[PATCH 00/16] branch tracing support

[markus dot t dot metzger at intel dot com]

From: Markus Metzger <markus.t.metzger@intel.com>

IA hardware offers a feature called Branch Trace Store (BTS) that stores a log
of branches into an OS provided ring buffer.

Linux supports this feature since 2.6.32 as part of the perf_event interface.

Branch tracing is very useful to debug problems that do not immediatly result in
a crash. It is particularly useful for bugs that make other debugger features
fail, e.g. a corrupted stack that breaks unwinding.

In comparison with reverse debugging, branch tracing is less powerful but
faster. In addition, the list view (see below) provides a quick overview of
where you are, comparable with the backtrace command.

This series adds commands to enable/disable branch tracing as well as to display
the recorded trace:

  - "btrace enable/disable" perform the obvious operation

    They accept an optional range argument specifying the range of threads to
    enable/disable branch tracing for. If no argument is given, they target the
    current thread.

    They further accept the following arguments:

      all    targets all threads
      auto   turns automatic enabling for new threads on/off

  - "btrace list" prints the blocks that have been traced; one line per block.

    The output may be configured using modifiers (default: /fl). It prints:
         the block number
      /a the begin and end code address of that block
      /f the function containing the block
      /l the source lines contained in the block

    It accepts an optional range argument specifying the range of blocks to be
    listed. If no argument is given, all blocks are listed.

    Blocks are ordered from newest to oldest; block 1 always contains the
    current location.

      (gdb) btrace list 24-34
      24     in stdio_file_flush () at ../../../git/gdb/ui-file.c:525-529
      25     in ui_file_data () at ../../../git/gdb/ui-file.c:175-180
      26     in stdio_file_flush () at ../../../git/gdb/ui-file.c:522-523
      27     in gdb_flush () at ../../../git/gdb/ui-file.c:185
      28     in gdb_wait_for_event () at ../../../git/gdb/event-loop.c:840-847
      29     in gdb_do_one_event () at ../../../git/gdb/event-loop.c:461
      30     in gdb_do_one_event () at ../../../git/gdb/event-loop.c:453
      31     in process_event () at ../../../git/gdb/event-loop.c:407
      32     in process_event () at ../../../git/gdb/event-loop.c:361-367
      33     in process_event () at ../../../git/gdb/event-loop.c:1041-1043
      34     in process_event () at ../../../git/gdb/event-loop.c:1041-1045

  - "btrace" prints the branch trace disassembly

    Branch trace is printed block-by-block. Typically, one block at a time is
    printed. Repeated commands will iterate over all blocks similar to the list
    command.

    It supports the /m and /r modifiers accepted by the disassemble command.

    It accepts an optional range argument specifying the range of blocks to be
    printed. If more than one block is given, blocks are printed in reverse
    order to preserve the original control flow.

      (gdb) btrace /m 25
      ../../../git/gdb/ui-file.c:175	{
         0x0000000000635410 <ui_file_data+0>:	sub    $0x8,%rsp
      
      ../../../git/gdb/ui-file.c:176	  if (file->magic != &ui_file_magic)
         0x0000000000635414 <ui_file_data+4>:	cmpq   $0xb33b94,(%rdi)
         0x000000000063541b <ui_file_data+11>:	jne    0x635426 <ui_file_data+22>
      
      ../../../git/gdb/ui-file.c:177	    internal_error (__FILE__, __LINE__,
         0x000000000063541d <ui_file_data+13>:	mov    0x50(%rdi),%rax
      
      ../../../git/gdb/ui-file.c:178			    _("ui_file_data: bad magic number"));
      ../../../git/gdb/ui-file.c:179	  return file->to_data;
      ../../../git/gdb/ui-file.c:180	}
         0x0000000000635421 <ui_file_data+17>:	add    $0x8,%rsp
         0x0000000000635425 <ui_file_data+21>:	retq   

    Mixed source and disassembly does not work very well for inlined functions,
    a problem that it shares with the disassemble command.

Barkha Ahuja (1):
  test, btrace: more branch tracing tests

Markus Metzger (15):
  disas: add precise instructions flag
  source: add flags to print_source_lines ()
  source, disasm: optionally prefix source lines with filename
  thread, btrace: add generic branch trace support
  cli, btrace: add btrace cli
  configure: add check for perf_event header
  configure: autoreconf
  linux, btrace: perf_event based branch tracing
  btrace, linux: add linux native btrace target ops
  btrace, config: enable btrace for 32bit and 64bit linux native
  test, btrace: add branch trace tests
  xml, btrace: define btrace xml document style
  remote, btrace: add branch trace remote ops
  gdbserver, btrace: add generic btrace support
  gdbserver, linux, btrace: add btrace support for linux-low

 .gitignore                                       |    2 +
 gdb/Makefile.in                                  |   14 +-
 gdb/amd64-linux-nat.c                            |    2 +
 gdb/btrace.c                                     |  939 ++++++++++++++++++++++
 gdb/btrace.h                                     |   92 +++
 gdb/command.h                                    |    2 +-
 gdb/common/linux-btrace.c                        |  368 +++++++++
 gdb/common/linux-btrace.h                        |   76 ++
 gdb/config.in                                    |    3 +
 gdb/config/i386/linux.mh                         |    3 +-
 gdb/config/i386/linux64.mh                       |    2 +-
 gdb/configure                                    |   13 +
 gdb/configure.ac                                 |    2 +
 gdb/disasm.c                                     |   40 +-
 gdb/disasm.h                                     |    8 +-
 gdb/features/btrace.dtd                          |   12 +
 gdb/gdbserver/Makefile.in                        |    6 +-
 gdb/gdbserver/config.in                          |    3 +
 gdb/gdbserver/configure                          |    2 +-
 gdb/gdbserver/configure.ac                       |    2 +-
 gdb/gdbserver/configure.srv                      |   34 +-
 gdb/gdbserver/gdbthread.h                        |    5 +
 gdb/gdbserver/inferiors.c                        |    3 +
 gdb/gdbserver/linux-low.c                        |   42 +
 gdb/gdbserver/server.c                           |  171 ++++
 gdb/gdbserver/target.h                           |   38 +
 gdb/gdbthread.h                                  |    4 +
 gdb/i386-linux-nat.c                             |    2 +
 gdb/infcmd.c                                     |    2 +
 gdb/linux-nat-btrace.c                           |   86 ++
 gdb/linux-nat-btrace.h                           |   28 +
 gdb/remote.c                                     |  208 +++++
 gdb/source.c                                     |   19 +-
 gdb/symtab.h                                     |    6 +
 gdb/target.c                                     |   20 +
 gdb/target.h                                     |   36 +-
 gdb/testsuite/configure.ac                       |    2 +-
 gdb/testsuite/gdb.base/page.exp                  |    3 +-
 gdb/testsuite/gdb.btrace/Makefile.in             |   13 +
 gdb/testsuite/gdb.btrace/a.s                     |   24 +
 gdb/testsuite/gdb.btrace/allthreads_trace.exp    |  270 +++++++
 gdb/testsuite/gdb.btrace/b.s                     |   23 +
 gdb/testsuite/gdb.btrace/dec.c                   |    4 +
 gdb/testsuite/gdb.btrace/decrement.exp           |  140 ++++
 gdb/testsuite/gdb.btrace/decrement.s             |   32 +
 gdb/testsuite/gdb.btrace/disable_all.exp         |  198 +++++
 gdb/testsuite/gdb.btrace/enable.exp              |   83 ++
 gdb/testsuite/gdb.btrace/enable_all.exp          |  201 +++++
 gdb/testsuite/gdb.btrace/enable_range.exp        |  198 +++++
 gdb/testsuite/gdb.btrace/inc.c                   |    4 +
 gdb/testsuite/gdb.btrace/list.exp                |  169 ++++
 gdb/testsuite/gdb.btrace/list.s                  |   68 ++
 gdb/testsuite/gdb.btrace/list_function.c         |   12 +
 gdb/testsuite/gdb.btrace/list_function.exp       |   59 ++
 gdb/testsuite/gdb.btrace/list_options.exp        |  107 +++
 gdb/testsuite/gdb.btrace/main.s                  |   32 +
 gdb/testsuite/gdb.btrace/main_asm.exp            |  113 +++
 gdb/testsuite/gdb.btrace/main_segv.exp           |   84 ++
 gdb/testsuite/gdb.btrace/main_segv.s             |   28 +
 gdb/testsuite/gdb.btrace/sanity_crash.exp        |   69 ++
 gdb/testsuite/gdb.btrace/sanity_crash.s          |   52 ++
 gdb/testsuite/gdb.btrace/thr_callback_32.s       |  116 +++
 gdb/testsuite/gdb.btrace/thr_callback_64.s       |  116 +++
 gdb/testsuite/gdb.btrace/threads.c               |   96 +++
 gdb/testsuite/gdb.btrace/threads_asm.c           |   78 ++
 gdb/testsuite/gdb.btrace/threads_auto.exp        |  113 +++
 gdb/testsuite/gdb.btrace/threads_independent.exp |  119 +++
 gdb/testsuite/gdb.btrace/threads_nonstop.exp     |  182 +++++
 gdb/testsuite/gdb.btrace/trace_iteration.exp     |  264 ++++++
 gdb/testsuite/lib/btrace.exp                     |   72 ++
 gdb/thread.c                                     |    3 +
 71 files changed, 5393 insertions(+), 49 deletions(-)
 create mode 100644 gdb/btrace.c
 create mode 100644 gdb/btrace.h
 create mode 100644 gdb/common/linux-btrace.c
 create mode 100644 gdb/common/linux-btrace.h
 create mode 100644 gdb/features/btrace.dtd
 create mode 100644 gdb/linux-nat-btrace.c
 create mode 100644 gdb/linux-nat-btrace.h
 create mode 100755 gdb/testsuite/gdb.btrace/Makefile.in
 create mode 100755 gdb/testsuite/gdb.btrace/a.s
 create mode 100755 gdb/testsuite/gdb.btrace/allthreads_trace.exp
 create mode 100755 gdb/testsuite/gdb.btrace/b.s
 create mode 100644 gdb/testsuite/gdb.btrace/dec.c
 create mode 100755 gdb/testsuite/gdb.btrace/decrement.exp
 create mode 100755 gdb/testsuite/gdb.btrace/decrement.s
 create mode 100755 gdb/testsuite/gdb.btrace/disable_all.exp
 create mode 100644 gdb/testsuite/gdb.btrace/enable.exp
 create mode 100755 gdb/testsuite/gdb.btrace/enable_all.exp
 create mode 100755 gdb/testsuite/gdb.btrace/enable_range.exp
 create mode 100644 gdb/testsuite/gdb.btrace/inc.c
 create mode 100644 gdb/testsuite/gdb.btrace/list.exp
 create mode 100644 gdb/testsuite/gdb.btrace/list.s
 create mode 100644 gdb/testsuite/gdb.btrace/list_function.c
 create mode 100644 gdb/testsuite/gdb.btrace/list_function.exp
 create mode 100755 gdb/testsuite/gdb.btrace/list_options.exp
 create mode 100755 gdb/testsuite/gdb.btrace/main.s
 create mode 100755 gdb/testsuite/gdb.btrace/main_asm.exp
 create mode 100755 gdb/testsuite/gdb.btrace/main_segv.exp
 create mode 100755 gdb/testsuite/gdb.btrace/main_segv.s
 create mode 100755 gdb/testsuite/gdb.btrace/sanity_crash.exp
 create mode 100755 gdb/testsuite/gdb.btrace/sanity_crash.s
 create mode 100755 gdb/testsuite/gdb.btrace/thr_callback_32.s
 create mode 100755 gdb/testsuite/gdb.btrace/thr_callback_64.s
 create mode 100755 gdb/testsuite/gdb.btrace/threads.c
 create mode 100755 gdb/testsuite/gdb.btrace/threads_asm.c
 create mode 100755 gdb/testsuite/gdb.btrace/threads_auto.exp
 create mode 100755 gdb/testsuite/gdb.btrace/threads_independent.exp
 create mode 100755 gdb/testsuite/gdb.btrace/threads_nonstop.exp
 create mode 100755 gdb/testsuite/gdb.btrace/trace_iteration.exp
 create mode 100644 gdb/testsuite/lib/btrace.exp