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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Wed, 25 Nov 2020 22:29:11 +0900
Message-ID: <CAM9d7ciNd7FuscyB1x884uQKVXyRexQD60fTei3AUP3RLN_BaA@mail.gmail.com>
Subject: Re: [PATCH 22/25] perf buildid-cache: Add support to add build ids
 from perf data
To:     Jiri Olsa <jolsa@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Michael Petlan <mpetlan@redhat.com>,
        Song Liu <songliubraving@fb.com>,
        Ian Rogers <irogers@google.com>,
        Stephane Eranian <eranian@google.com>,
        Alexey Budankov <alexey.budankov@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>
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On Tue, Nov 24, 2020 at 8:06 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> 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.
>
>   $ 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            | 215 +++++++++++++++++-
>  tools/perf/util/probe-event.c                 |   6 +-
>  3 files changed, 227 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..0bfb54ee1e5e 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 +353,205 @@ 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;
> +       bool     force_download;

Where is it set?

Thanks,
Namhyung


> +};
> +
> +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 (!data->force_download && !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;
> +}