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
do_exec(unsigned long parent_dscr)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
dscr_inherit_exec(void)42 int dscr_inherit_exec(void)
43 {
44 unsigned long i, dscr = 0;
45 pid_t pid;
46
47 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
48
49 for (i = 0; i < COUNT; i++) {
50 dscr++;
51 if (dscr > DSCR_MAX)
52 dscr = 0;
53
54 if (dscr == get_default_dscr())
55 continue;
56
57 if (i % 2 == 0)
58 set_dscr_usr(dscr);
59 else
60 set_dscr(dscr);
61
62 pid = fork();
63 if (pid == -1) {
64 perror("fork() failed");
65 exit(1);
66 } else if (pid) {
67 int status;
68
69 if (waitpid(pid, &status, 0) == -1) {
70 perror("waitpid() failed");
71 exit(1);
72 }
73
74 if (!WIFEXITED(status)) {
75 fprintf(stderr, "Child didn't exit cleanly\n");
76 exit(1);
77 }
78
79 if (WEXITSTATUS(status) != 0) {
80 fprintf(stderr, "Child didn't exit cleanly\n");
81 return 1;
82 }
83 } else {
84 char dscr_str[16];
85
86 sprintf(dscr_str, "%ld", dscr);
87 execlp(prog, prog, "exec", dscr_str, NULL);
88 exit(1);
89 }
90 }
91 return 0;
92 }
93
main(int argc,char * argv[])94 int main(int argc, char *argv[])
95 {
96 if (argc == 3 && !strcmp(argv[1], "exec")) {
97 unsigned long parent_dscr;
98
99 parent_dscr = atoi(argv[2]);
100 do_exec(parent_dscr);
101 } else if (argc != 1) {
102 fprintf(stderr, "Usage: %s\n", argv[0]);
103 exit(1);
104 }
105
106 prog = argv[0];
107 return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
108 }
109
