Re: [PATCH v4] perf inject: Add a command line option to specify build ids.

From: Namhyung Kim
Date: Tue Aug 16 2022 - 03:56:56 EST


Hello,

On Mon, Aug 15, 2022 at 3:59 PM Raul Silvera <rsilvera@xxxxxxxxxx> wrote:
>
> This commit adds the option --known-build-ids to perf inject.
> It allows the user to explicitly specify the build id for a given
> path, instead of retrieving it from the current system. This is
> useful in cases where a perf.data file is processed on a different
> system from where it was collected, or if some of the binaries are
> no longer available.
>
> The build ids and paths are specified in pairs in the command line.
> Using the file:// specifier, build ids can be loaded from a file
> directly generated by perf buildid-list. This is convenient to copy
> build ids from one perf.data file to another.
>
> ** Example: In this example we use perf record to create two
> perf.data files, one with build ids and another without, and use
> perf buildid-list and perf inject to copy the build ids from the
> first file to the second.
>
> $ perf record ls /tmp
> $ perf record --no-buildid -o perf.data.no-buildid ls /tmp
> $ perf buildid-list > build-ids.txt
> $ perf inject -b --known-build-ids='file://build-ids.txt' \
> -i perf.data.no-buildid -o perf.data.buildid
>
> Signed-off-by: Raul Silvera <rsilvera@xxxxxxxxxx>

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Thanks,
Namhyung


> ---
>
> V3 -> V4: Perform upfront validation of build ids
> V2 -> V3: Added documentation and removed unnecessary temps
> V1 -> V2: Cleaned up patch description, deleted the strlist during
> cleanup, and updated validation of the build id strings
>
> tools/perf/Documentation/perf-inject.txt | 7 +-
> tools/perf/builtin-inject.c | 85 ++++++++++++++++++++++++
> 2 files changed, 91 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/Documentation/perf-inject.txt b/tools/perf/Documentation/perf-inject.txt
> index ffc293fdf61d..70e2ac3cc91a 100644
> --- a/tools/perf/Documentation/perf-inject.txt
> +++ b/tools/perf/Documentation/perf-inject.txt
> @@ -27,9 +27,14 @@ OPTIONS
> --build-ids::
> Inject build-ids into the output stream
>
> ---buildid-all:
> +--buildid-all::
> Inject build-ids of all DSOs into the output stream
>
> +--known-build-ids=::
> + Override build-ids to inject using these comma-separated pairs of
> + build-id and path. Understands file://filename to read these pairs
> + from a file, which can be generated with perf buildid-list.
> +
> -v::
> --verbose::
> Be more verbose.
> diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
> index 2a0f992ca0be..8ec955402488 100644
> --- a/tools/perf/builtin-inject.c
> +++ b/tools/perf/builtin-inject.c
> @@ -21,6 +21,7 @@
> #include "util/data.h"
> #include "util/auxtrace.h"
> #include "util/jit.h"
> +#include "util/string2.h"
> #include "util/symbol.h"
> #include "util/synthetic-events.h"
> #include "util/thread.h"
> @@ -38,6 +39,7 @@
> #include <linux/string.h>
> #include <linux/zalloc.h>
> #include <linux/hash.h>
> +#include <ctype.h>
> #include <errno.h>
> #include <signal.h>
> #include <inttypes.h>
> @@ -123,6 +125,7 @@ struct perf_inject {
> char event_copy[PERF_SAMPLE_MAX_SIZE];
> struct perf_file_section secs[HEADER_FEAT_BITS];
> struct guest_session guest_session;
> + struct strlist *known_build_ids;
> };
>
> struct event_entry {
> @@ -634,9 +637,73 @@ static int dso__read_build_id(struct dso *dso)
> return dso->has_build_id ? 0 : -1;
> }
>
> +static struct strlist *perf_inject__parse_known_build_ids(
> + const char *known_build_ids_string)
> +{
> + struct str_node *pos, *tmp;
> + struct strlist *known_build_ids;
> + int bid_len;
> +
> + known_build_ids = strlist__new(known_build_ids_string, NULL);
> + if (known_build_ids == NULL)
> + return NULL;
> + strlist__for_each_entry_safe(pos, tmp, known_build_ids) {
> + const char *build_id, *dso_name;
> +
> + build_id = skip_spaces(pos->s);
> + dso_name = strchr(build_id, ' ');
> + if (dso_name == NULL) {
> + strlist__remove(known_build_ids, pos);
> + continue;
> + }
> + bid_len = dso_name - pos->s;
> + dso_name = skip_spaces(dso_name);
> + if (bid_len % 2 != 0 || bid_len >= SBUILD_ID_SIZE) {
> + strlist__remove(known_build_ids, pos);
> + continue;
> + }
> + for (int ix = 0; 2 * ix + 1 < bid_len; ++ix) {
> + if (!isxdigit(build_id[2 * ix]) ||
> + !isxdigit(build_id[2 * ix + 1])) {
> + strlist__remove(known_build_ids, pos);
> + break;
> + }
> + }
> + }
> + return known_build_ids;
> +}
> +
> +static bool perf_inject__lookup_known_build_id(struct perf_inject *inject,
> + struct dso *dso)
> +{
> + struct str_node *pos;
> + int bid_len;
> +
> + strlist__for_each_entry(pos, inject->known_build_ids) {
> + const char *build_id, *dso_name;
> +
> + build_id = skip_spaces(pos->s);
> + dso_name = strchr(build_id, ' ');
> + bid_len = dso_name - pos->s;
> + dso_name = skip_spaces(dso_name);
> + if (strcmp(dso->long_name, dso_name))
> + continue;
> + for (int ix = 0; 2 * ix + 1 < bid_len; ++ix) {
> + dso->bid.data[ix] = (hex(build_id[2 * ix]) << 4 |
> + hex(build_id[2 * ix + 1]));
> + }
> + dso->bid.size = bid_len / 2;
> + dso->has_build_id = 1;
> + return true;
> + }
> + return false;
> +}
> +
> static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
> struct machine *machine, u8 cpumode, u32 flags)
> {
> + struct perf_inject *inject = container_of(tool, struct perf_inject,
> + tool);
> int err;
>
> if (is_anon_memory(dso->long_name) || flags & MAP_HUGETLB)
> @@ -644,6 +711,10 @@ static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
> if (is_no_dso_memory(dso->long_name))
> return 0;
>
> + if (inject->known_build_ids != NULL &&
> + perf_inject__lookup_known_build_id(inject, dso))
> + return 1;
> +
> if (dso__read_build_id(dso) < 0) {
> pr_debug("no build_id found for %s\n", dso->long_name);
> return -1;
> @@ -2112,12 +2183,16 @@ int cmd_inject(int argc, const char **argv)
> };
> int ret;
> bool repipe = true;
> + const char *known_build_ids = NULL;
>
> struct option options[] = {
> OPT_BOOLEAN('b', "build-ids", &inject.build_ids,
> "Inject build-ids into the output stream"),
> OPT_BOOLEAN(0, "buildid-all", &inject.build_id_all,
> "Inject build-ids of all DSOs into the output stream"),
> + OPT_STRING(0, "known-build-ids", &known_build_ids,
> + "buildid path [,buildid path...]",
> + "build-ids to use for given paths"),
> OPT_STRING('i', "input", &inject.input_name, "file",
> "input file name"),
> OPT_STRING('o', "output", &inject.output.path, "file",
> @@ -2257,6 +2332,15 @@ int cmd_inject(int argc, const char **argv)
> */
> inject.tool.ordered_events = true;
> inject.tool.ordering_requires_timestamps = true;
> + if (known_build_ids != NULL) {
> + inject.known_build_ids =
> + perf_inject__parse_known_build_ids(known_build_ids);
> +
> + if (inject.known_build_ids == NULL) {
> + pr_err("Couldn't parse known build ids.\n");
> + goto out_delete;
> + }
> + }
> }
>
> if (inject.sched_stat) {
> @@ -2285,6 +2369,7 @@ int cmd_inject(int argc, const char **argv)
> guest_session__exit(&inject.guest_session);
>
> out_delete:
> + strlist__delete(inject.known_build_ids);
> zstd_fini(&(inject.session->zstd_data));
> perf_session__delete(inject.session);
> out_close_output:
> --
> 2.37.1.595.g718a3a8f04-goog
>