1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright 2019, Gustavo Romero, Michael Neuling, IBM Corp. 4 * 5 * This test will spawn two processes. Both will be attached to the same 6 * CPU (CPU 0). The child will be in a loop writing to FP register f31 and 7 * VMX/VEC/Altivec register vr31 a known value, called poison, calling 8 * sched_yield syscall after to allow the parent to switch on the CPU. 9 * Parent will set f31 and vr31 to 1 and in a loop will check if f31 and 10 * vr31 remain 1 as expected until a given timeout (2m). If the issue is 11 * present child's poison will leak into parent's f31 or vr31 registers, 12 * otherwise, poison will never leak into parent's f31 and vr31 registers. 13 */ 14 15 #define _GNU_SOURCE 16 #include <stdio.h> 17 #include <stdlib.h> 18 #include <unistd.h> 19 #include <inttypes.h> 20 #include <sched.h> 21 #include <sys/types.h> 22 #include <signal.h> 23 #include <inttypes.h> 24 25 #include "tm.h" 26 27 int tm_poison_test(void) 28 { 29 int pid; 30 cpu_set_t cpuset; 31 uint64_t poison = 0xdeadbeefc0dec0fe; 32 uint64_t unknown = 0; 33 bool fail_fp = false; 34 bool fail_vr = false; 35 36 SKIP_IF(!have_htm()); 37 38 /* Attach both Child and Parent to CPU 0 */ 39 CPU_ZERO(&cpuset); 40 CPU_SET(0, &cpuset); 41 sched_setaffinity(0, sizeof(cpuset), &cpuset); 42 43 pid = fork(); 44 if (!pid) { 45 /** 46 * child 47 */ 48 while (1) { 49 sched_yield(); 50 asm ( 51 "mtvsrd 31, %[poison];" // f31 = poison 52 "mtvsrd 63, %[poison];" // vr31 = poison 53 54 : : [poison] "r" (poison) : ); 55 } 56 } 57 58 /** 59 * parent 60 */ 61 asm ( 62 /* 63 * Set r3, r4, and f31 to known value 1 before entering 64 * in transaction. They won't be written after that. 65 */ 66 " li 3, 0x1 ;" 67 " li 4, 0x1 ;" 68 " mtvsrd 31, 4 ;" 69 70 /* 71 * The Time Base (TB) is a 64-bit counter register that is 72 * independent of the CPU clock and which is incremented 73 * at a frequency of 512000000 Hz, so every 1.953125ns. 74 * So it's necessary 120s/0.000000001953125s = 61440000000 75 * increments to get a 2 minutes timeout. Below we set that 76 * value in r5 and then use r6 to track initial TB value, 77 * updating TB values in r7 at every iteration and comparing it 78 * to r6. When r7 (current) - r6 (initial) > 61440000000 we bail 79 * out since for sure we spent already 2 minutes in the loop. 80 * SPR 268 is the TB register. 81 */ 82 " lis 5, 14 ;" 83 " ori 5, 5, 19996 ;" 84 " sldi 5, 5, 16 ;" // r5 = 61440000000 85 86 " mfspr 6, 268 ;" // r6 (TB initial) 87 "1: mfspr 7, 268 ;" // r7 (TB current) 88 " subf 7, 6, 7 ;" // r7 - r6 > 61440000000 ? 89 " cmpd 7, 5 ;" 90 " bgt 3f ;" // yes, exit 91 92 /* 93 * Main loop to check f31 94 */ 95 " tbegin. ;" // no, try again 96 " beq 1b ;" // restart if no timeout 97 " mfvsrd 3, 31 ;" // read f31 98 " cmpd 3, 4 ;" // f31 == 1 ? 99 " bne 2f ;" // broken :-( 100 " tabort. 3 ;" // try another transaction 101 "2: tend. ;" // commit transaction 102 "3: mr %[unknown], 3 ;" // record r3 103 104 : [unknown] "=r" (unknown) 105 : 106 : "cr0", "r3", "r4", "r5", "r6", "r7", "vs31" 107 108 ); 109 110 /* 111 * On leak 'unknown' will contain 'poison' value from child, 112 * otherwise (no leak) 'unknown' will contain the same value 113 * as r3 before entering in transactional mode, i.e. 0x1. 114 */ 115 fail_fp = unknown != 0x1; 116 if (fail_fp) 117 printf("Unknown value %#"PRIx64" leaked into f31!\n", unknown); 118 else 119 printf("Good, no poison or leaked value into FP registers\n"); 120 121 asm ( 122 /* 123 * Set r3, r4, and vr31 to known value 1 before entering 124 * in transaction. They won't be written after that. 125 */ 126 " li 3, 0x1 ;" 127 " li 4, 0x1 ;" 128 " mtvsrd 63, 4 ;" 129 130 " lis 5, 14 ;" 131 " ori 5, 5, 19996 ;" 132 " sldi 5, 5, 16 ;" // r5 = 61440000000 133 134 " mfspr 6, 268 ;" // r6 (TB initial) 135 "1: mfspr 7, 268 ;" // r7 (TB current) 136 " subf 7, 6, 7 ;" // r7 - r6 > 61440000000 ? 137 " cmpd 7, 5 ;" 138 " bgt 3f ;" // yes, exit 139 140 /* 141 * Main loop to check vr31 142 */ 143 " tbegin. ;" // no, try again 144 " beq 1b ;" // restart if no timeout 145 " mfvsrd 3, 63 ;" // read vr31 146 " cmpd 3, 4 ;" // vr31 == 1 ? 147 " bne 2f ;" // broken :-( 148 " tabort. 3 ;" // try another transaction 149 "2: tend. ;" // commit transaction 150 "3: mr %[unknown], 3 ;" // record r3 151 152 : [unknown] "=r" (unknown) 153 : 154 : "cr0", "r3", "r4", "r5", "r6", "r7", "vs63" 155 156 ); 157 158 /* 159 * On leak 'unknown' will contain 'poison' value from child, 160 * otherwise (no leak) 'unknown' will contain the same value 161 * as r3 before entering in transactional mode, i.e. 0x1. 162 */ 163 fail_vr = unknown != 0x1; 164 if (fail_vr) 165 printf("Unknown value %#"PRIx64" leaked into vr31!\n", unknown); 166 else 167 printf("Good, no poison or leaked value into VEC registers\n"); 168 169 kill(pid, SIGKILL); 170 171 return (fail_fp | fail_vr); 172 } 173 174 int main(int argc, char *argv[]) 175 { 176 /* Test completes in about 4m */ 177 test_harness_set_timeout(250); 178 return test_harness(tm_poison_test, "tm_poison_test"); 179 } 180