linux-kernel - Re: [PATCH 1/2] perf script: Make it possible to see perf's kernel and module memory mappings

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Message-ID: <4983cc09-20ad-450b-8eba-219f75a5fab2@intel.com>
Date: Mon, 5 Feb 2024 09:08:46 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
 Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
 Ian Rogers <irogers@...gle.com>, Like Xu <like.xu.linux@...il.com>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 linux-perf-users <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH 1/2] perf script: Make it possible to see perf's kernel
 and module memory mappings

On 3/02/24 03:56, Arnaldo Carvalho de Melo wrote:
> 
> 
> On Fri, Feb 2, 2024, 10:50 PM Namhyung Kim <namhyung@...nel.org <mailto:namhyung@...nel.org>> wrote:
> 
>     On Fri, Feb 2, 2024 at 3:01 AM Adrian Hunter <adrian.hunter@...el.com <mailto:adrian.hunter@...el.com>> wrote:
>     >
>     > Dump kmaps if verbose > 2.
> 
>     Maybe we can add '--debug kmap' option rather than using an
>     arbitrary verbose level.

That is a global option but would only work for tools that are
explicitly programmed to do the dump.  Could just do perf script
and perf report?

> 
> 
> I think we have 'perf report --mmap', no?

Only shows user space maps.  Could add 'perf report --kmaps'?

> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/Documentation/perf-report.txt#n542 <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/Documentation/perf-report.txt#n542>
> 
> - Arnaldo
> 
> Sent from smartphone
> 
> 
>     Thanks,
>     Namhyung
> 
>     >
>     > Example:
>     >
>     >   $ perf script -vvv 2>&1 >/dev/null | grep kvm.intel
>     >   build id event received for /lib/modules/6.7.2-local/kernel/arch/x86/kvm/kvm-intel.ko: 0691d75e10e72ebbbd45a44c59f6d00a5604badf [20]
>     >   Map: 0-3a3 4f5d8 [kvm_intel].modinfo
>     >   Map: 0-5240 5f280 [kvm_intel]__versions
>     >   Map: 0-30 64 [kvm_intel].note.Linux
>     >   Map: 0-14 644c0 [kvm_intel].orc_header
>     >   Map: 0-5297 43680 [kvm_intel].rodata
>     >   Map: 0-5bee 3b837 [kvm_intel].text.unlikely
>     >   Map: 0-7e0 41430 [kvm_intel].noinstr.text
>     >   Map: 0-2080 713c0 [kvm_intel].bss
>     >   Map: 0-26 705c8 [kvm_intel].data..read_mostly
>     >   Map: 0-5888 6a4c0 [kvm_intel].data
>     >   Map: 0-22 70220 [kvm_intel].data.once
>     >   Map: 0-40 705f0 [kvm_intel].data..percpu
>     >   Map: 0-1685 41d20 [kvm_intel].init.text
>     >   Map: 0-4b8 6fd60 [kvm_intel].init.data
>     >   Map: 0-380 70248 [kvm_intel]__dyndbg
>     >   Map: 0-8 70218 [kvm_intel].exit.data
>     >   Map: 0-438 4f980 [kvm_intel]__param
>     >   Map: 0-5f5 4ca0f [kvm_intel].rodata.str1.1
>     >   Map: 0-3657 493b8 [kvm_intel].rodata.str1.8
>     >   Map: 0-e0 70640 [kvm_intel].data..ro_after_init
>     >   Map: 0-500 70ec0 [kvm_intel].gnu.linkonce.this_module
>     >   Map: ffffffffc13a7000-ffffffffc1421000 a0 /lib/modules/6.7.2-local/kernel/arch/x86/kvm/kvm-intel.ko
>     >
>     > The example above shows how the module section mappings are all wrong
>     > except for the main .text mapping at 0xffffffffc13a7000.
>     >
>     > Signed-off-by: Adrian Hunter <adrian.hunter@...el.com <mailto:adrian.hunter@...el.com>>
>     > ---
>     >  tools/perf/builtin-script.c | 13 +++++++++++++
>     >  1 file changed, 13 insertions(+)
>     >
>     > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
>     > index b1f57401ff23..e764b319ef59 100644
>     > --- a/tools/perf/builtin-script.c
>     > +++ b/tools/perf/builtin-script.c
>     > @@ -3806,6 +3806,16 @@ static int parse_callret_trace(const struct option *opt __maybe_unused,
>     >         return 0;
>     >  }
>     >
>     > +static void dump_kmaps(struct perf_session *session)
>     > +{
>     > +       int save_verbose = verbose;
>     > +
>     > +       pr_debug("Kernel and module maps:\n");
>     > +       verbose = 0; /* Suppress verbose to print a summary only */
>     > +       maps__fprintf(machine__kernel_maps(&session->machines.host), stderr);
>     > +       verbose = save_verbose;
>     > +}
>     > +
>     >  int cmd_script(int argc, const char **argv)
>     >  {
>     >         bool show_full_info = false;
>     > @@ -4366,6 +4376,9 @@ int cmd_script(int argc, const char **argv)
>     >
>     >         flush_scripting();
>     >
>     > +       if (verbose > 2)
>     > +               dump_kmaps(session);
>     > +
>     >  out_delete:
>     >         if (script.ptime_range) {
>     >                 itrace_synth_opts__clear_time_range(&itrace_synth_opts);
>     > --
>     > 2.34.1
>     >
>