sys/mips/mips/elf_trampoline.c

   1 /*-
   2  * Copyright (c) 2005 Olivier Houchard.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  23  */
  24
  25 #include <sys/cdefs.h>
  26 __FBSDID("$FreeBSD$");
  27 #include <machine/asm.h>
  28 #include <sys/param.h>
  29
  30 #ifdef __mips_n64
  31 #include <sys/elf64.h>
  32 #else
  33 #include <sys/elf32.h>
  34 #endif
  35 #include <sys/inflate.h>
  36 #include <machine/elf.h>
  37 #include <machine/cpufunc.h>
  38 #include <machine/stdarg.h>
  39
  40 /*
  41  * Since we are compiled outside of the normal kernel build process, we
  42  * need to include opt_global.h manually.
  43  */
  44 #include "opt_global.h"
  45 #include "opt_kernname.h"
  46
  47 extern char kernel_start[];
  48 extern char kernel_end[];
  49
  50 static __inline void *
  51 memcpy(void *dst, const void *src, size_t len)
  52 {
  53         const char *s = src;
  54         char *d = dst;
  55
  56         while (len) {
  57                 if (0 && len >= 4 && !((vm_offset_t)d & 3) &&
  58                     !((vm_offset_t)s & 3)) {
  59                         *(uint32_t *)d = *(uint32_t *)s;
  60                         s += 4;
  61                         d += 4;
  62                         len -= 4;
  63                 } else {
  64                         *d++ = *s++;
  65                         len--;
  66                 }
  67         }
  68         return (dst);
  69 }
  70
  71 static __inline void
  72 bzero(void *addr, size_t count)
  73 {
  74         char *tmp = (char *)addr;
  75
  76         while (count > 0) {
  77                 if (count >= 4 && !((vm_offset_t)tmp & 3)) {
  78                         *(uint32_t *)tmp = 0;
  79                         tmp += 4;
  80                         count -= 4;
  81                 } else {
  82                         *tmp = 0;
  83                         tmp++;
  84                         count--;
  85                 }
  86         }
  87 }
  88
  89 /*
  90  * Relocate PT_LOAD segements of kernel ELF image to their respective
  91  * virtual addresses and return entry point
  92  */
  93 void *
  94 load_kernel(void * kstart)
  95 {
  96 #ifdef __mips_n64
  97         Elf64_Ehdr *eh;
  98         Elf64_Phdr phdr[64] /* XXX */;
  99         Elf64_Shdr shdr[64] /* XXX */;
 100 #else
 101         Elf32_Ehdr *eh;
 102         Elf32_Phdr phdr[64] /* XXX */;
 103         Elf32_Shdr shdr[64] /* XXX */;
 104 #endif
 105         int i, j;
 106         void *entry_point;
 107         vm_offset_t lastaddr = 0;
 108         int symtabindex = -1;
 109         int symstrindex = -1;
 110
 111 #ifdef __mips_n64
 112         eh = (Elf64_Ehdr *)kstart;
 113 #else
 114         eh = (Elf32_Ehdr *)kstart;
 115 #endif
 116         entry_point = (void*)eh->e_entry;
 117         memcpy(phdr, (void *)(kstart + eh->e_phoff ),
 118             eh->e_phnum * sizeof(phdr[0]));
 119
 120         memcpy(shdr, (void *)(kstart + eh->e_shoff),
 121             sizeof(*shdr) * eh->e_shnum);
 122
 123         if (eh->e_shnum * eh->e_shentsize != 0 && eh->e_shoff != 0) {
 124                 for (i = 0; i < eh->e_shnum; i++) {
 125                         if (shdr[i].sh_type == SHT_SYMTAB) {
 126                                 /*
 127                                  * XXX: check if .symtab is in PT_LOAD?
 128                                  */
 129                                 if (shdr[i].sh_offset != 0 &&
 130                                     shdr[i].sh_size != 0) {
 131                                         symtabindex = i;
 132                                         symstrindex = shdr[i].sh_link;
 133                                 }
 134                         }
 135                 }
 136         }
 137
 138         /*
 139          * Copy loadable segments
 140          */
 141         for (i = 0; i < eh->e_phnum; i++) {
 142                 volatile char c;
 143
 144                 if (phdr[i].p_type != PT_LOAD)
 145                         continue;
 146
 147                 memcpy((void *)(phdr[i].p_vaddr),
 148                     (void*)(kstart + phdr[i].p_offset), phdr[i].p_filesz);
 149
 150                 /* Clean space from oversized segments, eg: bss. */
 151                 if (phdr[i].p_filesz < phdr[i].p_memsz)
 152                         bzero((void *)(phdr[i].p_vaddr + phdr[i].p_filesz),
 153                             phdr[i].p_memsz - phdr[i].p_filesz);
 154
 155                 if (lastaddr < phdr[i].p_vaddr + phdr[i].p_memsz)
 156                         lastaddr = phdr[i].p_vaddr + phdr[i].p_memsz;
 157         }
 158
 159         /* Now grab the symbol tables. */
 160         if (symtabindex >= 0 && symstrindex >= 0) {
 161                 *(Elf_Size *)lastaddr = SYMTAB_MAGIC;
 162                 lastaddr += sizeof(Elf_Size);
 163                 *(Elf_Size *)lastaddr = shdr[symtabindex].sh_size +
 164                     shdr[symstrindex].sh_size + 2*sizeof(Elf_Size);
 165                 lastaddr += sizeof(Elf_Size);
 166                 /* .symtab size */
 167                 *(Elf_Size *)lastaddr = shdr[symtabindex].sh_size;
 168                 lastaddr += sizeof(shdr[symtabindex].sh_size);
 169                 /* .symtab data */
 170                 memcpy((void*)lastaddr,
 171                     shdr[symtabindex].sh_offset + kstart,
 172                     shdr[symtabindex].sh_size);
 173                 lastaddr += shdr[symtabindex].sh_size;
 174
 175                 /* .strtab size */
 176                 *(Elf_Size *)lastaddr = shdr[symstrindex].sh_size;
 177                 lastaddr += sizeof(shdr[symstrindex].sh_size);
 178
 179                 /* .strtab data */
 180                 memcpy((void*)lastaddr,
 181                     shdr[symstrindex].sh_offset + kstart,
 182                     shdr[symstrindex].sh_size);
 183         } else
 184                 /* Do not take any chances */
 185                 *(Elf_Size *)lastaddr = 0;
 186
 187         return entry_point;
 188 }
 189
 190 void
 191 _startC(register_t a0, register_t a1, register_t a2, register_t a3)
 192 {
 193         unsigned int * code;
 194         int i;
 195         void (*entry_point)(register_t, register_t, register_t, register_t);
 196
 197         /*
 198          * Relocate segment to the predefined memory location
 199          * Most likely it will be KSEG0/KSEG1 address
 200          */
 201         entry_point = load_kernel(kernel_start);
 202
 203         /* Pass saved registers to original _start */
 204         entry_point(a0, a1, a2, a3);
 205 }