1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Userspace test harness for load_unaligned_zeropad. Creates two 4 * pages and uses mprotect to prevent access to the second page and 5 * a SEGV handler that walks the exception tables and runs the fixup 6 * routine. 7 * 8 * The results are compared against a normal load that is that is 9 * performed while access to the second page is enabled via mprotect. 10 * 11 * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM 12 */ 13 14 #include <stdlib.h> 15 #include <string.h> 16 #include <stdio.h> 17 #include <stdbool.h> 18 #include <signal.h> 19 #include <unistd.h> 20 #include <sys/mman.h> 21 22 #define FIXUP_SECTION ".ex_fixup" 23 24 static inline unsigned long __fls(unsigned long x); 25 26 #include "word-at-a-time.h" 27 28 #include "utils.h" 29 30 static inline unsigned long __fls(unsigned long x) 31 { 32 int lz; 33 34 asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x)); 35 return sizeof(unsigned long) - 1 - lz; 36 } 37 38 static int page_size; 39 static char *mem_region; 40 41 static int protect_region(void) 42 { 43 if (mprotect(mem_region + page_size, page_size, PROT_NONE)) { 44 perror("mprotect"); 45 return 1; 46 } 47 48 return 0; 49 } 50 51 static int unprotect_region(void) 52 { 53 if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) { 54 perror("mprotect"); 55 return 1; 56 } 57 58 return 0; 59 } 60 61 extern char __start___ex_table[]; 62 extern char __stop___ex_table[]; 63 64 struct extbl_entry { 65 int insn; 66 int fixup; 67 }; 68 69 static void segv_handler(int signr, siginfo_t *info, void *ptr) 70 { 71 ucontext_t *uc = (ucontext_t *)ptr; 72 unsigned long addr = (unsigned long)info->si_addr; 73 unsigned long *ip = &UCONTEXT_NIA(uc); 74 struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table; 75 76 while (entry < (struct extbl_entry *)__stop___ex_table) { 77 unsigned long insn, fixup; 78 79 insn = (unsigned long)&entry->insn + entry->insn; 80 fixup = (unsigned long)&entry->fixup + entry->fixup; 81 82 if (insn == *ip) { 83 *ip = fixup; 84 return; 85 } 86 } 87 88 printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr); 89 abort(); 90 } 91 92 static void setup_segv_handler(void) 93 { 94 struct sigaction action; 95 96 memset(&action, 0, sizeof(action)); 97 action.sa_sigaction = segv_handler; 98 action.sa_flags = SA_SIGINFO; 99 sigaction(SIGSEGV, &action, NULL); 100 } 101 102 static int do_one_test(char *p, int page_offset) 103 { 104 unsigned long should; 105 unsigned long got; 106 107 FAIL_IF(unprotect_region()); 108 should = *(unsigned long *)p; 109 FAIL_IF(protect_region()); 110 111 got = load_unaligned_zeropad(p); 112 113 if (should != got) { 114 printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should); 115 return 1; 116 } 117 118 return 0; 119 } 120 121 static int test_body(void) 122 { 123 unsigned long i; 124 125 page_size = getpagesize(); 126 mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE, 127 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 128 129 FAIL_IF(mem_region == MAP_FAILED); 130 131 for (i = 0; i < page_size; i++) 132 mem_region[i] = i; 133 134 memset(mem_region+page_size, 0, page_size); 135 136 setup_segv_handler(); 137 138 for (i = 0; i < page_size; i++) 139 FAIL_IF(do_one_test(mem_region+i, i)); 140 141 return 0; 142 } 143 144 int main(void) 145 { 146 return test_harness(test_body, "load_unaligned_zeropad"); 147 } 148