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 privileged and the kernel emulates them
11 * for us. Instructions using problem state SPR can be executed
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 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
26
27 srand(getpid());
28 set_dscr(dscr);
29
30 for (i = 0; i < COUNT; i++) {
31 unsigned long cur_dscr, cur_dscr_usr;
32
33 dscr++;
34 if (dscr > DSCR_MAX)
35 dscr = 0;
36
37 if (i % 2 == 0)
38 set_dscr_usr(dscr);
39 else
40 set_dscr(dscr);
41
42 pid = fork();
43 if (pid == -1) {
44 perror("fork() failed");
45 exit(1);
46 } else if (pid) {
47 int status;
48
49 if (waitpid(pid, &status, 0) == -1) {
50 perror("waitpid() failed");
51 exit(1);
52 }
53
54 if (!WIFEXITED(status)) {
55 fprintf(stderr, "Child didn't exit cleanly\n");
56 exit(1);
57 }
58
59 if (WEXITSTATUS(status) != 0) {
60 fprintf(stderr, "Child didn't exit cleanly\n");
61 return 1;
62 }
63 } else {
64 cur_dscr = get_dscr();
65 if (cur_dscr != dscr) {
66 fprintf(stderr, "Kernel DSCR should be %ld "
67 "but is %ld\n", dscr, cur_dscr);
68 exit(1);
69 }
70
71 cur_dscr_usr = get_dscr_usr();
72 if (cur_dscr_usr != dscr) {
73 fprintf(stderr, "User DSCR should be %ld "
74 "but is %ld\n", dscr, cur_dscr_usr);
75 exit(1);
76 }
77 exit(0);
78 }
79 }
80 return 0;
81 }
82
83 int main(int argc, char *argv[])
84 {
85 return test_harness(dscr_inherit, "dscr_inherit_test");
86 }
87
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