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 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 92 int main(void) 93 { 94 return test_harness(test_body, "tm_resched_dscr"); 95 } 96