[patch v6 00/12] branch tracing support for Atom

markus.t.metzger
2012-12-17T16:02:15Z

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

This version is identical to v5 except that pointers are now explicitly checked
for == NULL and != NULL and that I moved the disable_btrace call from
free_thread to clear_thread_inferior_resources.

I will add documentation shortly.

Is the patch series OK to commit?

Here's an overview of the feature:

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. I do expect some discussion around the commands and their
exact spelling and would therefore postpone documentation.

- "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 (11):
thread, btrace: add generic branch trace support
cli, btrace: add btrace cli
linux, btrace: perf_event based branch tracing
linux, i386, amd64: enable btrace for 32bit and 64bit linux native
xml, btrace: define btrace xml document style
remote, btrace: add branch trace remote ops
btrace, doc: document remote serial protocol
gdbserver, btrace: add generic btrace support
gdbserver, linux, btrace: add btrace support for linux-low
test, btrace: add branch tracing tests
btrace, x86: disable on some processors

gdb/Makefile.in | 13 +-
gdb/amd64-linux-nat.c | 42 +
gdb/btrace.c | 863 ++++++++++++++++++++++
gdb/btrace.h | 86 +++
gdb/command.h | 2 +-
gdb/common/btrace-common.h | 62 ++
gdb/common/linux-btrace.c | 468 ++++++++++++
gdb/common/linux-btrace.h | 76 ++
gdb/config/i386/linux.mh | 3 +-
gdb/config/i386/linux64.mh | 2 +-
gdb/doc/gdb.texinfo | 125 ++++
gdb/features/btrace.dtd | 12 +
gdb/gdbserver/Makefile.in | 7 +-
gdb/gdbserver/config.in | 3 +
gdb/gdbserver/configure | 6 +
gdb/gdbserver/configure.ac | 5 +
gdb/gdbserver/configure.srv | 6 +-
gdb/gdbserver/gdbthread.h | 5 +
gdb/gdbserver/inferiors.c | 3 +
gdb/gdbserver/linux-low.c | 57 ++
gdb/gdbserver/server.c | 175 +++++
gdb/gdbserver/target.h | 33 +
gdb/gdbthread.h | 4 +
gdb/i386-linux-nat.c | 42 +
gdb/infcmd.c | 2 +
gdb/remote.c | 171 +++++
gdb/target.c | 69 ++
gdb/target.h | 39 +-
gdb/testsuite/Makefile.in | 3 +-
gdb/testsuite/configure | 3 +-
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 | 23 +
gdb/testsuite/gdb.btrace/allthreads_trace.exp | 345 +++++++++
gdb/testsuite/gdb.btrace/amd64-thr-callback.S | 116 +++
gdb/testsuite/gdb.btrace/b.S | 23 +
gdb/testsuite/gdb.btrace/dec.c | 23 +
gdb/testsuite/gdb.btrace/decrement.S | 32 +
gdb/testsuite/gdb.btrace/decrement.exp | 141 ++++
gdb/testsuite/gdb.btrace/disable_all.exp | 279 +++++++
gdb/testsuite/gdb.btrace/enable.exp | 89 +++
gdb/testsuite/gdb.btrace/enable_all.exp | 282 +++++++
gdb/testsuite/gdb.btrace/enable_range.exp | 281 +++++++
gdb/testsuite/gdb.btrace/i386-thr-callback.S | 116 +++
gdb/testsuite/gdb.btrace/inc.c | 23 +
gdb/testsuite/gdb.btrace/list.exp | 175 +++++
gdb/testsuite/gdb.btrace/list_function.c | 31 +
gdb/testsuite/gdb.btrace/list_function.exp | 50 ++
gdb/testsuite/gdb.btrace/list_options.exp | 107 +++
gdb/testsuite/gdb.btrace/main.S | 36 +
gdb/testsuite/gdb.btrace/main_asm.exp | 109 +++
gdb/testsuite/gdb.btrace/main_segv.S | 32 +
gdb/testsuite/gdb.btrace/main_segv.exp | 84 +++
gdb/testsuite/gdb.btrace/threads.c | 96 +++
gdb/testsuite/gdb.btrace/threads_asm.c | 78 ++
gdb/testsuite/gdb.btrace/threads_auto.exp | 123 +++
gdb/testsuite/gdb.btrace/threads_independent.exp | 125 ++++
gdb/testsuite/gdb.btrace/threads_nonstop.exp | 231 ++++++
gdb/testsuite/gdb.btrace/trace_iteration.exp | 265 +++++++
gdb/testsuite/gdb.btrace/x86-list.S | 70 ++
gdb/testsuite/lib/btrace.exp | 78 ++
gdb/thread.c | 3 +
63 files changed, 5856 insertions(+), 15 deletions(-)
create mode 100644 gdb/btrace.c
create mode 100644 gdb/btrace.h
create mode 100644 gdb/common/btrace-common.h
create mode 100644 gdb/common/linux-btrace.c
create mode 100644 gdb/common/linux-btrace.h
create mode 100644 gdb/features/btrace.dtd
mode change 100644 => 100755 gdb/remote.c
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/amd64-thr-callback.S
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.S
create mode 100755 gdb/testsuite/gdb.btrace/decrement.exp
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 100755 gdb/testsuite/gdb.btrace/i386-thr-callback.S
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_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.S
create mode 100755 gdb/testsuite/gdb.btrace/main_segv.exp
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/gdb.btrace/x86-list.S
create mode 100644 gdb/testsuite/lib/btrace.exp

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1.7.6.5