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
19static char *prog;
20
21static 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
42int 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
94int 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