1 /*-
2 * Copyright (c) 2013 Dmitry Chagin
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer
10 * in this position and unchanged.
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/compat/linux/linux_vdso.c 321728 2017-07-30 21:24:20Z dchagin $");
29
30 #include "opt_compat.h"
31
32 #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
33 #define __ELF_WORD_SIZE 32
34 #else
35 #define __ELF_WORD_SIZE 64
36 #endif
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/elf.h>
41 #include <sys/kernel.h>
42 #include <sys/lock.h>
43 #include <sys/rwlock.h>
44 #include <sys/queue.h>
45 #include <sys/sysent.h>
46
47 #include <vm/vm.h>
48 #include <vm/vm_param.h>
49 #include <vm/pmap.h>
50 #include <vm/vm_extern.h>
51 #include <vm/vm_kern.h>
52 #include <vm/vm_map.h>
53 #include <vm/vm_object.h>
54 #include <vm/vm_page.h>
55 #include <vm/vm_pager.h>
56
57 #include <compat/linux/linux_vdso.h>
58
59 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
60 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
61
62 static int __elfN(symtabindex);
63 static int __elfN(symstrindex);
64
65 static void
66 __elfN(linux_vdso_lookup)(Elf_Ehdr *, struct linux_vdso_sym *);
67
68
69 void
70 __elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
71 {
72
73 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
74 }
75
76 vm_object_t
77 __elfN(linux_shared_page_init)(char **mapping)
78 {
79 vm_page_t m;
80 vm_object_t obj;
81 vm_offset_t addr;
82
83 obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
84 VM_PROT_DEFAULT, 0, NULL);
85 VM_OBJECT_WLOCK(obj);
86 m = vm_page_grab(obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
87 m->valid = VM_PAGE_BITS_ALL;
88 VM_OBJECT_WUNLOCK(obj);
89 addr = kva_alloc(PAGE_SIZE);
90 pmap_qenter(addr, &m, 1);
91 *mapping = (char *)addr;
92 return (obj);
93 }
94
95 void
96 __elfN(linux_shared_page_fini)(vm_object_t obj)
97 {
98
99 vm_object_deallocate(obj);
100 }
101
102 void
103 __elfN(linux_vdso_fixup)(struct sysentvec *sv)
104 {
105 Elf_Ehdr *ehdr;
106 Elf_Shdr *shdr;
107 int i;
108
109 ehdr = (Elf_Ehdr *) sv->sv_sigcode;
110
111 if (!IS_ELF(*ehdr) ||
112 ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
113 ehdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
114 ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
115 ehdr->e_shoff == 0 ||
116 ehdr->e_shentsize != sizeof(Elf_Shdr))
117 panic("Linux invalid vdso header.\n");
118
119 if (ehdr->e_type != ET_DYN)
120 panic("Linux invalid vdso header.\n");
121
122 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
123
124 __elfN(symtabindex) = -1;
125 __elfN(symstrindex) = -1;
126 for (i = 0; i < ehdr->e_shnum; i++) {
127 if (shdr[i].sh_size == 0)
128 continue;
129 if (shdr[i].sh_type == SHT_DYNSYM) {
130 __elfN(symtabindex) = i;
131 __elfN(symstrindex) = shdr[i].sh_link;
132 }
133 }
134
135 if (__elfN(symtabindex) == -1 || __elfN(symstrindex) == -1)
136 panic("Linux invalid vdso header.\n");
137
138 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;
139 }
140
141 void
142 __elfN(linux_vdso_reloc)(struct sysentvec *sv)
143 {
144 struct linux_vdso_sym *lsym;
145 Elf_Ehdr *ehdr;
146 Elf_Phdr *phdr;
147 Elf_Shdr *shdr;
148 Elf_Dyn *dyn;
149 Elf_Sym *sym;
150 int i, j, symcnt;
151
152 ehdr = (Elf_Ehdr *) sv->sv_sigcode;
153
154 /* Adjust our so relative to the sigcode_base */
155 if (sv->sv_shared_page_base != 0) {
156 ehdr->e_entry += sv->sv_shared_page_base;
157 phdr = (Elf_Phdr *)((caddr_t)ehdr + ehdr->e_phoff);
158
159 /* phdrs */
160 for (i = 0; i < ehdr->e_phnum; i++) {
161 phdr[i].p_vaddr += sv->sv_shared_page_base;
162 if (phdr[i].p_type != PT_DYNAMIC)
163 continue;
164 dyn = (Elf_Dyn *)((caddr_t)ehdr + phdr[i].p_offset);
165 for(; dyn->d_tag != DT_NULL; dyn++) {
166 switch (dyn->d_tag) {
167 case DT_PLTGOT:
168 case DT_HASH:
169 case DT_STRTAB:
170 case DT_SYMTAB:
171 case DT_RELA:
172 case DT_INIT:
173 case DT_FINI:
174 case DT_REL:
175 case DT_DEBUG:
176 case DT_JMPREL:
177 case DT_VERSYM:
178 case DT_VERDEF:
179 case DT_VERNEED:
180 case DT_ADDRRNGLO ... DT_ADDRRNGHI:
181 dyn->d_un.d_ptr += sv->sv_shared_page_base;
182 break;
183 case DT_ENCODING ... DT_LOOS-1:
184 case DT_LOOS ... DT_HIOS:
185 if (dyn->d_tag >= DT_ENCODING &&
186 (dyn->d_tag & 1) == 0)
187 dyn->d_un.d_ptr += sv->sv_shared_page_base;
188 break;
189 default:
190 break;
191 }
192 }
193 }
194
195 /* sections */
196 shdr = (Elf_Shdr *)((caddr_t)ehdr + ehdr->e_shoff);
197 for(i = 0; i < ehdr->e_shnum; i++) {
198 if (!(shdr[i].sh_flags & SHF_ALLOC))
199 continue;
200 shdr[i].sh_addr += sv->sv_shared_page_base;
201 if (shdr[i].sh_type != SHT_SYMTAB &&
202 shdr[i].sh_type != SHT_DYNSYM)
203 continue;
204
205 sym = (Elf_Sym *)((caddr_t)ehdr + shdr[i].sh_offset);
206 symcnt = shdr[i].sh_size / sizeof(*sym);
207
208 for(j = 0; j < symcnt; j++, sym++) {
209 if (sym->st_shndx == SHN_UNDEF ||
210 sym->st_shndx == SHN_ABS)
211 continue;
212 sym->st_value += sv->sv_shared_page_base;
213 }
214 }
215 }
216
217 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym)
218 __elfN(linux_vdso_lookup)(ehdr, lsym);
219 }
220
221 static void
222 __elfN(linux_vdso_lookup)(Elf_Ehdr *ehdr, struct linux_vdso_sym *vsym)
223 {
224 vm_offset_t strtab, symname;
225 uint32_t symcnt;
226 Elf_Shdr *shdr;
227 int i;
228
229 shdr = (Elf_Shdr *) ((caddr_t)ehdr + ehdr->e_shoff);
230
231 strtab = (vm_offset_t)((caddr_t)ehdr +
232 shdr[__elfN(symstrindex)].sh_offset);
233 Elf_Sym *sym = (Elf_Sym *)((caddr_t)ehdr +
234 shdr[__elfN(symtabindex)].sh_offset);
235 symcnt = shdr[__elfN(symtabindex)].sh_size / sizeof(*sym);
236
237 for (i = 0; i < symcnt; ++i, ++sym) {
238 symname = strtab + sym->st_name;
239 if (strncmp(vsym->symname, (char *)symname, vsym->size) == 0) {
240 *vsym->ptr = (uintptr_t)sym->st_value;
241 break;
242 }
243 }
244 }
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