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-rw-r--r--tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c86
1 files changed, 86 insertions, 0 deletions
diff --git a/tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c b/tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c
new file mode 100644
index 000000000..f9dfd3d3c
--- /dev/null
+++ b/tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * POWER Data Stream Control Register (DSCR) fork test
+ *
+ * This testcase modifies the DSCR using mtspr, forks and then
+ * verifies that the child process has the correct changed DSCR
+ * value using mfspr.
+ *
+ * When using the privilege state SPR, the instructions such as
+ * mfspr or mtspr are priviledged and the kernel emulates them
+ * for us. Instructions using problem state SPR can be exuecuted
+ * directly without any emulation if the HW supports them. Else
+ * they also get emulated by the kernel.
+ *
+ * Copyright 2012, Anton Blanchard, IBM Corporation.
+ * Copyright 2015, Anshuman Khandual, IBM Corporation.
+ */
+#include "dscr.h"
+
+int dscr_inherit(void)
+{
+ unsigned long i, dscr = 0;
+ pid_t pid;
+
+ SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
+
+ srand(getpid());
+ set_dscr(dscr);
+
+ for (i = 0; i < COUNT; i++) {
+ unsigned long cur_dscr, cur_dscr_usr;
+
+ dscr++;
+ if (dscr > DSCR_MAX)
+ dscr = 0;
+
+ if (i % 2 == 0)
+ set_dscr_usr(dscr);
+ else
+ set_dscr(dscr);
+
+ pid = fork();
+ if (pid == -1) {
+ perror("fork() failed");
+ exit(1);
+ } else if (pid) {
+ int status;
+
+ if (waitpid(pid, &status, 0) == -1) {
+ perror("waitpid() failed");
+ exit(1);
+ }
+
+ if (!WIFEXITED(status)) {
+ fprintf(stderr, "Child didn't exit cleanly\n");
+ exit(1);
+ }
+
+ if (WEXITSTATUS(status) != 0) {
+ fprintf(stderr, "Child didn't exit cleanly\n");
+ return 1;
+ }
+ } else {
+ cur_dscr = get_dscr();
+ if (cur_dscr != dscr) {
+ fprintf(stderr, "Kernel DSCR should be %ld "
+ "but is %ld\n", dscr, cur_dscr);
+ exit(1);
+ }
+
+ cur_dscr_usr = get_dscr_usr();
+ if (cur_dscr_usr != dscr) {
+ fprintf(stderr, "User DSCR should be %ld "
+ "but is %ld\n", dscr, cur_dscr_usr);
+ exit(1);
+ }
+ exit(0);
+ }
+ }
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ return test_harness(dscr_inherit, "dscr_inherit_test");
+}