1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * POWER Data Stream Control Register (DSCR) explicit test
4 *
5 * This test modifies the DSCR value using mtspr instruction and
6 * verifies the change with mfspr instruction. It uses both the
7 * privilege state SPR and the problem state SPR for this purpose.
8 *
9 * When using the privilege state SPR, the instructions such as
10 * mfspr or mtspr are priviledged and the kernel emulates them
11 * for us. Instructions using problem state SPR can be exuecuted
12 * directly without any emulation if the HW supports them. Else
13 * they also get emulated by the kernel.
14 *
15 * Copyright 2012, Anton Blanchard, IBM Corporation.
16 * Copyright 2015, Anshuman Khandual, IBM Corporation.
17 */
18 #include "dscr.h"
19
dscr_explicit(void)20 int dscr_explicit(void)
21 {
22 unsigned long i, dscr = 0;
23
24 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
25
26 srand(getpid());
27 set_dscr(dscr);
28
29 for (i = 0; i < COUNT; i++) {
30 unsigned long cur_dscr, cur_dscr_usr;
31 double ret = uniform_deviate(rand());
32
33 if (ret < 0.001) {
34 dscr++;
35 if (dscr > DSCR_MAX)
36 dscr = 0;
37
38 set_dscr(dscr);
39 }
40
41 cur_dscr = get_dscr();
42 if (cur_dscr != dscr) {
43 fprintf(stderr, "Kernel DSCR should be %ld but "
44 "is %ld\n", dscr, cur_dscr);
45 return 1;
46 }
47
48 ret = uniform_deviate(rand());
49 if (ret < 0.001) {
50 dscr++;
51 if (dscr > DSCR_MAX)
52 dscr = 0;
53
54 set_dscr_usr(dscr);
55 }
56
57 cur_dscr_usr = get_dscr_usr();
58 if (cur_dscr_usr != dscr) {
59 fprintf(stderr, "User DSCR should be %ld but "
60 "is %ld\n", dscr, cur_dscr_usr);
61 return 1;
62 }
63 }
64 return 0;
65 }
66
main(int argc,char * argv[])67 int main(int argc, char *argv[])
68 {
69 return test_harness(dscr_explicit, "dscr_explicit_test");
70 }
71