1 /* 2 * Transactional Memory Unit Tests 3 * 4 * Copyright 2016 Suraj Jitindar Singh, IBM. 5 * 6 * This work is licensed under the terms of the GNU LGPL, version 2. 7 */ 8 #include <libcflat.h> 9 #include <asm/hcall.h> 10 #include <asm/processor.h> 11 #include <asm/handlers.h> 12 #include <asm/smp.h> 13 #include <asm/setup.h> 14 #include <devicetree.h> 15 16 /* Check "ibm,pa-features" property of a CPU node for the TM flag */ 17 static void cpu_has_tm(int fdtnode, u64 regval __unused, void *ptr) 18 { 19 const struct fdt_property *prop; 20 int plen; 21 22 prop = fdt_get_property(dt_fdt(), fdtnode, "ibm,pa-features", &plen); 23 if (!prop) /* No features means TM is also not available */ 24 return; 25 /* Sanity check for the property layout (first two bytes are header) */ 26 assert(plen >= 8 && prop->data[1] == 0 && prop->data[0] <= plen - 2); 27 28 /* 29 * The "Transactional Memory Category Support" flags are at byte 30 * offset 22 and 23 of the attribute type 0, so when adding the 31 * two bytes for the header, we've got to look at offset 24 for 32 * the TM support bit. 33 */ 34 if (prop->data[0] >= 24 && (prop->data[24] & 0x80) != 0) 35 *(int *)ptr += 1; 36 } 37 38 /* Check amount of CPUs nodes that have the TM flag */ 39 static int count_cpus_with_tm(void) 40 { 41 int ret; 42 int available = 0; 43 44 ret = dt_for_each_cpu_node(cpu_has_tm, &available); 45 if (ret < 0) 46 return ret; 47 48 return available; 49 } 50 51 /* 52 * Enable transactional memory 53 * Returns: FALSE - Failure 54 * TRUE - Success 55 */ 56 static bool enable_tm(void) 57 { 58 uint64_t msr = 0; 59 60 asm volatile ("mfmsr %[msr]" : [msr] "=r" (msr)); 61 62 msr |= (((uint64_t) 1) << 32); 63 64 asm volatile ("mtmsrd %[msr]\n\t" 65 "mfmsr %[msr]" : [msr] "+r" (msr)); 66 67 return !!(msr & (((uint64_t) 1) << 32)); 68 } 69 70 /* 71 * Test H_CEDE call while transactional memory transaction is suspended 72 * 73 * WARNING: This tests for a known vulnerability in which the host may go down. 74 * Probably best not to run this if your host going down is going to cause 75 * problems. 76 * 77 * If the test passes then your kernel probably has the necessary patch. 78 * If the test fails then the H_CEDE call was unsuccessful and the 79 * vulnerability wasn't tested. 80 * If the test hits the vulnerability then it will never complete or report and 81 * the qemu process will block indefinitely. RCU stalls will be detected on the 82 * cpu and any process scheduled on the lost cpu will also block indefinitely. 83 */ 84 static void test_h_cede_tm(int argc, char **argv) 85 { 86 int i; 87 88 if (argc > 2) 89 report_abort("Unsupported argument: '%s'", argv[2]); 90 91 if (!start_all_cpus(halt, 0)) 92 report_abort("Failed to start secondary cpus"); 93 94 if (!enable_tm()) 95 report_abort("Failed to enable tm"); 96 97 /* 98 * Begin a transaction and guarantee we are in the suspend state 99 * before continuing 100 */ 101 asm volatile ("1: .long 0x7c00051d\n\t" /* tbegin. */ 102 "beq 2f\n\t" 103 ".long 0x7c0005dd\n\t" /* tsuspend. */ 104 "2: .long 0x7c00059c\n\t" /* tcheck cr0 */ 105 "bf 2,1b" : : : "cr0"); 106 107 for (i = 0; i < 500; i++) { 108 msleep(10); 109 mdelay(5); 110 } 111 112 report(i == 500, "H_CEDE TM"); 113 } 114 115 struct { 116 const char *name; 117 void (*func)(int argc, char **argv); 118 } hctests[] = { 119 { "h_cede_tm", test_h_cede_tm }, 120 { NULL, NULL } 121 }; 122 123 int main(int argc, char **argv) 124 { 125 bool all; 126 int i, cpus_with_tm; 127 128 report_prefix_push("tm"); 129 130 cpus_with_tm = count_cpus_with_tm(); 131 if (cpus_with_tm == 0) { 132 report_skip("TM is not available"); 133 goto done; 134 } 135 report(cpus_with_tm == nr_cpus, 136 "TM available in all 'ibm,pa-features' properties"); 137 138 all = argc == 1 || !strcmp(argv[1], "all"); 139 140 for (i = 0; hctests[i].name != NULL; i++) { 141 if (all || strcmp(argv[1], hctests[i].name) == 0) { 142 report_prefix_push(hctests[i].name); 143 hctests[i].func(argc, argv); 144 report_prefix_pop(); 145 } 146 } 147 148 done: 149 report_prefix_pop(); 150 return report_summary(); 151 } 152