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> |
18d0a6fd | 18 | #include <asm/hpet.h> |
2aae950b | 19 | |
b4b541a6 | 20 | #if defined(CONFIG_X86_64) |
3d7ee969 | 21 | unsigned int __read_mostly vdso64_enabled = 1; |
7f3646aa | 22 | |
2aae950b | 23 | extern unsigned short vdso_sync_cpuid; |
b4b541a6 | 24 | #endif |
1a21d4e0 | 25 | |
6f121e54 | 26 | void __init init_vdso_image(const struct vdso_image *image) |
1a21d4e0 | 27 | { |
1a21d4e0 | 28 | int i; |
6f121e54 | 29 | int npages = (image->size) / PAGE_SIZE; |
1a21d4e0 | 30 | |
6f121e54 AL |
31 | BUG_ON(image->size % PAGE_SIZE != 0); |
32 | for (i = 0; i < npages; i++) | |
a62c34bd AL |
33 | image->text_mapping.pages[i] = |
34 | virt_to_page(image->data + i*PAGE_SIZE); | |
1a21d4e0 | 35 | |
6f121e54 AL |
36 | apply_alternatives((struct alt_instr *)(image->data + image->alt), |
37 | (struct alt_instr *)(image->data + image->alt + | |
38 | image->alt_len)); | |
1a21d4e0 | 39 | } |
1b3f2a72 | 40 | |
6f121e54 | 41 | #if defined(CONFIG_X86_64) |
aafade24 | 42 | static int __init init_vdso(void) |
2aae950b | 43 | { |
6f121e54 | 44 | init_vdso_image(&vdso_image_64); |
2aae950b | 45 | |
1a21d4e0 | 46 | #ifdef CONFIG_X86_X32_ABI |
6f121e54 | 47 | init_vdso_image(&vdso_image_x32); |
1a21d4e0 L |
48 | #endif |
49 | ||
2aae950b | 50 | return 0; |
2aae950b | 51 | } |
aafade24 | 52 | subsys_initcall(init_vdso); |
18d0a6fd | 53 | #endif |
2aae950b AK |
54 | |
55 | struct linux_binprm; | |
56 | ||
57 | /* Put the vdso above the (randomized) stack with another randomized offset. | |
58 | This way there is no hole in the middle of address space. | |
59 | To save memory make sure it is still in the same PTE as the stack top. | |
18d0a6fd AL |
60 | This doesn't give that many random bits. |
61 | ||
62 | Only used for the 64-bit and x32 vdsos. */ | |
2aae950b AK |
63 | static unsigned long vdso_addr(unsigned long start, unsigned len) |
64 | { | |
d093601b JB |
65 | #ifdef CONFIG_X86_32 |
66 | return 0; | |
67 | #else | |
2aae950b AK |
68 | unsigned long addr, end; |
69 | unsigned offset; | |
70 | end = (start + PMD_SIZE - 1) & PMD_MASK; | |
d9517346 IM |
71 | if (end >= TASK_SIZE_MAX) |
72 | end = TASK_SIZE_MAX; | |
2aae950b AK |
73 | end -= len; |
74 | /* This loses some more bits than a modulo, but is cheaper */ | |
75 | offset = get_random_int() & (PTRS_PER_PTE - 1); | |
76 | addr = start + (offset << PAGE_SHIFT); | |
77 | if (addr >= end) | |
78 | addr = end; | |
dfb09f9b BP |
79 | |
80 | /* | |
81 | * page-align it here so that get_unmapped_area doesn't | |
82 | * align it wrongfully again to the next page. addr can come in 4K | |
83 | * unaligned here as a result of stack start randomization. | |
84 | */ | |
85 | addr = PAGE_ALIGN(addr); | |
f9902472 | 86 | addr = align_vdso_addr(addr); |
dfb09f9b | 87 | |
2aae950b | 88 | return addr; |
d093601b | 89 | #endif |
2aae950b AK |
90 | } |
91 | ||
18d0a6fd | 92 | static int map_vdso(const struct vdso_image *image, bool calculate_addr) |
2aae950b AK |
93 | { |
94 | struct mm_struct *mm = current->mm; | |
18d0a6fd | 95 | struct vm_area_struct *vma; |
e6577a7c | 96 | unsigned long addr, text_start; |
18d0a6fd | 97 | int ret = 0; |
1e844fb4 | 98 | static struct page *no_pages[] = {NULL}; |
a62c34bd AL |
99 | static struct vm_special_mapping vvar_mapping = { |
100 | .name = "[vvar]", | |
101 | .pages = no_pages, | |
102 | }; | |
2aae950b | 103 | |
18d0a6fd AL |
104 | if (calculate_addr) { |
105 | addr = vdso_addr(current->mm->start_stack, | |
e6577a7c | 106 | image->size - image->sym_vvar_start); |
18d0a6fd AL |
107 | } else { |
108 | addr = 0; | |
109 | } | |
2aae950b AK |
110 | |
111 | down_write(&mm->mmap_sem); | |
18d0a6fd | 112 | |
e6577a7c AL |
113 | addr = get_unmapped_area(NULL, addr, |
114 | image->size - image->sym_vvar_start, 0, 0); | |
2aae950b AK |
115 | if (IS_ERR_VALUE(addr)) { |
116 | ret = addr; | |
117 | goto up_fail; | |
118 | } | |
119 | ||
e6577a7c AL |
120 | text_start = addr - image->sym_vvar_start; |
121 | current->mm->context.vdso = (void __user *)text_start; | |
f7b6eb3f | 122 | |
18d0a6fd AL |
123 | /* |
124 | * MAYWRITE to allow gdb to COW and set breakpoints | |
125 | */ | |
a62c34bd | 126 | vma = _install_special_mapping(mm, |
e6577a7c | 127 | text_start, |
a62c34bd AL |
128 | image->size, |
129 | VM_READ|VM_EXEC| | |
130 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, | |
131 | &image->text_mapping); | |
18d0a6fd | 132 | |
a62c34bd AL |
133 | if (IS_ERR(vma)) { |
134 | ret = PTR_ERR(vma); | |
18d0a6fd | 135 | goto up_fail; |
a62c34bd | 136 | } |
18d0a6fd AL |
137 | |
138 | vma = _install_special_mapping(mm, | |
e6577a7c AL |
139 | addr, |
140 | -image->sym_vvar_start, | |
ac379835 | 141 | VM_READ|VM_MAYREAD, |
a62c34bd | 142 | &vvar_mapping); |
18d0a6fd AL |
143 | |
144 | if (IS_ERR(vma)) { | |
145 | ret = PTR_ERR(vma); | |
2aae950b | 146 | goto up_fail; |
f7b6eb3f | 147 | } |
2aae950b | 148 | |
18d0a6fd AL |
149 | if (image->sym_vvar_page) |
150 | ret = remap_pfn_range(vma, | |
e6577a7c | 151 | text_start + image->sym_vvar_page, |
18d0a6fd AL |
152 | __pa_symbol(&__vvar_page) >> PAGE_SHIFT, |
153 | PAGE_SIZE, | |
154 | PAGE_READONLY); | |
155 | ||
156 | if (ret) | |
157 | goto up_fail; | |
158 | ||
159 | #ifdef CONFIG_HPET_TIMER | |
160 | if (hpet_address && image->sym_hpet_page) { | |
161 | ret = io_remap_pfn_range(vma, | |
e6577a7c | 162 | text_start + image->sym_hpet_page, |
18d0a6fd AL |
163 | hpet_address >> PAGE_SHIFT, |
164 | PAGE_SIZE, | |
165 | pgprot_noncached(PAGE_READONLY)); | |
166 | ||
167 | if (ret) | |
168 | goto up_fail; | |
169 | } | |
170 | #endif | |
171 | ||
2aae950b | 172 | up_fail: |
18d0a6fd AL |
173 | if (ret) |
174 | current->mm->context.vdso = NULL; | |
175 | ||
2aae950b AK |
176 | up_write(&mm->mmap_sem); |
177 | return ret; | |
178 | } | |
179 | ||
18d0a6fd AL |
180 | #if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT) |
181 | static int load_vdso32(void) | |
182 | { | |
183 | int ret; | |
184 | ||
185 | if (vdso32_enabled != 1) /* Other values all mean "disabled" */ | |
186 | return 0; | |
187 | ||
188 | ret = map_vdso(selected_vdso32, false); | |
189 | if (ret) | |
190 | return ret; | |
191 | ||
192 | if (selected_vdso32->sym_VDSO32_SYSENTER_RETURN) | |
193 | current_thread_info()->sysenter_return = | |
194 | current->mm->context.vdso + | |
195 | selected_vdso32->sym_VDSO32_SYSENTER_RETURN; | |
196 | ||
197 | return 0; | |
198 | } | |
199 | #endif | |
200 | ||
201 | #ifdef CONFIG_X86_64 | |
1a21d4e0 L |
202 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
203 | { | |
18d0a6fd AL |
204 | if (!vdso64_enabled) |
205 | return 0; | |
206 | ||
207 | return map_vdso(&vdso_image_64, true); | |
1a21d4e0 L |
208 | } |
209 | ||
18d0a6fd AL |
210 | #ifdef CONFIG_COMPAT |
211 | int compat_arch_setup_additional_pages(struct linux_binprm *bprm, | |
212 | int uses_interp) | |
213 | { | |
1a21d4e0 | 214 | #ifdef CONFIG_X86_X32_ABI |
18d0a6fd AL |
215 | if (test_thread_flag(TIF_X32)) { |
216 | if (!vdso64_enabled) | |
217 | return 0; | |
218 | ||
219 | return map_vdso(&vdso_image_x32, true); | |
220 | } | |
221 | #endif | |
222 | ||
223 | return load_vdso32(); | |
224 | } | |
225 | #endif | |
226 | #else | |
227 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) | |
1a21d4e0 | 228 | { |
18d0a6fd | 229 | return load_vdso32(); |
1a21d4e0 L |
230 | } |
231 | #endif | |
232 | ||
18d0a6fd | 233 | #ifdef CONFIG_X86_64 |
2aae950b AK |
234 | static __init int vdso_setup(char *s) |
235 | { | |
3d7ee969 | 236 | vdso64_enabled = simple_strtoul(s, NULL, 0); |
2aae950b AK |
237 | return 0; |
238 | } | |
239 | __setup("vdso=", vdso_setup); | |
b4b541a6 | 240 | #endif |