1 // SPDX-License-Identifier: GPL-2.0+ 2 // 3 // Copyright 2019, Michael Ellerman, IBM Corp. 4 // 5 // Test that out-of-bounds reads/writes behave as expected. 6 7 #include <setjmp.h> 8 #include <stdbool.h> 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <sys/types.h> 13 #include <sys/wait.h> 14 #include <unistd.h> 15 16 #include "utils.h" 17 18 // Old distros (Ubuntu 16.04 at least) don't define this 19 #ifndef SEGV_BNDERR 20 #define SEGV_BNDERR 3 21 #endif 22 23 // 64-bit kernel is always here 24 #define PAGE_OFFSET (0xcul << 60) 25 26 static unsigned long kernel_virt_end; 27 28 static volatile int fault_code; 29 static volatile unsigned long fault_addr; 30 static jmp_buf setjmp_env; 31 32 static void segv_handler(int n, siginfo_t *info, void *ctxt_v) 33 { 34 fault_code = info->si_code; 35 fault_addr = (unsigned long)info->si_addr; 36 siglongjmp(setjmp_env, 1); 37 } 38 39 int bad_access(char *p, bool write) 40 { 41 char x = 0; 42 43 fault_code = 0; 44 fault_addr = 0; 45 46 if (sigsetjmp(setjmp_env, 1) == 0) { 47 if (write) 48 *p = 1; 49 else 50 x = *p; 51 52 printf("Bad - no SEGV! (%c)\n", x); 53 return 1; 54 } 55 56 // If we see MAPERR that means we took a page fault rather than an SLB 57 // miss. We only expect to take page faults for addresses within the 58 // valid kernel range. 59 FAIL_IF(fault_code == SEGV_MAPERR && \ 60 (fault_addr < PAGE_OFFSET || fault_addr >= kernel_virt_end)); 61 62 FAIL_IF(fault_code != SEGV_MAPERR && fault_code != SEGV_BNDERR); 63 64 return 0; 65 } 66 67 static int test(void) 68 { 69 unsigned long i, j, addr, region_shift, page_shift, page_size; 70 struct sigaction sig; 71 bool hash_mmu; 72 73 sig = (struct sigaction) { 74 .sa_sigaction = segv_handler, 75 .sa_flags = SA_SIGINFO, 76 }; 77 78 FAIL_IF(sigaction(SIGSEGV, &sig, NULL) != 0); 79 80 FAIL_IF(using_hash_mmu(&hash_mmu)); 81 82 page_size = sysconf(_SC_PAGESIZE); 83 if (page_size == (64 * 1024)) 84 page_shift = 16; 85 else 86 page_shift = 12; 87 88 if (page_size == (64 * 1024) || !hash_mmu) { 89 region_shift = 52; 90 91 // We have 7 512T regions (4 kernel linear, vmalloc, io, vmemmap) 92 kernel_virt_end = PAGE_OFFSET + (7 * (512ul << 40)); 93 } else if (page_size == (4 * 1024) && hash_mmu) { 94 region_shift = 46; 95 96 // We have 7 64T regions (4 kernel linear, vmalloc, io, vmemmap) 97 kernel_virt_end = PAGE_OFFSET + (7 * (64ul << 40)); 98 } else 99 FAIL_IF(true); 100 101 printf("Using %s MMU, PAGE_SIZE = %dKB start address 0x%016lx\n", 102 hash_mmu ? "hash" : "radix", 103 (1 << page_shift) >> 10, 104 1ul << region_shift); 105 106 // This generates access patterns like: 107 // 0x0010000000000000 108 // 0x0010000000010000 109 // 0x0010000000020000 110 // ... 111 // 0x0014000000000000 112 // 0x0018000000000000 113 // 0x0020000000000000 114 // 0x0020000000010000 115 // 0x0020000000020000 116 // ... 117 // 0xf400000000000000 118 // 0xf800000000000000 119 120 for (i = 1; i <= ((0xful << 60) >> region_shift); i++) { 121 for (j = page_shift - 1; j < 60; j++) { 122 unsigned long base, delta; 123 124 base = i << region_shift; 125 delta = 1ul << j; 126 127 if (delta >= base) 128 break; 129 130 addr = (base | delta) & ~((1 << page_shift) - 1); 131 132 FAIL_IF(bad_access((char *)addr, false)); 133 FAIL_IF(bad_access((char *)addr, true)); 134 } 135 } 136 137 return 0; 138 } 139 140 int main(void) 141 { 142 test_harness_set_timeout(300); 143 return test_harness(test, "bad_accesses"); 144 } 145