linux-kernel - Re: [PATCH v2 2/2] perf record: Save DSO build-ID for synthesizing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 21 Sep 2022 14:50:23 +0100
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 2/2] perf record: Save DSO build-ID for synthesizing

Em Tue, Sep 20, 2022 at 03:28:22PM -0700, Namhyung Kim escreveu:
> When synthesizing MMAP2 with build-id, it'd read the same file repeatedly as
> it has no idea if it's done already.  Maintain a dsos to check that and skip
> the file access if possible.
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
> v2 change)
>  * Remove perf_event__synthesize_{start,stop} and use machine->dsos  (Adrian)

Will wait till I merge perf/urgent into perf/core so that this applies.

- Arnaldo
 
>  tools/perf/util/synthetic-events.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index 289ea17ac5f7..cccd293b5312 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -364,11 +364,14 @@ static bool read_proc_maps_line(struct io *io, __u64 *start, __u64 *end,
>  }
>  
>  static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
> +					     struct machine *machine,
>  					     bool is_kernel)
>  {
>  	struct build_id bid;
>  	struct nsinfo *nsi;
>  	struct nscookie nc;
> +	struct dso *dso = NULL;
> +	struct dso_id id;
>  	int rc;
>  
>  	if (is_kernel) {
> @@ -376,6 +379,18 @@ static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
>  		goto out;
>  	}
>  
> +	id.maj = event->maj;
> +	id.min = event->min;
> +	id.ino = event->ino;
> +	id.ino_generation = event->ino_generation;
> +
> +	dso = dsos__findnew_id(&machine->dsos, event->filename, &id);
> +	if (dso && dso->has_build_id) {
> +		bid = dso->bid;
> +		rc = 0;
> +		goto out;
> +	}
> +
>  	nsi = nsinfo__new(event->pid);
>  	nsinfo__mountns_enter(nsi, &nc);
>  
> @@ -391,12 +406,16 @@ static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
>  		event->header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
>  		event->__reserved_1 = 0;
>  		event->__reserved_2 = 0;
> +
> +		if (dso && !dso->has_build_id)
> +			dso__set_build_id(dso, &bid);
>  	} else {
>  		if (event->filename[0] == '/') {
>  			pr_debug2("Failed to read build ID for %s\n",
>  				  event->filename);
>  		}
>  	}
> +	dso__put(dso);
>  }
>  
>  int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> @@ -507,7 +526,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
>  		event->mmap2.tid = pid;
>  
>  		if (symbol_conf.buildid_mmap2)
> -			perf_record_mmap2__read_build_id(&event->mmap2, false);
> +			perf_record_mmap2__read_build_id(&event->mmap2, machine, false);
>  
>  		if (perf_tool__process_synth_event(tool, event, machine, process) != 0) {
>  			rc = -1;
> @@ -690,7 +709,7 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
>  			memcpy(event->mmap2.filename, pos->dso->long_name,
>  			       pos->dso->long_name_len + 1);
>  
> -			perf_record_mmap2__read_build_id(&event->mmap2, false);
> +			perf_record_mmap2__read_build_id(&event->mmap2, machine, false);
>  		} else {
>  			size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
>  			event->mmap.header.type = PERF_RECORD_MMAP;
> @@ -1126,7 +1145,7 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
>  		event->mmap2.len   = map->end - event->mmap.start;
>  		event->mmap2.pid   = machine->pid;
>  
> -		perf_record_mmap2__read_build_id(&event->mmap2, true);
> +		perf_record_mmap2__read_build_id(&event->mmap2, machine, true);
>  	} else {
>  		size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
>  				"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
> -- 
> 2.37.3.968.ga6b4b080e4-goog

-- 

- Arnaldo