1 /*
2 * POWER Data Stream Control Register (DSCR) fork exec test
3 *
4 * This testcase modifies the DSCR using mtspr, forks & execs and
5 * verifies that the child is using the changed DSCR using mfspr.
6 *
7 * When using the privilege state SPR, the instructions such as
8 * mfspr or mtspr are priviledged and the kernel emulates them
9 * for us. Instructions using problem state SPR can be exuecuted
10 * directly without any emulation if the HW supports them. Else
11 * they also get emulated by the kernel.
12 *
13 * Copyright 2012, Anton Blanchard, IBM Corporation.
14 * Copyright 2015, Anshuman Khandual, IBM Corporation.
15 *
16 * This program is free software; you can redistribute it and/or modify it
17 * under the terms of the GNU General Public License version 2 as published
18 * by the Free Software Foundation.
19 */
20 #include "dscr.h"
21
22 static char prog[LEN_MAX];
23
do_exec(unsigned long parent_dscr)24 static void do_exec(unsigned long parent_dscr)
25 {
26 unsigned long cur_dscr, cur_dscr_usr;
27
28 cur_dscr = get_dscr();
29 cur_dscr_usr = get_dscr_usr();
30
31 if (cur_dscr != parent_dscr) {
32 fprintf(stderr, "Parent DSCR %ld was not inherited "
33 "over exec (kernel value)\n", parent_dscr);
34 exit(1);
35 }
36
37 if (cur_dscr_usr != parent_dscr) {
38 fprintf(stderr, "Parent DSCR %ld was not inherited "
39 "over exec (user value)\n", parent_dscr);
40 exit(1);
41 }
42 exit(0);
43 }
44
dscr_inherit_exec(void)45 int dscr_inherit_exec(void)
46 {
47 unsigned long i, dscr = 0;
48 pid_t pid;
49
50 for (i = 0; i < COUNT; i++) {
51 dscr++;
52 if (dscr > DSCR_MAX)
53 dscr = 0;
54
55 if (dscr == get_default_dscr())
56 continue;
57
58 if (i % 2 == 0)
59 set_dscr_usr(dscr);
60 else
61 set_dscr(dscr);
62
63 /*
64 * XXX: Force a context switch out so that DSCR
65 * current value is copied into the thread struct
66 * which is required for the child to inherit the
67 * changed value.
68 */
69 sleep(1);
70
71 pid = fork();
72 if (pid == -1) {
73 perror("fork() failed");
74 exit(1);
75 } else if (pid) {
76 int status;
77
78 if (waitpid(pid, &status, 0) == -1) {
79 perror("waitpid() failed");
80 exit(1);
81 }
82
83 if (!WIFEXITED(status)) {
84 fprintf(stderr, "Child didn't exit cleanly\n");
85 exit(1);
86 }
87
88 if (WEXITSTATUS(status) != 0) {
89 fprintf(stderr, "Child didn't exit cleanly\n");
90 return 1;
91 }
92 } else {
93 char dscr_str[16];
94
95 sprintf(dscr_str, "%ld", dscr);
96 execlp(prog, prog, "exec", dscr_str, NULL);
97 exit(1);
98 }
99 }
100 return 0;
101 }
102
main(int argc,char * argv[])103 int main(int argc, char *argv[])
104 {
105 if (argc == 3 && !strcmp(argv[1], "exec")) {
106 unsigned long parent_dscr;
107
108 parent_dscr = atoi(argv[2]);
109 do_exec(parent_dscr);
110 } else if (argc != 1) {
111 fprintf(stderr, "Usage: %s\n", argv[0]);
112 exit(1);
113 }
114
115 strncpy(prog, argv[0], strlen(argv[0]));
116 return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
117 }
118