1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2013-2021 Dmitry Chagin <dchagin@FreeBSD.org>
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 AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
29 #define __ELF_WORD_SIZE 32
30 #else
31 #define __ELF_WORD_SIZE 64
32 #endif
33
34 #include <sys/param.h>
35 #include <sys/elf.h>
36 #include <sys/imgact.h>
37 #include <sys/lock.h>
38 #include <sys/proc.h>
39 #include <sys/rwlock.h>
40 #include <sys/sysent.h>
41
42 #include <vm/pmap.h>
43 #include <vm/vm_extern.h>
44 #include <vm/vm_map.h>
45 #include <vm/vm_object.h>
46 #include <vm/vm_page.h>
47 #include <vm/vm_pager.h>
48 #include <vm/vm_param.h>
49
50 #include <compat/linux/linux_vdso.h>
51
52 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
53 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
54
55 void
__elfN(linux_vdso_sym_init)56 __elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
57 {
58
59 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
60 }
61
62 vm_object_t
__elfN(linux_shared_page_init)63 __elfN(linux_shared_page_init)(char **mapping, vm_size_t size)
64 {
65 vm_page_t m;
66 vm_object_t obj;
67 char *addr;
68 size_t n, pages;
69
70 pages = size / PAGE_SIZE;
71
72 addr = kva_alloc(size);
73 obj = vm_pager_allocate(OBJT_PHYS, 0, size,
74 VM_PROT_DEFAULT, 0, NULL);
75 VM_OBJECT_WLOCK(obj);
76 for (n = 0; n < pages; n++) {
77 m = vm_page_grab(obj, n,
78 VM_ALLOC_ZERO);
79 vm_page_valid(m);
80 vm_page_xunbusy(m);
81 pmap_qenter(addr + n * PAGE_SIZE, &m, 1);
82 }
83 VM_OBJECT_WUNLOCK(obj);
84 *mapping = addr;
85 return (obj);
86 }
87
88 void
__elfN(linux_shared_page_fini)89 __elfN(linux_shared_page_fini)(vm_object_t obj, void *mapping,
90 vm_size_t size)
91 {
92 pmap_qremove(mapping, size / PAGE_SIZE);
93 kva_free(mapping, size);
94 vm_object_deallocate(obj);
95 }
96
97 void
__elfN(linux_vdso_fixup)98 __elfN(linux_vdso_fixup)(char *base, vm_offset_t offset)
99 {
100 struct linux_vdso_sym *lsym;
101 const Elf_Shdr *shdr;
102 Elf_Ehdr *ehdr;
103 Elf_Sym *dsym, *sym;
104 char *strtab, *symname;
105 int i, symcnt;
106
107 ehdr = (Elf_Ehdr *)base;
108
109 MPASS(IS_ELF(*ehdr));
110 MPASS(ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS);
111 MPASS(ehdr->e_ident[EI_DATA] == ELF_TARG_DATA);
112 MPASS(ehdr->e_ident[EI_VERSION] == EV_CURRENT);
113 MPASS(ehdr->e_shentsize == sizeof(Elf_Shdr));
114 MPASS(ehdr->e_shoff != 0);
115 MPASS(ehdr->e_type == ET_DYN);
116
117 shdr = (const Elf_Shdr *)(base + ehdr->e_shoff);
118
119 dsym = NULL;
120 for (i = 0; i < ehdr->e_shnum; i++) {
121 if (shdr[i].sh_size == 0)
122 continue;
123 if (shdr[i].sh_type == SHT_DYNSYM) {
124 dsym = (Elf_Sym *)(base + shdr[i].sh_offset);
125 strtab = base + shdr[shdr[i].sh_link].sh_offset;
126 symcnt = shdr[i].sh_size / sizeof(*dsym);
127 break;
128 }
129 }
130 MPASS(dsym != NULL);
131
132 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;
133
134 /*
135 * VDSO is readonly mapped to the process VA and
136 * can't be relocated by rtld.
137 */
138 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) {
139 for (i = 0, sym = dsym; i < symcnt; i++, sym++) {
140 symname = strtab + sym->st_name;
141 if (strncmp(lsym->symname, symname, lsym->size) == 0) {
142 sym->st_value += offset;
143 *lsym->ptr = sym->st_value;
144 break;
145
146 }
147 }
148 }
149 }
150
151 int
linux_map_vdso(struct proc * p,vm_object_t obj,vm_offset_t base,vm_offset_t size,struct image_params * imgp)152 linux_map_vdso(struct proc *p, vm_object_t obj, vm_offset_t base,
153 vm_offset_t size, struct image_params *imgp)
154 {
155 struct vmspace *vmspace;
156 vm_map_t map;
157 int error;
158
159 MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX);
160 MPASS(obj != NULL);
161
162 vmspace = p->p_vmspace;
163 map = &vmspace->vm_map;
164
165 vm_object_reference(obj);
166 error = vm_map_fixed(map, obj, 0, base, size,
167 VM_PROT_READ | VM_PROT_EXECUTE,
168 VM_PROT_READ | VM_PROT_EXECUTE,
169 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
170 if (error != KERN_SUCCESS) {
171 vm_object_deallocate(obj);
172 return (vm_mmap_to_errno(error));
173 }
174 return (0);
175 }
176