[PATCH] selftests:arm64: Test PR_SVE_VL_INHERIT after a double fork

Dorine Tipo
2024-04-29T04:40:49Z

Add a new test, double_fork_test() to check the inheritance of the SVE
vector length after a double fork.
The `EXPECTED_TESTS` macro has been updated to account for this additional
test.
This patch addresses task 7 on the TODO list.

Signed-off-by: Dorine Tipo <dorine.a.tipo@gmail.com>
---
tools/testing/selftests/arm64/fp/za-fork.c | 95 +++++++++++++++++++++-
1 file changed, 94 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/fp/za-fork.c b/tools/testing/selftests/arm64/fp/za-fork.c
index 587b94648222..35229e570dcf 100644
--- a/tools/testing/selftests/arm64/fp/za-fork.c
+++ b/tools/testing/selftests/arm64/fp/za-fork.c
@@ -11,7 +11,7 @@

#include "kselftest.h"

-#define EXPECTED_TESTS 1
+#define EXPECTED_TESTS 2

int fork_test(void);
int verify_fork(void);
@@ -69,6 +69,97 @@ int fork_test_c(void)
}
}

+int double_fork_test(void)
+{
+ pid_t newpid, grandchild_pid, waiting;
+ int ret, child_status, parent_result;
+
+ ret = prctl(PR_SVE_SET_VL, vl | PR_SVE_VL_INHERIT);
+ if (ret < 0)
+ ksft_exit_fail_msg("Failed to set SVE VL %d\n", vl);
+
+ newpid = fork();
+ if (newpid == 0) {
+ /* In child */
+ if (!verify_fork()) {
+ ksft_print_msg("ZA state invalid in child\n");
+ exit(0);
+ }
+
+ grandchild_pid = fork();
+ if (grandchild_pid == 0) {
+ /* in grandchild */
+ if (!verfy_fork()) {
+ ksft_print_msg("ZA state invalid in grandchild\n");
+ exit(0);
+ }
+
+ ret = prctl(PR_SVE_GET_VL);
+ if (ret & PR_SVE_VL_INHERIT) {
+ ksft_print_msg("prctl() reports _INHERIT\n");
+ return;
+ }
+ ksft_print_msg("prctl() does not report _INHERIT\n");
+
+ } else if (grandchild_pid < 0) {
+ ksft_print_msg("fork() failed in first child: %d\n", grandchild_pid);
+ return 0;
+ }
+
+ /* Wait for the grandchild process to exit */
+ waiting = waitpid(grandchild_pid, &child_status, 0);
+ if (waiting < 0) {
+ if (errno == EINTR)
+ continue;
+ ksft_print_msg("waitpid() failed: %d\n", errno);
+ return 0;
+ }
+ if (waiting != grandchild_pid) {
+ ksft_print_msg("waitpid() returned wrong PID\n");
+ return 0;
+ }
+
+ if (!WIFEXITED(child_status)) {
+ ksft_print_msg("grandchild did not exit\n");
+ return 0;
+ }
+
+ exit(1);
+ }
+ }
+ if (newpid < 0) {
+ ksft_print_msg("fork() failed: %d\n", newpid);
+
+ return 0;
+ }
+
+ parent_result = verify_fork();
+ if (!parent_result)
+ ksft_print_msg("ZA state invalid in parent\n");
+
+ for (;;) {
+ waiting = waitpid(newpid, &child_status, 0);
+
+ if (waiting < 0) {
+ if (errno == EINTR)
+ continue;
+ ksft_print_msg("waitpid() failed: %d\n", errno);
+ return 0;
+ }
+ if (waiting != newpid) {
+ ksft_print_msg("waitpid() returned wrong PID\n");
+ return 0;
+ }
+
+ if (!WIFEXITED(child_status)) {
+ ksft_print_msg("child did not exit\n");
+ return 0;
+ }
+
+ return WEXITSTATUS(child_status) && parent_result;
+ }
+}
+
int main(int argc, char **argv)
{
int ret, i;
@@ -86,11 +177,13 @@ int main(int argc, char **argv)
ret = open("/proc/sys/abi/sme_default_vector_length", O_RDONLY, 0);
if (ret >= 0) {
ksft_test_result(fork_test(), "fork_test\n");
+ ksft_test_result(double_fork_test(), "double_fork_test\n");

} else {
ksft_print_msg("SME not supported\n");
for (i = 0; i < EXPECTED_TESTS; i++) {
ksft_test_result_skip("fork_test\n");
+ ksft_test_result_skip("double_fork_test\n");
}
}

--
2.25.1