netdev - Re: [PATCH perf 3/3] tools/perf: recognize and process RECORD

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Date:   Fri, 21 Sep 2018 15:57:57 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        Peter Zijlstra <peterz@...radead.org>, acme@...nel.org,
        Networking <netdev@...r.kernel.org>, kernel-team@...com
Subject: Re: [PATCH perf 3/3] tools/perf: recognize and process RECORD_MMAP
 events for bpf progs

On Wed, Sep 19, 2018 at 3:51 PM Alexei Starovoitov <ast@...nel.org> wrote:
>
> Recognize JITed bpf prog load/unload events.
> Add/remove kernel symbols accordingly.
>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Acked-by: Song Liu <songliubraving@...com>

> ---
>  tools/perf/util/machine.c | 27 +++++++++++++++++++++++++++
>  tools/perf/util/symbol.c  | 13 +++++++++++++
>  tools/perf/util/symbol.h  |  1 +
>  3 files changed, 41 insertions(+)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index c4acd2001db0..ae4f8a0fdc7e 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -25,6 +25,7 @@
>  #include "sane_ctype.h"
>  #include <symbol/kallsyms.h>
>  #include <linux/mman.h>
> +#include <linux/magic.h>
>
>  static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock);
>
> @@ -1460,6 +1461,32 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
>         enum dso_kernel_type kernel_type;
>         bool is_kernel_mmap;
>
> +       /* process JITed bpf programs load/unload events */
> +       if (event->mmap.pid == ~0u && event->mmap.tid == BPF_FS_MAGIC) {
> +               struct symbol *sym;
> +               u64 ip;
> +
> +               map = map_groups__find(&machine->kmaps, event->mmap.start);
> +               if (!map) {
> +                       pr_err("No kernel map for IP %lx\n", event->mmap.start);
> +                       goto out_problem;
> +               }
> +               ip = event->mmap.start - map->start + map->pgoff;
> +               if (event->mmap.filename[0]) {
> +                       sym = symbol__new(ip, event->mmap.len, 0, 0,
> +                                         event->mmap.filename);
> +                       dso__insert_symbol(map->dso, sym);
> +               } else {
> +                       if (symbols__erase(&map->dso->symbols, ip)) {
> +                               pr_err("No bpf prog at IP %lx/%lx\n",
> +                                      event->mmap.start, ip);
> +                               goto out_problem;
> +                       }
> +                       dso__reset_find_symbol_cache(map->dso);
> +               }
> +               return 0;
> +       }
> +
>         /* If we have maps from kcore then we do not need or want any others */
>         if (machine__uses_kcore(machine))
>                 return 0;
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index d188b7588152..0653f313661d 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -353,6 +353,19 @@ static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
>         return NULL;
>  }
>
> +int symbols__erase(struct rb_root *symbols, u64 ip)
> +{
> +       struct symbol *s;
> +
> +       s = symbols__find(symbols, ip);
> +       if (!s)
> +               return -ENOENT;
> +
> +       rb_erase(&s->rb_node, symbols);
> +       symbol__delete(s);
> +       return 0;
> +}
> +
>  static struct symbol *symbols__first(struct rb_root *symbols)
>  {
>         struct rb_node *n = rb_first(symbols);
> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> index f25fae4b5743..92ef31953d9a 100644
> --- a/tools/perf/util/symbol.h
> +++ b/tools/perf/util/symbol.h
> @@ -310,6 +310,7 @@ char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name);
>
>  void __symbols__insert(struct rb_root *symbols, struct symbol *sym, bool kernel);
>  void symbols__insert(struct rb_root *symbols, struct symbol *sym);
> +int symbols__erase(struct rb_root *symbols, u64 ip);
>  void symbols__fixup_duplicate(struct rb_root *symbols);
>  void symbols__fixup_end(struct rb_root *symbols);
>  void map_groups__fixup_end(struct map_groups *mg);
> --
> 2.17.1
>