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 #include "../pmu/lib.h" 34 35 #define SPRN_DSCR 0x03 36 37 int test_body(void) 38 { 39 uint64_t rv, dscr1 = 1, dscr2, texasr; 40 41 SKIP_IF(!have_htm()); 42 43 printf("Check DSCR TM context switch: "); 44 fflush(stdout); 45 for (;;) { 46 asm __volatile__ ( 47 /* set a known value into the DSCR */ 48 "ld 3, %[dscr1];" 49 "mtspr %[sprn_dscr], 3;" 50 51 "li %[rv], 1;" 52 /* start and suspend a transaction */ 53 "tbegin.;" 54 "beq 1f;" 55 "tsuspend.;" 56 57 /* hard loop until the transaction becomes doomed */ 58 "2: ;" 59 "tcheck 0;" 60 "bc 4, 0, 2b;" 61 62 /* record DSCR and TEXASR */ 63 "mfspr 3, %[sprn_dscr];" 64 "std 3, %[dscr2];" 65 "mfspr 3, %[sprn_texasr];" 66 "std 3, %[texasr];" 67 68 "tresume.;" 69 "tend.;" 70 "li %[rv], 0;" 71 "1: ;" 72 : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr) 73 : [dscr1]"m"(dscr1) 74 , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR) 75 : "memory", "r3" 76 ); 77 assert(rv); /* make sure the transaction aborted */ 78 if ((texasr >> 56) != TM_CAUSE_RESCHED) { 79 continue; 80 } 81 if (dscr2 != dscr1) { 82 printf(" FAIL\n"); 83 return 1; 84 } else { 85 printf(" OK\n"); 86 return 0; 87 } 88 } 89 } 90 91 static int tm_resched_dscr(void) 92 { 93 return eat_cpu(test_body); 94 } 95 96 int main(int argc, const char *argv[]) 97 { 98 return test_harness(tm_resched_dscr, "tm_resched_dscr"); 99 } 100