linux_vdso.c revision 283407
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: head/sys/compat/linux/linux_vdso.c 283407 2015-05-24 15:28:17Z dchagin $"); 29 30#include "opt_compat.h" 31 32#define __ELF_WORD_SIZE 32 33 34#include <sys/param.h> 35#include <sys/systm.h> 36#include <sys/elf.h> 37#include <sys/kernel.h> 38#include <sys/lock.h> 39#include <sys/rwlock.h> 40#include <sys/queue.h> 41#include <sys/sysent.h> 42 43#include <vm/vm.h> 44#include <vm/vm_param.h> 45#include <vm/pmap.h> 46#include <vm/vm_extern.h> 47#include <vm/vm_kern.h> 48#include <vm/vm_map.h> 49#include <vm/vm_object.h> 50#include <vm/vm_page.h> 51#include <vm/vm_pager.h> 52 53#include <compat/linux/linux_vdso.h> 54 55SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) = 56 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms)); 57 58static int __elfN(symtabindex); 59static int __elfN(symstrindex); 60 61static void 62__elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *); 63 64 65void 66__elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s) 67{ 68 69 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym); 70} 71 72vm_object_t 73__elfN(linux_shared_page_init)(char **mapping) 74{ 75 vm_page_t m; 76 vm_object_t obj; 77 vm_offset_t addr; 78 79 obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE, 80 VM_PROT_DEFAULT, 0, NULL); 81 VM_OBJECT_WLOCK(obj); 82 m = vm_page_grab(obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO); 83 m->valid = VM_PAGE_BITS_ALL; 84 VM_OBJECT_WUNLOCK(obj); 85 addr = kva_alloc(PAGE_SIZE); 86 pmap_qenter(addr, &m, 1); 87 *mapping = (char *)addr; 88 return (obj); 89} 90 91void 92__elfN(linux_shared_page_fini)(vm_object_t obj) 93{ 94 95 vm_object_deallocate(obj); 96} 97 98void 99__elfN(linux_vdso_fixup)(struct sysentvec *sv) 100{ 101 Elf_Ehdr *ehdr; 102 Elf_Shdr *shdr; 103 int i; 104 105 ehdr = (Elf_Ehdr *) sv->sv_sigcode; 106 107 if (!IS_ELF(*ehdr) || 108 ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || 109 ehdr->e_ident[EI_DATA] != ELF_TARG_DATA || 110 ehdr->e_ident[EI_VERSION] != EV_CURRENT || 111 ehdr->e_shoff == 0 || 112 ehdr->e_shentsize != sizeof(Elf_Shdr)) 113 panic("Linux invalid vdso header.\n"); 114 115 if (ehdr->e_type != ET_DYN) 116 panic("Linux invalid vdso header.\n"); 117 118 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff); 119 120 __elfN(symtabindex) = -1; 121 __elfN(symstrindex) = -1; 122 for (i = 0; i < ehdr->e_shnum; i++) { 123 if (shdr[i].sh_size == 0) 124 continue; 125 if (shdr[i].sh_type == SHT_DYNSYM) { 126 __elfN(symtabindex) = i; 127 __elfN(symstrindex) = shdr[i].sh_link; 128 } 129 } 130 131 if (__elfN(symtabindex) == -1 || __elfN(symstrindex) == -1) 132 panic("Linux invalid vdso header.\n"); 133 134 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX; 135} 136 137void 138__elfN(linux_vdso_reloc)(struct sysentvec *sv, int vdso_adjust) 139{ 140 struct linux_vdso_sym *lsym; 141 Elf_Ehdr *ehdr; 142 Elf_Phdr *phdr; 143 Elf_Shdr *shdr; 144 Elf_Dyn *dyn; 145 Elf_Sym *sym; 146 int i, symcnt; 147 148 ehdr = (Elf_Ehdr *) sv->sv_sigcode; 149 150 /* Adjust our so relative to the sigcode_base */ 151 if (vdso_adjust != 0) { 152 ehdr->e_entry += vdso_adjust; 153 phdr = (Elf_Phdr *)((caddr_t)ehdr + ehdr->e_phoff); 154 155 /* phdrs */ 156 for (i = 0; i < ehdr->e_phnum; i++) { 157 phdr[i].p_vaddr += vdso_adjust; 158 if (phdr[i].p_type != PT_DYNAMIC) 159 continue; 160 dyn = (Elf_Dyn *)((caddr_t)ehdr + phdr[i].p_offset); 161 for(; dyn->d_tag != DT_NULL; dyn++) { 162 switch (dyn->d_tag) { 163 case DT_PLTGOT: 164 case DT_HASH: 165 case DT_STRTAB: 166 case DT_SYMTAB: 167 case DT_RELA: 168 case DT_INIT: 169 case DT_FINI: 170 case DT_REL: 171 case DT_DEBUG: 172 case DT_JMPREL: 173 case DT_VERSYM: 174 case DT_VERDEF: 175 case DT_VERNEED: 176 case DT_ADDRRNGLO ... DT_ADDRRNGHI: 177 dyn->d_un.d_ptr += vdso_adjust; 178 break; 179 case DT_ENCODING ... DT_LOOS-1: 180 case DT_LOOS ... DT_HIOS: 181 if (dyn->d_tag >= DT_ENCODING && 182 (dyn->d_tag & 1) == 0) 183 dyn->d_un.d_ptr += vdso_adjust; 184 break; 185 default: 186 break; 187 } 188 } 189 } 190 191 /* sections */ 192 shdr = (Elf_Shdr *)((caddr_t)ehdr + ehdr->e_shoff); 193 for(i = 0; i < ehdr->e_shnum; i++) { 194 if (!(shdr[i].sh_flags & SHF_ALLOC)) 195 continue; 196 shdr[i].sh_addr += vdso_adjust; 197 if (shdr[i].sh_type != SHT_SYMTAB && 198 shdr[i].sh_type != SHT_DYNSYM) 199 continue; 200 201 sym = (Elf_Sym *)((caddr_t)ehdr + shdr[i].sh_offset); 202 symcnt = shdr[i].sh_size / sizeof(*sym); 203 204 for(i = 0; i < symcnt; i++, sym++) { 205 if (sym->st_shndx == SHN_UNDEF || 206 sym->st_shndx == SHN_ABS) 207 continue; 208 sym->st_value += vdso_adjust; 209 } 210 } 211 } 212 213 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) 214 __elfN(linux_vdso_lookup)(ehdr, lsym); 215} 216 217static void 218__elfN(linux_vdso_lookup)(Elf_Ehdr *ehdr, struct linux_vdso_sym *vsym) 219{ 220 vm_offset_t strtab, symname; 221 uint32_t symcnt; 222 Elf_Shdr *shdr; 223 int i; 224 225 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff); 226 227 strtab = (vm_offset_t)((caddr_t)ehdr + 228 shdr[__elfN(symstrindex)].sh_offset); 229 Elf_Sym *sym = (Elf_Sym *)((caddr_t)ehdr + 230 shdr[__elfN(symtabindex)].sh_offset); 231 symcnt = shdr[__elfN(symtabindex)].sh_size / sizeof(*sym); 232 233 for (i = 0; i < symcnt; ++i, ++sym) { 234 symname = strtab + sym->st_name; 235 if (strncmp(vsym->symname, (char *)symname, vsym->size) == 0) { 236 *vsym->ptr = (uintptr_t)sym->st_value; 237 break; 238 } 239 } 240} 241