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 #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
  55 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
  56     SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
  57
  58 static int __elfN(symtabindex);
  59 static int __elfN(symstrindex);
  60
  61 static void
  62 __elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *);
  63
  64
  65 void
  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
  72 vm_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
  91 void
  92 __elfN(linux_shared_page_fini)(vm_object_t obj)
  93 {
  94
  95         vm_object_deallocate(obj);
  96 }
  97
  98 void
  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
 137 void
 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
 217 static 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 }