selftests/powerpc: Add test for DSCR value inheritence across fork

This patch adds a test to verify that the changed DSCR value inside any
process would be inherited to it's child process across the fork system
call.

Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/tools/testing/selftests/powerpc/dscr/Makefile b/tools/testing/selftests/powerpc/dscr/Makefile
index 3c3856be6bf9ed6fba84773284ef10bf5069eddd..764fadc36cbb084a5f064566ad84849fe71cb623 100644 (file)
--- a/tools/testing/selftests/powerpc/dscr/Makefile
+++ b/tools/testing/selftests/powerpc/dscr/Makefile
@@ -1,4 +1,5 @@
-TEST_PROGS := dscr_default_test dscr_explicit_test dscr_user_test
+TEST_PROGS := dscr_default_test dscr_explicit_test dscr_user_test      \
+             dscr_inherit_test
 
 dscr_default_test: LDLIBS += -lpthread
 

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 (file)
index 0000000..4e414ca
--- /dev/null
+++ b/tools/testing/selftests/powerpc/dscr/dscr_inherit_test.c
@@ -0,0 +1,95 @@
+/*
+ * 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.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+#include "dscr.h"
+
+int dscr_inherit(void)
+{
+       unsigned long i, dscr = 0;
+       pid_t pid;
+
+       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);
+
+               /*
+                * 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");
+                       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");
+}