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, u32 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 whether all CPU nodes have the TM flag */ 39 static bool all_cpus_have_tm(void) 40 { 41 int ret; 42 int available = 0; 43 44 ret = dt_for_each_cpu_node(cpu_has_tm, &available); 45 46 return ret == 0 && available == nr_cpus; 47 } 48 49 static int h_cede(void) 50 { 51 register uint64_t r3 asm("r3") = H_CEDE; 52 53 asm volatile ("sc 1" : "+r"(r3) : 54 : "r0", "r4", "r5", "r6", "r7", "r8", "r9", 55 "r10", "r11", "r12", "xer", "ctr", "cc"); 56 57 return r3; 58 } 59 60 /* 61 * Enable transactional memory 62 * Returns: FALSE - Failure 63 * TRUE - Success 64 */ 65 static bool enable_tm(void) 66 { 67 uint64_t msr = 0; 68 69 asm volatile ("mfmsr %[msr]" : [msr] "=r" (msr)); 70 71 msr |= (((uint64_t) 1) << 32); 72 73 asm volatile ("mtmsrd %[msr]\n\t" 74 "mfmsr %[msr]" : [msr] "+r" (msr)); 75 76 return !!(msr & (((uint64_t) 1) << 32)); 77 } 78 79 /* 80 * Test H_CEDE call while transactional memory transaction is suspended 81 * 82 * WARNING: This tests for a known vulnerability in which the host may go down. 83 * Probably best not to run this if your host going down is going to cause 84 * problems. 85 * 86 * If the test passes then your kernel probably has the necessary patch. 87 * If the test fails then the H_CEDE call was unsuccessful and the 88 * vulnerability wasn't tested. 89 * If the test hits the vulnerability then it will never complete or report and 90 * the qemu process will block indefinitely. RCU stalls will be detected on the 91 * cpu and any process scheduled on the lost cpu will also block indefinitely. 92 */ 93 static void test_h_cede_tm(int argc, char **argv) 94 { 95 int i; 96 97 if (argc > 2) 98 report_abort("Unsupported argument: '%s'", argv[2]); 99 100 handle_exception(0x900, &dec_except_handler, NULL); 101 102 if (!start_all_cpus(halt, 0)) 103 report_abort("Failed to start secondary cpus"); 104 105 if (!enable_tm()) 106 report_abort("Failed to enable tm"); 107 108 /* 109 * Begin a transaction and guarantee we are in the suspend state 110 * before continuing 111 */ 112 asm volatile ("1: .long 0x7c00051d\n\t" /* tbegin. */ 113 "beq 2f\n\t" 114 ".long 0x7c0005dd\n\t" /* tsuspend. */ 115 "2: .long 0x7c00059c\n\t" /* tcheck cr0 */ 116 "bf 2,1b" : : : "cr0"); 117 118 for (i = 0; i < 500; i++) { 119 uint64_t rval = h_cede(); 120 121 if (rval != H_SUCCESS) 122 break; 123 mdelay(5); 124 } 125 126 report("H_CEDE TM", i == 500); 127 } 128 129 struct { 130 const char *name; 131 void (*func)(int argc, char **argv); 132 } hctests[] = { 133 { "h_cede_tm", test_h_cede_tm }, 134 { NULL, NULL } 135 }; 136 137 int main(int argc, char **argv) 138 { 139 bool all, has_tm; 140 int i; 141 142 report_prefix_push("tm"); 143 144 has_tm = all_cpus_have_tm(); 145 report_xfail("TM available in 'ibm,pa-features' property", 146 !has_tm, has_tm); 147 if (!has_tm) 148 return report_summary(); 149 150 all = argc == 1 || !strcmp(argv[1], "all"); 151 152 for (i = 0; hctests[i].name != NULL; i++) { 153 if (all || strcmp(argv[1], hctests[i].name) == 0) { 154 report_prefix_push(hctests[i].name); 155 hctests[i].func(argc, argv); 156 report_prefix_pop(); 157 } 158 } 159 160 return report_summary(); 161 } 162