1 /* Test context switching to see if the DSCR SPR is correctly preserved
2 * when within a transaction.
3 *
4 * Note: We assume that the DSCR has been left at the default value (0)
5 * for all CPUs.
6 *
7 * Method:
8 *
9 * Set a value into the DSCR.
10 *
11 * Start a transaction, and suspend it (*).
12 *
13 * Hard loop checking to see if the transaction has become doomed.
14 *
15 * Now that we *may* have been preempted, record the DSCR and TEXASR SPRS.
16 *
17 * If the abort was because of a context switch, check the DSCR value.
18 * Otherwise, try again.
19 *
20 * (*) If the transaction is not suspended we can't see the problem because
21 * the transaction abort handler will restore the DSCR to it's checkpointed
22 * value before we regain control.
23 */
24
25 #include <inttypes.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <assert.h>
29 #include <asm/tm.h>
30
31 #include "utils.h"
32 #include "tm.h"
33
34 #define SPRN_DSCR 0x03
35
test_body(void)36 int test_body(void)
37 {
38 uint64_t rv, dscr1 = 1, dscr2, texasr;
39
40 SKIP_IF(!have_htm());
41
42 printf("Check DSCR TM context switch: ");
43 fflush(stdout);
44 for (;;) {
45 asm __volatile__ (
46 /* set a known value into the DSCR */
47 "ld 3, %[dscr1];"
48 "mtspr %[sprn_dscr], 3;"
49
50 "li %[rv], 1;"
51 /* start and suspend a transaction */
52 "tbegin.;"
53 "beq 1f;"
54 "tsuspend.;"
55
56 /* hard loop until the transaction becomes doomed */
57 "2: ;"
58 "tcheck 0;"
59 "bc 4, 0, 2b;"
60
61 /* record DSCR and TEXASR */
62 "mfspr 3, %[sprn_dscr];"
63 "std 3, %[dscr2];"
64 "mfspr 3, %[sprn_texasr];"
65 "std 3, %[texasr];"
66
67 "tresume.;"
68 "tend.;"
69 "li %[rv], 0;"
70 "1: ;"
71 : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr)
72 : [dscr1]"m"(dscr1)
73 , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR)
74 : "memory", "r3"
75 );
76 assert(rv); /* make sure the transaction aborted */
77 if ((texasr >> 56) != TM_CAUSE_RESCHED) {
78 putchar('.');
79 fflush(stdout);
80 continue;
81 }
82 if (dscr2 != dscr1) {
83 printf(" FAIL\n");
84 return 1;
85 } else {
86 printf(" OK\n");
87 return 0;
88 }
89 }
90 }
91
main(void)92 int main(void)
93 {
94 return test_harness(test_body, "tm_resched_dscr");
95 }
96