[PATCHv3 0/3] AMD64 Displaced Stepping Fix

[Andrew Burgess <aburgess@redhat.com>]

In V3:

  - Change of direction since v2.  As Pedro pointed out, using the $pc
    value to decide if the displaced step succeeded is not good
    enough.  This new version switches back to using the
    target_waitstatus value.

  - The target_waitstatus is examined, and the result (a bool) is
    passed to each architecture's fixup routine.

  - Just like in v2, each fixup routine is updated, with amd64 being
    "fixed", while aarch64, ppc, and s390 (which aren't broken) just
    have an early return case added to handle the unsuccessful
    displaced step case.

  - As with v2, ARM is left broken, though this is no more broken than
    it was before this patch series.

  - As Simon suggested, the debug has now moved to
    displaced_step_prepare_throw, so the (not yet upstreamed)
    displaced stepping for the AMD GPU target should still see the
    debug output,

  - The debug code now handles a failure to disassemble better:
    there's nothing worse than enabling debug to try and solve a
    problem, and having GDB crash in a different way.  If an
    instruction fails to disassemble GDB will now print a basic debug
    message and skip the rest of the debug output,

  - As suggested, I've moved the displaced_step_dump_bytes helper
    function into gdbsupport/ and given it a better name,

  - I have NOT tried to implement the improvement Simon suggested
    where the architecture backend tells GDB core how many bytes the
    replacement instruction(s) occupied.  This still means that in
    some cases we will disassemble the entire displaced step buffer
    unnecessarily, but I don't see that as a huge problem.  Fixing
    this just to reduce some debug output a little seems excessive.
    Let me know if you feel this is a blocker for this work being
    merged and I can take another look at it.

Thanks,
Andrew

---

Andrew Burgess (3):
  gdb: more debug output for displaced stepping
  gdb: move displaced_step_dump_bytes into gdbsupport (and rename)
  gdb: fix reg corruption from displaced stepping on amd64

 gdb/aarch64-tdep.c                            |  17 ++-
 gdb/aarch64-tdep.h                            |   2 +-
 gdb/amd64-tdep.c                              |  29 +++--
 gdb/amd64-tdep.h                              |   2 +-
 gdb/arm-tdep.c                                |  26 ++++-
 gdb/arm-tdep.h                                |   3 +-
 gdb/displaced-stepping.c                      |  26 ++---
 gdb/gdbarch-gen.h                             |  25 +++--
 gdb/gdbarch.c                                 |   4 +-
 gdb/gdbarch_components.py                     |  22 +++-
 gdb/i386-tdep.c                               |  26 ++---
 gdb/i386-tdep.h                               |   2 +-
 gdb/infrun.c                                  | 101 +++++++++++------
 gdb/infrun.h                                  |   3 -
 gdb/rs6000-tdep.c                             |  14 ++-
 gdb/s390-tdep.c                               |  16 ++-
 .../amd64-disp-step-self-call-alarm.c         |  24 ++++
 .../gdb.arch/amd64-disp-step-self-call.S      |  50 +++++++++
 .../gdb.arch/amd64-disp-step-self-call.exp    |  81 +++++++++++++
 .../gdb.arch/amd64-disp-step-signal.c         |  30 +++++
 gdb/testsuite/gdb.arch/amd64-disp-step.S      |  15 +++
 gdb/testsuite/gdb.arch/amd64-disp-step.exp    | 106 +++++++++++++++---
 .../gdb.arch/i386-disp-step-self-call-alarm.c |  24 ++++
 .../gdb.arch/i386-disp-step-self-call.S       |  50 +++++++++
 .../gdb.arch/i386-disp-step-self-call.exp     |  81 +++++++++++++
 gdbsupport/array-view.h                       |   1 +
 gdbsupport/common-utils.cc                    |  18 +++
 gdbsupport/common-utils.h                     |  15 +++
 28 files changed, 679 insertions(+), 134 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/amd64-disp-step-self-call-alarm.c
 create mode 100644 gdb/testsuite/gdb.arch/amd64-disp-step-self-call.S
 create mode 100644 gdb/testsuite/gdb.arch/amd64-disp-step-self-call.exp
 create mode 100644 gdb/testsuite/gdb.arch/amd64-disp-step-signal.c
 create mode 100644 gdb/testsuite/gdb.arch/i386-disp-step-self-call-alarm.c
 create mode 100644 gdb/testsuite/gdb.arch/i386-disp-step-self-call.S
 create mode 100644 gdb/testsuite/gdb.arch/i386-disp-step-self-call.exp


base-commit: 1770eca698ad0018cd504b9744306fc9928d9a86
-- 
2.25.4