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Commit | Line | Data |
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2aae950b AK |
1 | /* |
2 | * Set up the VMAs to tell the VM about the vDSO. | |
3 | * Copyright 2007 Andi Kleen, SUSE Labs. | |
4 | * Subject to the GPL, v.2 | |
5 | */ | |
6 | #include <linux/mm.h> | |
4e950f6f | 7 | #include <linux/err.h> |
2aae950b | 8 | #include <linux/sched.h> |
5a0e3ad6 | 9 | #include <linux/slab.h> |
2aae950b AK |
10 | #include <linux/init.h> |
11 | #include <linux/random.h> | |
3fa89ca7 | 12 | #include <linux/elf.h> |
2aae950b AK |
13 | #include <asm/vsyscall.h> |
14 | #include <asm/vgtod.h> | |
15 | #include <asm/proto.h> | |
7f3646aa | 16 | #include <asm/vdso.h> |
aafade24 | 17 | #include <asm/page.h> |
2aae950b | 18 | |
b4b541a6 | 19 | #if defined(CONFIG_X86_64) |
3d7ee969 | 20 | unsigned int __read_mostly vdso64_enabled = 1; |
7f3646aa | 21 | |
b67e612c | 22 | DECLARE_VDSO_IMAGE(vdso); |
2aae950b | 23 | extern unsigned short vdso_sync_cpuid; |
369c9920 | 24 | static unsigned vdso_size; |
2aae950b | 25 | |
1a21d4e0 | 26 | #ifdef CONFIG_X86_X32_ABI |
b67e612c | 27 | DECLARE_VDSO_IMAGE(vdsox32); |
1a21d4e0 | 28 | static unsigned vdsox32_size; |
b4b541a6 AL |
29 | #endif |
30 | #endif | |
1a21d4e0 | 31 | |
b4b541a6 AL |
32 | #if defined(CONFIG_X86_32) || defined(CONFIG_X86_X32_ABI) || \ |
33 | defined(CONFIG_COMPAT) | |
34 | void __init patch_vdso32(void *vdso, size_t len) | |
1a21d4e0 L |
35 | { |
36 | Elf32_Ehdr *hdr = vdso; | |
37 | Elf32_Shdr *sechdrs, *alt_sec = 0; | |
38 | char *secstrings; | |
39 | void *alt_data; | |
40 | int i; | |
41 | ||
42 | BUG_ON(len < sizeof(Elf32_Ehdr)); | |
43 | BUG_ON(memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0); | |
44 | ||
45 | sechdrs = (void *)hdr + hdr->e_shoff; | |
46 | secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; | |
47 | ||
48 | for (i = 1; i < hdr->e_shnum; i++) { | |
49 | Elf32_Shdr *shdr = &sechdrs[i]; | |
50 | if (!strcmp(secstrings + shdr->sh_name, ".altinstructions")) { | |
51 | alt_sec = shdr; | |
52 | goto found; | |
53 | } | |
54 | } | |
55 | ||
56 | /* If we get here, it's probably a bug. */ | |
b4b541a6 | 57 | pr_warning("patch_vdso32: .altinstructions not found\n"); |
1a21d4e0 L |
58 | return; /* nothing to patch */ |
59 | ||
60 | found: | |
61 | alt_data = (void *)hdr + alt_sec->sh_offset; | |
62 | apply_alternatives(alt_data, alt_data + alt_sec->sh_size); | |
63 | } | |
64 | #endif | |
65 | ||
b4b541a6 | 66 | #if defined(CONFIG_X86_64) |
1a21d4e0 | 67 | static void __init patch_vdso64(void *vdso, size_t len) |
1b3f2a72 AL |
68 | { |
69 | Elf64_Ehdr *hdr = vdso; | |
70 | Elf64_Shdr *sechdrs, *alt_sec = 0; | |
71 | char *secstrings; | |
72 | void *alt_data; | |
73 | int i; | |
74 | ||
75 | BUG_ON(len < sizeof(Elf64_Ehdr)); | |
76 | BUG_ON(memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0); | |
77 | ||
78 | sechdrs = (void *)hdr + hdr->e_shoff; | |
79 | secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; | |
80 | ||
81 | for (i = 1; i < hdr->e_shnum; i++) { | |
82 | Elf64_Shdr *shdr = &sechdrs[i]; | |
83 | if (!strcmp(secstrings + shdr->sh_name, ".altinstructions")) { | |
84 | alt_sec = shdr; | |
85 | goto found; | |
86 | } | |
87 | } | |
88 | ||
89 | /* If we get here, it's probably a bug. */ | |
1a21d4e0 | 90 | pr_warning("patch_vdso64: .altinstructions not found\n"); |
1b3f2a72 AL |
91 | return; /* nothing to patch */ |
92 | ||
93 | found: | |
94 | alt_data = (void *)hdr + alt_sec->sh_offset; | |
95 | apply_alternatives(alt_data, alt_data + alt_sec->sh_size); | |
96 | } | |
97 | ||
aafade24 | 98 | static int __init init_vdso(void) |
2aae950b AK |
99 | { |
100 | int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE; | |
101 | int i; | |
2aae950b | 102 | |
1a21d4e0 | 103 | patch_vdso64(vdso_start, vdso_end - vdso_start); |
1b3f2a72 | 104 | |
369c9920 | 105 | vdso_size = npages << PAGE_SHIFT; |
aafade24 AL |
106 | for (i = 0; i < npages; i++) |
107 | vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE); | |
2aae950b | 108 | |
1a21d4e0 | 109 | #ifdef CONFIG_X86_X32_ABI |
b4b541a6 | 110 | patch_vdso32(vdsox32_start, vdsox32_end - vdsox32_start); |
1a21d4e0 L |
111 | npages = (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE; |
112 | vdsox32_size = npages << PAGE_SHIFT; | |
113 | for (i = 0; i < npages; i++) | |
114 | vdsox32_pages[i] = virt_to_page(vdsox32_start + i*PAGE_SIZE); | |
115 | #endif | |
116 | ||
2aae950b | 117 | return 0; |
2aae950b | 118 | } |
aafade24 | 119 | subsys_initcall(init_vdso); |
2aae950b AK |
120 | |
121 | struct linux_binprm; | |
122 | ||
123 | /* Put the vdso above the (randomized) stack with another randomized offset. | |
124 | This way there is no hole in the middle of address space. | |
125 | To save memory make sure it is still in the same PTE as the stack top. | |
126 | This doesn't give that many random bits */ | |
127 | static unsigned long vdso_addr(unsigned long start, unsigned len) | |
128 | { | |
129 | unsigned long addr, end; | |
130 | unsigned offset; | |
131 | end = (start + PMD_SIZE - 1) & PMD_MASK; | |
d9517346 IM |
132 | if (end >= TASK_SIZE_MAX) |
133 | end = TASK_SIZE_MAX; | |
2aae950b AK |
134 | end -= len; |
135 | /* This loses some more bits than a modulo, but is cheaper */ | |
136 | offset = get_random_int() & (PTRS_PER_PTE - 1); | |
137 | addr = start + (offset << PAGE_SHIFT); | |
138 | if (addr >= end) | |
139 | addr = end; | |
dfb09f9b BP |
140 | |
141 | /* | |
142 | * page-align it here so that get_unmapped_area doesn't | |
143 | * align it wrongfully again to the next page. addr can come in 4K | |
144 | * unaligned here as a result of stack start randomization. | |
145 | */ | |
146 | addr = PAGE_ALIGN(addr); | |
f9902472 | 147 | addr = align_vdso_addr(addr); |
dfb09f9b | 148 | |
2aae950b AK |
149 | return addr; |
150 | } | |
151 | ||
152 | /* Setup a VMA at program startup for the vsyscall page. | |
153 | Not called for compat tasks */ | |
1a21d4e0 L |
154 | static int setup_additional_pages(struct linux_binprm *bprm, |
155 | int uses_interp, | |
156 | struct page **pages, | |
157 | unsigned size) | |
2aae950b AK |
158 | { |
159 | struct mm_struct *mm = current->mm; | |
160 | unsigned long addr; | |
161 | int ret; | |
2aae950b | 162 | |
3d7ee969 | 163 | if (!vdso64_enabled) |
2aae950b AK |
164 | return 0; |
165 | ||
166 | down_write(&mm->mmap_sem); | |
1a21d4e0 L |
167 | addr = vdso_addr(mm->start_stack, size); |
168 | addr = get_unmapped_area(NULL, addr, size, 0, 0); | |
2aae950b AK |
169 | if (IS_ERR_VALUE(addr)) { |
170 | ret = addr; | |
171 | goto up_fail; | |
172 | } | |
173 | ||
f7b6eb3f PZ |
174 | current->mm->context.vdso = (void *)addr; |
175 | ||
1a21d4e0 | 176 | ret = install_special_mapping(mm, addr, size, |
2aae950b | 177 | VM_READ|VM_EXEC| |
909af768 | 178 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
1a21d4e0 | 179 | pages); |
f7b6eb3f PZ |
180 | if (ret) { |
181 | current->mm->context.vdso = NULL; | |
2aae950b | 182 | goto up_fail; |
f7b6eb3f | 183 | } |
2aae950b | 184 | |
2aae950b AK |
185 | up_fail: |
186 | up_write(&mm->mmap_sem); | |
187 | return ret; | |
188 | } | |
189 | ||
1a21d4e0 L |
190 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
191 | { | |
22e842d4 PA |
192 | return setup_additional_pages(bprm, uses_interp, vdso_pages, |
193 | vdso_size); | |
1a21d4e0 L |
194 | } |
195 | ||
196 | #ifdef CONFIG_X86_X32_ABI | |
197 | int x32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) | |
198 | { | |
22e842d4 PA |
199 | return setup_additional_pages(bprm, uses_interp, vdsox32_pages, |
200 | vdsox32_size); | |
1a21d4e0 L |
201 | } |
202 | #endif | |
203 | ||
2aae950b AK |
204 | static __init int vdso_setup(char *s) |
205 | { | |
3d7ee969 | 206 | vdso64_enabled = simple_strtoul(s, NULL, 0); |
2aae950b AK |
207 | return 0; |
208 | } | |
209 | __setup("vdso=", vdso_setup); | |
b4b541a6 | 210 | #endif |