sys/compat/linux/linux_vdso.c

   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("$FreeBSD$");
  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
  59 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
  60     SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
  61
  62 static int __elfN(symtabindex);
  63 static int __elfN(symstrindex);
  64
  65 static void
  66 __elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *);
  67
  68
  69 void
  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
  76 vm_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
  95 void
  96 __elfN(linux_shared_page_fini)(vm_object_t obj)
  97 {
  98
  99         vm_object_deallocate(obj);
 100 }
 101
 102 void
 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
 141 void
 142 __elfN(linux_vdso_reloc)(struct sysentvec *sv, long vdso_adjust)
 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, symcnt;
 151
 152         ehdr = (Elf_Ehdr *) sv->sv_sigcode;
 153
 154         /* Adjust our so relative to the sigcode_base */
 155         if (vdso_adjust != 0) {
 156                 ehdr->e_entry += vdso_adjust;
 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 += vdso_adjust;
 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 += vdso_adjust;
 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 += vdso_adjust;
 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 += vdso_adjust;
 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(i = 0; i < symcnt; i++, sym++) {
 209                                 if (sym->st_shndx == SHN_UNDEF ||
 210                                     sym->st_shndx == SHN_ABS)
 211                                         continue;
 212                                 sym->st_value += vdso_adjust;
 213                         }
 214                 }
 215         }
 216
 217         SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym)
 218                 __elfN(linux_vdso_lookup)(ehdr, lsym);
 219 }
 220
 221 static 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 }