1 // SPDX-License-Identifier: GPL-2.0 2 /* Test context switching to see if the DSCR SPR is correctly preserved 3 * when within a transaction. 4 * 5 * Note: We assume that the DSCR has been left at the default value (0) 6 * for all CPUs. 7 * 8 * Method: 9 * 10 * Set a value into the DSCR. 11 * 12 * Start a transaction, and suspend it (*). 13 * 14 * Hard loop checking to see if the transaction has become doomed. 15 * 16 * Now that we *may* have been preempted, record the DSCR and TEXASR SPRS. 17 * 18 * If the abort was because of a context switch, check the DSCR value. 19 * Otherwise, try again. 20 * 21 * (*) If the transaction is not suspended we can't see the problem because 22 * the transaction abort handler will restore the DSCR to it's checkpointed 23 * value before we regain control. 24 */ 25 26 #include <inttypes.h> 27 #include <stdio.h> 28 #include <stdlib.h> 29 #include <assert.h> 30 #include <asm/tm.h> 31 32 #include "utils.h" 33 #include "tm.h" 34 #include "../pmu/lib.h" 35 36 #define SPRN_DSCR 0x03 37 38 int test_body(void) 39 { 40 uint64_t rv, dscr1 = 1, dscr2, texasr; 41 42 SKIP_IF(!have_htm()); 43 SKIP_IF(htm_is_synthetic()); 44 45 printf("Check DSCR TM context switch: "); 46 fflush(stdout); 47 for (;;) { 48 asm __volatile__ ( 49 /* set a known value into the DSCR */ 50 "ld 3, %[dscr1];" 51 "mtspr %[sprn_dscr], 3;" 52 53 "li %[rv], 1;" 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 0;" 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 continue; 82 } 83 if (dscr2 != dscr1) { 84 printf(" FAIL\n"); 85 return 1; 86 } else { 87 printf(" OK\n"); 88 return 0; 89 } 90 } 91 } 92 93 static int tm_resched_dscr(void) 94 { 95 return eat_cpu(test_body); 96 } 97 98 int main(int argc, const char *argv[]) 99 { 100 return test_harness(tm_resched_dscr, "tm_resched_dscr"); 101 } 102