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Subject[PATCH 34/44] perf annotate: Introduce --ignore-vmlinux command line option
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

This is already present in 'perf top', albeit undocumented (will fix),
and is useful to use /proc/kcore instead of vmlinux and then get what is
really in place, not what the kernel starts with, before alternatives,
ftrace .text patching, etc, see the differences:

# perf annotate --stdio2 _raw_spin_lock_irqsave
_raw_spin_lock_irqsave() /lib/modules/4.16.0-rc4/build/vmlinux
Event: anon group { cycles, instructions }

0.00 3.17 → callq __fentry__
0.00 7.94 push %rbx
7.69 36.51 → callq __page_file_index
mov %rax,%rbx
7.69 3.17 → callq *ffffffff82225cd0
xor %eax,%eax
mov $0x1,%edx
80.77 49.21 lock cmpxchg %edx,(%rdi)
test %eax,%eax
↓ jne 2b
3.85 0.00 mov %rbx,%rax
pop %rbx
← retq
2b: mov %eax,%esi
→ callq queued_spin_lock_slowpath
mov %rbx,%rax
pop %rbx
← retq
[root@jouet ~]# perf annotate --ignore-vmlinux --stdio2 _raw_spin_lock_irqsave
_raw_spin_lock_irqsave() /proc/kcore
Event: anon group { cycles, instructions }

0.00 3.17 nop
0.00 7.94 push %rbx
0.00 23.81 pushfq
7.69 12.70 pop %rax
nop
mov %rax,%rbx
7.69 3.17 cli
nop
xor %eax,%eax
mov $0x1,%edx
80.77 49.21 lock cmpxchg %edx,(%rdi)
test %eax,%eax
↓ jne 2b
3.85 0.00 mov %rbx,%rax
pop %rbx
← retq
2b: mov %eax,%esi
→ callq *ffffffff820e96b0
mov %rbx,%rax
pop %rbx
← retq
#

Diff of the output of those commands:

# perf annotate --stdio2 _raw_spin_lock_irqsave > /tmp/vmlinux
# perf annotate --ignore-vmlinux --stdio2 _raw_spin_lock_irqsave > /tmp/kcore
# diff -y /tmp/vmlinux /tmp/kcore
_raw_spin_lock_irqsave() vmlinux | _raw_spin_lock_irqsave() /proc/kcore
Event: anon group { cycles, instructions } Event: anon group { cycles, instructions }

0.00 3.17 → callq __fentry__ | 0.00 3.17 nop
0.00 7.94 push %rbx 0.00 7.94 push %rbx
7.69 36.51 → callq __page_file_index | 0.00 23.81 pushfq
> 7.69 12.70 pop %rax
> nop
mov %rax,%rbx mov %rax,%rbx
7.69 3.17 → callq *ffffffff82225cd0 | 7.69 3.17 cli
> nop
xor %eax,%eax xor %eax,%eax
mov $0x1,%edx mov $0x1,%edx
80.77 49.21 lock cmpxchg %edx,(%rdi) 80.77 49.21 lock cmpxchg %edx,(%rdi)
test %eax,%eax test %eax,%eax
↓ jne 2b ↓ jne 2b
3.85 0.00 mov %rbx,%rax 3.85 0.00 mov %rbx,%rax
pop %rbx pop %rbx
← retq ← retq
2b: mov %eax,%esi 2b: mov %eax,%esi
→ callq queued_spin_lock_slowpath| → callq *ffffffff820e96b0
mov %rbx,%rax mov %rbx,%rax
pop %rbx pop %rbx
← retq ← retq
#

This should be further streamlined by doing both annotations and
allowing the TUI to toggle initial/current, and show the patched
instructions in a slightly different color.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-wz8d269hxkcwaczr0r4rhyjg@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-annotate.txt | 3 +++
tools/perf/builtin-annotate.c | 2 ++
2 files changed, 5 insertions(+)

diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
index c29c7fc93023..749cc6055dac 100644
--- a/tools/perf/Documentation/perf-annotate.txt
+++ b/tools/perf/Documentation/perf-annotate.txt
@@ -55,6 +55,9 @@ OPTIONS
--vmlinux=<file>::
vmlinux pathname.

+--ignore-vmlinux::
+ Ignore vmlinux files.
+
-m::
--modules::
Load module symbols. WARNING: use only with -k and LIVE kernel.
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index fd5aac3fd949..51709a961496 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -496,6 +496,8 @@ int cmd_annotate(int argc, const char **argv)
OPT_BOOLEAN(0, "tui", &annotate.use_tui, "Use the TUI interface"),
OPT_BOOLEAN(0, "stdio", &annotate.use_stdio, "Use the stdio interface"),
OPT_BOOLEAN(0, "stdio2", &annotate.use_stdio2, "Use the stdio interface"),
+ OPT_BOOLEAN(0, "ignore-vmlinux", &symbol_conf.ignore_vmlinux,
+ "don't load vmlinux even if found"),
OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
"file", "vmlinux pathname"),
OPT_BOOLEAN('m', "modules", &symbol_conf.use_modules,
--
2.14.3
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