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Message-ID: <20190116141932.GC2243@kernel.org>
Date: Wed, 16 Jan 2019 11:19:32 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Song Liu <songliubraving@...com>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
peterz@...radead.org, ast@...nel.org, daniel@...earbox.net,
kernel-team@...com, dsahern@...il.com
Subject: Re: [PATCH v9 perf, bpf-next 7/9] perf tools: synthesize
PERF_RECORD_* for loaded BPF programs
Em Tue, Jan 15, 2019 at 04:14:08PM -0800, Song Liu escreveu:
> This patch synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for
> BPF programs loaded before perf-record. This is achieved by gathering
> information about all BPF programs via sys_bpf.
>
> Signed-off-by: Song Liu <songliubraving@...com>
> ---
> tools/perf/builtin-record.c | 6 ++
> tools/perf/util/bpf-event.c | 206 ++++++++++++++++++++++++++++++++++++
> tools/perf/util/bpf-event.h | 5 +
> 3 files changed, 217 insertions(+)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index deaf9b902094..88ea11d57c6f 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -41,6 +41,7 @@
> #include "util/perf-hooks.h"
> #include "util/time-utils.h"
> #include "util/units.h"
> +#include "util/bpf-event.h"
> #include "asm/bug.h"
>
> #include <errno.h>
> @@ -1082,6 +1083,11 @@ static int record__synthesize(struct record *rec, bool tail)
> return err;
> }
>
> + err = perf_event__synthesize_bpf_events(tool, process_synthesized_event,
> + machine, opts);
> + if (err < 0)
> + pr_warning("Couldn't synthesize bpf events.\n");
> +
> err = __machine__synthesize_threads(machine, tool, &opts->target, rec->evlist->threads,
> process_synthesized_event, opts->sample_address,
> 1);
> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> index 87004706874f..4fe30ad622b8 100644
> --- a/tools/perf/util/bpf-event.c
> +++ b/tools/perf/util/bpf-event.c
> @@ -1,10 +1,24 @@
> // SPDX-License-Identifier: GPL-2.0
> #include <errno.h>
> #include <bpf/bpf.h>
> +#include <bpf/btf.h>
> +#include <linux/btf.h>
> #include "bpf-event.h"
> #include "debug.h"
> #include "symbol.h"
>
> +#define ptr_to_u64(ptr) ((__u64)(unsigned long)(ptr))
> +
> +static int snprintf_hex(char *buf, size_t size, unsigned char *data, size_t len)
> +{
> + int ret = 0;
> + size_t i;
> +
> + for (i = 0; i < len; i++)
> + ret += snprintf(buf + ret, size - ret, "%02x", data[i]);
> + return ret;
> +}
> +
> int machine__process_bpf_event(struct machine *machine __maybe_unused,
> union perf_event *event,
> struct perf_sample *sample __maybe_unused)
> @@ -13,3 +27,195 @@ int machine__process_bpf_event(struct machine *machine __maybe_unused,
> perf_event__fprintf_bpf_event(event, stdout);
> return 0;
> }
> +
> +/*
> + * Synthesize PERF_RECORD_KSYMBOL and PERF_RECORD_BPF_EVENT for one bpf
> + * program. One PERF_RECORD_BPF_EVENT is generated for the program. And
> + * one PERF_RECORD_KSYMBOL is generated for each sub program.
> + */
> +static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> + perf_event__handler_t process,
> + struct machine *machine,
> + int fd,
> + union perf_event *event,
> + struct record_opts *opts)
> +{
> + struct ksymbol_event *ksymbol_event = &event->ksymbol_event;
> + struct bpf_event *bpf_event = &event->bpf_event;
> + u32 sub_prog_cnt, i, func_info_rec_size;
> + u8 (*prog_tags)[BPF_TAG_SIZE] = NULL;
> + struct bpf_prog_info info = {};
> + u32 info_len = sizeof(info);
> + void *func_infos = NULL;
> + u64 *prog_addrs = NULL;
> + struct btf *btf = NULL;
> + u32 *prog_lens = NULL;
> + bool has_btf = false;
> + int err = 0;
> +
> + /* Call bpf_obj_get_info_by_fd() to get sizes of arrays */
> + err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
> +
> + if (err || info_len < 192 /* need field prog_tags */)
> + return -1;
perhaps:
> offsetof(bpf_prog_info, prog_tags)
Makes this clearer, i.e. the kernel needs to be providing a struct
bpf_prog_info with that field?
> +
> + /* number of ksyms, func_lengths, and tags should match */
> + sub_prog_cnt = info.nr_jited_ksyms;
> + if (sub_prog_cnt != info.nr_prog_tags ||
> + sub_prog_cnt != info.nr_jited_func_lens)
> + return -1;
> +
> + /* check BTF func info support */
> + if (info.btf_id && info.nr_func_info && info.func_info_rec_size) {
> + /* btf func info number should be same as sub_prog_cnt */
> + if (sub_prog_cnt != info.nr_func_info)
Can you ad some pr_debug() with some informative message to help with
debugging?
> + return -1;
> + if (btf__get_from_id(info.btf_id, &btf))
Ditto.
> + return -1;
> + func_info_rec_size = info.func_info_rec_size;
> + func_infos = malloc(sub_prog_cnt * func_info_rec_size);
> + if (!func_infos)
Ditto.
> + return -1;
> + has_btf = true;
> + }
> +
> + /*
> + * We need address, length, and tag for each sub program.
> + * Allocate memory and call bpf_obj_get_info_by_fd() again
> + */
> + prog_addrs = (u64 *)malloc(sizeof(u64) * sub_prog_cnt);
> + prog_lens = (u32 *)malloc(sizeof(u64) * sub_prog_cnt);
Why the casting? And also since its for N elements of a sizeof, why not
use calloc():
> + prog_tags = malloc(sizeof(u8) * BPF_TAG_SIZE * sub_prog_cnt);
> +
> + err = !prog_addrs || !prog_lens || !prog_tags;
> + if (err)
> + goto out;
> +
> + memset(&info, 0, sizeof(info));
> + info.nr_jited_ksyms = sub_prog_cnt;
> + info.nr_jited_func_lens = sub_prog_cnt;
> + info.nr_prog_tags = sub_prog_cnt;
> + info.jited_ksyms = ptr_to_u64(prog_addrs);
> + info.jited_func_lens = ptr_to_u64(prog_lens);
> + info.prog_tags = ptr_to_u64(prog_tags);
> + info_len = sizeof(info);
> + if (has_btf) {
> + info.nr_func_info = sub_prog_cnt;
> + info.func_info_rec_size = func_info_rec_size;
> + info.func_info = ptr_to_u64(func_infos);
> + }
> +
> + err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
> + if (err)
This is all new, its better to have pr_debug() stuff in here to help
debugging.
> + goto out;
> +
> + /* Synthesize PERF_RECORD_KSYMBOL */
> + for (i = 0; i < sub_prog_cnt; i++) {
> + const struct bpf_func_info *finfo;
> + const char *short_name = NULL;
> + const struct btf_type *t;
> + int name_len;
> +
> + *ksymbol_event = (struct ksymbol_event){
> + .header = {
> + .type = PERF_RECORD_KSYMBOL,
> + .size = sizeof(struct ksymbol_event),
> + },
> + .addr = prog_addrs[i],
> + .len = prog_lens[i],
> + .ksym_type = PERF_RECORD_KSYMBOL_TYPE_BPF,
> + .flags = 0,
> + };
> + name_len = snprintf(ksymbol_event->name, KSYM_NAME_LEN,
> + "bpf_prog_");
> + name_len += snprintf_hex(ksymbol_event->name + name_len,
> + KSYM_NAME_LEN - name_len,
> + prog_tags[i], BPF_TAG_SIZE);
> + if (has_btf) {
> + finfo = func_infos + i * info.func_info_rec_size;
> + t = btf__type_by_id(btf, finfo->type_id);
> + short_name = btf__name_by_offset(btf, t->name_off);
> + } else if (i == 0 && sub_prog_cnt == 1) {
> + /* no subprog */
> + if (info.name[0])
> + short_name = info.name;
> + } else
> + short_name = "F";
> + if (short_name)
> + name_len += snprintf(ksymbol_event->name + name_len,
> + KSYM_NAME_LEN - name_len,
> + "_%s", short_name);
> +
> + ksymbol_event->header.size += PERF_ALIGN(name_len + 1,
> + sizeof(u64));
> + err = perf_tool__process_synth_event(tool, event,
> + machine, process);
> + }
> +
> + /* Synthesize PERF_RECORD_BPF_EVENT */
> + if (opts->bpf_event) {
> + *bpf_event = (struct bpf_event){
> + .header = {
> + .type = PERF_RECORD_BPF_EVENT,
> + .size = sizeof(struct bpf_event),
> + },
> + .type = PERF_BPF_EVENT_PROG_LOAD,
> + .flags = 0,
> + .id = info.id,
> + };
> + memcpy(bpf_event->tag, prog_tags[i], BPF_TAG_SIZE);
> + err = perf_tool__process_synth_event(tool, event,
> + machine, process);
> + }
> +
> +out:
> + free(prog_tags);
> + free(prog_lens);
> + free(prog_addrs);
> + free(func_infos);
> + free(btf);
> + return err ? -1 : 0;
> +}
> +
> +int perf_event__synthesize_bpf_events(struct perf_tool *tool,
> + perf_event__handler_t process,
> + struct machine *machine,
> + struct record_opts *opts)
> +{
> + union perf_event *event;
> + __u32 id = 0;
> + int err;
> + int fd;
> +
> + event = malloc(sizeof(event->bpf_event) + KSYM_NAME_LEN);
> + if (!event)
> + return -1;
> + while (true) {
> + err = bpf_prog_get_next_id(id, &id);
> + if (err) {
> + if (errno == ENOENT) {
> + err = 0;
> + break;
> + }
> + pr_err("can't get next program: %s%s",
> + strerror(errno),
> + errno == EINVAL ? " -- kernel too old?" : "");
> + /* don't report error on old kernel */
> + err = (errno == EINVAL) ? 0 : -1;
> + break;
> + }
> + fd = bpf_prog_get_fd_by_id(id);
> + if (fd < 0) {
> + pr_debug("Failed to get fd for prog_id %u\n", id);
> + continue;
> + }
> +
> + err = perf_event__synthesize_one_bpf_prog(
> + tool, process, machine, fd, event, opts);
first parameter on the same line of the function call, please.
> + close(fd);
> + if (err)
> + break;
> + }
> + free(event);
> + return err;
> +}
> diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
> index d5ca355dd298..38aee4040f12 100644
> --- a/tools/perf/util/bpf-event.h
> +++ b/tools/perf/util/bpf-event.h
> @@ -8,4 +8,9 @@ int machine__process_bpf_event(struct machine *machine,
> union perf_event *event,
> struct perf_sample *sample);
>
> +int perf_event__synthesize_bpf_events(struct perf_tool *tool,
> + perf_event__handler_t process,
> + struct machine *machine,
> + struct record_opts *opts);
> +
> #endif
> --
> 2.17.1
--
- Arnaldo
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