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SubjectRe: [PATCH v9 perf,bpf 09/15] perf, bpf: save btf information as headers to perf.data
Em Mon, Mar 11, 2019 at 10:30:45PM -0700, Song Liu escreveu:
> This patch enables perf-record to save btf information as headers to
> perf.data A new header type HEADER_BPF_BTF is introduced for this data.
>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
> tools/perf/util/header.c | 101 ++++++++++++++++++++++++++++++++++++++-
> tools/perf/util/header.h | 1 +
> 2 files changed, 101 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index a4ef8f657ad0..7decd2d1dbda 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -905,6 +905,39 @@ static int write_bpf_prog_info(struct feat_fd *ff,
> return ret;
> }
>
> +static int write_bpf_btf(struct feat_fd *ff,
> + struct perf_evlist *evlist __maybe_unused)
> +{
> + struct perf_env *env = &ff->ph->env;
> + struct rb_root *root;
> + struct rb_node *next;
> + int ret;
> +
> + down_read(&env->bpf_progs.lock);
> +
> + ret = do_write(ff, &env->bpf_progs.btfs_cnt,
> + sizeof(env->bpf_progs.btfs_cnt));
> +
> + if (ret < 0)
> + goto out;
> +
> + root = &env->bpf_progs.btfs;
> + next = rb_first(root);
> + while (next) {
> + struct btf_node *node;
> +
> + node = rb_entry(next, struct btf_node, rb_node);
> + next = rb_next(&node->rb_node);
> + ret = do_write(ff, &node->id,
> + sizeof(u32) * 2 + node->data_size);
> + if (ret < 0)
> + goto out;
> + }
> +out:
> + up_read(&env->bpf_progs.lock);
> + return ret;
> +}
> +
> static int cpu_cache_level__sort(const void *a, const void *b)
> {
> struct cpu_cache_level *cache_a = (struct cpu_cache_level *)a;
> @@ -1408,6 +1441,28 @@ static void print_bpf_prog_info(struct feat_fd *ff, FILE *fp)
> up_read(&env->bpf_progs.lock);
> }
>
> +static void print_bpf_btf(struct feat_fd *ff, FILE *fp)
> +{
> + struct perf_env *env = &ff->ph->env;
> + struct rb_root *root;
> + struct rb_node *next;
> +
> + down_read(&env->bpf_progs.lock);
> +
> + root = &env->bpf_progs.btfs;
> + next = rb_first(root);
> +
> + while (next) {
> + struct btf_node *node;
> +
> + node = rb_entry(next, struct btf_node, rb_node);
> + next = rb_next(&node->rb_node);
> + fprintf(fp, "# btf info of id %u\n", node->id);

So, I couldn't get this to work right now, and I have BPF programs that
are loaded and that have BTF info:

[root@quaco ~]# bpftool prog | tail -6
208: tracepoint name sys_enter tag 819967866022f1e1 gpl
loaded_at 2019-03-12T11:16:55-0300 uid 0
xlated 528B jited 381B memlock 4096B map_ids 107,106,105
209: tracepoint name sys_exit tag c1bd85c092d6e4aa gpl
loaded_at 2019-03-12T11:16:55-0300 uid 0
xlated 256B jited 191B memlock 4096B map_ids 107,106
[root@quaco ~]#


[root@quaco ~]# bpftool map | tail -6
105: perf_event_array name __augmented_sys flags 0x0
key 4B value 4B max_entries 8 memlock 4096B
106: array name syscalls flags 0x0
key 4B value 1B max_entries 512 memlock 8192B
107: hash name pids_filtered flags 0x0
key 4B value 1B max_entries 64 memlock 8192B
[root@quaco ~]#

[root@quaco ~]# bpftool map dump id 107
[{
"key": 8104,
"value": true
},{
"key": 18868,
"value": true
}
]
[root@quaco ~]# ps ax|egrep 8104\|18868 | grep -v grep
8104 pts/8 S+ 0:07 trace -e recvmmsg
18868 ? Ssl 21:21 /usr/libexec/gnome-terminal-server
[root@quaco ~]#

So I was expecting to see those btf lines there :-\

All the patches up to this point I have already merged and tested in my
local branch.

Will continue right after lunch to try to figure out why this BTF info
isn't landing on this new header feature...

- Arnaldo



> + }
> +
> + up_read(&env->bpf_progs.lock);
> +}
> +
> static void free_event_desc(struct perf_evsel *events)
> {
> struct perf_evsel *evsel;
> @@ -2509,6 +2564,49 @@ static int process_bpf_prog_info(struct feat_fd *ff,
> return err;
> }
>
> +static int process_bpf_btf(struct feat_fd *ff, void *data __maybe_unused)
> +{
> + struct perf_env *env = &ff->ph->env;
> + u32 count, i;
> +
> + if (ff->ph->needs_swap) {
> + pr_warning("interpreting btf from systems with endianity is not yet supported\n");
> + return 0;
> + }
> +
> + if (do_read_u32(ff, &count))
> + return -1;
> +
> + down_write(&env->bpf_progs.lock);
> +
> + for (i = 0; i < count; ++i) {
> + struct btf_node *node;
> + u32 id, data_size;
> +
> + if (do_read_u32(ff, &id))
> + return -1;
> + if (do_read_u32(ff, &data_size))
> + return -1;
> +
> + node = malloc(sizeof(struct btf_node) + data_size);
> + if (!node)
> + return -1;
> +
> + node->id = id;
> + node->data_size = data_size;
> +
> + if (__do_read(ff, node->data, data_size)) {
> + free(node);
> + return -1;
> + }
> +
> + perf_env__insert_btf(env, node);
> + }
> +
> + up_write(&env->bpf_progs.lock);
> + return 0;
> +}
> +
> struct feature_ops {
> int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
> void (*print)(struct feat_fd *ff, FILE *fp);
> @@ -2569,7 +2667,8 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
> FEAT_OPR(SAMPLE_TIME, sample_time, false),
> FEAT_OPR(MEM_TOPOLOGY, mem_topology, true),
> FEAT_OPR(CLOCKID, clockid, false),
> - FEAT_OPR(BPF_PROG_INFO, bpf_prog_info, false)
> + FEAT_OPR(BPF_PROG_INFO, bpf_prog_info, false),
> + FEAT_OPR(BPF_BTF, bpf_btf, false)
> };
>
> struct header_print_data {
> diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
> index 0785c91b4c3a..9e7d931f7c0d 100644
> --- a/tools/perf/util/header.h
> +++ b/tools/perf/util/header.h
> @@ -40,6 +40,7 @@ enum {
> HEADER_MEM_TOPOLOGY,
> HEADER_CLOCKID,
> HEADER_BPF_PROG_INFO,
> + HEADER_BPF_BTF,
> HEADER_LAST_FEATURE,
> HEADER_FEAT_BITS = 256,
> };
> --
> 2.17.1

--

- Arnaldo

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