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 44 printf("Check DSCR TM context switch: "); 45 fflush(stdout); 46 for (;;) { 47 asm __volatile__ ( 48 /* set a known value into the DSCR */ 49 "ld 3, %[dscr1];" 50 "mtspr %[sprn_dscr], 3;" 51 52 "li %[rv], 1;" 53 /* start and suspend a transaction */ 54 "tbegin.;" 55 "beq 1f;" 56 "tsuspend.;" 57 58 /* hard loop until the transaction becomes doomed */ 59 "2: ;" 60 "tcheck 0;" 61 "bc 4, 0, 2b;" 62 63 /* record DSCR and TEXASR */ 64 "mfspr 3, %[sprn_dscr];" 65 "std 3, %[dscr2];" 66 "mfspr 3, %[sprn_texasr];" 67 "std 3, %[texasr];" 68 69 "tresume.;" 70 "tend.;" 71 "li %[rv], 0;" 72 "1: ;" 73 : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr) 74 : [dscr1]"m"(dscr1) 75 , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR) 76 : "memory", "r3" 77 ); 78 assert(rv); /* make sure the transaction aborted */ 79 if ((texasr >> 56) != TM_CAUSE_RESCHED) { 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 static int tm_resched_dscr(void) 93 { 94 return eat_cpu(test_body); 95 } 96 97 int main(int argc, const char *argv[]) 98 { 99 return test_harness(tm_resched_dscr, "tm_resched_dscr"); 100 } 101