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Subject[PATCH V3 10/13] selftests, powerpc: Add test for DSCR inheritence across fork & exec
Date
This patch adds a test case to verify that the changed DSCR value
inside any process would be inherited to it's child across the fork
and exec system call.

Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
tools/testing/selftests/powerpc/dscr/Makefile | 2 +-
.../powerpc/dscr/dscr_inherit_exec_test.c | 118 +++++++++++++++++++++
2 files changed, 119 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c

diff --git a/tools/testing/selftests/powerpc/dscr/Makefile b/tools/testing/selftests/powerpc/dscr/Makefile
index 81239e2..4e84309 100644
--- a/tools/testing/selftests/powerpc/dscr/Makefile
+++ b/tools/testing/selftests/powerpc/dscr/Makefile
@@ -1,5 +1,5 @@
PROGS := dscr_default_test dscr_explicit_test dscr_user_test \
- dscr_inherit_test
+ dscr_inherit_test dscr_inherit_exec_test

CFLAGS := $(CFLAGS) -lpthread

diff --git a/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c b/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c
new file mode 100644
index 0000000..5ff3849
--- /dev/null
+++ b/tools/testing/selftests/powerpc/dscr/dscr_inherit_exec_test.c
@@ -0,0 +1,118 @@
+/*
+ * POWER Data Stream Control Register (DSCR) fork exec test
+ *
+ * This testcase modifies the DSCR using mtspr, forks & execs and
+ * verifies that the child is using the changed DSCR 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 (C) 2012 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2015 Anshuman Khandual <khandual@linux.vnet.ibm.com>, IBM
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include "dscr.h"
+
+static char prog[LEN_MAX];
+
+static void do_exec(unsigned long parent_dscr)
+{
+ unsigned long cur_dscr, cur_dscr_usr;
+
+ cur_dscr = get_dscr();
+ cur_dscr_usr = get_dscr_usr();
+
+ if (cur_dscr != parent_dscr) {
+ fprintf(stderr, "Parent DSCR %ld was not inherited "
+ "over exec (kernel value)\n", parent_dscr);
+ exit(1);
+ }
+
+ if (cur_dscr_usr != parent_dscr) {
+ fprintf(stderr, "Parent DSCR %ld was not inherited "
+ "over exec (user value)\n", parent_dscr);
+ exit(1);
+ }
+ exit(0);
+}
+
+int test_body(void)
+{
+ unsigned long i, dscr = 0;
+ pid_t pid;
+
+ for (i = 0; i < COUNT; i++) {
+ dscr++;
+ if (dscr > DSCR_MAX)
+ dscr = 0;
+
+ if (dscr == get_default_dscr())
+ continue;
+
+ if (i % 2 == 0)
+ set_dscr_usr(dscr);
+ else
+ set_dscr(dscr);
+
+ /*
+ * XXX: Force a context switch out so that DSCR
+ * current value is copied into the thread struct
+ * which is required for the child to inherit the
+ * changed value.
+ */
+ sleep(1);
+
+ pid = fork();
+ if (pid == -1) {
+ perror("fork() failed\n");
+ exit(1);
+ } else if (pid) {
+ int status;
+
+ if (waitpid(pid, &status, 0) == -1) {
+ perror("waitpid() failed\n");
+ 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 {
+ char dscr_str[16];
+
+ sprintf(dscr_str, "%ld", dscr);
+ execlp(prog, prog, "exec", dscr_str, NULL);
+ exit(1);
+ }
+ }
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ if (argc == 3 && !strcmp(argv[1], "exec")) {
+ unsigned long parent_dscr;
+
+ parent_dscr = atoi(argv[2]);
+ do_exec(parent_dscr);
+ } else if (argc != 1) {
+ fprintf(stderr, "Usage: %s\n", argv[0]);
+ exit(1);
+ }
+
+ strncpy(prog, argv[0], strlen(argv[0]));
+ return test_harness(test_body, "dscr_inherit_exec_test");
+}
--
1.9.3


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