Re: [PATCH v6 perf,bpf 07/15] perf, bpf: save bpf_prog_info information as headers to perf.data

Song Liu
2019-03-07T17:22:11Z

> On Mar 7, 2019, at 6:05 AM, Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Tue, Mar 05, 2019 at 11:13:51PM -0800, Song Liu wrote:
>
> SNIP
>
>> +static int process_bpf_prog_info(struct feat_fd *ff,
>> + void *data __maybe_unused)
>> +{
>> + struct bpf_prog_info_linear *info_linear;
>> + struct bpf_prog_info_node *info_node;
>> + struct perf_env *env = &ff->ph->env;
>> + u32 count, i;
>> + int err = -1;
>> +
>> + if (do_read_u32(ff, &count))
>> + return -1;
>> +
>> + if (ff->ph->needs_swap)
>> + pr_warning("interpreting bpf_prog_info from systems with endianity is not yet supported\n");
>
> return 0; ?
>
> what's here to process?
>
> jirka

Aha, I didn't notice the lseek() call in perf_file_section__process(),
so I was thinking we need to keep proper offset. With the lseek(),
this is not necessary.

I will fix it in the next version.

Thanks,
Song

>> +
>> + down_write(&env->bpf_progs.lock);
>> +
>> + for (i = 0; i < count; ++i) {
>> + u32 info_len, data_len;
>> +
>> + info_linear = NULL;
>> + info_node = NULL;
>> + if (do_read_u32(ff, &info_len))
>> + goto out;
>> + if (do_read_u32(ff, &data_len))
>> + goto out;
>> +
>> + if (info_len > sizeof(struct bpf_prog_info)) {
>> + pr_warning("detected invalid bpf_prog_info\n");
>> + goto out;
>> + }
>> +
>> + info_linear = malloc(sizeof(struct bpf_prog_info_linear) +
>> + data_len);
>> + if (!info_linear)
>> + goto out;
>> + info_linear->info_len = sizeof(struct bpf_prog_info);
>> + info_linear->data_len = data_len;
>> + if (do_read_u64(ff, (u64 *)(&info_linear->arrays)))
>> + goto out;
>> + if (__do_read(ff, &info_linear->info, info_len))
>> + goto out;
>> + if (info_len < sizeof(struct bpf_prog_info))
>> + memset(((void *)(&info_linear->info)) + info_len, 0,
>> + sizeof(struct bpf_prog_info) - info_len);
>> +
>> + if (__do_read(ff, info_linear->data, data_len))
>> + goto out;
>> +
>> + /* endian mismatch, drop the info, continue */
>> + if (ff->ph->needs_swap) {
>> + free(info_linear);
>> + continue;
>> + }
>> +
>> + info_node = malloc(sizeof(struct bpf_prog_info_node));
>> + if (!info_node)
>> + goto out;
>> +
>> + /* after reading from file, translate offset to address */
>> + bpf_program__bpil_offs_to_addr(info_linear);
>> + info_node->info_linear = info_linear;
>> + perf_env__insert_bpf_prog_info(env, info_node);
>> + }
>> +
>> + return 0;
>> +out:
>> + free(info_linear);
>> + free(info_node);
>> + up_write(&env->bpf_progs.lock);
>> + return err;
>> +}
>
> SNIP