferris
61d4097737 Add EH frame and debug frame support.
Bug: 23762183

Test: Pass new unit tests.
Change-Id: I1bfe900e068017ff31998f359bf98d4c5c9af2a5
2017-06-16 14:25:29 -07:00
Christopher Ferris
3958f8060a Elf interface for new unwinder.
This cl includes the code to read arm unwind information from a shared
library.

Bug: 23762183

Test: Passes all unit tests. I can dump the arm unwind information
Test: for an arm shared library.
Change-Id: I43501ea2eab843b81de8bd5128401dd1971af8d3
2017-03-09 12:27:16 -08:00