1 /*-
2 * Copyright (c) 2013-2021 Dmitry Chagin <dchagin@FreeBSD.org>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer
9 * in this position and unchanged.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include <sys/cdefs.h>
27 #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32))
28 #define __ELF_WORD_SIZE 32
29 #else
30 #define __ELF_WORD_SIZE 64
31 #endif
32
33 #include <sys/param.h>
34 #include <sys/elf.h>
35 #include <sys/imgact.h>
36 #include <sys/lock.h>
37 #include <sys/proc.h>
38 #include <sys/rwlock.h>
39 #include <sys/sysent.h>
40
41 #include <vm/pmap.h>
42 #include <vm/vm_extern.h>
43 #include <vm/vm_map.h>
44 #include <vm/vm_object.h>
45 #include <vm/vm_page.h>
46 #include <vm/vm_pager.h>
47 #include <vm/vm_param.h>
48
49 #include <compat/linux/linux_vdso.h>
50
51 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) =
52 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms));
53
54 void
__elfN(linux_vdso_sym_init)55 __elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s)
56 {
57
58 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym);
59 }
60
61 vm_object_t
__elfN(linux_shared_page_init)62 __elfN(linux_shared_page_init)(char **mapping, vm_size_t size)
63 {
64 vm_page_t m;
65 vm_object_t obj;
66 vm_offset_t addr;
67 size_t n, pages;
68
69 pages = size / PAGE_SIZE;
70
71 addr = kva_alloc(size);
72 obj = vm_pager_allocate(OBJT_PHYS, 0, size,
73 VM_PROT_DEFAULT, 0, NULL);
74 VM_OBJECT_WLOCK(obj);
75 for (n = 0; n < pages; n++) {
76 m = vm_page_grab(obj, n,
77 VM_ALLOC_ZERO);
78 vm_page_valid(m);
79 vm_page_xunbusy(m);
80 pmap_qenter(addr + n * PAGE_SIZE, &m, 1);
81 }
82 VM_OBJECT_WUNLOCK(obj);
83 *mapping = (char *)addr;
84 return (obj);
85 }
86
87 void
__elfN(linux_shared_page_fini)88 __elfN(linux_shared_page_fini)(vm_object_t obj, void *mapping,
89 vm_size_t size)
90 {
91 vm_offset_t va;
92
93 va = (vm_offset_t)mapping;
94 pmap_qremove(va, size / PAGE_SIZE);
95 kva_free(va, size);
96 vm_object_deallocate(obj);
97 }
98
99 void
__elfN(linux_vdso_fixup)100 __elfN(linux_vdso_fixup)(char *base, vm_offset_t offset)
101 {
102 struct linux_vdso_sym *lsym;
103 const Elf_Shdr *shdr;
104 Elf_Ehdr *ehdr;
105 Elf_Sym *dsym, *sym;
106 char *strtab, *symname;
107 int i, symcnt;
108
109 ehdr = __DECONST(Elf_Ehdr *, base);
110
111 MPASS(IS_ELF(*ehdr));
112 MPASS(ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS);
113 MPASS(ehdr->e_ident[EI_DATA] == ELF_TARG_DATA);
114 MPASS(ehdr->e_ident[EI_VERSION] == EV_CURRENT);
115 MPASS(ehdr->e_shentsize == sizeof(Elf_Shdr));
116 MPASS(ehdr->e_shoff != 0);
117 MPASS(ehdr->e_type == ET_DYN);
118
119 shdr = (const Elf_Shdr *)(base + ehdr->e_shoff);
120
121 dsym = NULL;
122 for (i = 0; i < ehdr->e_shnum; i++) {
123 if (shdr[i].sh_size == 0)
124 continue;
125 if (shdr[i].sh_type == SHT_DYNSYM) {
126 dsym = (Elf_Sym *)(base + shdr[i].sh_offset);
127 strtab = base + shdr[shdr[i].sh_link].sh_offset;
128 symcnt = shdr[i].sh_size / sizeof(*dsym);
129 break;
130 }
131 }
132 MPASS(dsym != NULL);
133
134 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX;
135 /*
136 * VDSO is readonly mapped to the process VA and
137 * can't be relocated by rtld.
138 */
139 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) {
140 for (i = 0, sym = dsym; i < symcnt; i++, sym++) {
141 symname = strtab + sym->st_name;
142 if (strncmp(lsym->symname, symname, lsym->size) == 0) {
143 sym->st_value += offset;
144 *lsym->ptr = sym->st_value;
145 break;
146
147 }
148 }
149 }
150 }
151
152 int
linux_map_vdso(struct proc * p,vm_object_t obj,vm_offset_t base,vm_offset_t size,struct image_params * imgp)153 linux_map_vdso(struct proc *p, vm_object_t obj, vm_offset_t base,
154 vm_offset_t size, struct image_params *imgp)
155 {
156 struct vmspace *vmspace;
157 vm_map_t map;
158 int error;
159
160 MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX);
161 MPASS(obj != NULL);
162
163 vmspace = p->p_vmspace;
164 map = &vmspace->vm_map;
165
166 vm_object_reference(obj);
167 error = vm_map_fixed(map, obj, 0, base, size,
168 VM_PROT_READ | VM_PROT_EXECUTE,
169 VM_PROT_READ | VM_PROT_EXECUTE,
170 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
171 if (error != KERN_SUCCESS) {
172 vm_object_deallocate(obj);
173 return (vm_mmap_to_errno(error));
174 }
175 return (0);
176 }
177