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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 | ||
eeab78b0 HC |
47 | /* |
48 | * The VVAR page layout depends on whether a task belongs to the root or | |
49 | * non-root time namespace. Whenever a task changes its namespace, the VVAR | |
50 | * page tables are cleared and then they will be re-faulted with a | |
51 | * corresponding layout. | |
52 | * See also the comment near timens_setup_vdso_data() for details. | |
53 | */ | |
54 | int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) | |
55 | { | |
56 | struct mm_struct *mm = task->mm; | |
e7b6b990 | 57 | VMA_ITERATOR(vmi, mm, 0); |
eeab78b0 HC |
58 | struct vm_area_struct *vma; |
59 | ||
60 | mmap_read_lock(mm); | |
e7b6b990 | 61 | for_each_vma(vmi, vma) { |
eeab78b0 HC |
62 | if (!vma_is_special_mapping(vma, &vvar_mapping)) |
63 | continue; | |
e9adcfec | 64 | zap_vma_pages(vma); |
eeab78b0 HC |
65 | break; |
66 | } | |
67 | mmap_read_unlock(mm); | |
68 | return 0; | |
69 | } | |
eeab78b0 HC |
70 | #endif |
71 | ||
5056c2c5 HC |
72 | static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, |
73 | struct vm_area_struct *vma, struct vm_fault *vmf) | |
74 | { | |
eeab78b0 | 75 | struct page *timens_page = find_timens_vvar_page(vma); |
fe8344a0 HC |
76 | unsigned long addr, pfn; |
77 | vm_fault_t err; | |
eeab78b0 HC |
78 | |
79 | switch (vmf->pgoff) { | |
80 | case VVAR_DATA_PAGE_OFFSET: | |
fe8344a0 HC |
81 | pfn = virt_to_pfn(vdso_data); |
82 | if (timens_page) { | |
83 | /* | |
84 | * Fault in VVAR page too, since it will be accessed | |
85 | * to get clock data anyway. | |
86 | */ | |
87 | addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE; | |
88 | err = vmf_insert_pfn(vma, addr, pfn); | |
89 | if (unlikely(err & VM_FAULT_ERROR)) | |
90 | return err; | |
eeab78b0 | 91 | pfn = page_to_pfn(timens_page); |
fe8344a0 | 92 | } |
eeab78b0 HC |
93 | break; |
94 | #ifdef CONFIG_TIME_NS | |
95 | case VVAR_TIMENS_PAGE_OFFSET: | |
96 | /* | |
97 | * If a task belongs to a time namespace then a namespace | |
98 | * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and | |
99 | * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET | |
100 | * offset. | |
101 | * See also the comment near timens_setup_vdso_data(). | |
102 | */ | |
103 | if (!timens_page) | |
104 | return VM_FAULT_SIGBUS; | |
105 | pfn = virt_to_pfn(vdso_data); | |
106 | break; | |
107 | #endif /* CONFIG_TIME_NS */ | |
108 | default: | |
109 | return VM_FAULT_SIGBUS; | |
110 | } | |
111 | return vmf_insert_pfn(vma, vmf->address, pfn); | |
5056c2c5 HC |
112 | } |
113 | ||
35bb092a MS |
114 | static int vdso_mremap(const struct vm_special_mapping *sm, |
115 | struct vm_area_struct *vma) | |
116 | { | |
35bb092a MS |
117 | current->mm->context.vdso_base = vma->vm_start; |
118 | return 0; | |
119 | } | |
120 | ||
5056c2c5 HC |
121 | static struct vm_special_mapping vvar_mapping = { |
122 | .name = "[vvar]", | |
123 | .fault = vvar_fault, | |
124 | }; | |
125 | ||
779df224 SS |
126 | static struct vm_special_mapping vdso64_mapping = { |
127 | .name = "[vdso]", | |
128 | .mremap = vdso_mremap, | |
129 | }; | |
130 | ||
131 | static struct vm_special_mapping vdso32_mapping = { | |
35bb092a | 132 | .name = "[vdso]", |
35bb092a MS |
133 | .mremap = vdso_mremap, |
134 | }; | |
135 | ||
96c0c7ae | 136 | int vdso_getcpu_init(void) |
80f06306 HC |
137 | { |
138 | set_tod_programmable_field(smp_processor_id()); | |
96c0c7ae | 139 | return 0; |
80f06306 | 140 | } |
96c0c7ae | 141 | early_initcall(vdso_getcpu_init); /* Must be called before SMP init */ |
80f06306 | 142 | |
57761da4 | 143 | static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len) |
b020632e | 144 | { |
57761da4 | 145 | unsigned long vvar_start, vdso_text_start, vdso_text_len; |
779df224 | 146 | struct vm_special_mapping *vdso_mapping; |
b020632e | 147 | struct mm_struct *mm = current->mm; |
35bb092a | 148 | struct vm_area_struct *vma; |
b020632e MS |
149 | int rc; |
150 | ||
eeab78b0 | 151 | BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); |
d8ed45c5 | 152 | if (mmap_write_lock_killable(mm)) |
69048176 | 153 | return -EINTR; |
779df224 SS |
154 | |
155 | if (is_compat_task()) { | |
156 | vdso_text_len = vdso32_end - vdso32_start; | |
157 | vdso_mapping = &vdso32_mapping; | |
158 | } else { | |
159 | vdso_text_len = vdso64_end - vdso64_start; | |
160 | vdso_mapping = &vdso64_mapping; | |
161 | } | |
57761da4 | 162 | vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0); |
214b3564 HC |
163 | rc = vvar_start; |
164 | if (IS_ERR_VALUE(vvar_start)) | |
8d4be7f3 | 165 | goto out; |
eeab78b0 HC |
166 | vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE, |
167 | VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP| | |
168 | VM_PFNMAP, | |
214b3564 HC |
169 | &vvar_mapping); |
170 | rc = PTR_ERR(vma); | |
171 | if (IS_ERR(vma)) | |
172 | goto out; | |
eeab78b0 | 173 | vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE; |
5056c2c5 | 174 | /* VM_MAYWRITE for COW so gdb can set breakpoints */ |
214b3564 | 175 | vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len, |
35bb092a MS |
176 | VM_READ|VM_EXEC| |
177 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, | |
779df224 | 178 | vdso_mapping); |
5056c2c5 | 179 | if (IS_ERR(vma)) { |
214b3564 | 180 | do_munmap(mm, vvar_start, PAGE_SIZE, NULL); |
5056c2c5 HC |
181 | rc = PTR_ERR(vma); |
182 | } else { | |
183 | current->mm->context.vdso_base = vdso_text_start; | |
184 | rc = 0; | |
185 | } | |
8d4be7f3 | 186 | out: |
d8ed45c5 | 187 | mmap_write_unlock(mm); |
b020632e MS |
188 | return rc; |
189 | } | |
190 | ||
41cd81ab SS |
191 | static unsigned long vdso_addr(unsigned long start, unsigned long len) |
192 | { | |
193 | unsigned long addr, end, offset; | |
194 | ||
195 | /* | |
196 | * Round up the start address. It can start out unaligned as a result | |
197 | * of stack start randomization. | |
198 | */ | |
199 | start = PAGE_ALIGN(start); | |
200 | ||
201 | /* Round the lowest possible end address up to a PMD boundary. */ | |
202 | end = (start + len + PMD_SIZE - 1) & PMD_MASK; | |
203 | if (end >= VDSO_BASE) | |
204 | end = VDSO_BASE; | |
205 | end -= len; | |
206 | ||
207 | if (end > start) { | |
8032bf12 | 208 | offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1); |
41cd81ab SS |
209 | addr = start + (offset << PAGE_SHIFT); |
210 | } else { | |
211 | addr = start; | |
212 | } | |
213 | return addr; | |
214 | } | |
215 | ||
57761da4 SS |
216 | unsigned long vdso_size(void) |
217 | { | |
218 | unsigned long size = VVAR_NR_PAGES * PAGE_SIZE; | |
219 | ||
220 | if (is_compat_task()) | |
221 | size += vdso32_end - vdso32_start; | |
222 | else | |
223 | size += vdso64_end - vdso64_start; | |
224 | return PAGE_ALIGN(size); | |
225 | } | |
226 | ||
227 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) | |
228 | { | |
41cd81ab SS |
229 | unsigned long addr = VDSO_BASE; |
230 | unsigned long size = vdso_size(); | |
231 | ||
232 | if (current->flags & PF_RANDOMIZE) | |
233 | addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size); | |
234 | return map_vdso(addr, size); | |
57761da4 SS |
235 | } |
236 | ||
779df224 | 237 | static struct page ** __init vdso_setup_pages(void *start, void *end) |
b020632e | 238 | { |
779df224 SS |
239 | int pages = (end - start) >> PAGE_SHIFT; |
240 | struct page **pagelist; | |
b020632e MS |
241 | int i; |
242 | ||
779df224 SS |
243 | pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); |
244 | if (!pagelist) | |
245 | panic("%s: Cannot allocate page list for VDSO", __func__); | |
246 | for (i = 0; i < pages; i++) | |
247 | pagelist[i] = virt_to_page(start + i * PAGE_SIZE); | |
248 | return pagelist; | |
249 | } | |
d57778fe | 250 | |
779df224 SS |
251 | static int __init vdso_init(void) |
252 | { | |
253 | vdso64_mapping.pages = vdso_setup_pages(vdso64_start, vdso64_end); | |
254 | if (IS_ENABLED(CONFIG_COMPAT)) | |
255 | vdso32_mapping.pages = vdso_setup_pages(vdso32_start, vdso32_end); | |
b020632e MS |
256 | return 0; |
257 | } | |
96c0c7ae | 258 | arch_initcall(vdso_init); |