bpf: add selftest for stackmap with build_id in NMI context

This new test captures stackmap with build_id with hardware event
PERF_COUNT_HW_CPU_CYCLES.

Because we only support one ips-to-build_id lookup per cpu in NMI
context, stack_amap will not be able to do the lookup in this test.
Therefore, we didn't do compare_stack_ips(), as it will alwasy fail.

urandom_read.c is extended to run configurable cycles so that it can be
caught by the perf event.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 8 insertions, 2 deletions

diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c
index 4acfdebf36fa..9de8b7cb4e6d 100644
--- a/tools/testing/selftests/bpf/urandom_read.c
+++ b/tools/testing/selftests/bpf/urandom_read.c
@@ -6,15 +6,21 @@
 #include <stdlib.h>
 
 #define BUF_SIZE 256
-int main(void)
+
+int main(int argc, char *argv[])
 {
 	int fd = open("/dev/urandom", O_RDONLY);
 	int i;
 	char buf[BUF_SIZE];
+	int count = 4;
 
 	if (fd < 0)
 		return 1;
-	for (i = 0; i < 4; ++i)
+
+	if (argc == 2)
+		count = atoi(argv[1]);
+
+	for (i = 0; i < count; ++i)
 		read(fd, buf, BUF_SIZE);
 
 	close(fd);