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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#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"
#include "machine.h"
#include "session.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)
{
if (dump_trace)
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.
*
* Returns:
* 0 for success;
* -1 for failures;
* -2 for lack of kernel support.
*/
static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
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;
struct bpf_prog_info_linear *info_linear;
struct perf_tool *tool = session->tool;
struct bpf_prog_info *info;
struct btf *btf = NULL;
bool has_btf = false;
u32 sub_prog_cnt, i;
int err = 0;
u64 arrays;
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;
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_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)
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) {
pr_debug("%s: mismatch in BPF sub program count and BTF function info count, aborting\n", __func__);
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);
err = -1;
btf = NULL;
goto out;
}
has_btf = true;
}
/* 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;
int name_len;
*ksymbol_event = (struct ksymbol_event){
.header = {
.type = PERF_RECORD_KSYMBOL,
.size = offsetof(struct ksymbol_event, name),
},
.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));
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,
machine, process);
}
/* Synthesize PERF_RECORD_BPF_EVENT */
if (!opts->no_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, 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,
machine, process);
}
out:
free(info_linear);
free(btf);
return err ? -1 : 0;
}
int perf_event__synthesize_bpf_events(struct perf_session *session,
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 + machine->id_hdr_size);
if (!event)
return -1;
while (true) {
err = bpf_prog_get_next_id(id, &id);
if (err) {
if (errno == ENOENT) {
err = 0;
break;
}
pr_debug("%s: can't get next program: %s%s\n",
__func__, strerror(errno),
errno == EINVAL ? " -- kernel too old?" : "");
/* don't report error on old kernel or EPERM */
err = (errno == EINVAL || errno == EPERM) ? 0 : -1;
break;
}
fd = bpf_prog_get_fd_by_id(id);
if (fd < 0) {
pr_debug("%s: failed to get fd for prog_id %u\n",
__func__, id);
continue;
}
err = perf_event__synthesize_one_bpf_prog(session, process,
machine, fd,
event, opts);
close(fd);
if (err) {
/* do not return error for old kernel */
if (err == -2)
err = 0;
break;
}
}
free(event);
return err;
}
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