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Message-ID: <20201117124437.GO614220@kernel.org>
Date: Tue, 17 Nov 2020 09:44:37 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Jiri Olsa <jolsa@...nel.org>
Cc: lkml <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Namhyung Kim <namhyung@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Michael Petlan <mpetlan@...hat.com>,
Song Liu <songliubraving@...com>,
Ian Rogers <irogers@...gle.com>,
Stephane Eranian <eranian@...gle.com>,
Alexey Budankov <alexey.budankov@...ux.intel.com>,
Andi Kleen <ak@...ux.intel.com>,
Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel
image
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?
- Arnaldo
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
> tools/perf/util/symbol_conf.h | 3 ++-
> tools/perf/util/synthetic-events.c | 40 ++++++++++++++++++++----------
> 2 files changed, 29 insertions(+), 14 deletions(-)
>
> diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
> index b916afb95ec5..b18f9c8dbb75 100644
> --- a/tools/perf/util/symbol_conf.h
> +++ b/tools/perf/util/symbol_conf.h
> @@ -42,7 +42,8 @@ struct symbol_conf {
> report_block,
> report_individual_block,
> inline_name,
> - disable_add2line_warn;
> + disable_add2line_warn,
> + buildid_mmap2;
> const char *vmlinux_name,
> *kallsyms_name,
> *source_prefix,
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index 8a23391558cf..872df6d6dbef 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -988,11 +988,12 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
> perf_event__handler_t process,
> struct machine *machine)
> {
> - size_t size;
> + union perf_event *event;
> + size_t size = symbol_conf.buildid_mmap2 ?
> + sizeof(event->mmap2) : sizeof(event->mmap);
> struct map *map = machine__kernel_map(machine);
> struct kmap *kmap;
> int err;
> - union perf_event *event;
>
> if (map == NULL)
> return -1;
> @@ -1006,7 +1007,7 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
> * available use this, and after it is use this as a fallback for older
> * kernels.
> */
> - event = zalloc((sizeof(event->mmap) + machine->id_hdr_size));
> + event = zalloc(size + machine->id_hdr_size);
> if (event == NULL) {
> pr_debug("Not enough memory synthesizing mmap event "
> "for kernel modules\n");
> @@ -1023,16 +1024,29 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
> event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
> }
>
> - size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
> - "%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
> - size = PERF_ALIGN(size, sizeof(u64));
> - event->mmap.header.type = PERF_RECORD_MMAP;
> - event->mmap.header.size = (sizeof(event->mmap) -
> - (sizeof(event->mmap.filename) - size) + machine->id_hdr_size);
> - event->mmap.pgoff = kmap->ref_reloc_sym->addr;
> - event->mmap.start = map->start;
> - event->mmap.len = map->end - event->mmap.start;
> - event->mmap.pid = machine->pid;
> + if (symbol_conf.buildid_mmap2) {
> + size = snprintf(event->mmap2.filename, sizeof(event->mmap2.filename),
> + "%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
> + size = PERF_ALIGN(size, sizeof(u64));
> + event->mmap2.header.type = PERF_RECORD_MMAP2;
> + event->mmap2.header.size = (sizeof(event->mmap2) -
> + (sizeof(event->mmap2.filename) - size) + machine->id_hdr_size);
> + event->mmap2.pgoff = kmap->ref_reloc_sym->addr;
> + event->mmap2.start = map->start;
> + event->mmap2.len = map->end - event->mmap.start;
> + event->mmap2.pid = machine->pid;
> + } else {
> + size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
> + "%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
> + size = PERF_ALIGN(size, sizeof(u64));
> + event->mmap.header.type = PERF_RECORD_MMAP;
> + event->mmap.header.size = (sizeof(event->mmap) -
> + (sizeof(event->mmap.filename) - size) + machine->id_hdr_size);
> + event->mmap.pgoff = kmap->ref_reloc_sym->addr;
> + event->mmap.start = map->start;
> + event->mmap.len = map->end - event->mmap.start;
> + event->mmap.pid = machine->pid;
> + }
>
> err = perf_tool__process_synth_event(tool, event, machine, process);
> free(event);
> --
> 2.26.2
>
--
- Arnaldo
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