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Date: Wed, 13 Mar 2019 18:00:30 -0300
From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To: Song Liu <songliubraving@...com>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
kernel-team@...com, peterz@...radead.org, acme@...hat.com,
jolsa@...nel.org, namhyung@...nel.org, sdf@...ichev.me
Subject: Re: [PATCH v9 perf,bpf 04/15] perf, bpf: synthesize bpf events with
bpf_program__get_prog_info_linear()
Em Mon, Mar 11, 2019 at 10:30:40PM -0700, Song Liu escreveu:
> With bpf_program__get_prog_info_linear, we can simplify the logic that
> synthesizes bpf events.
>
> This patch doesn't change the behavior of the code.
>
> Signed-off-by: Song Liu <songliubraving@...com>
> ---
> tools/perf/util/bpf-event.c | 118 ++++++++++++------------------------
> 1 file changed, 40 insertions(+), 78 deletions(-)
>
> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> index ea012b735a37..e9d9854be506 100644
> --- a/tools/perf/util/bpf-event.c
> +++ b/tools/perf/util/bpf-event.c
> @@ -3,7 +3,9 @@
> #include <stdlib.h>
> #include <bpf/bpf.h>
> #include <bpf/btf.h>
> +#include <bpf/libbpf.h>
> #include <linux/btf.h>
> +#include <linux/err.h>
> #include "bpf-event.h"
> #include "debug.h"
> #include "symbol.h"
> @@ -49,99 +51,62 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> {
> 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 = 0;
> - u8 (*prog_tags)[BPF_TAG_SIZE] = NULL;
> - struct bpf_prog_info info = { .type = 0, };
> - u32 info_len = sizeof(info);
> - void *func_infos = NULL;
> - u64 *prog_addrs = NULL;
> + struct bpf_prog_info_linear *info_linear;
> + struct bpf_prog_info *info;
> struct btf *btf = NULL;
> - u32 *prog_lens = NULL;
> bool has_btf = false;
> - char errbuf[512];
> + u32 sub_prog_cnt, i;
> int err = 0;
> + u64 arrays;
>
> - /* Call bpf_obj_get_info_by_fd() to get sizes of arrays */
> - err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
> + arrays = 1UL << BPF_PROG_INFO_JITED_KSYMS;
> + arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
> + arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
> + arrays |= 1UL << BPF_PROG_INFO_PROG_TAGS;
>
> - if (err) {
> - pr_debug("%s: failed to get BPF program info: %s, aborting\n",
> - __func__, str_error_r(errno, errbuf, sizeof(errbuf)));
> + info_linear = bpf_program__get_prog_info_linear(fd, arrays);
> + if (IS_ERR_OR_NULL(info_linear)) {
> + info_linear = NULL;
> + pr_debug("%s: failed to get BPF program info. aborting\n", __func__);
> return -1;
> }
> - if (info_len < offsetof(struct bpf_prog_info, prog_tags)) {
> +
> + if (info_linear->info_len < offsetof(struct bpf_prog_info, prog_tags)) {
> pr_debug("%s: the kernel is too old, aborting\n", __func__);
> return -2;
> }
>
> + info = &info_linear->info;
> +
> /* 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)
> + 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) {
> + 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) {
> + if (sub_prog_cnt != info->nr_func_info) {
> pr_debug("%s: mismatch in BPF sub program count and BTF function info count, aborting\n", __func__);
> - return -1;
> - }
> - if (btf__get_from_id(info.btf_id, &btf)) {
> - pr_debug("%s: failed to get BTF of id %u, aborting\n", __func__, info.btf_id);
> - return -1;
> + err = -1;
> + goto out;
> }
> - func_info_rec_size = info.func_info_rec_size;
> - func_infos = calloc(sub_prog_cnt, func_info_rec_size);
> - if (!func_infos) {
> - pr_debug("%s: failed to allocate memory for func_infos, aborting\n", __func__);
> - return -1;
> + if (btf__get_from_id(info->btf_id, &btf)) {
> + pr_debug("%s: failed to get BTF of id %u, aborting\n", __func__, info->btf_id);
> + err = -1;
> + btf = NULL;
> + goto out;
> }
> 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 = calloc(sub_prog_cnt, sizeof(u64));
> - if (!prog_addrs) {
> - pr_debug("%s: failed to allocate memory for prog_addrs, aborting\n", __func__);
> - goto out;
> - }
> - prog_lens = calloc(sub_prog_cnt, sizeof(u32));
> - if (!prog_lens) {
> - pr_debug("%s: failed to allocate memory for prog_lens, aborting\n", __func__);
> - goto out;
> - }
> - prog_tags = calloc(sub_prog_cnt, BPF_TAG_SIZE);
> - if (!prog_tags) {
> - pr_debug("%s: failed to allocate memory for prog_tags, aborting\n", __func__);
> - 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) {
> - pr_debug("%s: failed to get BPF program info, aborting\n", __func__);
> - goto out;
> - }
> -
> /* Synthesize PERF_RECORD_KSYMBOL */
> for (i = 0; i < sub_prog_cnt; i++) {
> + u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
Need this:
- u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
+ u8 (*prog_tags)[BPF_TAG_SIZE] = (u8 *)(info->prog_tags);
To overcome this on debian:experimental-x-mips, i.e. Debian Experimental
cross building to MIPS 32-bit:
util/bpf-event.c: In function 'perf_event__synthesize_one_bpf_prog':
util/bpf-event.c:143:35: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
^
util/bpf-event.c:144:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
__u32 *prog_lens = (__u32 *)(info->jited_func_lens);
^
util/bpf-event.c:145:23: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
__u64 *prog_addrs = (__u64 *)(info->jited_ksyms);
^
util/bpf-event.c:146:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
void *func_infos = (void *)(info->func_info);
^
CC /tmp/build/perf/util/pmu.o
CC /tmp/build/perf/util/pmu-flex.o
cc1: all warnings being treated as errors
> + __u32 *prog_lens = (__u32 *)(info->jited_func_lens);
> + __u64 *prog_addrs = (__u64 *)(info->jited_ksyms);
> + void *func_infos = (void *)(info->func_info);
> const struct bpf_func_info *finfo;
> const char *short_name = NULL;
> const struct btf_type *t;
> @@ -163,13 +128,13 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> KSYM_NAME_LEN - name_len,
> prog_tags[i], BPF_TAG_SIZE);
> if (has_btf) {
> - finfo = func_infos + i * info.func_info_rec_size;
> + 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;
> + if (info->name[0])
> + short_name = info->name;
> } else
> short_name = "F";
> if (short_name)
> @@ -195,9 +160,9 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> },
> .type = PERF_BPF_EVENT_PROG_LOAD,
> .flags = 0,
> - .id = info.id,
> + .id = info->id,
> };
> - memcpy(bpf_event->tag, prog_tags[i], BPF_TAG_SIZE);
> + memcpy(bpf_event->tag, info->tag, BPF_TAG_SIZE);
> memset((void *)event + event->header.size, 0, machine->id_hdr_size);
> event->header.size += machine->id_hdr_size;
> err = perf_tool__process_synth_event(tool, event,
> @@ -205,10 +170,7 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> }
>
> out:
> - free(prog_tags);
> - free(prog_lens);
> - free(prog_addrs);
> - free(func_infos);
> + free(info_linear);
> free(btf);
> return err ? -1 : 0;
> }
> --
> 2.17.1
--
- Arnaldo
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