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Subject[PATCH 29/44] perf bpf: Synthesize bpf events with bpf_program__get_prog_info_linear()
Date
From: Song Liu <songliubraving@fb.com>

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>
---
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..e0cbe7f87170 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 *)(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;
}
--
2.20.1
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