Re: [PATCH 00/16] branch tracing support

[Hui Zhu <teawater at gmail dot com>]

Hi Markus,

Thanks for your work.  I think this function is very interesting.

But I didn't find the patch for the doc in your patches list.   I
suggest you add it.

PS, do you have any data about  how much speed decrease when btrace enable.

Thanks,
Hui

On Thu, May 10, 2012 at 11:13 PM,  <markus.t.metzger@intel.com> wrote:
> 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
>