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
vdso_setup(char * s)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 */
vdso_init_data(struct vdso_data * vd)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 */
vdso_init_per_cpu_data(int cpu,struct vdso_per_cpu_data * vpcd)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
vdso_alloc_per_cpu(int cpu,struct _lowcore * lowcore)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
vdso_free_per_cpu(int cpu,struct _lowcore * lowcore)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
__vdso_init_cr5(void * dummy)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
vdso_init_cr5(void)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 */
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)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 #ifdef CONFIG_64BIT
207 vdso_pagelist = vdso64_pagelist;
208 vdso_pages = vdso64_pages;
209 #ifdef CONFIG_COMPAT
210 if (is_compat_task()) {
211 vdso_pagelist = vdso32_pagelist;
212 vdso_pages = vdso32_pages;
213 }
214 #endif
215 #else
216 vdso_pagelist = vdso32_pagelist;
217 vdso_pages = vdso32_pages;
218 #endif
219
220 /*
221 * vDSO has a problem and was disabled, just don't "enable" it for
222 * the process
223 */
224 if (vdso_pages == 0)
225 return 0;
226
227 current->mm->context.vdso_base = 0;
228
229 /*
230 * pick a base address for the vDSO in process space. We try to put
231 * it at vdso_base which is the "natural" base for it, but we might
232 * fail and end up putting it elsewhere.
233 */
234 down_write(&mm->mmap_sem);
235 vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
236 if (IS_ERR_VALUE(vdso_base)) {
237 rc = vdso_base;
238 goto out_up;
239 }
240
241 /*
242 * Put vDSO base into mm struct. We need to do this before calling
243 * install_special_mapping or the perf counter mmap tracking code
244 * will fail to recognise it as a vDSO (since arch_vma_name fails).
245 */
246 current->mm->context.vdso_base = vdso_base;
247
248 /*
249 * our vma flags don't have VM_WRITE so by default, the process
250 * isn't allowed to write those pages.
251 * gdb can break that with ptrace interface, and thus trigger COW
252 * on those pages but it's then your responsibility to never do that
253 * on the "data" page of the vDSO or you'll stop getting kernel
254 * updates and your nice userland gettimeofday will be totally dead.
255 * It's fine to use that for setting breakpoints in the vDSO code
256 * pages though
257 *
258 * Make sure the vDSO gets into every core dump.
259 * Dumping its contents makes post-mortem fully interpretable later
260 * without matching up the same kernel and hardware config to see
261 * what PC values meant.
262 */
263 rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
264 VM_READ|VM_EXEC|
265 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
266 VM_ALWAYSDUMP,
267 vdso_pagelist);
268 if (rc)
269 current->mm->context.vdso_base = 0;
270 out_up:
271 up_write(&mm->mmap_sem);
272 return rc;
273 }
274
arch_vma_name(struct vm_area_struct * vma)275 const char *arch_vma_name(struct vm_area_struct *vma)
276 {
277 if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
278 return "[vdso]";
279 return NULL;
280 }
281
vdso_init(void)282 static int __init vdso_init(void)
283 {
284 int i;
285
286 if (!vdso_enabled)
287 return 0;
288 vdso_init_data(vdso_data);
289 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
290 /* Calculate the size of the 32 bit vDSO */
291 vdso32_pages = ((&vdso32_end - &vdso32_start
292 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
293
294 /* Make sure pages are in the correct state */
295 vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
296 GFP_KERNEL);
297 BUG_ON(vdso32_pagelist == NULL);
298 for (i = 0; i < vdso32_pages - 1; i++) {
299 struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
300 ClearPageReserved(pg);
301 get_page(pg);
302 vdso32_pagelist[i] = pg;
303 }
304 vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
305 vdso32_pagelist[vdso32_pages] = NULL;
306 #endif
307
308 #ifdef CONFIG_64BIT
309 /* Calculate the size of the 64 bit vDSO */
310 vdso64_pages = ((&vdso64_end - &vdso64_start
311 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
312
313 /* Make sure pages are in the correct state */
314 vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
315 GFP_KERNEL);
316 BUG_ON(vdso64_pagelist == NULL);
317 for (i = 0; i < vdso64_pages - 1; i++) {
318 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
319 ClearPageReserved(pg);
320 get_page(pg);
321 vdso64_pagelist[i] = pg;
322 }
323 vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
324 vdso64_pagelist[vdso64_pages] = NULL;
325 #ifndef CONFIG_SMP
326 if (vdso_alloc_per_cpu(0, &S390_lowcore))
327 BUG();
328 #endif
329 vdso_init_cr5();
330 #endif /* CONFIG_64BIT */
331
332 get_page(virt_to_page(vdso_data));
333
334 smp_wmb();
335
336 return 0;
337 }
338 arch_initcall(vdso_init);
339
in_gate_area_no_mm(unsigned long addr)340 int in_gate_area_no_mm(unsigned long addr)
341 {
342 return 0;
343 }
344
in_gate_area(struct mm_struct * mm,unsigned long addr)345 int in_gate_area(struct mm_struct *mm, unsigned long addr)
346 {
347 return 0;
348 }
349
get_gate_vma(struct mm_struct * mm)350 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
351 {
352 return NULL;
353 }
354