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 *
memcpy(void * dst,const void * src,size_t len)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
bzero(void * addr,size_t count)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 *
load_kernel(void * kstart)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
_startC(register_t a0,register_t a1,register_t a2,register_t a3)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 }
226