linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jiri Olsa <jolsa@redhat.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Ingo Molnar <mingo@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Michael Petlan <mpetlan@redhat.com>,
	Song Liu <songliubraving@fb.com>, Ian Rogers <irogers@google.com>,
	Stephane Eranian <eranian@google.com>,
	Alexey Budankov <alexey.budankov@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel image
Date: Tue, 17 Nov 2020 21:45:37 +0100	[thread overview]
Message-ID: <20201117204537.GH1216482@krava> (raw)
In-Reply-To: <20201117174333.GU614220@kernel.org>

On Tue, Nov 17, 2020 at 02:43:33PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Nov 17, 2020 at 04:16:51PM +0100, Jiri Olsa escreveu:
> > On Tue, Nov 17, 2020 at 09:44:37AM -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Tue, Nov 17, 2020 at 12:00:42PM +0100, Jiri Olsa escreveu:
> > > > Allow mmap2 event to synthesize kernel image,
> > > > so we can synthesize kernel build id data in
> > > > following changes.
> > > > 
> > > > It's enabled by new symbol_conf.buildid_mmap2
> > > > bool, which will be switched in following
> > > > changes.
> > > 
> > > Why make this an option? MMAP2 goes back years:
> > > 
> > > 13d7a2410fa637f45 (Stephane Eranian         2013-08-21 12:10:24 +0200  904)      * The MMAP2 records are an augmented version of MMAP, they add
> > > 13d7a2410fa637f45 (Stephane Eranian         2013-08-21 12:10:24 +0200  905)      * maj, min, ino numbers to be used to uniquely identify each mapping
> > > 
> > > Also we unconditionally generate MMAP2 events if the kernel supports it,
> > > from evsel__config():
> > > 
> > >   attr->mmap  = track;
> > >   attr->mmap2 = track && !perf_missing_features.mmap2;
> > > 
> > > So perhaps we should reuse that logic? I.e. use mmap2 if the kernel
> > > supports it?
> > 
> > mmap2 itself is not a problem, the problem is the new
> > bit (PERF_RECORD_MISC_MMAP_BUILD_ID) that says there's
> > build id in mmap2.. older perf tool won't understand
> > that and report will crash
> 
> Is this theoretical or have you experienced it?
> 
> Would be good to tweak the perf.data reader code to not crash on unknown
> bits like that :-\
> 
> But by looking at machine__process_mmap2_event() I couldn't imagine how
> that would crash.
> 
> It would get bogus maj, min, ino, ino_generation, but probably that
> wouldn't make it crash.

right, I shouldn't said crash, sry ;-) but bogus values are worse
than that anyway

jirka


  reply	other threads:[~2020-11-17 20:46 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-17 11:00 [PATCHv2 00/24] perf: Add mmap2 build id support Jiri Olsa
2020-11-17 11:00 ` [PATCH 01/24] bpf: Move stack_map_get_build_id into lib Jiri Olsa
2020-11-17 11:00 ` [PATCH 02/24] bpf: Add size arg to build_id_parse function Jiri Olsa
2020-11-17 11:00 ` [PATCH 03/24] perf: Add build id data in mmap2 event Jiri Olsa
2020-11-17 11:13   ` Peter Zijlstra
2020-11-26 16:55     ` Jiri Olsa
2020-11-17 11:00 ` [PATCH 04/24] tools headers uapi: Sync tools/include/uapi/linux/perf_event.h Jiri Olsa
2020-11-17 11:00 ` [PATCH 05/24] perf tools: Do not swap mmap2 fields in case it contains build id Jiri Olsa
2020-11-17 11:00 ` [PATCH 06/24] perf tools: Add build_id__is_defined function Jiri Olsa
     [not found]   ` <CAP-5=fUrf9Kq3XwKALSZut3M6NXtnJCAMw0Pe2rh8_31a7tX4w@mail.gmail.com>
2020-11-17 20:53     ` Jiri Olsa
2020-11-17 23:33       ` Arnaldo Carvalho de Melo
2020-11-18  9:35         ` Jiri Olsa
2020-11-17 11:00 ` [PATCH 07/24] perf tools: Add filename__decompress function Jiri Olsa
2020-11-17 11:00 ` [PATCH 08/24] perf tools: Add support to read build id from compressed elf Jiri Olsa
2020-11-17 12:33   ` Arnaldo Carvalho de Melo
2020-11-17 11:00 ` [PATCH 09/24] perf tools: Add check for existing link in buildid dir Jiri Olsa
     [not found]   ` <CAP-5=fVc9i2EXPEqzOEHt5xrxqXiR_58KettKqrR9GJdic4sOQ@mail.gmail.com>
2020-11-18  9:11     ` Jiri Olsa
2020-11-17 11:00 ` [PATCH 10/24] perf tools: Use struct extra_kernel_map in machine__process_kernel_mmap_event Jiri Olsa
2020-11-17 11:00 ` [PATCH 11/24] perf tools: Try to load vmlinux from buildid database Jiri Olsa
2020-11-17 11:00 ` [PATCH 12/24] perf tools: Store build id from mmap2 events Jiri Olsa
2020-11-17 12:38   ` Arnaldo Carvalho de Melo
2020-11-17 14:38     ` Jiri Olsa
2020-11-17 11:00 ` [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel image Jiri Olsa
2020-11-17 12:44   ` Arnaldo Carvalho de Melo
2020-11-17 15:16     ` Jiri Olsa
2020-11-17 17:43       ` Arnaldo Carvalho de Melo
2020-11-17 20:45         ` Jiri Olsa [this message]
2020-11-17 11:00 ` [PATCH 14/24] perf tools: Allow mmap2 event to synthesize modules Jiri Olsa
2020-11-17 12:46   ` Arnaldo Carvalho de Melo
2020-11-17 11:00 ` [PATCH 15/24] perf tools: Synthesize build id for kernel/modules/tasks Jiri Olsa
2020-11-17 12:47   ` Arnaldo Carvalho de Melo
2020-11-17 11:00 ` [PATCH 16/24] perf tools: Add support to display build id for mmap2 events Jiri Olsa
2020-11-17 11:00 ` [PATCH 17/24] perf tools: Use machine__for_each_dso in perf_session__cache_build_ids Jiri Olsa
2020-11-17 11:00 ` [PATCH 18/24] perf tools: Add __perf_session__cache_build_ids function Jiri Olsa
2020-11-17 11:00 ` [PATCH 19/24] perf tools: Add is_perf_data function Jiri Olsa
2020-11-17 11:00 ` [PATCH 20/24] perf tools: Add build_id_cache__add function Jiri Olsa
2020-11-17 11:00 ` [PATCH 21/24] perf buildid-cache: Add support to add build ids from perf data Jiri Olsa
2020-11-17 12:48   ` Arnaldo Carvalho de Melo
2020-11-17 11:00 ` [PATCH 22/24] perf buildid-cache: Add --debuginfod option Jiri Olsa
2020-11-17 12:49   ` Arnaldo Carvalho de Melo
2020-11-17 11:00 ` [PATCH 23/24] perf buildid-list: Add support for mmap2's buildid events Jiri Olsa
2020-11-17 12:50   ` Arnaldo Carvalho de Melo
2020-11-17 15:21     ` Jiri Olsa
2020-11-17 17:54       ` Arnaldo Carvalho de Melo
2020-11-17 20:50         ` Jiri Olsa
2020-11-17 11:00 ` [PATCH 24/24] perf record: Add --buildid-mmap option to enable mmap's build id Jiri Olsa
  -- strict thread matches above, loose matches on Subject: below --
2020-11-09 21:53 [PATCH 00/24] perf: Add mmap2 build id support Jiri Olsa
2020-11-09 21:54 ` [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel image Jiri Olsa

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201117204537.GH1216482@krava \
    --to=jolsa@redhat.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=acme@kernel.org \
    --cc=adrian.hunter@intel.com \
    --cc=ak@linux.intel.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=alexey.budankov@linux.intel.com \
    --cc=eranian@google.com \
    --cc=irogers@google.com \
    --cc=jolsa@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@kernel.org \
    --cc=mpetlan@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=songliubraving@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).