tools/mbh_patch/mbh_patch.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #include <stdlib.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #include <strings.h>
  31 #include <stdio.h>
  32 #include <sys/types.h>
  33 #include <sys/inttypes.h>
  34 #include <sys/elf.h>
  35 #include <sys/elf_notes.h>
  36 #include <sys/mman.h>
  37 #include <sys/stat.h>
  38 #include <sys/sysmacros.h>
  39 #include "sys/multiboot.h"
  40 #include "sys/multiboot2.h"
  41
  42 static char *pname;
  43 static char *fname;
  44 static char *image;     /* pointer to the ELF file in memory */
  45
  46 #define ELFSEEK(offset) ((void *)(image + offset))
  47
  48 /*
  49  * Find MB2 header tags for entry and patch it.
  50  * The first tag is right after header.
  51  */
  52 static int
  53 patch64_mb2(multiboot2_header_t *mbh2, int file_offset,
  54     Elf64_Addr ptload_start, Elf32_Off ptload_offset)
  55 {
  56         multiboot_header_tag_t *tagp = mbh2->mb2_tags;
  57         multiboot_header_tag_address_t *mbaddr = NULL;
  58         multiboot_header_tag_entry_address_t *mbentry = NULL;
  59
  60         /*
  61          * Loop until we get end TAG or we have both tags.
  62          */
  63         while (tagp->mbh_type != MULTIBOOT_HEADER_TAG_END &&
  64             (mbaddr == NULL || mbentry == NULL)) {
  65                 switch (tagp->mbh_type) {
  66                 case MULTIBOOT_HEADER_TAG_ADDRESS:
  67                         mbaddr = (multiboot_header_tag_address_t *)tagp;
  68                         break;
  69                 case MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS:
  70                         mbentry = (multiboot_header_tag_entry_address_t *)tagp;
  71                         break;
  72                 }
  73                 tagp = (multiboot_header_tag_t *)
  74                     ((uintptr_t)tagp +
  75                     P2ROUNDUP(tagp->mbh_size, MULTIBOOT_TAG_ALIGN));
  76         }
  77
  78         if (mbaddr == NULL || mbentry == NULL) {
  79                 (void) fprintf(stderr, "Missing multiboot2 %s tag\n",
  80                     (mbaddr == NULL)? "address" : "entry");
  81                 return (1);
  82         }
  83
  84         /* Patch it. */
  85         mbaddr->mbh_load_addr = ptload_start - ptload_offset;
  86         mbaddr->mbh_header_addr = mbaddr->mbh_load_addr + file_offset;
  87         mbentry->mbh_entry_addr = ptload_start;
  88
  89 #ifdef VERBOSE
  90         (void) printf("  ELF64 MB2 header patched\n");
  91         (void) printf("\tload_addr now:   0x%x\n", mbaddr->mbh_load_addr);
  92         (void) printf("\theader_addr now: 0x%x\n", mbaddr->mbh_header_addr);
  93         (void) printf("\tentry_addr now:  0x%x\n", mbentry->mbh_entry_addr);
  94 #endif
  95         return (0);
  96 }
  97
  98 /*
  99  * Patch the load address / entry address for MB1 and MB2 if present.
 100  * Find the physical load address of the 1st PT_LOAD segment.
 101  * Find the amount that e_entry exceeds that amount.
 102  * Now go back and subtract the excess from the p_paddr of the LOAD segment.
 103  */
 104 static int
 105 patch64(Elf64_Ehdr *eh)
 106 {
 107         Elf64_Phdr              *phdr;
 108         caddr_t                 phdrs = NULL;
 109         int                     ndx, mem, mem2;
 110         multiboot_header_t      *mbh;
 111         multiboot2_header_t     *mbh2;
 112
 113         /*
 114          * Verify some ELF basics - this must be an executable with program
 115          * headers.
 116          */
 117         if (eh->e_type != ET_EXEC) {
 118                 (void) fprintf(stderr, "%s: %s: not ET_EXEC, e_type = 0x%x\n",
 119                     pname, fname, eh->e_type);
 120                 return (1);
 121         }
 122         if ((eh->e_phnum == 0) || (eh->e_phoff == 0)) {
 123                 (void) fprintf(stderr, "%s: %s: no program headers\n", pname,
 124                     fname);
 125                 return (1);
 126         }
 127
 128         /*
 129          * Get the program headers.
 130          */
 131         if ((phdrs = ELFSEEK(eh->e_phoff)) == NULL) {
 132                 (void) fprintf(stderr, "%s: %s: failed to get %d program "
 133                     "hdrs\n", pname, fname, eh->e_phnum);
 134                 return (1);
 135         }
 136
 137         /*
 138          * Look for multiboot1 header.  It must be 32-bit aligned and
 139          * completely contained in the 1st 8K of the file.
 140          */
 141         for (mem = 0; mem < 8192 - sizeof (multiboot_header_t); mem += 4) {
 142                 mbh = ELFSEEK(mem);
 143                 if (mbh->magic == MB_HEADER_MAGIC)
 144                         break;
 145         }
 146
 147         if (mem >= 8192 - sizeof (multiboot_header_t)) {
 148                 (void) fprintf(stderr, "%s: %s: Didn't find multiboot header\n",
 149                     pname, fname);
 150                 return (1);
 151         }
 152
 153         /*
 154          * Look for multiboot2 header.  It must be 64-bit aligned and
 155          * completely contained in the 1st 32K of the file.
 156          * We do not require it to be present.
 157          */
 158         ndx = 0;
 159         for (mem2 = 0;
 160             mem2 <= MULTIBOOT_SEARCH - sizeof (multiboot2_header_t);
 161             mem2 += MULTIBOOT_HEADER_ALIGN) {
 162                 mbh2 = ELFSEEK(mem2);
 163                 ndx = mbh2->mb2_header_length;
 164                 if (mbh2->mb2_magic == MULTIBOOT2_HEADER_MAGIC)
 165                         break;
 166                 ndx = 0;
 167         }
 168
 169         if (ndx == 0 || mem2 + ndx > MULTIBOOT_SEARCH) {
 170 #ifdef VERBOSE
 171                 (void) fprintf(stderr, "%s: %s: Didn't find multiboot2 "
 172                     "header\n", pname, fname);
 173 #endif
 174                 mbh2 = NULL;
 175         }
 176
 177         /*
 178          * Find the 1:1 mapped PT_LOAD section
 179          */
 180         for (ndx = 0; ndx < eh->e_phnum; ndx++) {
 181                 /*LINTED [ELF program header alignment]*/
 182                 phdr = (Elf64_Phdr *)(phdrs + eh->e_phentsize * ndx);
 183
 184                 /*
 185                  * Find the low memory 1:1 PT_LOAD section!
 186                  */
 187                 if (phdr->p_type != PT_LOAD)
 188                         continue;
 189
 190                 if (phdr->p_memsz == 0)
 191                         continue;
 192
 193                 if (phdr->p_paddr != phdr->p_vaddr)
 194                         continue;
 195
 196                 /*
 197                  * Make sure the multiboot header is part of the first PT_LOAD
 198                  * segment, and that the executables entry point starts at the
 199                  * same segment.
 200                  */
 201                 if ((mem < phdr->p_offset) ||
 202                     (mem >= (phdr->p_offset + phdr->p_filesz))) {
 203                         (void) fprintf(stderr, "%s: %s: identity mapped "
 204                             "PT_LOAD wasn't 1st PT_LOAD\n", pname, fname);
 205                         return (1);
 206                 }
 207                 if (eh->e_entry != phdr->p_paddr) {
 208                         (void) fprintf(stderr, "%s: %s: entry != paddr\n",
 209                             pname, fname);
 210                         return (1);
 211                 }
 212
 213                 if (mbh2 != NULL && ((mem2 < phdr->p_offset) ||
 214                     (mem2 >= (phdr->p_offset + phdr->p_filesz)))) {
 215 #ifdef VERBOSE
 216                         (void) fprintf(stderr, "%s: %s: multiboot2 header not"
 217                             " in 1st PT_LOAD\n", pname, fname);
 218 #endif
 219                         mem2 = 0;
 220                         mbh2 = NULL;
 221                 }
 222
 223                 /*
 224                  * Patch the multiboot header fields to get entire file loaded.
 225                  * Grub uses the MB header for 64 bit loading.
 226                  */
 227                 mbh->load_addr = phdr->p_paddr - phdr->p_offset;
 228                 mbh->entry_addr = phdr->p_paddr;
 229                 mbh->header_addr = mbh->load_addr + mem;
 230 #ifdef VERBOSE
 231                 (void) printf("  %s: ELF64 MB header patched\n", fname);
 232                 (void) printf("\tload_addr now:   0x%x\n", mbh->load_addr);
 233                 (void) printf("\tentry_addr now:  0x%x\n", mbh->entry_addr);
 234                 (void) printf("\theader_addr now: 0x%x\n", mbh->header_addr);
 235 #endif
 236                 if (mbh2 != NULL)
 237                         return (patch64_mb2(mbh2, mem2, phdr->p_paddr,
 238                             phdr->p_offset));
 239                 return (0);
 240         }
 241
 242         (void) fprintf(stderr, "%s: %s: Didn't find 1:1 mapped PT_LOAD "
 243             "section\n", pname, fname);
 244         return (1);
 245 }
 246
 247 int
 248 main(int argc, char **argv)
 249 {
 250         int     fd;
 251         uchar_t *ident;
 252         void    *hdr = NULL;
 253         struct  stat sb;
 254
 255         /*
 256          * We expect one argument -- the elf file.
 257          */
 258         if (argc != 2) {
 259                 (void) fprintf(stderr, "usage: %s <unix-elf-file>\n", argv[0]);
 260                 return (1);
 261         }
 262
 263         pname = strrchr(argv[0], '/');
 264         if (pname == NULL)
 265                 pname = argv[0];
 266         else
 267                 ++pname;
 268
 269         fname = argv[1];
 270         if ((fd = open(fname, O_RDWR)) < 0) {
 271                 (void) fprintf(stderr, "%s: open(%s, O_RDWR) failed: %s\n",
 272                     pname, fname, strerror(errno));
 273                 return (1);
 274         }
 275
 276         if (fstat(fd, &sb) != 0) {
 277                 (void) fprintf(stderr, "%s: fstat failed: %s\n",
 278                     pname, strerror(errno));
 279                 return (1);
 280         }
 281
 282         /* Make sure we have at least MULTIBOOT_SEARCH bytes. */
 283         if (sb.st_size < MULTIBOOT_SEARCH) {
 284                 (void) fprintf(stderr, "%s: %s is too small for a kernel\n",
 285                     pname, fname);
 286                 return (1);
 287         }
 288
 289         /*
 290          * mmap the 1st 32K -- MB1 header is within first 8k and MB2 header
 291          * is within 32k.
 292          */
 293         image = mmap(NULL, MULTIBOOT_SEARCH, PROT_READ | PROT_WRITE,
 294             MAP_SHARED, fd, 0);
 295         if (image == MAP_FAILED) {
 296                 (void) fprintf(stderr, "%s: mmap() of %s failed: %s\n",
 297                     pname, fname, strerror(errno));
 298                 return (1);
 299         }
 300
 301         ident = ELFSEEK(0);
 302         if (ident[EI_MAG0] != ELFMAG0 || ident[EI_MAG1] != ELFMAG1 ||
 303             ident[EI_MAG2] != ELFMAG2 || ident[EI_MAG3] != ELFMAG3) {
 304                 (void) fprintf(stderr, "%s: %s: not an ELF file!\n", pname,
 305                     fname);
 306                 return (1);
 307         }
 308
 309         if (ident[EI_CLASS] == ELFCLASS64) {
 310                 hdr = ELFSEEK(0);
 311                 return (patch64(hdr));
 312         }
 313         if (ident[EI_CLASS] != ELFCLASS32) {
 314                 (void) fprintf(stderr, "%s: Unknown ELF class 0x%x\n", pname,
 315                     ident[EI_CLASS]);
 316                 return (1);
 317         }
 318         return (0);
 319 }