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1 | /* |
2 | * VDSO implementation for AArch64 and vector page setup for AArch32. | |
3 | * | |
4 | * Copyright (C) 2012 ARM Limited | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
17 | * | |
18 | * Author: Will Deacon <will.deacon@arm.com> | |
19 | */ | |
20 | ||
21 | #include <linux/kernel.h> | |
22 | #include <linux/clocksource.h> | |
23 | #include <linux/elf.h> | |
24 | #include <linux/err.h> | |
25 | #include <linux/errno.h> | |
26 | #include <linux/gfp.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/signal.h> | |
30 | #include <linux/slab.h> | |
31 | #include <linux/vmalloc.h> | |
32 | ||
33 | #include <asm/cacheflush.h> | |
34 | #include <asm/signal32.h> | |
35 | #include <asm/vdso.h> | |
36 | #include <asm/vdso_datapage.h> | |
37 | ||
38 | extern char vdso_start, vdso_end; | |
39 | static unsigned long vdso_pages; | |
40 | static struct page **vdso_pagelist; | |
41 | ||
42 | /* | |
43 | * The vDSO data page. | |
44 | */ | |
45 | static union { | |
46 | struct vdso_data data; | |
47 | u8 page[PAGE_SIZE]; | |
48 | } vdso_data_store __page_aligned_data; | |
49 | struct vdso_data *vdso_data = &vdso_data_store.data; | |
50 | ||
51 | #ifdef CONFIG_COMPAT | |
52 | /* | |
53 | * Create and map the vectors page for AArch32 tasks. | |
54 | */ | |
55 | static struct page *vectors_page[1]; | |
56 | ||
57 | static int alloc_vectors_page(void) | |
58 | { | |
59 | extern char __kuser_helper_start[], __kuser_helper_end[]; | |
60 | int kuser_sz = __kuser_helper_end - __kuser_helper_start; | |
61 | unsigned long vpage; | |
62 | ||
63 | vpage = get_zeroed_page(GFP_ATOMIC); | |
64 | ||
65 | if (!vpage) | |
66 | return -ENOMEM; | |
67 | ||
68 | /* kuser helpers */ | |
69 | memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start, | |
70 | kuser_sz); | |
71 | ||
72 | /* sigreturn code */ | |
73 | memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET, | |
74 | aarch32_sigret_code, sizeof(aarch32_sigret_code)); | |
75 | ||
76 | flush_icache_range(vpage, vpage + PAGE_SIZE); | |
77 | vectors_page[0] = virt_to_page(vpage); | |
78 | ||
79 | return 0; | |
80 | } | |
81 | arch_initcall(alloc_vectors_page); | |
82 | ||
83 | int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) | |
84 | { | |
85 | struct mm_struct *mm = current->mm; | |
86 | unsigned long addr = AARCH32_VECTORS_BASE; | |
87 | int ret; | |
88 | ||
89 | down_write(&mm->mmap_sem); | |
90 | current->mm->context.vdso = (void *)addr; | |
91 | ||
92 | /* Map vectors page at the high address. */ | |
93 | ret = install_special_mapping(mm, addr, PAGE_SIZE, | |
94 | VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, | |
95 | vectors_page); | |
96 | ||
97 | up_write(&mm->mmap_sem); | |
98 | ||
99 | return ret; | |
100 | } | |
101 | #endif /* CONFIG_COMPAT */ | |
102 | ||
103 | static int __init vdso_init(void) | |
104 | { | |
105 | struct page *pg; | |
106 | char *vbase; | |
107 | int i, ret = 0; | |
108 | ||
109 | vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; | |
110 | pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n", | |
111 | vdso_pages + 1, vdso_pages, 1L, &vdso_start); | |
112 | ||
113 | /* Allocate the vDSO pagelist, plus a page for the data. */ | |
114 | vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1), | |
115 | GFP_KERNEL); | |
116 | if (vdso_pagelist == NULL) { | |
117 | pr_err("Failed to allocate vDSO pagelist!\n"); | |
118 | return -ENOMEM; | |
119 | } | |
120 | ||
121 | /* Grab the vDSO code pages. */ | |
122 | for (i = 0; i < vdso_pages; i++) { | |
123 | pg = virt_to_page(&vdso_start + i*PAGE_SIZE); | |
124 | ClearPageReserved(pg); | |
125 | get_page(pg); | |
126 | vdso_pagelist[i] = pg; | |
127 | } | |
128 | ||
129 | /* Sanity check the shared object header. */ | |
130 | vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL); | |
131 | if (vbase == NULL) { | |
132 | pr_err("Failed to map vDSO pagelist!\n"); | |
133 | return -ENOMEM; | |
134 | } else if (memcmp(vbase, "\177ELF", 4)) { | |
135 | pr_err("vDSO is not a valid ELF object!\n"); | |
136 | ret = -EINVAL; | |
137 | goto unmap; | |
138 | } | |
139 | ||
140 | /* Grab the vDSO data page. */ | |
141 | pg = virt_to_page(vdso_data); | |
142 | get_page(pg); | |
143 | vdso_pagelist[i] = pg; | |
144 | ||
145 | unmap: | |
146 | vunmap(vbase); | |
147 | return ret; | |
148 | } | |
149 | arch_initcall(vdso_init); | |
150 | ||
151 | int arch_setup_additional_pages(struct linux_binprm *bprm, | |
152 | int uses_interp) | |
153 | { | |
154 | struct mm_struct *mm = current->mm; | |
155 | unsigned long vdso_base, vdso_mapping_len; | |
156 | int ret; | |
157 | ||
158 | /* Be sure to map the data page */ | |
159 | vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT; | |
160 | ||
161 | down_write(&mm->mmap_sem); | |
162 | vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); | |
163 | if (IS_ERR_VALUE(vdso_base)) { | |
164 | ret = vdso_base; | |
165 | goto up_fail; | |
166 | } | |
167 | mm->context.vdso = (void *)vdso_base; | |
168 | ||
169 | ret = install_special_mapping(mm, vdso_base, vdso_mapping_len, | |
170 | VM_READ|VM_EXEC| | |
171 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, | |
172 | vdso_pagelist); | |
173 | if (ret) { | |
174 | mm->context.vdso = NULL; | |
175 | goto up_fail; | |
176 | } | |
177 | ||
178 | up_fail: | |
179 | up_write(&mm->mmap_sem); | |
180 | ||
181 | return ret; | |
182 | } | |
183 | ||
184 | const char *arch_vma_name(struct vm_area_struct *vma) | |
185 | { | |
186 | /* | |
187 | * We can re-use the vdso pointer in mm_context_t for identifying | |
188 | * the vectors page for compat applications. The vDSO will always | |
189 | * sit above TASK_UNMAPPED_BASE and so we don't need to worry about | |
190 | * it conflicting with the vectors base. | |
191 | */ | |
192 | if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) { | |
193 | #ifdef CONFIG_COMPAT | |
194 | if (vma->vm_start == AARCH32_VECTORS_BASE) | |
195 | return "[vectors]"; | |
196 | #endif | |
197 | return "[vdso]"; | |
198 | } | |
199 | ||
200 | return NULL; | |
201 | } | |
202 | ||
203 | /* | |
204 | * We define AT_SYSINFO_EHDR, so we need these function stubs to keep | |
205 | * Linux happy. | |
206 | */ | |
207 | int in_gate_area_no_mm(unsigned long addr) | |
208 | { | |
209 | return 0; | |
210 | } | |
211 | ||
212 | int in_gate_area(struct mm_struct *mm, unsigned long addr) | |
213 | { | |
214 | return 0; | |
215 | } | |
216 | ||
217 | struct vm_area_struct *get_gate_vma(struct mm_struct *mm) | |
218 | { | |
219 | return NULL; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Update the vDSO data page to keep in sync with kernel timekeeping. | |
224 | */ | |
225 | void update_vsyscall(struct timespec *ts, struct timespec *wtm, | |
226 | struct clocksource *clock, u32 mult) | |
227 | { | |
228 | struct timespec xtime_coarse; | |
229 | u32 use_syscall = strcmp(clock->name, "arch_sys_counter"); | |
230 | ||
231 | ++vdso_data->tb_seq_count; | |
232 | smp_wmb(); | |
233 | ||
234 | xtime_coarse = __current_kernel_time(); | |
235 | vdso_data->use_syscall = use_syscall; | |
236 | vdso_data->xtime_coarse_sec = xtime_coarse.tv_sec; | |
237 | vdso_data->xtime_coarse_nsec = xtime_coarse.tv_nsec; | |
238 | ||
239 | if (!use_syscall) { | |
240 | vdso_data->cs_cycle_last = clock->cycle_last; | |
241 | vdso_data->xtime_clock_sec = ts->tv_sec; | |
242 | vdso_data->xtime_clock_nsec = ts->tv_nsec; | |
243 | vdso_data->cs_mult = mult; | |
244 | vdso_data->cs_shift = clock->shift; | |
245 | vdso_data->wtm_clock_sec = wtm->tv_sec; | |
246 | vdso_data->wtm_clock_nsec = wtm->tv_nsec; | |
247 | } | |
248 | ||
249 | smp_wmb(); | |
250 | ++vdso_data->tb_seq_count; | |
251 | } | |
252 | ||
253 | void update_vsyscall_tz(void) | |
254 | { | |
255 | ++vdso_data->tb_seq_count; | |
256 | smp_wmb(); | |
257 | vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; | |
258 | vdso_data->tz_dsttime = sys_tz.tz_dsttime; | |
259 | smp_wmb(); | |
260 | ++vdso_data->tb_seq_count; | |
261 | } |