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 #if ELFSIZE == 64
  31 #include <sys/elf64.h>
  32 #else
  33 #include <sys/elf32.h>
  34 #endif
  35
  36 /*
  37  * Since we are compiled outside of the normal kernel build process, we
  38  * need to include opt_global.h manually.
  39  */
  40 #include "opt_global.h"
  41
  42 #include <sys/inflate.h>
  43 #include <machine/elf.h>
  44 #include <machine/cpufunc.h>
  45 #include <machine/stdarg.h>
  46
  47 #ifndef KERNNAME
  48 #error Kernel name not provided
  49 #endif
  50
  51 extern char kernel_start[];
  52 extern char kernel_end[];
  53
  54 static __inline void *
  55 memcpy(void *dst, const void *src, size_t len)
  56 {
  57         const char *s = src;
  58         char *d = dst;
  59
  60         while (len) {
  61                 if (0 && len >= 4 && !((vm_offset_t)d & 3) &&
  62                     !((vm_offset_t)s & 3)) {
  63                         *(uint32_t *)d = *(uint32_t *)s;
  64                         s += 4;
  65                         d += 4;
  66                         len -= 4;
  67                 } else {
  68                         *d++ = *s++;
  69                         len--;
  70                 }
  71         }
  72         return (dst);
  73 }
  74
  75 static __inline void
  76 bzero(void *addr, size_t count)
  77 {
  78         char *tmp = (char *)addr;
  79
  80         while (count > 0) {
  81                 if (count >= 4 && !((vm_offset_t)tmp & 3)) {
  82                         *(uint32_t *)tmp = 0;
  83                         tmp += 4;
  84                         count -= 4;
  85                 } else {
  86                         *tmp = 0;
  87                         tmp++;
  88                         count--;
  89                 }
  90         }
  91 }
  92
  93 /*
  94  * Convert number to pointer, truncate on 64->32 case, sign extend
  95  * in 32->64 case
  96  */
  97 #define mkptr(x)        ((void *)(intptr_t)(int)(x))
  98
  99 /*
 100  * Relocate PT_LOAD segements of kernel ELF image to their respective
 101  * virtual addresses and return entry point
 102  */
 103 void *
 104 load_kernel(void * kstart)
 105 {
 106 #if ELFSIZE == 64
 107         Elf64_Ehdr *eh;
 108         Elf64_Phdr phdr[64] /* XXX */;
 109         Elf64_Shdr shdr[64] /* XXX */;
 110 #else
 111         Elf32_Ehdr *eh;
 112         Elf32_Phdr phdr[64] /* XXX */;
 113         Elf32_Shdr shdr[64] /* XXX */;
 114 #endif
 115         int i, j;
 116         void *entry_point;
 117         vm_offset_t loadend = 0;
 118         intptr_t lastaddr;
 119         int symtabindex = -1;
 120         int symstrindex = -1;
 121         Elf_Size tmp;
 122
 123 #if ELFSIZE == 64
 124         eh = (Elf64_Ehdr *)kstart;
 125 #else
 126         eh = (Elf32_Ehdr *)kstart;
 127 #endif
 128         entry_point = mkptr(eh->e_entry);
 129         memcpy(phdr, (void *)(kstart + eh->e_phoff),
 130             eh->e_phnum * sizeof(phdr[0]));
 131
 132         memcpy(shdr, (void *)(kstart + eh->e_shoff),
 133             sizeof(*shdr) * eh->e_shnum);
 134
 135         if (eh->e_shnum * eh->e_shentsize != 0 && eh->e_shoff != 0) {
 136                 for (i = 0; i < eh->e_shnum; i++) {
 137                         if (shdr[i].sh_type == SHT_SYMTAB) {
 138                                 /*
 139                                  * XXX: check if .symtab is in PT_LOAD?
 140                                  */
 141                                 if (shdr[i].sh_offset != 0 &&
 142                                     shdr[i].sh_size != 0) {
 143                                         symtabindex = i;
 144                                         symstrindex = shdr[i].sh_link;
 145                                 }
 146                         }
 147                 }
 148         }
 149
 150         /*
 151          * Copy loadable segments
 152          */
 153         for (i = 0; i < eh->e_phnum; i++) {
 154                 volatile char c;
 155
 156                 if (phdr[i].p_type != PT_LOAD)
 157                         continue;
 158
 159                 memcpy(mkptr(phdr[i].p_vaddr),
 160                     (void*)(kstart + phdr[i].p_offset), phdr[i].p_filesz);
 161
 162                 /* Clean space from oversized segments, eg: bss. */
 163                 if (phdr[i].p_filesz < phdr[i].p_memsz)
 164                         bzero(mkptr(phdr[i].p_vaddr + phdr[i].p_filesz),
 165                             phdr[i].p_memsz - phdr[i].p_filesz);
 166
 167                 if (loadend < phdr[i].p_vaddr + phdr[i].p_memsz)
 168                         loadend = phdr[i].p_vaddr + phdr[i].p_memsz;
 169         }
 170
 171         /* Now grab the symbol tables. */
 172         lastaddr = (intptr_t)(int)loadend;
 173         if (symtabindex >= 0 && symstrindex >= 0) {
 174                 tmp = SYMTAB_MAGIC;
 175                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 176                 lastaddr += sizeof(Elf_Size);
 177                 tmp = shdr[symtabindex].sh_size +
 178                     shdr[symstrindex].sh_size + 2*sizeof(Elf_Size);
 179                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 180                 lastaddr += sizeof(Elf_Size);
 181                 /* .symtab size */
 182                 tmp = shdr[symtabindex].sh_size;
 183                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 184                 lastaddr += sizeof(shdr[symtabindex].sh_size);
 185                 /* .symtab data */
 186                 memcpy((void*)lastaddr,
 187                     shdr[symtabindex].sh_offset + kstart,
 188                     shdr[symtabindex].sh_size);
 189                 lastaddr += shdr[symtabindex].sh_size;
 190
 191                 /* .strtab size */
 192                 tmp = shdr[symstrindex].sh_size;
 193                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 194                 lastaddr += sizeof(shdr[symstrindex].sh_size);
 195
 196                 /* .strtab data */
 197                 memcpy((void*)lastaddr,
 198                     shdr[symstrindex].sh_offset + kstart,
 199                     shdr[symstrindex].sh_size);
 200         } else {
 201                 /* Do not take any chances */
 202                 tmp = 0;
 203                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 204         }
 205
 206         return entry_point;
 207 }
 208
 209 void
 210 _startC(register_t a0, register_t a1, register_t a2, register_t a3)
 211 {
 212         unsigned int * code;
 213         int i;
 214         void (*entry_point)(register_t, register_t, register_t, register_t);
 215
 216         /*
 217          * Relocate segment to the predefined memory location
 218          * Most likely it will be KSEG0/KSEG1 address
 219          */
 220         entry_point = load_kernel(kernel_start);
 221
 222         /* Pass saved registers to original _start */
 223         entry_point(a0, a1, a2, a3);
 224 }