sys/mips/mips/elf_trampoline.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2005 Olivier Houchard.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  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 #include <machine/asm.h>
  30 #include <sys/param.h>
  31
  32 #if ELFSIZE == 64
  33 #include <sys/elf64.h>
  34 #else
  35 #include <sys/elf32.h>
  36 #endif
  37
  38 /*
  39  * Since we are compiled outside of the normal kernel build process, we
  40  * need to include opt_global.h manually.
  41  */
  42 #include "opt_global.h"
  43
  44 #include <machine/elf.h>
  45 #include <machine/cpufunc.h>
  46 #include <machine/stdarg.h>
  47
  48 #ifndef KERNNAME
  49 #error Kernel name not provided
  50 #endif
  51
  52 extern char kernel_start[];
  53 extern char kernel_end[];
  54
  55 static __inline void *
  56 memcpy(void *dst, const void *src, size_t len)
  57 {
  58         const char *s = src;
  59         char *d = dst;
  60
  61         while (len) {
  62                 if (0 && len >= 4 && !((vm_offset_t)d & 3) &&
  63                     !((vm_offset_t)s & 3)) {
  64                         *(uint32_t *)d = *(uint32_t *)s;
  65                         s += 4;
  66                         d += 4;
  67                         len -= 4;
  68                 } else {
  69                         *d++ = *s++;
  70                         len--;
  71                 }
  72         }
  73         return (dst);
  74 }
  75
  76 static __inline void
  77 bzero(void *addr, size_t count)
  78 {
  79         char *tmp = (char *)addr;
  80
  81         while (count > 0) {
  82                 if (count >= 4 && !((vm_offset_t)tmp & 3)) {
  83                         *(uint32_t *)tmp = 0;
  84                         tmp += 4;
  85                         count -= 4;
  86                 } else {
  87                         *tmp = 0;
  88                         tmp++;
  89                         count--;
  90                 }
  91         }
  92 }
  93
  94 /*
  95  * Convert number to pointer, truncate on 64->32 case, sign extend
  96  * in 32->64 case
  97  */
  98 #define mkptr(x)        ((void *)(intptr_t)(int)(x))
  99
 100 /*
 101  * Relocate PT_LOAD segements of kernel ELF image to their respective
 102  * virtual addresses and return entry point
 103  */
 104 void *
 105 load_kernel(void * kstart)
 106 {
 107 #if ELFSIZE == 64
 108         Elf64_Ehdr *eh;
 109         Elf64_Phdr phdr[64] /* XXX */;
 110         Elf64_Shdr shdr[64] /* XXX */;
 111 #else
 112         Elf32_Ehdr *eh;
 113         Elf32_Phdr phdr[64] /* XXX */;
 114         Elf32_Shdr shdr[64] /* XXX */;
 115 #endif
 116         int i, j;
 117         void *entry_point;
 118         vm_offset_t loadend = 0;
 119         intptr_t lastaddr;
 120         int symtabindex = -1;
 121         int symstrindex = -1;
 122         Elf_Size tmp;
 123
 124 #if ELFSIZE == 64
 125         eh = (Elf64_Ehdr *)kstart;
 126 #else
 127         eh = (Elf32_Ehdr *)kstart;
 128 #endif
 129         entry_point = mkptr(eh->e_entry);
 130         memcpy(phdr, (void *)(kstart + eh->e_phoff),
 131             eh->e_phnum * sizeof(phdr[0]));
 132
 133         memcpy(shdr, (void *)(kstart + eh->e_shoff),
 134             sizeof(*shdr) * eh->e_shnum);
 135
 136         if (eh->e_shnum * eh->e_shentsize != 0 && eh->e_shoff != 0) {
 137                 for (i = 0; i < eh->e_shnum; i++) {
 138                         if (shdr[i].sh_type == SHT_SYMTAB) {
 139                                 /*
 140                                  * XXX: check if .symtab is in PT_LOAD?
 141                                  */
 142                                 if (shdr[i].sh_offset != 0 &&
 143                                     shdr[i].sh_size != 0) {
 144                                         symtabindex = i;
 145                                         symstrindex = shdr[i].sh_link;
 146                                 }
 147                         }
 148                 }
 149         }
 150
 151         /*
 152          * Copy loadable segments
 153          */
 154         for (i = 0; i < eh->e_phnum; i++) {
 155                 volatile char c;
 156
 157                 if (phdr[i].p_type != PT_LOAD)
 158                         continue;
 159
 160                 memcpy(mkptr(phdr[i].p_vaddr),
 161                     (void*)(kstart + phdr[i].p_offset), phdr[i].p_filesz);
 162
 163                 /* Clean space from oversized segments, eg: bss. */
 164                 if (phdr[i].p_filesz < phdr[i].p_memsz)
 165                         bzero(mkptr(phdr[i].p_vaddr + phdr[i].p_filesz),
 166                             phdr[i].p_memsz - phdr[i].p_filesz);
 167
 168                 if (loadend < phdr[i].p_vaddr + phdr[i].p_memsz)
 169                         loadend = phdr[i].p_vaddr + phdr[i].p_memsz;
 170         }
 171
 172         /* Now grab the symbol tables. */
 173         lastaddr = (intptr_t)(int)loadend;
 174         if (symtabindex >= 0 && symstrindex >= 0) {
 175                 tmp = SYMTAB_MAGIC;
 176                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 177                 lastaddr += sizeof(Elf_Size);
 178                 tmp = shdr[symtabindex].sh_size +
 179                     shdr[symstrindex].sh_size + 2*sizeof(Elf_Size);
 180                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 181                 lastaddr += sizeof(Elf_Size);
 182                 /* .symtab size */
 183                 tmp = shdr[symtabindex].sh_size;
 184                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 185                 lastaddr += sizeof(shdr[symtabindex].sh_size);
 186                 /* .symtab data */
 187                 memcpy((void*)lastaddr,
 188                     shdr[symtabindex].sh_offset + kstart,
 189                     shdr[symtabindex].sh_size);
 190                 lastaddr += shdr[symtabindex].sh_size;
 191
 192                 /* .strtab size */
 193                 tmp = shdr[symstrindex].sh_size;
 194                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 195                 lastaddr += sizeof(shdr[symstrindex].sh_size);
 196
 197                 /* .strtab data */
 198                 memcpy((void*)lastaddr,
 199                     shdr[symstrindex].sh_offset + kstart,
 200                     shdr[symstrindex].sh_size);
 201         } else {
 202                 /* Do not take any chances */
 203                 tmp = 0;
 204                 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
 205         }
 206
 207         return entry_point;
 208 }
 209
 210 void
 211 _startC(register_t a0, register_t a1, register_t a2, register_t a3)
 212 {
 213         unsigned int * code;
 214         int i;
 215         void (*entry_point)(register_t, register_t, register_t, register_t);
 216
 217         /*
 218          * Relocate segment to the predefined memory location
 219          * Most likely it will be KSEG0/KSEG1 address
 220          */
 221         entry_point = load_kernel(kernel_start);
 222
 223         /* Pass saved registers to original _start */
 224         entry_point(a0, a1, a2, a3);
 225 }