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Diffstat (limited to 'tools/lib/bpf/libbpf.c')
-rw-r--r--tools/lib/bpf/libbpf.c213
1 files changed, 172 insertions, 41 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ff3c0ee79d85..88d8825fc6f6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -193,6 +193,8 @@ enum kern_feature_id {
FEAT_MODULE_BTF,
/* BTF_KIND_FLOAT support */
FEAT_BTF_FLOAT,
+ /* BPF perf link support */
+ FEAT_PERF_LINK,
__FEAT_CNT,
};
@@ -4337,6 +4339,37 @@ static int probe_module_btf(void)
return !err;
}
+static int probe_perf_link(void)
+{
+ struct bpf_load_program_attr attr;
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int prog_fd, link_fd, err;
+
+ memset(&attr, 0, sizeof(attr));
+ attr.prog_type = BPF_PROG_TYPE_TRACEPOINT;
+ attr.insns = insns;
+ attr.insns_cnt = ARRAY_SIZE(insns);
+ attr.license = "GPL";
+ prog_fd = bpf_load_program_xattr(&attr, NULL, 0);
+ if (prog_fd < 0)
+ return -errno;
+
+ /* use invalid perf_event FD to get EBADF, if link is supported;
+ * otherwise EINVAL should be returned
+ */
+ link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
+ err = -errno; /* close() can clobber errno */
+
+ if (link_fd >= 0)
+ close(link_fd);
+ close(prog_fd);
+
+ return link_fd < 0 && err == -EBADF;
+}
+
enum kern_feature_result {
FEAT_UNKNOWN = 0,
FEAT_SUPPORTED = 1,
@@ -4387,6 +4420,9 @@ static struct kern_feature_desc {
[FEAT_BTF_FLOAT] = {
"BTF_KIND_FLOAT support", probe_kern_btf_float,
},
+ [FEAT_PERF_LINK] = {
+ "BPF perf link support", probe_perf_link,
+ },
};
static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
@@ -8810,7 +8846,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
struct bpf_link {
int (*detach)(struct bpf_link *link);
- int (*destroy)(struct bpf_link *link);
+ void (*dealloc)(struct bpf_link *link);
char *pin_path; /* NULL, if not pinned */
int fd; /* hook FD, -1 if not applicable */
bool disconnected;
@@ -8849,11 +8885,12 @@ int bpf_link__destroy(struct bpf_link *link)
if (!link->disconnected && link->detach)
err = link->detach(link);
- if (link->destroy)
- link->destroy(link);
if (link->pin_path)
free(link->pin_path);
- free(link);
+ if (link->dealloc)
+ link->dealloc(link);
+ else
+ free(link);
return libbpf_err(err);
}
@@ -8950,23 +8987,42 @@ int bpf_link__unpin(struct bpf_link *link)
return 0;
}
-static int bpf_link__detach_perf_event(struct bpf_link *link)
+struct bpf_link_perf {
+ struct bpf_link link;
+ int perf_event_fd;
+};
+
+static int bpf_link_perf_detach(struct bpf_link *link)
{
- int err;
+ struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+ int err = 0;
- err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0);
- if (err)
+ if (ioctl(perf_link->perf_event_fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
err = -errno;
+ if (perf_link->perf_event_fd != link->fd)
+ close(perf_link->perf_event_fd);
close(link->fd);
+
return libbpf_err(err);
}
-struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
+static void bpf_link_perf_dealloc(struct bpf_link *link)
+{
+ struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
+
+ free(perf_link);
+}
+
+struct bpf_link *bpf_program__attach_perf_event_opts(struct bpf_program *prog, int pfd,
+ const struct bpf_perf_event_opts *opts)
{
char errmsg[STRERR_BUFSIZE];
- struct bpf_link *link;
- int prog_fd, err;
+ struct bpf_link_perf *link;
+ int prog_fd, link_fd = -1, err;
+
+ if (!OPTS_VALID(opts, bpf_perf_event_opts))
+ return libbpf_err_ptr(-EINVAL);
if (pfd < 0) {
pr_warn("prog '%s': invalid perf event FD %d\n",
@@ -8983,27 +9039,59 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pf
link = calloc(1, sizeof(*link));
if (!link)
return libbpf_err_ptr(-ENOMEM);
- link->detach = &bpf_link__detach_perf_event;
- link->fd = pfd;
+ link->link.detach = &bpf_link_perf_detach;
+ link->link.dealloc = &bpf_link_perf_dealloc;
+ link->perf_event_fd = pfd;
- if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
- err = -errno;
- free(link);
- pr_warn("prog '%s': failed to attach to pfd %d: %s\n",
- prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
- if (err == -EPROTO)
- pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
- prog->name, pfd);
- return libbpf_err_ptr(err);
+ if (kernel_supports(prog->obj, FEAT_PERF_LINK)) {
+ DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_opts,
+ .perf_event.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0));
+
+ link_fd = bpf_link_create(prog_fd, pfd, BPF_PERF_EVENT, &link_opts);
+ if (link_fd < 0) {
+ err = -errno;
+ pr_warn("prog '%s': failed to create BPF link for perf_event FD %d: %d (%s)\n",
+ prog->name, pfd,
+ err, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ goto err_out;
+ }
+ link->link.fd = link_fd;
+ } else {
+ if (OPTS_GET(opts, bpf_cookie, 0)) {
+ pr_warn("prog '%s': user context value is not supported\n", prog->name);
+ err = -EOPNOTSUPP;
+ goto err_out;
+ }
+
+ if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
+ err = -errno;
+ pr_warn("prog '%s': failed to attach to perf_event FD %d: %s\n",
+ prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ if (err == -EPROTO)
+ pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
+ prog->name, pfd);
+ goto err_out;
+ }
+ link->link.fd = pfd;
}
if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
err = -errno;
- free(link);
- pr_warn("prog '%s': failed to enable pfd %d: %s\n",
+ pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n",
prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
- return libbpf_err_ptr(err);
+ goto err_out;
}
- return link;
+
+ return &link->link;
+err_out:
+ if (link_fd >= 0)
+ close(link_fd);
+ free(link);
+ return libbpf_err_ptr(err);
+}
+
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
+{
+ return bpf_program__attach_perf_event_opts(prog, pfd, NULL);
}
/*
@@ -9064,13 +9152,19 @@ static int determine_uprobe_retprobe_bit(void)
return parse_uint_from_file(file, "config:%d\n");
}
+#define PERF_UPROBE_REF_CTR_OFFSET_BITS 32
+#define PERF_UPROBE_REF_CTR_OFFSET_SHIFT 32
+
static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
- uint64_t offset, int pid)
+ uint64_t offset, int pid, size_t ref_ctr_off)
{
struct perf_event_attr attr = {};
char errmsg[STRERR_BUFSIZE];
int type, pfd, err;
+ if (ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
+ return -EINVAL;
+
type = uprobe ? determine_uprobe_perf_type()
: determine_kprobe_perf_type();
if (type < 0) {
@@ -9093,6 +9187,7 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
}
attr.size = sizeof(attr);
attr.type = type;
+ attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
attr.config2 = offset; /* kprobe_addr or probe_offset */
@@ -9114,8 +9209,9 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
struct bpf_link *
bpf_program__attach_kprobe_opts(struct bpf_program *prog,
const char *func_name,
- struct bpf_kprobe_opts *opts)
+ const struct bpf_kprobe_opts *opts)
{
+ DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
unsigned long offset;
@@ -9127,16 +9223,17 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog,
retprobe = OPTS_GET(opts, retprobe, false);
offset = OPTS_GET(opts, offset, 0);
+ pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
- offset, -1 /* pid */);
+ offset, -1 /* pid */, 0 /* ref_ctr_off */);
if (pfd < 0) {
pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n",
prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
- link = bpf_program__attach_perf_event(prog, pfd);
+ link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@@ -9191,17 +9288,27 @@ static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
return link;
}
-struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
- bool retprobe, pid_t pid,
- const char *binary_path,
- size_t func_offset)
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe_opts(struct bpf_program *prog, pid_t pid,
+ const char *binary_path, size_t func_offset,
+ const struct bpf_uprobe_opts *opts)
{
+ DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
+ size_t ref_ctr_off;
int pfd, err;
+ bool retprobe;
- pfd = perf_event_open_probe(true /* uprobe */, retprobe,
- binary_path, func_offset, pid);
+ if (!OPTS_VALID(opts, bpf_uprobe_opts))
+ return libbpf_err_ptr(-EINVAL);
+
+ retprobe = OPTS_GET(opts, retprobe, false);
+ ref_ctr_off = OPTS_GET(opts, ref_ctr_offset, 0);
+ pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
+ pfd = perf_event_open_probe(true /* uprobe */, retprobe, binary_path,
+ func_offset, pid, ref_ctr_off);
if (pfd < 0) {
pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
prog->name, retprobe ? "uretprobe" : "uprobe",
@@ -9209,7 +9316,7 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
- link = bpf_program__attach_perf_event(prog, pfd);
+ link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@@ -9222,6 +9329,16 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
return link;
}
+struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
+ bool retprobe, pid_t pid,
+ const char *binary_path,
+ size_t func_offset)
+{
+ DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts, .retprobe = retprobe);
+
+ return bpf_program__attach_uprobe_opts(prog, pid, binary_path, func_offset, &opts);
+}
+
static int determine_tracepoint_id(const char *tp_category,
const char *tp_name)
{
@@ -9272,14 +9389,21 @@ static int perf_event_open_tracepoint(const char *tp_category,
return pfd;
}
-struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
- const char *tp_category,
- const char *tp_name)
+struct bpf_link *bpf_program__attach_tracepoint_opts(struct bpf_program *prog,
+ const char *tp_category,
+ const char *tp_name,
+ const struct bpf_tracepoint_opts *opts)
{
+ DECLARE_LIBBPF_OPTS(bpf_perf_event_opts, pe_opts);
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
int pfd, err;
+ if (!OPTS_VALID(opts, bpf_tracepoint_opts))
+ return libbpf_err_ptr(-EINVAL);
+
+ pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0);
+
pfd = perf_event_open_tracepoint(tp_category, tp_name);
if (pfd < 0) {
pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
@@ -9287,7 +9411,7 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return libbpf_err_ptr(pfd);
}
- link = bpf_program__attach_perf_event(prog, pfd);
+ link = bpf_program__attach_perf_event_opts(prog, pfd, &pe_opts);
err = libbpf_get_error(link);
if (err) {
close(pfd);
@@ -9299,6 +9423,13 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
return link;
}
+struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
+ const char *tp_category,
+ const char *tp_name)
+{
+ return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
+}
+
static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
struct bpf_program *prog)
{
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-21 04:40:06 +0000