[PATCH bpf-next 2/2] tools/bpf: add a selftest for bpf_send_signal_thread()

[Yonghong Song <yhs@fb.com>]

The test_progs send_signal() is amended to test
bpf_send_signal_thread() as well.

  $ ./test_progs -n 40
  #40/1 send_signal_tracepoint:OK
  #40/2 send_signal_perf:OK
  #40/3 send_signal_nmi:OK
  #40/4 send_signal_tracepoint_thread:OK
  #40/5 send_signal_perf_thread:OK
  #40/6 send_signal_nmi_thread:OK
  #40 send_signal:OK
  Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/include/uapi/linux/bpf.h                | 18 +++++++++--
 .../selftests/bpf/prog_tests/send_signal.c    | 30 ++++++++++++-------
 .../bpf/progs/test_send_signal_kern.c         |  9 ++++--
 3 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 52966e758fe5..3320f8bdfe7e 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -2714,7 +2714,7 @@ union bpf_attr {
  *
  * int bpf_send_signal(u32 sig)
  *	Description
- *		Send signal *sig* to the current task.
+ *		Send signal *sig* to the process of the current task.
  *	Return
  *		0 on success or successfully queued.
  *
@@ -2850,6 +2850,19 @@ union bpf_attr {
  *	Return
  *		0 on success, or a negative error in case of failure.
  *
+ * int bpf_send_signal_thread(u32 sig)
+ *	Description
+ *		Send signal *sig* to the current task.
+ *	Return
+ *		0 on success or successfully queued.
+ *
+ *		**-EBUSY** if work queue under nmi is full.
+ *
+ *		**-EINVAL** if *sig* is invalid.
+ *
+ *		**-EPERM** if no permission to send the *sig*.
+ *
+ *		**-EAGAIN** if bpf program can try again.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2968,7 +2981,8 @@ union bpf_attr {
 	FN(probe_read_kernel),		\
 	FN(probe_read_user_str),	\
 	FN(probe_read_kernel_str),	\
-	FN(tcp_send_ack),
+	FN(tcp_send_ack),		\
+	FN(send_signal_thread),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c
index b607112c64e7..b12350832be3 100644
--- a/tools/testing/selftests/bpf/prog_tests/send_signal.c
+++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c
@@ -10,7 +10,8 @@ static void sigusr1_handler(int signum)
 
 static void test_send_signal_common(struct perf_event_attr *attr,
 				    int prog_type,
-				    const char *test_name)
+				    const char *test_name,
+				    bool send_thread)
 {
 	int err = -1, pmu_fd, prog_fd, info_map_fd, status_map_fd;
 	const char *file = "./test_send_signal_kern.o";
@@ -110,7 +111,7 @@ static void test_send_signal_common(struct perf_event_attr *attr,
 
 	/* trigger the bpf send_signal */
 	key = 0;
-	val = (((__u64)(SIGUSR1)) << 32) | pid;
+	val = (((__u64)send_thread) << 48) | (((__u64)(SIGUSR1)) << 32) | pid;
 	bpf_map_update_elem(info_map_fd, &key, &val, 0);
 
 	/* notify child that bpf program can send_signal now */
@@ -140,7 +141,7 @@ static void test_send_signal_common(struct perf_event_attr *attr,
 	wait(NULL);
 }
 
-static void test_send_signal_tracepoint(void)
+static void test_send_signal_tracepoint(bool send_thread)
 {
 	const char *id_path = "/sys/kernel/debug/tracing/events/syscalls/sys_enter_nanosleep/id";
 	struct perf_event_attr attr = {
@@ -168,10 +169,11 @@ static void test_send_signal_tracepoint(void)
 
 	attr.config = strtol(buf, NULL, 0);
 
-	test_send_signal_common(&attr, BPF_PROG_TYPE_TRACEPOINT, "tracepoint");
+	test_send_signal_common(&attr, BPF_PROG_TYPE_TRACEPOINT, "tracepoint",
+				send_thread);
 }
 
-static void test_send_signal_perf(void)
+static void test_send_signal_perf(bool send_thread)
 {
 	struct perf_event_attr attr = {
 		.sample_period = 1,
@@ -180,10 +182,10 @@ static void test_send_signal_perf(void)
 	};
 
 	test_send_signal_common(&attr, BPF_PROG_TYPE_PERF_EVENT,
-				"perf_sw_event");
+				"perf_sw_event", send_thread);
 }
 
-static void test_send_signal_nmi(void)
+static void test_send_signal_nmi(bool send_thread)
 {
 	struct perf_event_attr attr = {
 		.sample_freq = 50,
@@ -211,15 +213,21 @@ static void test_send_signal_nmi(void)
 	}
 
 	test_send_signal_common(&attr, BPF_PROG_TYPE_PERF_EVENT,
-				"perf_hw_event");
+				"perf_hw_event", send_thread);
 }
 
 void test_send_signal(void)
 {
 	if (test__start_subtest("send_signal_tracepoint"))
-		test_send_signal_tracepoint();
+		test_send_signal_tracepoint(false);
 	if (test__start_subtest("send_signal_perf"))
-		test_send_signal_perf();
+		test_send_signal_perf(false);
 	if (test__start_subtest("send_signal_nmi"))
-		test_send_signal_nmi();
+		test_send_signal_nmi(false);
+	if (test__start_subtest("send_signal_tracepoint_thread"))
+		test_send_signal_tracepoint(true);
+	if (test__start_subtest("send_signal_perf_thread"))
+		test_send_signal_perf(true);
+	if (test__start_subtest("send_signal_nmi_thread"))
+		test_send_signal_nmi(true);
 }
diff --git a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
index 0e6be01157e6..4a722024c32b 100644
--- a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
@@ -23,6 +23,7 @@ int bpf_send_signal_test(void *ctx)
 {
 	__u64 *info_val, *status_val;
 	__u32 key = 0, pid, sig;
+	int use_signal_thread;
 	int ret;
 
 	status_val = bpf_map_lookup_elem(&status_map, &key);
@@ -33,11 +34,15 @@ int bpf_send_signal_test(void *ctx)
 	if (!info_val || *info_val == 0)
 		return 0;
 
-	sig = *info_val >> 32;
+	use_signal_thread = *info_val >> 48;
+	sig = *info_val >> 32 & 0xFFFF;
 	pid = *info_val & 0xffffFFFF;
 
 	if ((bpf_get_current_pid_tgid() >> 32) == pid) {
-		ret = bpf_send_signal(sig);
+		if (use_signal_thread)
+			ret = bpf_send_signal_thread(sig);
+		else
+			ret = bpf_send_signal(sig);
 		if (ret == 0)
 			*status_val = 1;
 	}
-- 
2.17.1