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1// SPDX-License-Identifier: GPL-2.02/* Test context switching to see if the DSCR SPR is correctly preserved3 * 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 because22 * the transaction abort handler will restore the DSCR to it's checkpointed23 * 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 0x0337 38int 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 93static int tm_resched_dscr(void)94{95 return eat_cpu(test_body);96}97 98int main(int argc, const char *argv[])99{100 return test_harness(tm_resched_dscr, "tm_resched_dscr");101}102