Merge branch 'bpf-raw-tracepoints'

Alexei Starovoitov says:

====================
v7->v8:
- moved 'u32 num_args' from 'struct tracepoint' into 'struct bpf_raw_event_map'
  that increases memory overhead, but can be optimized/compressed later.
  Now it's zero changes in tracepoint.[ch]

v6->v7:
- adopted Steven's bpf_raw_tp_map section approach to find tracepoint
  and corresponding bpf probe function instead of kallsyms approach.
  dropped kernel_tracepoint_find_by_name() patch

v5->v6:
- avoid changing semantics of for_each_kernel_tracepoint() function, instead
  introduce kernel_tracepoint_find_by_name() helper

v4->v5:
- adopted Daniel's fancy REPEAT macro in bpf_trace.c in patch 6

v3->v4:
- adopted Linus's CAST_TO_U64 macro to cast any integer, pointer, or small
  struct to u64. That nicely reduced the size of patch 1

v2->v3:
- with Linus's suggestion introduced generic COUNT_ARGS and CONCATENATE macros
  (or rather moved them from apparmor)
  that cleaned up patch 6
- added patch 4 to refactor trace_iwlwifi_dev_ucode_error() from 17 args to 4
  Now any tracepoint with >12 args will have build error

v1->v2:
- simplified api by combing bpf_raw_tp_open(name) + bpf_attach(prog_fd) into
  bpf_raw_tp_open(name, prog_fd) as suggested by Daniel.
  That simplifies bpf_detach as well which is now simple close() of fd.
- fixed memory leak in error path which was spotted by Daniel.
- fixed bpf_get_stackid(), bpf_perf_event_output() called from raw tracepoints
- added more tests
- fixed allyesconfig build caught by buildbot

v1:
This patch set is a different way to address the pressing need to access
task_struct pointers in sched tracepoints from bpf programs.

The first approach simply added these pointers to sched tracepoints:
https://lkml.org/lkml/2017/12/14/753
which Peter nacked.
Few options were discussed and eventually the discussion converged on
doing bpf specific tracepoint_probe_register() probe functions.
Details here:
https://lkml.org/lkml/2017/12/20/929

Patch 1 is kernel wide cleanup of pass-struct-by-value into
pass-struct-by-reference into tracepoints.

Patches 2 and 3 are minor cleanups to address allyesconfig build

Patch 4 refactor trace_iwlwifi_dev_ucode_error from 17 to 4 args

Patch 5 introduces COUNT_ARGS macro

Patch 6 introduces BPF_RAW_TRACEPOINT api.
the auto-cleanup and multiple concurrent users are must have
features of tracing api. For bpf raw tracepoints it looks like:
  // load bpf prog with BPF_PROG_TYPE_RAW_TRACEPOINT type
  prog_fd = bpf_prog_load(...);

  // receive anon_inode fd for given bpf_raw_tracepoint
  // and attach bpf program to it
  raw_tp_fd = bpf_raw_tracepoint_open("xdp_exception", prog_fd);

Ctrl-C of tracing daemon or cmdline tool will automatically
detach bpf program, unload it and unregister tracepoint probe.
More details in patch 6.

Patch 7 - trivial support in libbpf
Patches 8, 9 - user space tests

samples/bpf/test_overhead performance on 1 cpu:

tracepoint    base  kprobe+bpf tracepoint+bpf raw_tracepoint+bpf
task_rename   1.1M   769K        947K            1.0M
urandom_read  789K   697K        750K            755K
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

4 files changed, 93 insertions, 21 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d245c41213ac..58060bec999d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -94,6 +94,7 @@ enum bpf_cmd {
 	BPF_MAP_GET_FD_BY_ID,
 	BPF_OBJ_GET_INFO_BY_FD,
 	BPF_PROG_QUERY,
+	BPF_RAW_TRACEPOINT_OPEN,
 };
 
 enum bpf_map_type {
@@ -134,6 +135,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_SK_SKB,
 	BPF_PROG_TYPE_CGROUP_DEVICE,
 	BPF_PROG_TYPE_SK_MSG,
+	BPF_PROG_TYPE_RAW_TRACEPOINT,
 };
 
 enum bpf_attach_type {
@@ -344,6 +346,11 @@ union bpf_attr {
 		__aligned_u64	prog_ids;
 		__u32		prog_cnt;
 	} query;
+
+	struct {
+		__u64 name;
+		__u32 prog_fd;
+	} raw_tracepoint;
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:
@@ -1151,4 +1158,8 @@ struct bpf_cgroup_dev_ctx {
 	__u32 minor;
 };
 
+struct bpf_raw_tracepoint_args {
+	__u64 args[0];
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 592a58a2b681..e0500055f1a6 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -428,6 +428,17 @@ int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)
 	return err;
 }
 
+int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.raw_tracepoint.name = ptr_to_u64(name);
+	attr.raw_tracepoint.prog_fd = prog_fd;
+
+	return sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));
+}
+
 int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 {
 	struct sockaddr_nl sa;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 8d18fb73d7fb..ee59342c6f42 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -79,4 +79,5 @@ int bpf_map_get_fd_by_id(__u32 id);
 int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);
 int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
 		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt);
+int bpf_raw_tracepoint_open(const char *name, int prog_fd);
 #endif
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index e9df48b306df..faadbe233966 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -877,7 +877,7 @@ static void test_stacktrace_map()
 
 	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;
+		return;
 
 	/* Get the ID for the sched/sched_switch tracepoint */
 	snprintf(buf, sizeof(buf),
@@ -888,8 +888,7 @@ static void test_stacktrace_map()
 
 	bytes = read(efd, buf, sizeof(buf));
 	close(efd);
-	if (CHECK(bytes <= 0 || bytes >= sizeof(buf),
-		  "read", "bytes %d errno %d\n", bytes, errno))
+	if (bytes <= 0 || bytes >= sizeof(buf))
 		goto close_prog;
 
 	/* Open the perf event and attach bpf progrram */
@@ -906,29 +905,24 @@ static void test_stacktrace_map()
 		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;
+	if (err)
+		goto disable_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))
+	if (err)
 		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",
-		  "err %d errno %d\n", err, errno))
+	if (control_map_fd < 0)
 		goto disable_pmu;
 
 	stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
-	if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
-		  "err %d errno %d\n", err, errno))
+	if (stackid_hmap_fd < 0)
 		goto disable_pmu;
 
 	stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
-	if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
-		  err, errno))
+	if (stackmap_fd < 0)
 		goto disable_pmu;
 
 	/* give some time for bpf program run */
@@ -945,24 +939,78 @@ static void test_stacktrace_map()
 	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
 	if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
 		  "err %d errno %d\n", err, errno))
-		goto disable_pmu;
+		goto disable_pmu_noerr;
 
 	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
 	if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
 		  "err %d errno %d\n", err, errno))
-		; /* fall through */
+		goto disable_pmu_noerr;
 
+	goto disable_pmu_noerr;
 disable_pmu:
+	error_cnt++;
+disable_pmu_noerr:
 	ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
-
-close_pmu:
 	close(pmu_fd);
-
 close_prog:
 	bpf_object__close(obj);
+}
 
-out:
-	return;
+static void test_stacktrace_map_raw_tp()
+{
+	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;
+	struct bpf_object *obj;
+
+	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))
+		goto close_prog;
+
+	/* find map fds */
+	control_map_fd = bpf_find_map(__func__, obj, "control_map");
+	if (control_map_fd < 0)
+		goto close_prog;
+
+	stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
+	if (stackid_hmap_fd < 0)
+		goto close_prog;
+
+	stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
+	if (stackmap_fd < 0)
+		goto close_prog;
+
+	/* give some time for bpf program run */
+	sleep(1);
+
+	/* disable stack trace collection */
+	key = 0;
+	val = 1;
+	bpf_map_update_elem(control_map_fd, &key, &val, 0);
+
+	/* for every element in stackid_hmap, we can find a corresponding one
+	 * in stackmap, and vise versa.
+	 */
+	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
+	if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
+		  "err %d errno %d\n", err, errno))
+		goto close_prog;
+
+	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
+	if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
+		  "err %d errno %d\n", err, errno))
+		goto close_prog;
+
+	goto close_prog_noerr;
+close_prog:
+	error_cnt++;
+close_prog_noerr:
+	bpf_object__close(obj);
 }
 
 static int extract_build_id(char *build_id, size_t size)
@@ -1138,6 +1186,7 @@ int main(void)
 	test_tp_attach_query();
 	test_stacktrace_map();
 	test_stacktrace_build_id();
+	test_stacktrace_map_raw_tp();
 
 	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
 	return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;