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

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Date: Fri, 2 Feb 2024 17:50:20 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
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@...r.kernel.org, 
	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 Fri, Feb 2, 2024 at 3:01 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> Dump kmaps if verbose > 2.

Maybe we can add '--debug kmap' option rather than using an
arbitrary verbose level.

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>
> ---
>  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
>