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 33 #define TBEGIN ".long 0x7C00051D ;" 34 #define TEND ".long 0x7C00055D ;" 35 #define TCHECK ".long 0x7C00059C ;" 36 #define TSUSPEND ".long 0x7C0005DD ;" 37 #define TRESUME ".long 0x7C2005DD ;" 38 #define SPRN_TEXASR 0x82 39 #define SPRN_DSCR 0x03 40 41 int test_body(void) 42 { 43 uint64_t rv, dscr1 = 1, dscr2, texasr; 44 45 printf("Check DSCR TM context switch: "); 46 fflush(stdout); 47 for (;;) { 48 rv = 1; 49 asm __volatile__ ( 50 /* set a known value into the DSCR */ 51 "ld 3, %[dscr1];" 52 "mtspr %[sprn_dscr], 3;" 53 54 /* start and suspend a transaction */ 55 TBEGIN 56 "beq 1f;" 57 TSUSPEND 58 59 /* hard loop until the transaction becomes doomed */ 60 "2: ;" 61 TCHECK 62 "bc 4, 0, 2b;" 63 64 /* record DSCR and TEXASR */ 65 "mfspr 3, %[sprn_dscr];" 66 "std 3, %[dscr2];" 67 "mfspr 3, %[sprn_texasr];" 68 "std 3, %[texasr];" 69 70 TRESUME 71 TEND 72 "li %[rv], 0;" 73 "1: ;" 74 : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr) 75 : [dscr1]"m"(dscr1) 76 , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR) 77 : "memory", "r3" 78 ); 79 assert(rv); /* make sure the transaction aborted */ 80 if ((texasr >> 56) != TM_CAUSE_RESCHED) { 81 putchar('.'); 82 fflush(stdout); 83 continue; 84 } 85 if (dscr2 != dscr1) { 86 printf(" FAIL\n"); 87 return 1; 88 } else { 89 printf(" OK\n"); 90 return 0; 91 } 92 } 93 } 94 95 int main(void) 96 { 97 return test_harness(test_body, "tm_resched_dscr"); 98 } 99