Re: [PATCH 15/24] perf tools: Synthesize build id for kernel/modules/tasks

[Namhyung Kim <namhyung@kernel.org>]

On Mon, Nov 09, 2020 at 10:54:06PM +0100, Jiri Olsa wrote:
> Adding build id to synthesized mmap2 events for
> everything - kernel/modules/tasks.
> 
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  tools/perf/util/synthetic-events.c | 33 ++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index a18ae502d765..a9d5d1ff2cad 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -347,6 +347,32 @@ 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,
> +					     bool is_kernel)
> +{
> +	struct build_id bid;
> +	int rc;
> +
> +	if (is_kernel)
> +		rc = sysfs__read_build_id("/sys/kernel/notes", &bid);
> +	else
> +		rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1;
> +
> +	if (rc == 0) {
> +		memcpy(event->build_id, bid.data, sizeof(bid.data));
> +		event->build_id_size = (u8) bid.size;
> +	} else {
> +		if (event->filename[0] == '/') {
> +			pr_debug2("Failed to read build ID for %s\n",
> +				  event->filename);
> +		}
> +		memset(event->build_id, 0x0, sizeof(event->build_id));

Likewise, we should not set the misc bit here IMHO.

Thanks,
Namhyung


> +	}
> +	event->header.misc |= PERF_RECORD_MISC_BUILD_ID;
> +	event->__reserved_1 = 0;
> +	event->__reserved_2 = 0;
> +}
> +
>  int perf_event__synthesize_mmap_events(struct perf_tool *tool,
>  				       union perf_event *event,
>  				       pid_t pid, pid_t tgid,
> @@ -453,6 +479,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
>  		event->mmap2.pid = tgid;
>  		event->mmap2.tid = pid;
>  
> +		if (symbol_conf.buildid_mmap2)
> +			perf_record_mmap2__read_build_id(&event->mmap2, false);
> +
>  		if (perf_tool__process_synth_event(tool, event, machine, process) != 0) {
>  			rc = -1;
>  			break;
> @@ -630,6 +659,8 @@ 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);
>  		} else {
>  			size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
>  			event->mmap.header.type = PERF_RECORD_MMAP;
> @@ -1050,6 +1081,8 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
>  		event->mmap2.start = map->start;
>  		event->mmap2.len   = map->end - event->mmap.start;
>  		event->mmap2.pid   = machine->pid;
> +
> +		perf_record_mmap2__read_build_id(&event->mmap2, true);
>  	} else {
>  		size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
>  				"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
> -- 
> 2.26.2
>