Re: [PATCH 22/25] perf buildid-cache: Add support to add build ids from perf data

Arnaldo Carvalho de Melo
2020-11-26T17:57:12Z

Em Thu, Nov 26, 2020 at 06:00:23PM +0100, Jiri Olsa escreveu:
> Adding support to specify perf data file as -a option file
> argument,
>
> If the file is detected to be perf data file, it is processed
> and all dso objects with sample hit are stored to the build
> id cache.

Would be interesting if the steps to have that debuginfod server running
at that 192.168.122.174:8002 URL were spelled out here, for
completeness.

- Arnaldo

> $ DEBUGINFOD_URLS=http://192.168.122.174:8002 perf buildid-cache -a perf.data
> OK 5dcec522abf136fcfd3128f47e131f2365834dd7 /home/jolsa/.debug/.build-id/5d/cec522abf136fcfd3128f47e131f2365834dd7/elf
> OK 5784f813b727a50cfd3363234aef9fcbab685cc4 /lib/modules/5.10.0-rc2speed+/kernel/fs/xfs/xfs.ko
>
> By default we store only dso with hits, but it's possible to
> specify 'all' to store all dso objects, like:
> -a perf.data,all
>
> $ DEBUGINFOD_URLS=http://192.168.122.174:8002 perf buildid-cache -a perf.data,all
> OK 5dcec522abf136fcfd3128f47e131f2365834dd7 /home/jolsa/.debug/.build-id/5d/cec522abf136fcfd3128f47e131f2365834dd7/elf
> OK 6ce92dc7c31f12fe5b7775a2bb8b14a3546ce2cd /lib/modules/5.10.0-rc2speed+/kernel/drivers/firmware/qemu_fw_cfg.ko
> OK bf3f6d32dccc159f841fc3658c241d0e74c61fbb /lib/modules/5.10.0-rc2speed+/kernel/drivers/block/virtio_blk.ko
> OK e896b4329cf9f190f1a0fae933f425ff8f71b052 /lib/modules/5.10.0-rc2speed+/kernel/drivers/char/virtio_console.ko
> OK 5bedc933cb59e053ecb472f327bd73c548364479 /lib/modules/5.10.0-rc2speed+/kernel/drivers/input/serio/serio_raw.ko
> OK cecc506368a8b7a473a5f900d26f0d3d914a9c23 /lib/modules/5.10.0-rc2speed+/kernel/arch/x86/crypto/crc32c-intel.ko
> OK 91076fb3646d061a0a42cf7bddb339a665ee4f80 /lib/modules/5.10.0-rc2speed+/kernel/arch/x86/crypto/ghash-clmulni-intel.ko
> OK 4e2a304d788bb8e2e950bc82a5944e042afa0bf2 /lib/modules/5.10.0-rc2speed+/kernel/drivers/media/cec/core/cec.ko
> OK 31ab0da5ad81e6803280177f507a95f3053d585e /lib/modules/5.10.0-rc2speed+/kernel/lib/libcrc32c.ko
> OK f6154bca47c149f48c942fcc3d653041dd285c65 /lib/modules/5.10.0-rc2speed+/kernel/drivers/gpu/drm/ttm/ttm.ko
> OK 723f5852de81590d54b23b38c160d3618b41951b /lib/modules/5.10.0-rc2speed+/kernel/arch/x86/crypto/crct10dif-pclmul.ko
> OK 06b1eab7f141cbc3e5a5db47909c8ab5cb242e40 /lib/modules/5.10.0-rc2speed+/kernel/drivers/gpu/drm/drm_ttm_helper.ko
> OK 38292b862cf3ff87489508fdb4895efa45780813 /lib/modules/5.10.0-rc2speed+/kernel/drivers/gpu/drm/qxl/qxl.ko
> OK cdf51e58609bf2ce4837a7b195e0ccae0a930907 /lib/modules/5.10.0-rc2speed+/kernel/arch/x86/crypto/crc32-pclmul.ko
> OK 5ca8958388f6688452ecc2cb83d6031394c659ad /lib/modules/5.10.0-rc2speed+/kernel/drivers/gpu/drm/drm.ko
> OK 236bc4e4f38bf3559007566cb32b3dcc1bc28d2d /lib/modules/5.10.0-rc2speed+/kernel/drivers/gpu/drm/drm_kms_helper.ko
> OK 5784f813b727a50cfd3363234aef9fcbab685cc4 /lib/modules/5.10.0-rc2speed+/kernel/fs/xfs/xfs.ko
> OK 66db2be3efaa43bb5a5c481986e9554e1885cc69 /usr/lib/systemd/systemd
> OK 7db607d9f2de89860d9639712da64c8bacd31e4b /usr/lib64/libm-2.30.so
> OK 55b5f9652e1d17c1dd58f62628d5063428e5db91 /usr/lib64/libudev.so.1.6.15
> OK 63b97070bf097130713bb6c89cf7100b5f3c9b17 /usr/lib64/libunistring.so.2.1.0
> ...
>
> Once perf data is specified, no other file can be specified in
> the option, otherwise it causes syntax error.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> .../perf/Documentation/perf-buildid-cache.txt | 12 +-
> tools/perf/builtin-buildid-cache.c | 213 +++++++++++++++++-
> tools/perf/util/probe-event.c | 6 +-
> 3 files changed, 225 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-buildid-cache.txt b/tools/perf/Documentation/perf-buildid-cache.txt
> index f6de0952ff3c..b77da5138bca 100644
> --- a/tools/perf/Documentation/perf-buildid-cache.txt
> +++ b/tools/perf/Documentation/perf-buildid-cache.txt
> @@ -23,7 +23,17 @@ OPTIONS
> -------
> -a::
> --add=::
> - Add specified file to the cache.
> + Add specified file or perf.data binaries to the cache.
> +
> + If the file is detected to be perf data file, it is processed
> + and all dso objects with sample hit are stored to the cache.
> +
> + It's possible to specify 'all' to store all dso objects, like:
> + -a perf.data,all
> +
> + Once perf data is specified, no other file can be specified in
> + the option, otherwise it causes syntax error.
> +
> -f::
> --force::
> Don't complain, do it.
> diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
> index a25411926e48..f0afb2c89e03 100644
> --- a/tools/perf/builtin-buildid-cache.c
> +++ b/tools/perf/builtin-buildid-cache.c
> @@ -29,6 +29,11 @@
> #include "util/probe-file.h"
> #include <linux/string.h>
> #include <linux/err.h>
> +#include <linux/zalloc.h>
> +#include <sys/stat.h>
> +#ifdef HAVE_DEBUGINFOD_SUPPORT
> +#include <elfutils/debuginfod.h>
> +#endif
>
> static int build_id_cache__kcore_buildid(const char *proc_dir, char *sbuildid)
> {
> @@ -348,6 +353,203 @@ static int build_id_cache__show_all(void)
> return 0;
> }
>
> +#ifdef HAVE_DEBUGINFOD_SUPPORT
> +static int call_debuginfod(const char *sbuild_id, char **path, bool debuginfo)
> +{
> + debuginfod_client *c;
> + int fd;
> +
> + c = debuginfod_begin();
> + if (c == NULL)
> + return -1;
> +
> + pr_debug("trying debuginfod for executable <%s> ... ", sbuild_id);
> +
> + if (debuginfo) {
> + fd = debuginfod_find_debuginfo(c, (const unsigned char *) sbuild_id,
> + 0, path);
> + } else {
> + fd = debuginfod_find_executable(c, (const unsigned char *) sbuild_id,
> + 0, path);
> + }
> + if (fd >= 0)
> + close(fd); /* retaining reference by realname */
> +
> + debuginfod_end(c);
> + pr_debug("%s%s\n", *path ? "OK " : "FAILED", *path ? *path : "");
> + return *path ? 0 : -1;
> +}
> +#else
> +static int call_debuginfod(const char *sbuild_id __maybe_unused,
> + char **path __maybe_unused,
> + bool debuginfo __maybe_unused)
> +{
> + return -1;
> +}
> +#endif
> +
> +struct dso_store_data {
> + bool hits;
> +};
> +
> +static int dso_store(struct dso *dso, struct machine *machine, void *priv)
> +{
> + struct dso_store_data *data = priv;
> + char sbuild_id[SBUILD_ID_SIZE];
> + struct build_id bid;
> + char *path = NULL, *link = NULL;
> + bool is_kallsyms;
> + int err = -1;
> +
> + /*
> + * There's no build id in dso, nothing to do..
> + */
> + if (!dso->has_build_id || !build_id__is_defined(&dso->bid))
> + return 0;
> +
> + if (data->hits && !dso->hit)
> + return 0;
> +
> + /*
> + * The storing process is:
> + * - get build id of the dso
> + * - check if it is already in cache
> + * - check if it matches provided build id from mmap2 event
> + * - if not, try debuginfod to download the binary
> + * - store binary to build id database
> + */
> + is_kallsyms = !strcmp(machine->mmap_name, dso->short_name);
> + build_id__sprintf(&dso->bid, sbuild_id);
> +
> + link = build_id_cache__linkname(sbuild_id, NULL, 0);
> + if (!link)
> + return -ENOMEM;
> +
> + if (!access(link, X_OK)) {
> + pr_debug("already in cache - %s <%s>\n", dso->long_name, sbuild_id);
> + err = 0;
> + goto out;
> + }
> +
> + path = strdup(dso->long_name);
> + if (!path)
> + goto out;
> +
> + if (is_kallsyms) {
> + /*
> + * Find out if we are on the same kernel as perf.data
> + * and store kallsyms in that case.
> + */
> + err = sysfs__read_build_id("/sys/kernel/notes", &bid);
> + if (err < 0)
> + goto out;
> + } else {
> + struct nscookie nsc;
> + struct stat st;
> +
> + nsinfo__mountns_enter(dso->nsinfo, &nsc);
> +
> + /*
> + * Does the file exists in the first place, if it does,
> + * resolve path and read the build id.
> + */
> + if (stat(dso->long_name, &st)) {
> + nsinfo__mountns_exit(&nsc);
> + zfree(&path);
> + goto try_download;
> + }
> +
> + err = filename__read_build_id(dso->long_name, &bid);
> + nsinfo__mountns_exit(&nsc);
> +
> + if (err <= 0)
> + goto out;
> + }
> +
> + /*
> + * If we match, then what we want in mmap2 event
> + * is what we got in the binary,
> + */
> + if (bid.size != dso->bid.size || memcmp(&bid, &dso->bid, bid.size)) {
> + char sbid[SBUILD_ID_SIZE];
> +
> + build_id__sprintf(&bid, sbid);
> + pr_debug("mmap build id <%s> does not match for %s <%s>\n",
> + sbuild_id, path, sbid);
> + zfree(&path);
> + }
> +
> +try_download:
> + /*
> + * We did not match build id or did not find the
> + * binary - try debuginfod as last resort.
> + */
> + if (!path) {
> + bool debuginfo;
> + char *tmp = NULL;
> +
> + /*
> + * The debuginfo retrieval for standard binaries
> + * is handled within build_id_cache__add function.
> + *
> + * For kernel and kernel modules we have to ask
> + * for debuginfo directly, because debuginfod
> + * does not treat them as binaries.
> + */
> + debuginfo = is_kallsyms ||
> + is_kernel_module(dso->long_name, PERF_RECORD_MISC_CPUMODE_UNKNOWN);
> +
> + if (call_debuginfod(sbuild_id, &tmp, debuginfo)) {
> + err = -1;
> + goto out;
> + }
> +
> + path = tmp;
> +
> + /*
> + * The kernel dso is now elf binary, so disable is_kallsyms
> + * so build_id_cache__add can prepare proper file names.
> + */
> + is_kallsyms = false;
> + }
> +
> + pr_debug("linking %s %s <%s>\n", dso->short_name, path, sbuild_id);
> +
> + err = build_id_cache__add(sbuild_id, path, path,
> + dso->nsinfo, is_kallsyms, false);
> +out:
> + free(path);
> + fprintf(stderr, "%s %s %s\n", err ? "FAIL" : "OK ", sbuild_id, dso->long_name);
> + return 0;
> +}
> +
> +static int
> +build_id_cache__add_perf_data(const char *path, bool all)
> +{
> + struct perf_session *session;
> + struct dso_store_data priv = {
> + .hits = !all,
> + };
> + struct perf_data data = {
> + .path = path,
> + .mode = PERF_DATA_MODE_READ,
> + };
> + int err;
> +
> + session = perf_session__new(&data, false, &build_id__mark_dso_hit_ops);
> + if (IS_ERR(session))
> + return PTR_ERR(session);
> +
> + err = perf_session__process_events(session);
> + if (err)
> + goto out;
> +
> + err = __perf_session__cache_build_ids(session, dso_store, &priv);
> +out:
> + perf_session__delete(session);
> + return err;
> +}
> +
> int cmd_buildid_cache(int argc, const char **argv)
> {
> struct strlist *list;
> @@ -440,7 +642,15 @@ int cmd_buildid_cache(int argc, const char **argv)
> list = strlist__new(add_name_list_str, NULL);
> if (list) {
> strlist__for_each_entry(pos, list)
> - if (build_id_cache__add_file(pos->s, nsi)) {
> + if (is_perf_data(pos->s)) {
> + struct str_node *all_pos = strlist__next(pos);
> + bool all = !strcmp("all", all_pos ? all_pos->s : "");
> +
> + if (build_id_cache__add_perf_data(pos->s, all))
> + pr_warning("Couldn't add build ids from %s\n", pos->s);
> + if (all)
> + pos = all_pos;
> + } else if (build_id_cache__add_file(pos->s, nsi)) {
> if (errno == EEXIST) {
> pr_debug("%s already in the cache\n",
> pos->s);
> @@ -449,7 +659,6 @@ int cmd_buildid_cache(int argc, const char **argv)
> pr_warning("Couldn't add %s: %s\n",
> pos->s, str_error_r(errno, sbuf, sizeof(sbuf)));
> }
> -
> strlist__delete(list);
> }
> }
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 8eae2afff71a..e821bb977c9b 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1616,9 +1616,9 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> return -EINVAL;
> }
>
> - pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
> - pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
> - pp->lazy_line);
> + pr_debug2("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
> + pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
> + pp->lazy_line);
> return 0;
> }
>
> --
> 2.26.2
>

--

- Arnaldo