[PATCH v3 0/7] extend branch tracing to use ARM CoreSight traces

[Simon Marchi]

On 2021-03-30 10:52 p.m., Zied Guermazi wrote:
>  This patch set adds support for branch tracing in GDB on arm platforms
>  using coresight etm traces
>  Branch tracing offers instructions and functions histories as well as
>  execution record and replay (forwards and reverse debugging)
>  this patch set was tested using the gdb.btrace testsuite on ARMv7 and ARMv8
>  cortex A processors running linux operating system with coresight drivers.
>  
>  test results of gdb.btrace testsuite on ARMv8, variation unix
>  # of expected passes		595
>  # of unexpected failures	1
>  # of unsupported tests	1
> 
>  test results of gdb.btrace testsuite on ARMv8 variation native-gdbserver
>  # of expected passes		582
>  # of unexpected failures	4
>  # of unsupported tests	2
>  
>  test results of gdb.btrace testsuite  on ARMv7, variation unix
>  
>  test results of gdb.btrace testsuite on ARMv7 variation native-gdbserver
> 
>  
>  known limitations:
>  for arm v7 only
> - some registers needed for breakpoint address calculation in forwards
>   executions may be missing.
>  for arm v7 and arm v8
> - sometimes trace buffers are not flushed properly or flushed in
>   the buffer of a different thread. this was observed
>   in test scripts only.
> - sometimes, in non-stop mode, while executing "stepi n" for two threads
>   in parallel, a thread is hitting breakpoints intended for stepping
>   the other one.
>   Gdb recognizes that it is intended for the second thread,
>   but decreases the step counter. leading to a stepping less than "n"
>   times.
>  patches are:
> 
> Zied Guermazi (7):
>   configure gdb build system for supporting btrace on arm processors
>   add btrace coresight related commands
>   start/stop btrace with coresight etm and parse etm buffer. nat
>     independant
>   start/stop btrace with coresight etm and collect etm buffer on linux
>     os
>   fix issue: gdb hangs in the command following a commad returning with
>     TARGET_WAITKIND_NO_HISTORY
>   add support for coresight btrace via remote protocol
>   adapt btrace testcases for arm target
> 
>  gdb/ChangeLog                                 | 139 +++
>  gdb/Makefile.in                               |   5 +-
>  gdb/NEWS                                      |  30 +
>  gdb/aarch64-linux-nat.c                       |  68 ++
>  gdb/arch/arm.h                                |  33 +
>  gdb/arm-linux-nat.c                           |  68 ++
>  gdb/btrace.c                                  | 977 +++++++++++++++++-
>  gdb/btrace.h                                  |  16 +-
>  gdb/config.in                                 |   3 +
>  gdb/configure                                 | 545 ++++++++++
>  gdb/configure.nat                             |   4 +-
>  gdb/doc/gdb.texinfo                           | 115 ++-
>  gdb/features/btrace-conf.dtd                  |  10 +-
>  gdb/features/btrace.dtd                       |  38 +-
>  gdb/infrun.c                                  |   3 +-
>  gdb/nat/linux-btrace.c                        | 400 ++++++-
>  gdb/nat/linux-btrace.h                        |  19 +
>  gdb/record-btrace.c                           | 168 ++-
>  gdb/record.c                                  |   2 +
>  gdb/remote.c                                  |  66 +-
>  .../gdb.btrace/aarch64-instruction_history.S  |  31 +
>  .../gdb.btrace/aarch64-record_goto.S          | 400 +++++++
>  .../gdb.btrace/aarch64-tailcall-only.S        | 517 +++++++++
>  gdb/testsuite/gdb.btrace/aarch64-tailcall.S   | 409 ++++++++
>  .../gdb.btrace/arm-instruction_history.S      |  31 +
>  gdb/testsuite/gdb.btrace/arm-record_goto.S    | 433 ++++++++
>  gdb/testsuite/gdb.btrace/arm-tailcall-only.S  | 504 +++++++++
>  gdb/testsuite/gdb.btrace/arm-tailcall.S       | 391 +++++++
>  gdb/testsuite/gdb.btrace/buffer-size.exp      |  15 +-
>  gdb/testsuite/gdb.btrace/delta.exp            |  10 +
>  .../gdb.btrace/instruction_history.exp        | 107 +-
>  gdb/testsuite/gdb.btrace/non-stop.exp         |  60 +-
>  gdb/testsuite/gdb.btrace/record_goto.exp      | 241 +++--
>  gdb/testsuite/gdb.btrace/stepi.exp            |  95 +-
>  gdb/testsuite/gdb.btrace/tailcall-only.exp    |   8 +
>  gdb/testsuite/gdb.btrace/tailcall.exp         |  46 +-
>  ...on_history.S => x86-instruction_history.S} |   0
>  gdb/testsuite/lib/gdb.exp                     |   2 +-
>  gdb/top.c                                     |  10 +-
>  gdbserver/ChangeLog                           |  16 +
>  gdbserver/config.in                           |   3 +
>  gdbserver/configure                           | 545 ++++++++++
>  gdbserver/configure.srv                       |   4 +
>  gdbserver/linux-low.cc                        | 104 +-
>  gdbserver/server.cc                           |  34 +-
>  gdbsupport/ChangeLog                          |  29 +
>  gdbsupport/Makefile.in                        |   3 +
>  gdbsupport/btrace-common.cc                   |  46 +
>  gdbsupport/btrace-common.h                    | 115 ++-
>  gdbsupport/common.m4                          |  39 +
>  gdbsupport/config.in                          |   3 +
>  gdbsupport/configure                          | 545 ++++++++++
>  52 files changed, 7347 insertions(+), 158 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.btrace/aarch64-instruction_history.S
>  create mode 100644 gdb/testsuite/gdb.btrace/aarch64-record_goto.S
>  create mode 100644 gdb/testsuite/gdb.btrace/aarch64-tailcall-only.S
>  create mode 100644 gdb/testsuite/gdb.btrace/aarch64-tailcall.S
>  create mode 100644 gdb/testsuite/gdb.btrace/arm-instruction_history.S
>  create mode 100644 gdb/testsuite/gdb.btrace/arm-record_goto.S
>  create mode 100644 gdb/testsuite/gdb.btrace/arm-tailcall-only.S
>  create mode 100644 gdb/testsuite/gdb.btrace/arm-tailcall.S
>  rename gdb/testsuite/gdb.btrace/{instruction_history.S => x86-instruction_history.S} (100%)
> 

Hi Zied,

I'd like to take a quick look, but I am not able to apply your patchset,
it seems you weren't on the latest master at the time you sent it.  Do
you know which sha1 your patchset applies on?

Simon