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perf bpf: Synthesize bpf events with bpf_program__get_prog_info_linear() 

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.

Commiter notes:

Needed this (for all four variables), suggested by Song, to overcome
build failure on debian experimental cross building to MIPS 32-bit:

  -               u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(info->prog_tags);
  +               u8 (*prog_tags)[BPF_TAG_SIZE] = (void *)(uintptr_t)(info->prog_tags);

  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);
                        ^
  cc1: all warnings being treated as errors

Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: kernel-team@fb.com
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislav Fomichev <sdf@google.com>
Link: http://lkml.kernel.org/r/20190312053051.2690567-5-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Song Liu 2019-03-11 22:30:40 -07:00 committed by Arnaldo Carvalho de Melo
parent cae73f2339
commit a742258af1
1 changed files with 40 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

118
tools/perf/util/bpf-event.c
View File

@ -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;
err = -1;
goto out;
}
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;
}
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 *)(uintptr_t)(info->prog_tags);
__u32 *prog_lens = (__u32 *)(uintptr_t)(info->jited_func_lens);
__u64 *prog_addrs = (__u64 *)(uintptr_t)(info->jited_ksyms);
void *func_infos = (void *)(uintptr_t)(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;
}