1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * POWER Data Stream Control Register (DSCR) fork exec test
4 *
5 * This testcase modifies the DSCR using mtspr, forks & execs and
6 * verifies that the child is using the changed DSCR using mfspr.
7 *
8 * When using the privilege state SPR, the instructions such as
9 * mfspr or mtspr are privileged and the kernel emulates them
10 * for us. Instructions using problem state SPR can be executed
11 * directly without any emulation if the HW supports them. Else
12 * they also get emulated by the kernel.
13 *
14 * Copyright 2012, Anton Blanchard, IBM Corporation.
15 * Copyright 2015, Anshuman Khandual, IBM Corporation.
16 */
17 #include "dscr.h"
18
19 static char *prog;
20
21 static void do_exec(unsigned long parent_dscr)
22 {
23 unsigned long cur_dscr, cur_dscr_usr;
24
25 cur_dscr = get_dscr();
26 cur_dscr_usr = get_dscr_usr();
27
28 if (cur_dscr != parent_dscr) {
29 fprintf(stderr, "Parent DSCR %ld was not inherited "
30 "over exec (kernel value)\n", parent_dscr);
31 exit(1);
32 }
33
34 if (cur_dscr_usr != parent_dscr) {
35 fprintf(stderr, "Parent DSCR %ld was not inherited "
36 "over exec (user value)\n", parent_dscr);
37 exit(1);
38 }
39 exit(0);
40 }
41
42 int dscr_inherit_exec(void)
43 {
44 unsigned long i, dscr = 0;
45 pid_t pid;
46
47 for (i = 0; i < COUNT; i++) {
48 dscr++;
49 if (dscr > DSCR_MAX)
50 dscr = 0;
51
52 if (dscr == get_default_dscr())
53 continue;
54
55 if (i % 2 == 0)
56 set_dscr_usr(dscr);
57 else
58 set_dscr(dscr);
59
60 pid = fork();
61 if (pid == -1) {
62 perror("fork() failed");
63 exit(1);
64 } else if (pid) {
65 int status;
66
67 if (waitpid(pid, &status, 0) == -1) {
68 perror("waitpid() failed");
69 exit(1);
70 }
71
72 if (!WIFEXITED(status)) {
73 fprintf(stderr, "Child didn't exit cleanly\n");
74 exit(1);
75 }
76
77 if (WEXITSTATUS(status) != 0) {
78 fprintf(stderr, "Child didn't exit cleanly\n");
79 return 1;
80 }
81 } else {
82 char dscr_str[16];
83
84 sprintf(dscr_str, "%ld", dscr);
85 execlp(prog, prog, "exec", dscr_str, NULL);
86 exit(1);
87 }
88 }
89 return 0;
90 }
91
92 int main(int argc, char *argv[])
93 {
94 if (argc == 3 && !strcmp(argv[1], "exec")) {
95 unsigned long parent_dscr;
96
97 parent_dscr = atoi(argv[2]);
98 do_exec(parent_dscr);
99 } else if (argc != 1) {
100 fprintf(stderr, "Usage: %s\n", argv[0]);
101 exit(1);
102 }
103
104 prog = argv[0];
105 return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
106 }