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SubjectRe: [PATCH 27/31] perf record: Support custom vmlinux path
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> 在 2015年9月2日,上午4:21,Arnaldo Carvalho de Melo <acme@redhat.com> 写道:
>
> Em Tue, Sep 01, 2015 at 05:19:17PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Sat, Aug 29, 2015 at 04:22:01AM +0000, Wang Nan escreveu:
>>> From: He Kuang <hekuang@huawei.com>
>>>
>>> Make perf-record command support --vmlinux option if BPF_PROLOGUE is on.
>>
>> Ok, this should be supported, i.e. letting the user specify a vmlinux
>> path to use.
>>
>> But it shouldn't be _required_, i.e. we have things like vmlinux_path to
>> try to find it in well known places.
>>
>> Right now it will search for it in the process of trying to load its
>> symtab, but I think we should have a function that tries to find a
>> vmlinux that matches the build-id of the running kernel, for things that
>> want to have access directly to the ELF file with debuginfo without
>> having to load the symtab in a struct dso, etc.
>>
>> I'll look at the next patches to check how you make use of this info...
>
> So, the do it all from 'perf record' is in not yet in this patchkit,
> right? At least not in [ N/31 ] with N > 27, can you point me to it?
>

It is for patch 8/31, which create kprobe points using add_perf_probe_events().

Before this patch it won't search debug info, prevent us use argument like this:

SEC("lock_page=lock_page page->flags")

or probe at line number, expect it finds a valid vmlinux from the default path.

Thank you.

> - Arnaldo
>
>> - Arnaldo
>>
>>> 'perf record' needs vmlinux as the source of DWARF info to generate
>>> prologue for BPF programs, so path of vmlinux should be specified.
>>>
>>> Short name 'k' has been taken by 'clockid'. This patch skips the short
>>> option name and use '--vmlinux' for vmlinux path.
>>>
>>> Signed-off-by: He Kuang <hekuang@huawei.com>
>>> Signed-off-by: Wang Nan <wangnan0@huawei.com>
>>> Cc: Alexei Starovoitov <ast@plumgrid.com>
>>> Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
>>> Cc: Daniel Borkmann <daniel@iogearbox.net>
>>> Cc: David Ahern <dsahern@gmail.com>
>>> Cc: He Kuang <hekuang@huawei.com>
>>> Cc: Jiri Olsa <jolsa@kernel.org>
>>> Cc: Kaixu Xia <xiakaixu@huawei.com>
>>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>>> Cc: Namhyung Kim <namhyung@kernel.org>
>>> Cc: Paul Mackerras <paulus@samba.org>
>>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>>> Cc: Zefan Li <lizefan@huawei.com>
>>> Cc: pi3orama@163.com
>>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>>> Link: http://lkml.kernel.org/n/1436445342-1402-38-git-send-email-wangnan0@huawei.com
>>> ---
>>> tools/perf/builtin-record.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>>> index 212718c..8eb39d5 100644
>>> --- a/tools/perf/builtin-record.c
>>> +++ b/tools/perf/builtin-record.c
>>> @@ -1100,6 +1100,10 @@ struct option __record_options[] = {
>>> "clang binary to use for compiling BPF scriptlets"),
>>> OPT_STRING(0, "clang-opt", &llvm_param.clang_opt, "clang options",
>>> "options passed to clang when compiling BPF scriptlets"),
>>> +#ifdef HAVE_BPF_PROLOGUE
>>> + OPT_STRING(0, "vmlinux", &symbol_conf.vmlinux_name,
>>> + "file", "vmlinux pathname"),
>>> +#endif
>>> #endif
>>> OPT_END()
>>> };
>>> --
>>> 2.1.0



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