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: releng/12.0/sys/mips/mips/elf_trampoline.c 326259 2017-11-27 15:07:26Z pfg $");
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 <sys/inflate.h>
45 #include <machine/elf.h>
46 #include <machine/cpufunc.h>
47 #include <machine/stdarg.h>
48
49 #ifndef KERNNAME
50 #error Kernel name not provided
51 #endif
52
53 extern char kernel_start[];
54 extern char kernel_end[];
55
56 static __inline void *
57 memcpy(void *dst, const void *src, size_t len)
58 {
59 const char *s = src;
60 char *d = dst;
61
62 while (len) {
63 if (0 && len >= 4 && !((vm_offset_t)d & 3) &&
64 !((vm_offset_t)s & 3)) {
65 *(uint32_t *)d = *(uint32_t *)s;
66 s += 4;
67 d += 4;
68 len -= 4;
69 } else {
70 *d++ = *s++;
71 len--;
72 }
73 }
74 return (dst);
75 }
76
77 static __inline void
78 bzero(void *addr, size_t count)
79 {
80 char *tmp = (char *)addr;
81
82 while (count > 0) {
83 if (count >= 4 && !((vm_offset_t)tmp & 3)) {
84 *(uint32_t *)tmp = 0;
85 tmp += 4;
86 count -= 4;
87 } else {
88 *tmp = 0;
89 tmp++;
90 count--;
91 }
92 }
93 }
94
95 /*
96 * Convert number to pointer, truncate on 64->32 case, sign extend
97 * in 32->64 case
98 */
99 #define mkptr(x) ((void *)(intptr_t)(int)(x))
100
101 /*
102 * Relocate PT_LOAD segements of kernel ELF image to their respective
103 * virtual addresses and return entry point
104 */
105 void *
106 load_kernel(void * kstart)
107 {
108 #if ELFSIZE == 64
109 Elf64_Ehdr *eh;
110 Elf64_Phdr phdr[64] /* XXX */;
111 Elf64_Shdr shdr[64] /* XXX */;
112 #else
113 Elf32_Ehdr *eh;
114 Elf32_Phdr phdr[64] /* XXX */;
115 Elf32_Shdr shdr[64] /* XXX */;
116 #endif
117 int i, j;
118 void *entry_point;
119 vm_offset_t loadend = 0;
120 intptr_t lastaddr;
121 int symtabindex = -1;
122 int symstrindex = -1;
123 Elf_Size tmp;
124
125 #if ELFSIZE == 64
126 eh = (Elf64_Ehdr *)kstart;
127 #else
128 eh = (Elf32_Ehdr *)kstart;
129 #endif
130 entry_point = mkptr(eh->e_entry);
131 memcpy(phdr, (void *)(kstart + eh->e_phoff),
132 eh->e_phnum * sizeof(phdr[0]));
133
134 memcpy(shdr, (void *)(kstart + eh->e_shoff),
135 sizeof(*shdr) * eh->e_shnum);
136
137 if (eh->e_shnum * eh->e_shentsize != 0 && eh->e_shoff != 0) {
138 for (i = 0; i < eh->e_shnum; i++) {
139 if (shdr[i].sh_type == SHT_SYMTAB) {
140 /*
141 * XXX: check if .symtab is in PT_LOAD?
142 */
143 if (shdr[i].sh_offset != 0 &&
144 shdr[i].sh_size != 0) {
145 symtabindex = i;
146 symstrindex = shdr[i].sh_link;
147 }
148 }
149 }
150 }
151
152 /*
153 * Copy loadable segments
154 */
155 for (i = 0; i < eh->e_phnum; i++) {
156 volatile char c;
157
158 if (phdr[i].p_type != PT_LOAD)
159 continue;
160
161 memcpy(mkptr(phdr[i].p_vaddr),
162 (void*)(kstart + phdr[i].p_offset), phdr[i].p_filesz);
163
164 /* Clean space from oversized segments, eg: bss. */
165 if (phdr[i].p_filesz < phdr[i].p_memsz)
166 bzero(mkptr(phdr[i].p_vaddr + phdr[i].p_filesz),
167 phdr[i].p_memsz - phdr[i].p_filesz);
168
169 if (loadend < phdr[i].p_vaddr + phdr[i].p_memsz)
170 loadend = phdr[i].p_vaddr + phdr[i].p_memsz;
171 }
172
173 /* Now grab the symbol tables. */
174 lastaddr = (intptr_t)(int)loadend;
175 if (symtabindex >= 0 && symstrindex >= 0) {
176 tmp = SYMTAB_MAGIC;
177 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
178 lastaddr += sizeof(Elf_Size);
179 tmp = shdr[symtabindex].sh_size +
180 shdr[symstrindex].sh_size + 2*sizeof(Elf_Size);
181 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
182 lastaddr += sizeof(Elf_Size);
183 /* .symtab size */
184 tmp = shdr[symtabindex].sh_size;
185 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
186 lastaddr += sizeof(shdr[symtabindex].sh_size);
187 /* .symtab data */
188 memcpy((void*)lastaddr,
189 shdr[symtabindex].sh_offset + kstart,
190 shdr[symtabindex].sh_size);
191 lastaddr += shdr[symtabindex].sh_size;
192
193 /* .strtab size */
194 tmp = shdr[symstrindex].sh_size;
195 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
196 lastaddr += sizeof(shdr[symstrindex].sh_size);
197
198 /* .strtab data */
199 memcpy((void*)lastaddr,
200 shdr[symstrindex].sh_offset + kstart,
201 shdr[symstrindex].sh_size);
202 } else {
203 /* Do not take any chances */
204 tmp = 0;
205 memcpy((void *)lastaddr, &tmp, sizeof(tmp));
206 }
207
208 return entry_point;
209 }
210
211 void
212 _startC(register_t a0, register_t a1, register_t a2, register_t a3)
213 {
214 unsigned int * code;
215 int i;
216 void (*entry_point)(register_t, register_t, register_t, register_t);
217
218 /*
219 * Relocate segment to the predefined memory location
220 * Most likely it will be KSEG0/KSEG1 address
221 */
222 entry_point = load_kernel(kernel_start);
223
224 /* Pass saved registers to original _start */
225 entry_point(a0, a1, a2, a3);
226 }
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