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