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1 | /* |
2 | * vdso setup for s390 |
3 | * |
4 | * Copyright IBM Corp. 2008 |
5 | * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License (version 2 only) |
9 | * as published by the Free Software Foundation. |
10 | */ |
11 | |
12 | #include <linux/module.h> |
13 | #include <linux/errno.h> |
14 | #include <linux/sched.h> |
15 | #include <linux/kernel.h> |
16 | #include <linux/mm.h> |
17 | #include <linux/smp.h> |
18 | #include <linux/stddef.h> |
19 | #include <linux/unistd.h> |
20 | #include <linux/slab.h> |
21 | #include <linux/user.h> |
22 | #include <linux/elf.h> |
23 | #include <linux/security.h> |
24 | #include <linux/bootmem.h> |
25 | #include <linux/compat.h> |
26 | #include <asm/asm-offsets.h> |
27 | #include <asm/pgtable.h> |
28 | #include <asm/system.h> |
29 | #include <asm/processor.h> |
30 | #include <asm/mmu.h> |
31 | #include <asm/mmu_context.h> |
32 | #include <asm/sections.h> |
33 | #include <asm/vdso.h> |
34 | |
35 | #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) |
36 | extern char vdso32_start, vdso32_end; |
37 | static void *vdso32_kbase = &vdso32_start; |
38 | static unsigned int vdso32_pages; |
39 | static struct page **vdso32_pagelist; |
40 | #endif |
41 | |
42 | #ifdef CONFIG_64BIT |
43 | extern char vdso64_start, vdso64_end; |
44 | static void *vdso64_kbase = &vdso64_start; |
45 | static unsigned int vdso64_pages; |
46 | static struct page **vdso64_pagelist; |
47 | #endif /* CONFIG_64BIT */ |
48 | |
49 | /* |
50 | * Should the kernel map a VDSO page into processes and pass its |
51 | * address down to glibc upon exec()? |
52 | */ |
53 | unsigned int __read_mostly vdso_enabled = 1; |
54 | |
55 | static int __init vdso_setup(char *s) |
56 | { |
57 | unsigned long val; |
58 | int rc; |
59 | |
60 | rc = 0; |
61 | if (strncmp(s, "on", 3) == 0) |
62 | vdso_enabled = 1; |
63 | else if (strncmp(s, "off", 4) == 0) |
64 | vdso_enabled = 0; |
65 | else { |
66 | rc = strict_strtoul(s, 0, &val); |
67 | vdso_enabled = rc ? 0 : !!val; |
68 | } |
69 | return !rc; |
70 | } |
71 | __setup("vdso=", vdso_setup); |
72 | |
73 | /* |
74 | * The vdso data page |
75 | */ |
76 | static union { |
77 | struct vdso_data data; |
78 | u8 page[PAGE_SIZE]; |
79 | } vdso_data_store __page_aligned_data; |
80 | struct vdso_data *vdso_data = &vdso_data_store.data; |
81 | |
82 | /* |
83 | * Setup vdso data page. |
84 | */ |
85 | static void vdso_init_data(struct vdso_data *vd) |
86 | { |
87 | vd->ectg_available = user_mode != HOME_SPACE_MODE && test_facility(31); |
88 | } |
89 | |
90 | #ifdef CONFIG_64BIT |
91 | /* |
92 | * Setup per cpu vdso data page. |
93 | */ |
94 | static void vdso_init_per_cpu_data(int cpu, struct vdso_per_cpu_data *vpcd) |
95 | { |
96 | } |
97 | |
98 | /* |
99 | * Allocate/free per cpu vdso data. |
100 | */ |
101 | #define SEGMENT_ORDER 2 |
102 | |
103 | int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore) |
104 | { |
105 | unsigned long segment_table, page_table, page_frame; |
106 | u32 *psal, *aste; |
107 | int i; |
108 | |
109 | lowcore->vdso_per_cpu_data = __LC_PASTE; |
110 | |
111 | if (user_mode == HOME_SPACE_MODE || !vdso_enabled) |
112 | return 0; |
113 | |
114 | segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER); |
115 | page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA); |
116 | page_frame = get_zeroed_page(GFP_KERNEL); |
117 | if (!segment_table || !page_table || !page_frame) |
118 | goto out; |
119 | |
120 | clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY, |
121 | PAGE_SIZE << SEGMENT_ORDER); |
122 | clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY, |
123 | 256*sizeof(unsigned long)); |
124 | |
125 | *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table; |
126 | *(unsigned long *) page_table = _PAGE_RO + page_frame; |
127 | |
128 | psal = (u32 *) (page_table + 256*sizeof(unsigned long)); |
129 | aste = psal + 32; |
130 | |
131 | for (i = 4; i < 32; i += 4) |
132 | psal[i] = 0x80000000; |
133 | |
134 | lowcore->paste[4] = (u32)(addr_t) psal; |
135 | psal[0] = 0x20000000; |
136 | psal[2] = (u32)(addr_t) aste; |
137 | *(unsigned long *) (aste + 2) = segment_table + |
138 | _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT; |
139 | aste[4] = (u32)(addr_t) psal; |
140 | lowcore->vdso_per_cpu_data = page_frame; |
141 | |
142 | vdso_init_per_cpu_data(cpu, (struct vdso_per_cpu_data *) page_frame); |
143 | return 0; |
144 | |
145 | out: |
146 | free_page(page_frame); |
147 | free_page(page_table); |
148 | free_pages(segment_table, SEGMENT_ORDER); |
149 | return -ENOMEM; |
150 | } |
151 | |
152 | void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore) |
153 | { |
154 | unsigned long segment_table, page_table, page_frame; |
155 | u32 *psal, *aste; |
156 | |
157 | if (user_mode == HOME_SPACE_MODE || !vdso_enabled) |
158 | return; |
159 | |
160 | psal = (u32 *)(addr_t) lowcore->paste[4]; |
161 | aste = (u32 *)(addr_t) psal[2]; |
162 | segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK; |
163 | page_table = *(unsigned long *) segment_table; |
164 | page_frame = *(unsigned long *) page_table; |
165 | |
166 | free_page(page_frame); |
167 | free_page(page_table); |
168 | free_pages(segment_table, SEGMENT_ORDER); |
169 | } |
170 | |
171 | static void __vdso_init_cr5(void *dummy) |
172 | { |
173 | unsigned long cr5; |
174 | |
175 | cr5 = offsetof(struct _lowcore, paste); |
176 | __ctl_load(cr5, 5, 5); |
177 | } |
178 | |
179 | static void vdso_init_cr5(void) |
180 | { |
181 | if (user_mode != HOME_SPACE_MODE && vdso_enabled) |
182 | on_each_cpu(__vdso_init_cr5, NULL, 1); |
183 | } |
184 | #endif /* CONFIG_64BIT */ |
185 | |
186 | /* |
187 | * This is called from binfmt_elf, we create the special vma for the |
188 | * vDSO and insert it into the mm struct tree |
189 | */ |
190 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
191 | { |
192 | struct mm_struct *mm = current->mm; |
193 | struct page **vdso_pagelist; |
194 | unsigned long vdso_pages; |
195 | unsigned long vdso_base; |
196 | int rc; |
197 | |
198 | if (!vdso_enabled) |
199 | return 0; |
200 | /* |
201 | * Only map the vdso for dynamically linked elf binaries. |
202 | */ |
203 | if (!uses_interp) |
204 | return 0; |
205 | |
206 | vdso_base = mm->mmap_base; |
207 | #ifdef CONFIG_64BIT |
208 | vdso_pagelist = vdso64_pagelist; |
209 | vdso_pages = vdso64_pages; |
210 | #ifdef CONFIG_COMPAT |
211 | if (is_compat_task()) { |
212 | vdso_pagelist = vdso32_pagelist; |
213 | vdso_pages = vdso32_pages; |
214 | } |
215 | #endif |
216 | #else |
217 | vdso_pagelist = vdso32_pagelist; |
218 | vdso_pages = vdso32_pages; |
219 | #endif |
220 | |
221 | /* |
222 | * vDSO has a problem and was disabled, just don't "enable" it for |
223 | * the process |
224 | */ |
225 | if (vdso_pages == 0) |
226 | return 0; |
227 | |
228 | current->mm->context.vdso_base = 0; |
229 | |
230 | /* |
231 | * pick a base address for the vDSO in process space. We try to put |
232 | * it at vdso_base which is the "natural" base for it, but we might |
233 | * fail and end up putting it elsewhere. |
234 | */ |
235 | down_write(&mm->mmap_sem); |
236 | vdso_base = get_unmapped_area(NULL, vdso_base, |
237 | vdso_pages << PAGE_SHIFT, 0, 0); |
238 | if (IS_ERR_VALUE(vdso_base)) { |
239 | rc = vdso_base; |
240 | goto out_up; |
241 | } |
242 | |
243 | /* |
244 | * Put vDSO base into mm struct. We need to do this before calling |
245 | * install_special_mapping or the perf counter mmap tracking code |
246 | * will fail to recognise it as a vDSO (since arch_vma_name fails). |
247 | */ |
248 | current->mm->context.vdso_base = vdso_base; |
249 | |
250 | /* |
251 | * our vma flags don't have VM_WRITE so by default, the process |
252 | * isn't allowed to write those pages. |
253 | * gdb can break that with ptrace interface, and thus trigger COW |
254 | * on those pages but it's then your responsibility to never do that |
255 | * on the "data" page of the vDSO or you'll stop getting kernel |
256 | * updates and your nice userland gettimeofday will be totally dead. |
257 | * It's fine to use that for setting breakpoints in the vDSO code |
258 | * pages though |
259 | * |
260 | * Make sure the vDSO gets into every core dump. |
261 | * Dumping its contents makes post-mortem fully interpretable later |
262 | * without matching up the same kernel and hardware config to see |
263 | * what PC values meant. |
264 | */ |
265 | rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT, |
266 | VM_READ|VM_EXEC| |
267 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| |
268 | VM_ALWAYSDUMP, |
269 | vdso_pagelist); |
270 | if (rc) |
271 | current->mm->context.vdso_base = 0; |
272 | out_up: |
273 | up_write(&mm->mmap_sem); |
274 | return rc; |
275 | } |
276 | |
277 | const char *arch_vma_name(struct vm_area_struct *vma) |
278 | { |
279 | if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base) |
280 | return "[vdso]"; |
281 | return NULL; |
282 | } |
283 | |
284 | static int __init vdso_init(void) |
285 | { |
286 | int i; |
287 | |
288 | if (!vdso_enabled) |
289 | return 0; |
290 | vdso_init_data(vdso_data); |
291 | #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) |
292 | /* Calculate the size of the 32 bit vDSO */ |
293 | vdso32_pages = ((&vdso32_end - &vdso32_start |
294 | + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; |
295 | |
296 | /* Make sure pages are in the correct state */ |
297 | vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1), |
298 | GFP_KERNEL); |
299 | BUG_ON(vdso32_pagelist == NULL); |
300 | for (i = 0; i < vdso32_pages - 1; i++) { |
301 | struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE); |
302 | ClearPageReserved(pg); |
303 | get_page(pg); |
304 | vdso32_pagelist[i] = pg; |
305 | } |
306 | vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data); |
307 | vdso32_pagelist[vdso32_pages] = NULL; |
308 | #endif |
309 | |
310 | #ifdef CONFIG_64BIT |
311 | /* Calculate the size of the 64 bit vDSO */ |
312 | vdso64_pages = ((&vdso64_end - &vdso64_start |
313 | + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; |
314 | |
315 | /* Make sure pages are in the correct state */ |
316 | vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1), |
317 | GFP_KERNEL); |
318 | BUG_ON(vdso64_pagelist == NULL); |
319 | for (i = 0; i < vdso64_pages - 1; i++) { |
320 | struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE); |
321 | ClearPageReserved(pg); |
322 | get_page(pg); |
323 | vdso64_pagelist[i] = pg; |
324 | } |
325 | vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data); |
326 | vdso64_pagelist[vdso64_pages] = NULL; |
327 | #ifndef CONFIG_SMP |
328 | if (vdso_alloc_per_cpu(0, &S390_lowcore)) |
329 | BUG(); |
330 | #endif |
331 | vdso_init_cr5(); |
332 | #endif /* CONFIG_64BIT */ |
333 | |
334 | get_page(virt_to_page(vdso_data)); |
335 | |
336 | smp_wmb(); |
337 | |
338 | return 0; |
339 | } |
340 | arch_initcall(vdso_init); |
341 | |
342 | int in_gate_area_no_task(unsigned long addr) |
343 | { |
344 | return 0; |
345 | } |
346 | |
347 | int in_gate_area(struct task_struct *task, unsigned long addr) |
348 | { |
349 | return 0; |
350 | } |
351 | |
352 | struct vm_area_struct *get_gate_vma(struct task_struct *tsk) |
353 | { |
354 | return NULL; |
355 | } |
356 |
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