Merge branch 'bpf-libbpf-link-trace'

Andrii Nakryiko says:

====================
This patchset adds the following APIs to allow attaching BPF programs to
tracing entities:
- bpf_program__attach_perf_event for attaching to any opened perf event FD,
  allowing users full control;
- bpf_program__attach_kprobe for attaching to kernel probes (both entry and
  return probes);
- bpf_program__attach_uprobe for attaching to user probes (both entry/return);
- bpf_program__attach_tracepoint for attaching to kernel tracepoints;
- bpf_program__attach_raw_tracepoint for attaching to raw kernel tracepoint
  (wrapper around bpf_raw_tracepoint_open);

This set of APIs makes libbpf more useful for tracing applications.

All attach APIs return abstract struct bpf_link that encapsulates logic of
detaching BPF program. See patch #2 for details. bpf_assoc was considered as
an alternative name for this opaque "handle", but bpf_link seems to be
appropriate semantically and is nice and short.

Pre-patch #1 makes internal libbpf_strerror_r helper function work w/ negative
error codes, lifting the burder off callers to keep track of error sign.
Patch #2 adds bpf_link abstraction.
Patch #3 adds attach_perf_event, which is the base for all other APIs.
Patch #4 adds kprobe/uprobe APIs.
Patch #5 adds tracepoint API.
Patch #6 adds raw_tracepoint API.
Patch #7 converts one existing test to use attach_perf_event.
Patch #8 adds new kprobe/uprobe tests.
Patch #9 converts some selftests currently using tracepoint to new APIs.

v4->v5:
- typo and small nits (Yonghong);
- validate pfd in attach_perf_event (Yonghong);
- parse_uint_from_file fixes (Yonghong);
- check for malloc failure in attach_raw_tracepoint (Yonghong);
- attach_probes selftests clean up fixes (Yonghong);
v3->v4:
- proper errno handling (Stanislav);
- bpf_fd -> prog_fd (Stanislav);
- switch to fprintf (Song);
v2->v3:
- added bpf_link concept (Daniel);
- didn't add generic bpf_link__attach_program for reasons described in [0];
- dropped Stanislav's Reviewed-by from patches #2-#6, in case he doesn't like
  the change;
v1->v2:
- preserve errno before close() call (Stanislav);
- use libbpf_perf_event_disable_and_close in selftest (Stanislav);
- remove unnecessary memset (Stanislav);

[0] https://lore.kernel.org/bpf/CAEf4BzZ7EM5eP2eaZn7T2Yb5QgVRiwAs+epeLR1g01TTx-6m6Q@mail.gmail.com/
====================
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/lib/bpf/libbpf.h

@@ -165,6 +165,27 @@ LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path);
 LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path);
 LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
 
+struct bpf_link;
+
+LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
+			   const char *func_name);
+LIBBPF_API 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_tracepoint(struct bpf_program *prog,
+			       const char *tp_category,
+			       const char *tp_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+				   const char *tp_name);
+
 struct bpf_insn;
 
 /*

tools/lib/bpf/libbpf.map

@@ -167,10 +167,16 @@ LIBBPF_0.0.3 {
 
 LIBBPF_0.0.4 {
 	global:
+		bpf_link__destroy;
+		bpf_object__load_xattr;
+		bpf_program__attach_kprobe;
+		bpf_program__attach_perf_event;
+		bpf_program__attach_raw_tracepoint;
+		bpf_program__attach_tracepoint;
+		bpf_program__attach_uprobe;
 		btf_dump__dump_type;
 		btf_dump__free;
 		btf_dump__new;
 		btf__parse_elf;
-		bpf_object__load_xattr;
 		libbpf_num_possible_cpus;
 } LIBBPF_0.0.3;

tools/lib/bpf/str_error.c

@@ -11,7 +11,7 @@
  */
 char *libbpf_strerror_r(int err, char *dst, int len)
 {
-	int ret = strerror_r(err, dst, len);
+	int ret = strerror_r(err < 0 ? -err : err, dst, len);
 	if (ret)
 		snprintf(dst, len, "ERROR: strerror_r(%d)=%d", err, ret);
 	return dst;

tools/testing/selftests/bpf/prog_tests/attach_probe.c

+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+ssize_t get_base_addr() {
+	size_t start;
+	char buf[256];
+	FILE *f;
+
+	f = fopen("/proc/self/maps", "r");
+	if (!f)
+		return -errno;
+
+	while (fscanf(f, "%zx-%*x %s %*s\n", &start, buf) == 2) {
+		if (strcmp(buf, "r-xp") == 0) {
+			fclose(f);
+			return start;
+		}
+	}
+
+	fclose(f);
+	return -EINVAL;
+}
+
+#ifdef __x86_64__
+#define SYS_KPROBE_NAME "__x64_sys_nanosleep"
+#else
+#define SYS_KPROBE_NAME "sys_nanosleep"
+#endif
+
+void test_attach_probe(void)
+{
+	const char *kprobe_name = "kprobe/sys_nanosleep";
+	const char *kretprobe_name = "kretprobe/sys_nanosleep";
+	const char *uprobe_name = "uprobe/trigger_func";
+	const char *uretprobe_name = "uretprobe/trigger_func";
+	const int kprobe_idx = 0, kretprobe_idx = 1;
+	const int uprobe_idx = 2, uretprobe_idx = 3;
+	const char *file = "./test_attach_probe.o";
+	struct bpf_program *kprobe_prog, *kretprobe_prog;
+	struct bpf_program *uprobe_prog, *uretprobe_prog;
+	struct bpf_object *obj;
+	int err, prog_fd, duration = 0, res;
+	struct bpf_link *kprobe_link = NULL;
+	struct bpf_link *kretprobe_link = NULL;
+	struct bpf_link *uprobe_link = NULL;
+	struct bpf_link *uretprobe_link = NULL;
+	int results_map_fd;
+	size_t uprobe_offset;
+	ssize_t base_addr;
+
+	base_addr = get_base_addr();
+	if (CHECK(base_addr < 0, "get_base_addr",
+		  "failed to find base addr: %zd", base_addr))
+		return;
+	uprobe_offset = (size_t)&get_base_addr - base_addr;
+
+	/* load programs */
+	err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
+	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
+		return;
+
+	kprobe_prog = bpf_object__find_program_by_title(obj, kprobe_name);
+	if (CHECK(!kprobe_prog, "find_probe",
+		  "prog '%s' not found\n", kprobe_name))
+		goto cleanup;
+	kretprobe_prog = bpf_object__find_program_by_title(obj, kretprobe_name);
+	if (CHECK(!kretprobe_prog, "find_probe",
+		  "prog '%s' not found\n", kretprobe_name))
+		goto cleanup;
+	uprobe_prog = bpf_object__find_program_by_title(obj, uprobe_name);
+	if (CHECK(!uprobe_prog, "find_probe",
+		  "prog '%s' not found\n", uprobe_name))
+		goto cleanup;
+	uretprobe_prog = bpf_object__find_program_by_title(obj, uretprobe_name);
+	if (CHECK(!uretprobe_prog, "find_probe",
+		  "prog '%s' not found\n", uretprobe_name))
+		goto cleanup;
+
+	/* load maps */
+	results_map_fd = bpf_find_map(__func__, obj, "results_map");
+	if (CHECK(results_map_fd < 0, "find_results_map",
+		  "err %d\n", results_map_fd))
+		goto cleanup;
+
+	kprobe_link = bpf_program__attach_kprobe(kprobe_prog,
+						 false /* retprobe */,
+						 SYS_KPROBE_NAME);
+	if (CHECK(IS_ERR(kprobe_link), "attach_kprobe",
+		  "err %ld\n", PTR_ERR(kprobe_link))) {
+		kprobe_link = NULL;
+		goto cleanup;
+	}
+	kretprobe_link = bpf_program__attach_kprobe(kretprobe_prog,
+						    true /* retprobe */,
+						    SYS_KPROBE_NAME);
+	if (CHECK(IS_ERR(kretprobe_link), "attach_kretprobe",
+		  "err %ld\n", PTR_ERR(kretprobe_link))) {
+		kretprobe_link = NULL;
+		goto cleanup;
+	}
+	uprobe_link = bpf_program__attach_uprobe(uprobe_prog,
+						 false /* retprobe */,
+						 0 /* self pid */,
+						 "/proc/self/exe",
+						 uprobe_offset);
+	if (CHECK(IS_ERR(uprobe_link), "attach_uprobe",
+		  "err %ld\n", PTR_ERR(uprobe_link))) {
+		uprobe_link = NULL;
+		goto cleanup;
+	}
+	uretprobe_link = bpf_program__attach_uprobe(uretprobe_prog,
+						    true /* retprobe */,
+						    -1 /* any pid */,
+						    "/proc/self/exe",
+						    uprobe_offset);
+	if (CHECK(IS_ERR(uretprobe_link), "attach_uretprobe",
+		  "err %ld\n", PTR_ERR(uretprobe_link))) {
+		uretprobe_link = NULL;
+		goto cleanup;
+	}
+
+	/* trigger & validate kprobe && kretprobe */
+	usleep(1);
+
+	err = bpf_map_lookup_elem(results_map_fd, &kprobe_idx, &res);
+	if (CHECK(err, "get_kprobe_res",
+		  "failed to get kprobe res: %d\n", err))
+		goto cleanup;
+	if (CHECK(res != kprobe_idx + 1, "check_kprobe_res",
+		  "wrong kprobe res: %d\n", res))
+		goto cleanup;
+
+	err = bpf_map_lookup_elem(results_map_fd, &kretprobe_idx, &res);
+	if (CHECK(err, "get_kretprobe_res",
+		  "failed to get kretprobe res: %d\n", err))
+		goto cleanup;
+	if (CHECK(res != kretprobe_idx + 1, "check_kretprobe_res",
+		  "wrong kretprobe res: %d\n", res))
+		goto cleanup;
+
+	/* trigger & validate uprobe & uretprobe */
+	get_base_addr();
+
+	err = bpf_map_lookup_elem(results_map_fd, &uprobe_idx, &res);
+	if (CHECK(err, "get_uprobe_res",
+		  "failed to get uprobe res: %d\n", err))
+		goto cleanup;
+	if (CHECK(res != uprobe_idx + 1, "check_uprobe_res",
+		  "wrong uprobe res: %d\n", res))
+		goto cleanup;
+
+	err = bpf_map_lookup_elem(results_map_fd, &uretprobe_idx, &res);
+	if (CHECK(err, "get_uretprobe_res",
+		  "failed to get uretprobe res: %d\n", err))
+		goto cleanup;
+	if (CHECK(res != uretprobe_idx + 1, "check_uretprobe_res",
+		  "wrong uretprobe res: %d\n", res))
+		goto cleanup;
+
+cleanup:
+	bpf_link__destroy(kprobe_link);
+	bpf_link__destroy(kretprobe_link);
+	bpf_link__destroy(uprobe_link);
+	bpf_link__destroy(uretprobe_link);
+	bpf_object__close(obj);
+}

tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c

@@ -4,11 +4,13 @@
 void test_stacktrace_build_id(void)
 {
 	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+	const char *prog_name = "tracepoint/random/urandom_read";
 	const char *file = "./test_stacktrace_build_id.o";
-	int bytes, efd, err, pmu_fd, prog_fd, stack_trace_len;
-	struct perf_event_attr attr = {};
+	int err, prog_fd, stack_trace_len;
 	__u32 key, previous_key, val, duration = 0;
+	struct bpf_program *prog;
 	struct bpf_object *obj;
+	struct bpf_link *link = NULL;
 	char buf[256];
 	int i, j;
 	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
@@ -18,44 +20,16 @@ void test_stacktrace_build_id(void)
 retry:
 	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
 	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
-		goto out;
-
-	/* Get the ID for the sched/sched_switch tracepoint */
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/random/urandom_read/id");
-	efd = open(buf, O_RDONLY, 0);
-	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
-		goto close_prog;
+		return;
 
-	bytes = read(efd, buf, sizeof(buf));
-	close(efd);
-	if (CHECK(bytes <= 0 || bytes >= sizeof(buf),
-		  "read", "bytes %d errno %d\n", bytes, errno))
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
 		goto close_prog;
 
-	/* Open the perf event and attach bpf progrram */
-	attr.config = strtol(buf, NULL, 0);
-	attr.type = PERF_TYPE_TRACEPOINT;
-	attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
-	attr.sample_period = 1;
-	attr.wakeup_events = 1;
-	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
-			 0 /* cpu 0 */, -1 /* group id */,
-			 0 /* flags */);
-	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
-		  pmu_fd, errno))
+	link = bpf_program__attach_tracepoint(prog, "random", "urandom_read");
+	if (CHECK(IS_ERR(link), "attach_tp", "err %ld\n", PTR_ERR(link)))
 		goto close_prog;
 
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
-	if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
-		  err, errno))
-		goto close_pmu;
-
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
-	if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
-		  err, errno))
-		goto disable_pmu;
-
 	/* find map fds */
 	control_map_fd = bpf_find_map(__func__, obj, "control_map");
 	if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
@@ -133,8 +107,7 @@ void test_stacktrace_build_id(void)
 	 * try it one more time.
 	 */
 	if (build_id_matches < 1 && retry--) {
-		ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-		close(pmu_fd);
+		bpf_link__destroy(link);
 		bpf_object__close(obj);
 		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 		       __func__);
@@ -152,14 +125,8 @@ void test_stacktrace_build_id(void)
 	      "err %d errno %d\n", err, errno);
 
 disable_pmu:
-	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-
-close_pmu:
-	close(pmu_fd);
+	bpf_link__destroy(link);
 
 close_prog:
 	bpf_object__close(obj);
-
-out:
-	return;
 }

tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c

@@ -17,6 +17,7 @@ static __u64 read_perf_max_sample_freq(void)
 void test_stacktrace_build_id_nmi(void)
 {
 	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+	const char *prog_name = "tracepoint/random/urandom_read";
 	const char *file = "./test_stacktrace_build_id.o";
 	int err, pmu_fd, prog_fd;
 	struct perf_event_attr attr = {
@@ -25,7 +26,9 @@ void test_stacktrace_build_id_nmi(void)
 		.config = PERF_COUNT_HW_CPU_CYCLES,
 	};
 	__u32 key, previous_key, val, duration = 0;
+	struct bpf_program *prog;
 	struct bpf_object *obj;
+	struct bpf_link *link;
 	char buf[256];
 	int i, j;
 	struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
@@ -39,6 +42,10 @@ void test_stacktrace_build_id_nmi(void)
 	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
 		return;
 
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
+		goto close_prog;
+
 	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
 			 0 /* cpu 0 */, -1 /* group id */,
 			 0 /* flags */);
@@ -47,15 +54,12 @@ void test_stacktrace_build_id_nmi(void)
 		  pmu_fd, errno))
 		goto close_prog;
 
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
-	if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
-		  err, errno))
-		goto close_pmu;
-
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
-	if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
-		  err, errno))
-		goto disable_pmu;
+	link = bpf_program__attach_perf_event(prog, pmu_fd);
+	if (CHECK(IS_ERR(link), "attach_perf_event",
+		  "err %ld\n", PTR_ERR(link))) {
+		close(pmu_fd);
+		goto close_prog;
+	}
 
 	/* find map fds */
 	control_map_fd = bpf_find_map(__func__, obj, "control_map");
@@ -134,8 +138,7 @@ void test_stacktrace_build_id_nmi(void)
 	 * try it one more time.
 	 */
 	if (build_id_matches < 1 && retry--) {
-		ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-		close(pmu_fd);
+		bpf_link__destroy(link);
 		bpf_object__close(obj);
 		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 		       __func__);
@@ -154,11 +157,7 @@ void test_stacktrace_build_id_nmi(void)
 	 */
 
 disable_pmu:
-	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-
-close_pmu:
-	close(pmu_fd);
-
+	bpf_link__destroy(link);
 close_prog:
 	bpf_object__close(obj);
 }

tools/testing/selftests/bpf/prog_tests/stacktrace_map.c

@@ -4,50 +4,26 @@
 void test_stacktrace_map(void)
 {
 	int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+	const char *prog_name = "tracepoint/sched/sched_switch";
+	int err, prog_fd, stack_trace_len;
 	const char *file = "./test_stacktrace_map.o";
-	int bytes, efd, err, pmu_fd, prog_fd, stack_trace_len;
-	struct perf_event_attr attr = {};
 	__u32 key, val, duration = 0;
+	struct bpf_program *prog;
 	struct bpf_object *obj;
-	char buf[256];
+	struct bpf_link *link;
 
 	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
 	if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
 		return;
 
-	/* Get the ID for the sched/sched_switch tracepoint */
-	snprintf(buf, sizeof(buf),
-		 "/sys/kernel/debug/tracing/events/sched/sched_switch/id");
-	efd = open(buf, O_RDONLY, 0);
-	if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
 		goto close_prog;
 
-	bytes = read(efd, buf, sizeof(buf));
-	close(efd);
-	if (bytes <= 0 || bytes >= sizeof(buf))
+	link = bpf_program__attach_tracepoint(prog, "sched", "sched_switch");
+	if (CHECK(IS_ERR(link), "attach_tp", "err %ld\n", PTR_ERR(link)))
 		goto close_prog;
 
-	/* Open the perf event and attach bpf progrram */
-	attr.config = strtol(buf, NULL, 0);
-	attr.type = PERF_TYPE_TRACEPOINT;
-	attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
-	attr.sample_period = 1;
-	attr.wakeup_events = 1;
-	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
-			 0 /* cpu 0 */, -1 /* group id */,
-			 0 /* flags */);
-	if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
-		  pmu_fd, errno))
-		goto close_prog;
-
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
-	if (err)
-		goto disable_pmu;
-
-	err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
-	if (err)
-		goto disable_pmu;
-
 	/* find map fds */
 	control_map_fd = bpf_find_map(__func__, obj, "control_map");
 	if (control_map_fd < 0)
@@ -96,8 +72,7 @@ void test_stacktrace_map(void)
 disable_pmu:
 	error_cnt++;
 disable_pmu_noerr:
-	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-	close(pmu_fd);
+	bpf_link__destroy(link);
 close_prog:
 	bpf_object__close(obj);
 }

tools/testing/selftests/bpf/prog_tests/stacktrace_map_raw_tp.c

@@ -3,18 +3,25 @@
 
 void test_stacktrace_map_raw_tp(void)
 {
+	const char *prog_name = "tracepoint/sched/sched_switch";
 	int control_map_fd, stackid_hmap_fd, stackmap_fd;
 	const char *file = "./test_stacktrace_map.o";
-	int efd, err, prog_fd;
 	__u32 key, val, duration = 0;
+	int err, prog_fd;
+	struct bpf_program *prog;
 	struct bpf_object *obj;
+	struct bpf_link *link = NULL;
 
 	err = bpf_prog_load(file, BPF_PROG_TYPE_RAW_TRACEPOINT, &obj, &prog_fd);
 	if (CHECK(err, "prog_load raw tp", "err %d errno %d\n", err, errno))
 		return;
 
-	efd = bpf_raw_tracepoint_open("sched_switch", prog_fd);
-	if (CHECK(efd < 0, "raw_tp_open", "err %d errno %d\n", efd, errno))
+	prog = bpf_object__find_program_by_title(obj, prog_name);
+	if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
+		goto close_prog;
+
+	link = bpf_program__attach_raw_tracepoint(prog, "sched_switch");
+	if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n", PTR_ERR(link)))
 		goto close_prog;
 
 	/* find map fds */
@@ -55,5 +62,7 @@ void test_stacktrace_map_raw_tp(void)
 close_prog:
 	error_cnt++;
 close_prog_noerr:
+	if (!IS_ERR_OR_NULL(link))
+		bpf_link__destroy(link);
 	bpf_object__close(obj);
 }

tools/testing/selftests/bpf/progs/test_attach_probe.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017 Facebook
+
+#include <linux/ptrace.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+struct {
+	int type;
+	int max_entries;
+	int *key;
+	int *value;
+} results_map SEC(".maps") = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.max_entries = 4,
+};
+
+SEC("kprobe/sys_nanosleep")
+int handle_sys_nanosleep_entry(struct pt_regs *ctx)
+{
+	const int key = 0, value = 1;
+
+	bpf_map_update_elem(&results_map, &key, &value, 0);
+	return 0;
+}
+
+SEC("kretprobe/sys_nanosleep")
+int handle_sys_getpid_return(struct pt_regs *ctx)
+{
+	const int key = 1, value = 2;
+
+	bpf_map_update_elem(&results_map, &key, &value, 0);
+	return 0;
+}
+
+SEC("uprobe/trigger_func")
+int handle_uprobe_entry(struct pt_regs *ctx)
+{
+	const int key = 2, value = 3;
+
+	bpf_map_update_elem(&results_map, &key, &value, 0);
+	return 0;
+}
+
+SEC("uretprobe/trigger_func")
+int handle_uprobe_return(struct pt_regs *ctx)
+{
+	const int key = 3, value = 4;
+
+	bpf_map_update_elem(&results_map, &key, &value, 0);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;