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 
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 
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 		pid = fork();
64 		if (pid == -1) {
65 			perror("fork() failed");
66 			exit(1);
67 		} else if (pid) {
68 			int status;
69 
70 			if (waitpid(pid, &status, 0) == -1) {
71 				perror("waitpid() failed");
72 				exit(1);
73 			}
74 
75 			if (!WIFEXITED(status)) {
76 				fprintf(stderr, "Child didn't exit cleanly\n");
77 				exit(1);
78 			}
79 
80 			if (WEXITSTATUS(status) != 0) {
81 				fprintf(stderr, "Child didn't exit cleanly\n");
82 				return 1;
83 			}
84 		} else {
85 			char dscr_str[16];
86 
87 			sprintf(dscr_str, "%ld", dscr);
88 			execlp(prog, prog, "exec", dscr_str, NULL);
89 			exit(1);
90 		}
91 	}
92 	return 0;
93 }
94 
95 int main(int argc, char *argv[])
96 {
97 	if (argc == 3 && !strcmp(argv[1], "exec")) {
98 		unsigned long parent_dscr;
99 
100 		parent_dscr = atoi(argv[2]);
101 		do_exec(parent_dscr);
102 	} else if (argc != 1) {
103 		fprintf(stderr, "Usage: %s\n", argv[0]);
104 		exit(1);
105 	}
106 
107 	strncpy(prog, argv[0], strlen(argv[0]));
108 	return test_harness(dscr_inherit_exec, "dscr_inherit_exec_test");
109 }
110