Due to a bug, an elf can have FDEs with a length of zero, while still
having another FDE for the same pc with a non-zero length. The
eh_frame_hdr can sometimes point to the zero length FDE, but it should
have pointed to the non-zero length FDE. In order to fix this, if the
eh_frame_hdr points at the zero length FDE then try and find the real FDE
directly from eh_frame.
The change cleans up and removes unused variables from DwarfEhFrameWithHdr
and changes the objects so that all of the DwarfSection objects and
DwarfEhFrameWithHdr object inherit from the same class.
Add new unit tests to verify this functionality.
Bug: 142483624
Test: Unit tests all pass.
Change-Id: I128a916e3ba378931de7d44ee15e57e24d4073df
Since there has never been a time that a sequential search has been
necessary, simply remove the sequential code and allow the DwarfEhFrame
object to be used in that case. If this does come up regularly, I'm not
sure that it wouldn't be more performant to use the DwarfEhFrame object
regardless.
Bug: 129550015
Test: libunwindstack unit tests, libbacktrace unit tests.
Change-Id: I738e81accb9bc1e182168cddc9c0c22823e3369b
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
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
- Add a new tool that can dump the register information given a pc.
- Add a new offline unwinder test that fails without this change.
- Update unit tests.
- Refactor offline unwind tests to make it easier to add tests.
Bug: 73048324
Test: Passes new unit tests.
Test: Passes libbacktrace unit tests.
Test: Ran debuggerd -b on random processes.
Change-Id: If6c70a044299505c2274ae6888b35bf9ac34b74b
The backtrace offline code uses these error codes to diagnose errors.
In addtion, I've had cases where seeing these errors would help diagnose
failures.
This also allows us to add a few features to indicate why an unwind
terminated (such as max frames exceeded).
Bug: 65682279
Test: Updated unit tests pass.
Change-Id: If82b5092698e8a194016d670efff1320f9b44d50
- Be a little more lenient when reading the cies/fdes. If next entry data
winds up incorrect, don't fail, simply stop processing the entries. This
only applies when reading all of the cies/fdes at once.
- Fail to init an eh_frame with no entries and fallback to assuming the
eh_frame has no header instead.
- Change the step to always try debug_frame first which has the most
accurate information.
- Add small unit tests and a couple of offline unit tests to verify
this behavior.
These changes are needed to support offline unwinding since it depends
on this new behavior.
Bug: 65682279
Test: Ran new unit tests.
Change-Id: I3529f1b0c8e14cd7409494e5de2f3c9e78d0855e
When stepping, it's necessary to use both the unaltered relative pc
and the adjusted relative pc. If the adjusted pc is not used, the
wrong unwind information can be used.
Added new offline unit tests that take real data and verifies that it
unwinds properly.
Fix a bug in the map code that would not properly parse map data for
a 64 bit process when done in a 32 bit process.
Fix bug in eh_frame processing that didn't adjust the pc correctly.
Fix unit tests related to the pc adjustment.
Bug: 69475565
Test: Passes libbacktrace/libunwindstack unit tests.
Test: Run debuggerd -b on processes on a hikey.
Change-Id: Ic501a1c4549c5f61d2742a7105c42a960f2c892b
In this case, if the .eh_frame_hdr doesn't exist, we would crash.
Bug: 68813077
Test: Pass new unit tests, verified that without the fix, the unit test
Test: would crash.
Change-Id: I4f1365a76fe5c2fb69fa106a1ef15889c14e7611
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
