1/*- 2 * Copyright (c) 2013 Dmitry Chagin 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: stable/11/sys/compat/linux/linux_vdso.c 346807 2019-04-28 09:35:39Z dchagin $"); 29 30#include "opt_compat.h" 31 32#if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32)) 33#define __ELF_WORD_SIZE 32 34#else 35#define __ELF_WORD_SIZE 64 36#endif 37 38#include <sys/param.h> 39#include <sys/systm.h> 40#include <sys/elf.h> 41#include <sys/kernel.h> 42#include <sys/lock.h> 43#include <sys/rwlock.h> 44#include <sys/queue.h> 45#include <sys/sysent.h> 46 47#include <vm/vm.h> 48#include <vm/vm_param.h> 49#include <vm/pmap.h> 50#include <vm/vm_extern.h> 51#include <vm/vm_kern.h> 52#include <vm/vm_map.h> 53#include <vm/vm_object.h> 54#include <vm/vm_page.h> 55#include <vm/vm_pager.h> 56 57#include <compat/linux/linux_vdso.h> 58 59SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) = 60 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms)); 61 62static int __elfN(symtabindex); 63static int __elfN(symstrindex); 64 65static void 66__elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *); 67 68 69void 70__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s) 71{ 72 73 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym); 74} 75 76vm_object_t 77__elfN(linux_shared_page_init)(char **mapping) 78{ 79 vm_page_t m; 80 vm_object_t obj; 81 vm_offset_t addr; 82 83 obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE, 84 VM_PROT_DEFAULT, 0, NULL); 85 VM_OBJECT_WLOCK(obj); 86 m = vm_page_grab(obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO); 87 m->valid = VM_PAGE_BITS_ALL; 88 VM_OBJECT_WUNLOCK(obj); 89 addr = kva_alloc(PAGE_SIZE); 90 pmap_qenter(addr, &m, 1); 91 *mapping = (char *)addr; 92 return (obj); 93} 94 95void 96__elfN(linux_shared_page_fini)(vm_object_t obj) 97{ 98 99 vm_object_deallocate(obj); 100} 101 102void 103__elfN(linux_vdso_fixup)(struct sysentvec *sv) 104{ 105 Elf_Ehdr *ehdr; 106 Elf_Shdr *shdr; 107 int i; 108 109 ehdr = (Elf_Ehdr *) sv->sv_sigcode; 110 111 if (!IS_ELF(*ehdr) || 112 ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || 113 ehdr->e_ident[EI_DATA] != ELF_TARG_DATA || 114 ehdr->e_ident[EI_VERSION] != EV_CURRENT || 115 ehdr->e_shoff == 0 || 116 ehdr->e_shentsize != sizeof(Elf_Shdr)) 117 panic("Linux invalid vdso header.\n"); 118 119 if (ehdr->e_type != ET_DYN) 120 panic("Linux invalid vdso header.\n"); 121 122 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff); 123 124 __elfN(symtabindex) = -1; 125 __elfN(symstrindex) = -1; 126 for (i = 0; i < ehdr->e_shnum; i++) { 127 if (shdr[i].sh_size == 0) 128 continue; 129 if (shdr[i].sh_type == SHT_DYNSYM) { 130 __elfN(symtabindex) = i; 131 __elfN(symstrindex) = shdr[i].sh_link; 132 } 133 } 134 135 if (__elfN(symtabindex) == -1 || __elfN(symstrindex) == -1) 136 panic("Linux invalid vdso header.\n"); 137 138 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX; 139} 140 141void 142__elfN(linux_vdso_reloc)(struct sysentvec *sv) 143{ 144 struct linux_vdso_sym *lsym; 145 Elf_Ehdr *ehdr; 146 Elf_Phdr *phdr; 147 Elf_Shdr *shdr; 148 Elf_Dyn *dyn; 149 Elf_Sym *sym; 150 int i, j, symcnt; 151 152 ehdr = (Elf_Ehdr *) sv->sv_sigcode; 153 154 /* Adjust our so relative to the sigcode_base */ 155 if (sv->sv_shared_page_base != 0) { 156 ehdr->e_entry += sv->sv_shared_page_base; 157 phdr = (Elf_Phdr *)((caddr_t)ehdr + ehdr->e_phoff); 158 159 /* phdrs */ 160 for (i = 0; i < ehdr->e_phnum; i++) { 161 phdr[i].p_vaddr += sv->sv_shared_page_base; 162 if (phdr[i].p_type != PT_DYNAMIC) 163 continue; 164 dyn = (Elf_Dyn *)((caddr_t)ehdr + phdr[i].p_offset); 165 for(; dyn->d_tag != DT_NULL; dyn++) { 166 switch (dyn->d_tag) { 167 case DT_PLTGOT: 168 case DT_HASH: 169 case DT_STRTAB: 170 case DT_SYMTAB: 171 case DT_RELA: 172 case DT_INIT: 173 case DT_FINI: 174 case DT_REL: 175 case DT_DEBUG: 176 case DT_JMPREL: 177 case DT_VERSYM: 178 case DT_VERDEF: 179 case DT_VERNEED: 180 case DT_ADDRRNGLO ... DT_ADDRRNGHI: 181 dyn->d_un.d_ptr += sv->sv_shared_page_base; 182 break; 183 case DT_ENCODING ... DT_LOOS-1: 184 case DT_LOOS ... DT_HIOS: 185 if (dyn->d_tag >= DT_ENCODING && 186 (dyn->d_tag & 1) == 0) 187 dyn->d_un.d_ptr += sv->sv_shared_page_base; 188 break; 189 default: 190 break; 191 } 192 } 193 } 194 195 /* sections */ 196 shdr = (Elf_Shdr *)((caddr_t)ehdr + ehdr->e_shoff); 197 for(i = 0; i < ehdr->e_shnum; i++) { 198 if (!(shdr[i].sh_flags & SHF_ALLOC)) 199 continue; 200 shdr[i].sh_addr += sv->sv_shared_page_base; 201 if (shdr[i].sh_type != SHT_SYMTAB && 202 shdr[i].sh_type != SHT_DYNSYM) 203 continue; 204 205 sym = (Elf_Sym *)((caddr_t)ehdr + shdr[i].sh_offset); 206 symcnt = shdr[i].sh_size / sizeof(*sym); 207 208 for(j = 0; j < symcnt; j++, sym++) { 209 if (sym->st_shndx == SHN_UNDEF || 210 sym->st_shndx == SHN_ABS) 211 continue; 212 sym->st_value += sv->sv_shared_page_base; 213 } 214 } 215 } 216 217 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) 218 __elfN(linux_vdso_lookup)(ehdr, lsym); 219} 220 221static void 222__elfN(linux_vdso_lookup)(Elf_Ehdr *ehdr, struct linux_vdso_sym *vsym) 223{ 224 vm_offset_t strtab, symname; 225 uint32_t symcnt; 226 Elf_Shdr *shdr; 227 int i; 228 229 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff); 230 231 strtab = (vm_offset_t)((caddr_t)ehdr + 232 shdr[__elfN(symstrindex)].sh_offset); 233 Elf_Sym *sym = (Elf_Sym *)((caddr_t)ehdr + 234 shdr[__elfN(symtabindex)].sh_offset); 235 symcnt = shdr[__elfN(symtabindex)].sh_size / sizeof(*sym); 236 237 for (i = 0; i < symcnt; ++i, ++sym) { 238 symname = strtab + sym->st_name; 239 if (strncmp(vsym->symname, (char *)symname, vsym->size) == 0) { 240 *vsym->ptr = (uintptr_t)sym->st_value; 241 break; 242 } 243 } 244} 245