[fdt] Add ability to parse a MAC address from a flattened device tree
[ipxe.git] / src / image / elf.c
1 /*
2 * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 *
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25
26 /**
27 * @file
28 *
29 * ELF image format
30 *
31 * A "pure" ELF image is not a bootable image. There are various
32 * bootable formats based upon ELF (e.g. Multiboot), which share
33 * common ELF-related functionality.
34 */
35
36 #include <errno.h>
37 #include <elf.h>
38 #include <ipxe/uaccess.h>
39 #include <ipxe/segment.h>
40 #include <ipxe/image.h>
41 #include <ipxe/elf.h>
42
43 /**
44 * Load ELF segment into memory
45 *
46 * @v image ELF file
47 * @v phdr ELF program header
48 * @v dest Destination address
49 * @ret rc Return status code
50 */
51 static int elf_load_segment ( struct image *image, Elf_Phdr *phdr,
52 physaddr_t dest ) {
53 userptr_t buffer = phys_to_user ( dest );
54 int rc;
55
56 DBGC ( image, "ELF %p loading segment [%x,%x) to [%lx,%lx,%lx)\n",
57 image, phdr->p_offset, ( phdr->p_offset + phdr->p_filesz ),
58 dest, ( dest + phdr->p_filesz ), ( dest + phdr->p_memsz ) );
59
60 /* Verify and prepare segment */
61 if ( ( rc = prep_segment ( buffer, phdr->p_filesz,
62 phdr->p_memsz ) ) != 0 ) {
63 DBGC ( image, "ELF %p could not prepare segment: %s\n",
64 image, strerror ( rc ) );
65 return rc;
66 }
67
68 /* Copy image to segment */
69 memcpy_user ( buffer, 0, image->data, phdr->p_offset, phdr->p_filesz );
70
71 return 0;
72 }
73
74 /**
75 * Process ELF segment
76 *
77 * @v image ELF file
78 * @v ehdr ELF executable header
79 * @v phdr ELF program header
80 * @v process Segment processor
81 * @ret entry Entry point, if found
82 * @ret max Maximum used address
83 * @ret rc Return status code
84 */
85 static int elf_segment ( struct image *image, Elf_Ehdr *ehdr, Elf_Phdr *phdr,
86 int ( * process ) ( struct image *image,
87 Elf_Phdr *phdr, physaddr_t dest ),
88 physaddr_t *entry, physaddr_t *max ) {
89 physaddr_t dest;
90 physaddr_t end;
91 unsigned long e_offset;
92 int rc;
93
94 /* Do nothing for non-PT_LOAD segments */
95 if ( phdr->p_type != PT_LOAD )
96 return 0;
97
98 /* Check segment lies within image */
99 if ( ( phdr->p_offset + phdr->p_filesz ) > image->len ) {
100 DBGC ( image, "ELF %p segment outside image\n", image );
101 return -ENOEXEC;
102 }
103
104 /* Find start address: use physical address for preference,
105 * fall back to virtual address if no physical address
106 * supplied.
107 */
108 dest = phdr->p_paddr;
109 if ( ! dest )
110 dest = phdr->p_vaddr;
111 if ( ! dest ) {
112 DBGC ( image, "ELF %p segment loads to physical address 0\n",
113 image );
114 return -ENOEXEC;
115 }
116 end = ( dest + phdr->p_memsz );
117
118 /* Update maximum used address, if applicable */
119 if ( end > *max )
120 *max = end;
121
122 /* Process segment */
123 if ( ( rc = process ( image, phdr, dest ) ) != 0 )
124 return rc;
125
126 /* Set execution address, if it lies within this segment */
127 if ( ( e_offset = ( ehdr->e_entry - dest ) ) < phdr->p_filesz ) {
128 *entry = ehdr->e_entry;
129 DBGC ( image, "ELF %p found physical entry point at %lx\n",
130 image, *entry );
131 } else if ( ( e_offset = ( ehdr->e_entry - phdr->p_vaddr ) )
132 < phdr->p_filesz ) {
133 if ( ! *entry ) {
134 *entry = ( dest + e_offset );
135 DBGC ( image, "ELF %p found virtual entry point at %lx"
136 " (virt %lx)\n", image, *entry,
137 ( ( unsigned long ) ehdr->e_entry ) );
138 }
139 }
140
141 return 0;
142 }
143
144 /**
145 * Process ELF segments
146 *
147 * @v image ELF file
148 * @v ehdr ELF executable header
149 * @v process Segment processor
150 * @ret entry Entry point, if found
151 * @ret max Maximum used address
152 * @ret rc Return status code
153 */
154 int elf_segments ( struct image *image, Elf_Ehdr *ehdr,
155 int ( * process ) ( struct image *image, Elf_Phdr *phdr,
156 physaddr_t dest ),
157 physaddr_t *entry, physaddr_t *max ) {
158 Elf_Phdr phdr;
159 Elf_Off phoff;
160 unsigned int phnum;
161 int rc;
162
163 /* Initialise maximum used address */
164 *max = 0;
165
166 /* Invalidate entry point */
167 *entry = 0;
168
169 /* Read and process ELF program headers */
170 for ( phoff = ehdr->e_phoff , phnum = ehdr->e_phnum ; phnum ;
171 phoff += ehdr->e_phentsize, phnum-- ) {
172 if ( phoff > image->len ) {
173 DBGC ( image, "ELF %p program header %d outside "
174 "image\n", image, phnum );
175 return -ENOEXEC;
176 }
177 copy_from_user ( &phdr, image->data, phoff, sizeof ( phdr ) );
178 if ( ( rc = elf_segment ( image, ehdr, &phdr, process,
179 entry, max ) ) != 0 )
180 return rc;
181 }
182
183 /* Check for a valid execution address */
184 if ( ! *entry ) {
185 DBGC ( image, "ELF %p entry point %lx outside image\n",
186 image, ( ( unsigned long ) ehdr->e_entry ) );
187 return -ENOEXEC;
188 }
189
190 return 0;
191 }
192
193 /**
194 * Load ELF image into memory
195 *
196 * @v image ELF file
197 * @ret entry Entry point
198 * @ret max Maximum used address
199 * @ret rc Return status code
200 */
201 int elf_load ( struct image *image, physaddr_t *entry, physaddr_t *max ) {
202 static const uint8_t e_ident[] = {
203 [EI_MAG0] = ELFMAG0,
204 [EI_MAG1] = ELFMAG1,
205 [EI_MAG2] = ELFMAG2,
206 [EI_MAG3] = ELFMAG3,
207 [EI_CLASS] = ELFCLASS,
208 };
209 Elf_Ehdr ehdr;
210 int rc;
211
212 /* Read ELF header */
213 copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
214 if ( memcmp ( &ehdr.e_ident[EI_MAG0], e_ident,
215 sizeof ( e_ident ) ) != 0 ) {
216 DBGC ( image, "ELF %p has invalid signature\n", image );
217 return -ENOEXEC;
218 }
219
220 /* Load ELF segments into memory */
221 if ( ( rc = elf_segments ( image, &ehdr, elf_load_segment,
222 entry, max ) ) != 0 )
223 return rc;
224
225 return 0;
226 }