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 TBEGIN ".long 0x7C00051D ;" 35 #define TEND ".long 0x7C00055D ;" 36 #define TCHECK ".long 0x7C00059C ;" 37 #define TSUSPEND ".long 0x7C0005DD ;" 38 #define TRESUME ".long 0x7C2005DD ;" 39 #define SPRN_TEXASR 0x82 40 #define SPRN_DSCR 0x03 41 42 int test_body(void) 43 { 44 uint64_t rv, dscr1 = 1, dscr2, texasr; 45 46 SKIP_IF(!have_htm()); 47 48 printf("Check DSCR TM context switch: "); 49 fflush(stdout); 50 for (;;) { 51 rv = 1; 52 asm __volatile__ ( 53 /* set a known value into the DSCR */ 54 "ld 3, %[dscr1];" 55 "mtspr %[sprn_dscr], 3;" 56 57 /* start and suspend a transaction */ 58 TBEGIN 59 "beq 1f;" 60 TSUSPEND 61 62 /* hard loop until the transaction becomes doomed */ 63 "2: ;" 64 TCHECK 65 "bc 4, 0, 2b;" 66 67 /* record DSCR and TEXASR */ 68 "mfspr 3, %[sprn_dscr];" 69 "std 3, %[dscr2];" 70 "mfspr 3, %[sprn_texasr];" 71 "std 3, %[texasr];" 72 73 TRESUME 74 TEND 75 "li %[rv], 0;" 76 "1: ;" 77 : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr) 78 : [dscr1]"m"(dscr1) 79 , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR) 80 : "memory", "r3" 81 ); 82 assert(rv); /* make sure the transaction aborted */ 83 if ((texasr >> 56) != TM_CAUSE_RESCHED) { 84 putchar('.'); 85 fflush(stdout); 86 continue; 87 } 88 if (dscr2 != dscr1) { 89 printf(" FAIL\n"); 90 return 1; 91 } else { 92 printf(" OK\n"); 93 return 0; 94 } 95 } 96 } 97 98 int main(void) 99 { 100 return test_harness(test_body, "tm_resched_dscr"); 101 } 102