1 /* 2 * QEMU access to the auxiliary vector 3 * 4 * Copyright (C) 2013 Red Hat, Inc 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include "qemu/osdep.h" 26 27 #ifdef CONFIG_GETAUXVAL 28 /* Don't inline this in qemu/osdep.h, because pulling in <sys/auxv.h> for 29 the system declaration of getauxval pulls in the system <elf.h>, which 30 conflicts with qemu's version. */ 31 32 #include <sys/auxv.h> 33 34 unsigned long qemu_getauxval(unsigned long key) 35 { 36 return getauxval(key); 37 } 38 #elif defined(__linux__) 39 #include "elf.h" 40 41 /* Our elf.h doesn't contain Elf32_auxv_t and Elf64_auxv_t, which is ok because 42 that just makes it easier to define it properly for the host here. */ 43 typedef struct { 44 unsigned long a_type; 45 unsigned long a_val; 46 } ElfW_auxv_t; 47 48 static const ElfW_auxv_t *auxv; 49 50 static const ElfW_auxv_t *qemu_init_auxval(void) 51 { 52 ElfW_auxv_t *a; 53 ssize_t size = 512, r, ofs; 54 int fd; 55 56 /* Allocate some initial storage. Make sure the first entry is set 57 to end-of-list, so that we've got a valid list in case of error. */ 58 auxv = a = g_malloc(size); 59 a[0].a_type = 0; 60 a[0].a_val = 0; 61 62 fd = open("/proc/self/auxv", O_RDONLY); 63 if (fd < 0) { 64 return a; 65 } 66 67 /* Read the first SIZE bytes. Hopefully, this covers everything. */ 68 r = read(fd, a, size); 69 70 if (r == size) { 71 /* Continue to expand until we do get a partial read. */ 72 do { 73 ofs = size; 74 size *= 2; 75 auxv = a = g_realloc(a, size); 76 r = read(fd, (char *)a + ofs, ofs); 77 } while (r == ofs); 78 } 79 80 close(fd); 81 return a; 82 } 83 84 unsigned long qemu_getauxval(unsigned long type) 85 { 86 const ElfW_auxv_t *a = auxv; 87 88 if (unlikely(a == NULL)) { 89 a = qemu_init_auxval(); 90 } 91 92 for (; a->a_type != 0; a++) { 93 if (a->a_type == type) { 94 return a->a_val; 95 } 96 } 97 98 errno = ENOENT; 99 return 0; 100 } 101 102 #elif defined(CONFIG_ELF_AUX_INFO) 103 #include <sys/auxv.h> 104 105 unsigned long qemu_getauxval(unsigned long type) 106 { 107 unsigned long aux = 0; 108 int ret = elf_aux_info(type, &aux, sizeof(aux)); 109 if (ret != 0) { 110 errno = ret; 111 } 112 return aux; 113 } 114 115 #else 116 117 unsigned long qemu_getauxval(unsigned long type) 118 { 119 errno = ENOSYS; 120 return 0; 121 } 122 123 #endif 124