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a17ae4c3 | 1 | // SPDX-License-Identifier: GPL-2.0 |
b020632e MS |
2 | /* |
3 | * vdso setup for s390 | |
4 | * | |
5 | * Copyright IBM Corp. 2008 | |
6 | * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) | |
b020632e MS |
7 | */ |
8 | ||
8d4be7f3 HC |
9 | #include <linux/binfmts.h> |
10 | #include <linux/compat.h> | |
11 | #include <linux/elf.h> | |
b020632e | 12 | #include <linux/errno.h> |
8d4be7f3 | 13 | #include <linux/init.h> |
b020632e MS |
14 | #include <linux/kernel.h> |
15 | #include <linux/mm.h> | |
b020632e | 16 | #include <linux/slab.h> |
8d4be7f3 | 17 | #include <linux/smp.h> |
eeab78b0 | 18 | #include <linux/time_namespace.h> |
41cd81ab | 19 | #include <linux/random.h> |
4bff8cb5 | 20 | #include <vdso/datapage.h> |
b020632e MS |
21 | #include <asm/vdso.h> |
22 | ||
6755270b | 23 | extern char vdso64_start[], vdso64_end[]; |
779df224 | 24 | extern char vdso32_start[], vdso32_end[]; |
b020632e | 25 | |
eeab78b0 HC |
26 | static struct vm_special_mapping vvar_mapping; |
27 | ||
8d4be7f3 HC |
28 | static union { |
29 | struct vdso_data data[CS_BASES]; | |
30 | u8 page[PAGE_SIZE]; | |
31 | } vdso_data_store __page_aligned_data; | |
32 | ||
33 | struct vdso_data *vdso_data = vdso_data_store.data; | |
34 | ||
eeab78b0 HC |
35 | enum vvar_pages { |
36 | VVAR_DATA_PAGE_OFFSET, | |
37 | VVAR_TIMENS_PAGE_OFFSET, | |
38 | VVAR_NR_PAGES, | |
39 | }; | |
40 | ||
eeab78b0 HC |
41 | #ifdef CONFIG_TIME_NS |
42 | struct vdso_data *arch_get_vdso_data(void *vvar_page) | |
43 | { | |
44 | return (struct vdso_data *)(vvar_page); | |
45 | } | |
46 | ||
47 | static struct page *find_timens_vvar_page(struct vm_area_struct *vma) | |
48 | { | |
49 | if (likely(vma->vm_mm == current->mm)) | |
50 | return current->nsproxy->time_ns->vvar_page; | |
51 | /* | |
52 | * VM_PFNMAP | VM_IO protect .fault() handler from being called | |
53 | * through interfaces like /proc/$pid/mem or | |
54 | * process_vm_{readv,writev}() as long as there's no .access() | |
55 | * in special_mapping_vmops(). | |
56 | * For more details check_vma_flags() and __access_remote_vm() | |
57 | */ | |
58 | WARN(1, "vvar_page accessed remotely"); | |
59 | return NULL; | |
60 | } | |
61 | ||
62 | /* | |
63 | * The VVAR page layout depends on whether a task belongs to the root or | |
64 | * non-root time namespace. Whenever a task changes its namespace, the VVAR | |
65 | * page tables are cleared and then they will be re-faulted with a | |
66 | * corresponding layout. | |
67 | * See also the comment near timens_setup_vdso_data() for details. | |
68 | */ | |
69 | int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) | |
70 | { | |
71 | struct mm_struct *mm = task->mm; | |
72 | struct vm_area_struct *vma; | |
73 | ||
74 | mmap_read_lock(mm); | |
75 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
76 | unsigned long size = vma->vm_end - vma->vm_start; | |
77 | ||
78 | if (!vma_is_special_mapping(vma, &vvar_mapping)) | |
79 | continue; | |
80 | zap_page_range(vma, vma->vm_start, size); | |
81 | break; | |
82 | } | |
83 | mmap_read_unlock(mm); | |
84 | return 0; | |
85 | } | |
86 | #else | |
87 | static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma) | |
88 | { | |
89 | return NULL; | |
90 | } | |
91 | #endif | |
92 | ||
5056c2c5 HC |
93 | static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, |
94 | struct vm_area_struct *vma, struct vm_fault *vmf) | |
95 | { | |
eeab78b0 | 96 | struct page *timens_page = find_timens_vvar_page(vma); |
fe8344a0 HC |
97 | unsigned long addr, pfn; |
98 | vm_fault_t err; | |
eeab78b0 HC |
99 | |
100 | switch (vmf->pgoff) { | |
101 | case VVAR_DATA_PAGE_OFFSET: | |
fe8344a0 HC |
102 | pfn = virt_to_pfn(vdso_data); |
103 | if (timens_page) { | |
104 | /* | |
105 | * Fault in VVAR page too, since it will be accessed | |
106 | * to get clock data anyway. | |
107 | */ | |
108 | addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE; | |
109 | err = vmf_insert_pfn(vma, addr, pfn); | |
110 | if (unlikely(err & VM_FAULT_ERROR)) | |
111 | return err; | |
eeab78b0 | 112 | pfn = page_to_pfn(timens_page); |
fe8344a0 | 113 | } |
eeab78b0 HC |
114 | break; |
115 | #ifdef CONFIG_TIME_NS | |
116 | case VVAR_TIMENS_PAGE_OFFSET: | |
117 | /* | |
118 | * If a task belongs to a time namespace then a namespace | |
119 | * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and | |
120 | * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET | |
121 | * offset. | |
122 | * See also the comment near timens_setup_vdso_data(). | |
123 | */ | |
124 | if (!timens_page) | |
125 | return VM_FAULT_SIGBUS; | |
126 | pfn = virt_to_pfn(vdso_data); | |
127 | break; | |
128 | #endif /* CONFIG_TIME_NS */ | |
129 | default: | |
130 | return VM_FAULT_SIGBUS; | |
131 | } | |
132 | return vmf_insert_pfn(vma, vmf->address, pfn); | |
5056c2c5 HC |
133 | } |
134 | ||
35bb092a MS |
135 | static int vdso_mremap(const struct vm_special_mapping *sm, |
136 | struct vm_area_struct *vma) | |
137 | { | |
35bb092a MS |
138 | current->mm->context.vdso_base = vma->vm_start; |
139 | return 0; | |
140 | } | |
141 | ||
5056c2c5 HC |
142 | static struct vm_special_mapping vvar_mapping = { |
143 | .name = "[vvar]", | |
144 | .fault = vvar_fault, | |
145 | }; | |
146 | ||
779df224 SS |
147 | static struct vm_special_mapping vdso64_mapping = { |
148 | .name = "[vdso]", | |
149 | .mremap = vdso_mremap, | |
150 | }; | |
151 | ||
152 | static struct vm_special_mapping vdso32_mapping = { | |
35bb092a | 153 | .name = "[vdso]", |
35bb092a MS |
154 | .mremap = vdso_mremap, |
155 | }; | |
156 | ||
96c0c7ae | 157 | int vdso_getcpu_init(void) |
80f06306 HC |
158 | { |
159 | set_tod_programmable_field(smp_processor_id()); | |
96c0c7ae | 160 | return 0; |
80f06306 | 161 | } |
96c0c7ae | 162 | early_initcall(vdso_getcpu_init); /* Must be called before SMP init */ |
80f06306 | 163 | |
57761da4 | 164 | static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len) |
b020632e | 165 | { |
57761da4 | 166 | unsigned long vvar_start, vdso_text_start, vdso_text_len; |
779df224 | 167 | struct vm_special_mapping *vdso_mapping; |
b020632e | 168 | struct mm_struct *mm = current->mm; |
35bb092a | 169 | struct vm_area_struct *vma; |
b020632e MS |
170 | int rc; |
171 | ||
eeab78b0 | 172 | BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); |
d8ed45c5 | 173 | if (mmap_write_lock_killable(mm)) |
69048176 | 174 | return -EINTR; |
779df224 SS |
175 | |
176 | if (is_compat_task()) { | |
177 | vdso_text_len = vdso32_end - vdso32_start; | |
178 | vdso_mapping = &vdso32_mapping; | |
179 | } else { | |
180 | vdso_text_len = vdso64_end - vdso64_start; | |
181 | vdso_mapping = &vdso64_mapping; | |
182 | } | |
57761da4 | 183 | vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0); |
214b3564 HC |
184 | rc = vvar_start; |
185 | if (IS_ERR_VALUE(vvar_start)) | |
8d4be7f3 | 186 | goto out; |
eeab78b0 HC |
187 | vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE, |
188 | VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP| | |
189 | VM_PFNMAP, | |
214b3564 HC |
190 | &vvar_mapping); |
191 | rc = PTR_ERR(vma); | |
192 | if (IS_ERR(vma)) | |
193 | goto out; | |
eeab78b0 | 194 | vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE; |
5056c2c5 | 195 | /* VM_MAYWRITE for COW so gdb can set breakpoints */ |
214b3564 | 196 | vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len, |
35bb092a MS |
197 | VM_READ|VM_EXEC| |
198 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, | |
779df224 | 199 | vdso_mapping); |
5056c2c5 | 200 | if (IS_ERR(vma)) { |
214b3564 | 201 | do_munmap(mm, vvar_start, PAGE_SIZE, NULL); |
5056c2c5 HC |
202 | rc = PTR_ERR(vma); |
203 | } else { | |
204 | current->mm->context.vdso_base = vdso_text_start; | |
205 | rc = 0; | |
206 | } | |
8d4be7f3 | 207 | out: |
d8ed45c5 | 208 | mmap_write_unlock(mm); |
b020632e MS |
209 | return rc; |
210 | } | |
211 | ||
41cd81ab SS |
212 | static unsigned long vdso_addr(unsigned long start, unsigned long len) |
213 | { | |
214 | unsigned long addr, end, offset; | |
215 | ||
216 | /* | |
217 | * Round up the start address. It can start out unaligned as a result | |
218 | * of stack start randomization. | |
219 | */ | |
220 | start = PAGE_ALIGN(start); | |
221 | ||
222 | /* Round the lowest possible end address up to a PMD boundary. */ | |
223 | end = (start + len + PMD_SIZE - 1) & PMD_MASK; | |
224 | if (end >= VDSO_BASE) | |
225 | end = VDSO_BASE; | |
226 | end -= len; | |
227 | ||
228 | if (end > start) { | |
229 | offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1); | |
230 | addr = start + (offset << PAGE_SHIFT); | |
231 | } else { | |
232 | addr = start; | |
233 | } | |
234 | return addr; | |
235 | } | |
236 | ||
57761da4 SS |
237 | unsigned long vdso_size(void) |
238 | { | |
239 | unsigned long size = VVAR_NR_PAGES * PAGE_SIZE; | |
240 | ||
241 | if (is_compat_task()) | |
242 | size += vdso32_end - vdso32_start; | |
243 | else | |
244 | size += vdso64_end - vdso64_start; | |
245 | return PAGE_ALIGN(size); | |
246 | } | |
247 | ||
248 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) | |
249 | { | |
41cd81ab SS |
250 | unsigned long addr = VDSO_BASE; |
251 | unsigned long size = vdso_size(); | |
252 | ||
253 | if (current->flags & PF_RANDOMIZE) | |
254 | addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size); | |
255 | return map_vdso(addr, size); | |
57761da4 SS |
256 | } |
257 | ||
779df224 | 258 | static struct page ** __init vdso_setup_pages(void *start, void *end) |
b020632e | 259 | { |
779df224 SS |
260 | int pages = (end - start) >> PAGE_SHIFT; |
261 | struct page **pagelist; | |
b020632e MS |
262 | int i; |
263 | ||
779df224 SS |
264 | pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); |
265 | if (!pagelist) | |
266 | panic("%s: Cannot allocate page list for VDSO", __func__); | |
267 | for (i = 0; i < pages; i++) | |
268 | pagelist[i] = virt_to_page(start + i * PAGE_SIZE); | |
269 | return pagelist; | |
270 | } | |
d57778fe | 271 | |
779df224 SS |
272 | static int __init vdso_init(void) |
273 | { | |
274 | vdso64_mapping.pages = vdso_setup_pages(vdso64_start, vdso64_end); | |
275 | if (IS_ENABLED(CONFIG_COMPAT)) | |
276 | vdso32_mapping.pages = vdso_setup_pages(vdso32_start, vdso32_end); | |
b020632e MS |
277 | return 0; |
278 | } | |
96c0c7ae | 279 | arch_initcall(vdso_init); |