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

[Namhyung Kim]

On Sun, Feb 4, 2024 at 11:08 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> On 3/02/24 03:56, Arnaldo Carvalho de Melo wrote:
> >
> >
> > On Fri, Feb 2, 2024, 10:50 PM Namhyung Kim <namhyung@xxxxxxxxxx <mailto:namhyung@xxxxxxxxxx>> wrote:
> >
> >     On Fri, Feb 2, 2024 at 3:01 AM Adrian Hunter <adrian.hunter@xxxxxxxxx <mailto:adrian.hunter@xxxxxxxxx>> 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 don't care.. actually `--debug perf-event-open` would work with
commands that call the syscall only.  But I'm fine either way.

>
> >
> >
> > I think we have 'perf report --mmap', no?
>
> Only shows user space maps.  Could add 'perf report --kmaps'?

That'd work too.  It's up to you.

Thanks,
Namhyung


>
> >
> > 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@xxxxxxxxx <mailto:adrian.hunter@xxxxxxxxx>>
> >     > ---
> >     >  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
> >     >
> >
>