On 03/15, Ivan Vecera wrote:
After some experiences I found that urandom_read does not need to be linked statically. When the 'read' syscall call is moved to separate non-inlined function then bpf_get_stackid() is able to find the executable in stack trace and extract its build_id from it.
But why? Do you have some problems with it being linked statically?
Signed-off-by: Ivan Vecera ivecera@redhat.com
tools/testing/selftests/bpf/Makefile | 2 +- tools/testing/selftests/bpf/urandom_read.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 2aed37ea61a4..c33900a8fec0 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -69,7 +69,7 @@ TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read all: $(TEST_CUSTOM_PROGS) $(OUTPUT)/urandom_read: $(OUTPUT)/%: %.c
- $(CC) -o $@ -static $< -Wl,--build-id
- $(CC) -o $@ $< -Wl,--build-id
BPFOBJ := $(OUTPUT)/libbpf.a diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c index 9de8b7cb4e6d..db781052758d 100644 --- a/tools/testing/selftests/bpf/urandom_read.c +++ b/tools/testing/selftests/bpf/urandom_read.c @@ -7,11 +7,19 @@ #define BUF_SIZE 256 +static __attribute__((noinline)) +void urandom_read(int fd, int count) +{
char buf[BUF_SIZE];int i;for (i = 0; i < count; ++i)read(fd, buf, BUF_SIZE);+}
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) @@ -20,8 +28,7 @@ int main(int argc, char *argv[]) if (argc == 2) count = atoi(argv[1]);
- for (i = 0; i < count; ++i)
read(fd, buf, BUF_SIZE);
- urandom_read(fd, count);
close(fd); return 0; -- 2.19.2