1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * POWER Data Stream Control Register (DSCR) fork test
4 *
5 * This testcase modifies the DSCR using mtspr, forks and then
6 * verifies that the child process has the correct changed DSCR
7 * value using mfspr.
8 *
9 * When using the privilege state SPR, the instructions such as
10 * mfspr or mtspr are priviledged and the kernel emulates them
11 * for us. Instructions using problem state SPR can be exuecuted
12 * directly without any emulation if the HW supports them. Else
13 * they also get emulated by the kernel.
14 *
15 * Copyright 2012, Anton Blanchard, IBM Corporation.
16 * Copyright 2015, Anshuman Khandual, IBM Corporation.
17 */
18 #include "dscr.h"
19
20 int dscr_inherit(void)
21 {
22 unsigned long i, dscr = 0;
23 pid_t pid;
24
25 srand(getpid());
26 set_dscr(dscr);
27
28 for (i = 0; i < COUNT; i++) {
29 unsigned long cur_dscr, cur_dscr_usr;
30
31 dscr++;
32 if (dscr > DSCR_MAX)
33 dscr = 0;
34
35 if (i % 2 == 0)
36 set_dscr_usr(dscr);
37 else
38 set_dscr(dscr);
39
40 pid = fork();
41 if (pid == -1) {
42 perror("fork() failed");
43 exit(1);
44 } else if (pid) {
45 int status;
46
47 if (waitpid(pid, &status, 0) == -1) {
48 perror("waitpid() failed");
49 exit(1);
50 }
51
52 if (!WIFEXITED(status)) {
53 fprintf(stderr, "Child didn't exit cleanly\n");
54 exit(1);
55 }
56
57 if (WEXITSTATUS(status) != 0) {
58 fprintf(stderr, "Child didn't exit cleanly\n");
59 return 1;
60 }
61 } else {
62 cur_dscr = get_dscr();
63 if (cur_dscr != dscr) {
64 fprintf(stderr, "Kernel DSCR should be %ld "
65 "but is %ld\n", dscr, cur_dscr);
66 exit(1);
67 }
68
69 cur_dscr_usr = get_dscr_usr();
70 if (cur_dscr_usr != dscr) {
71 fprintf(stderr, "User DSCR should be %ld "
72 "but is %ld\n", dscr, cur_dscr_usr);
73 exit(1);
74 }
75 exit(0);
76 }
77 }
78 return 0;
79 }
80
81 int main(int argc, char *argv[])
82 {
83 return test_harness(dscr_inherit, "dscr_inherit_test");
84 }