x86/speculation/mds: Fix documentation typo
[linux/fpc-iii.git] / arch / s390 / kernel / vdso.c
blobeacda05b45d7e0ac81b8b60f632a43fc0c268b6c
1 /*
2 * vdso setup for s390
4 * Copyright IBM Corp. 2008
5 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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.
12 #include <linux/init.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/processor.h>
29 #include <asm/mmu.h>
30 #include <asm/mmu_context.h>
31 #include <asm/sections.h>
32 #include <asm/vdso.h>
33 #include <asm/facility.h>
35 #ifdef 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
42 extern char vdso64_start, vdso64_end;
43 static void *vdso64_kbase = &vdso64_start;
44 static unsigned int vdso64_pages;
45 static struct page **vdso64_pagelist;
48 * Should the kernel map a VDSO page into processes and pass its
49 * address down to glibc upon exec()?
51 unsigned int __read_mostly vdso_enabled = 1;
53 static int vdso_fault(const struct vm_special_mapping *sm,
54 struct vm_area_struct *vma, struct vm_fault *vmf)
56 struct page **vdso_pagelist;
57 unsigned long vdso_pages;
59 vdso_pagelist = vdso64_pagelist;
60 vdso_pages = vdso64_pages;
61 #ifdef CONFIG_COMPAT
62 if (is_compat_task()) {
63 vdso_pagelist = vdso32_pagelist;
64 vdso_pages = vdso32_pages;
66 #endif
68 if (vmf->pgoff >= vdso_pages)
69 return VM_FAULT_SIGBUS;
71 vmf->page = vdso_pagelist[vmf->pgoff];
72 get_page(vmf->page);
73 return 0;
76 static int vdso_mremap(const struct vm_special_mapping *sm,
77 struct vm_area_struct *vma)
79 unsigned long vdso_pages;
81 vdso_pages = vdso64_pages;
82 #ifdef CONFIG_COMPAT
83 if (is_compat_task())
84 vdso_pages = vdso32_pages;
85 #endif
87 if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
88 return -EINVAL;
90 if (WARN_ON_ONCE(current->mm != vma->vm_mm))
91 return -EFAULT;
93 current->mm->context.vdso_base = vma->vm_start;
94 return 0;
97 static const struct vm_special_mapping vdso_mapping = {
98 .name = "[vdso]",
99 .fault = vdso_fault,
100 .mremap = vdso_mremap,
103 static int __init vdso_setup(char *s)
105 unsigned long val;
106 int rc;
108 rc = 0;
109 if (strncmp(s, "on", 3) == 0)
110 vdso_enabled = 1;
111 else if (strncmp(s, "off", 4) == 0)
112 vdso_enabled = 0;
113 else {
114 rc = kstrtoul(s, 0, &val);
115 vdso_enabled = rc ? 0 : !!val;
117 return !rc;
119 __setup("vdso=", vdso_setup);
122 * The vdso data page
124 static union {
125 struct vdso_data data;
126 u8 page[PAGE_SIZE];
127 } vdso_data_store __page_aligned_data;
128 struct vdso_data *vdso_data = &vdso_data_store.data;
131 * Setup vdso data page.
133 static void __init vdso_init_data(struct vdso_data *vd)
135 vd->ectg_available = test_facility(31);
139 * Allocate/free per cpu vdso data.
141 #define SEGMENT_ORDER 2
143 int vdso_alloc_per_cpu(struct lowcore *lowcore)
145 unsigned long segment_table, page_table, page_frame;
146 struct vdso_per_cpu_data *vd;
147 u32 *psal, *aste;
148 int i;
150 lowcore->vdso_per_cpu_data = __LC_PASTE;
152 if (!vdso_enabled)
153 return 0;
155 segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
156 page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
157 page_frame = get_zeroed_page(GFP_KERNEL);
158 if (!segment_table || !page_table || !page_frame)
159 goto out;
160 arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
161 arch_set_page_dat(virt_to_page(page_table), 0);
163 /* Initialize per-cpu vdso data page */
164 vd = (struct vdso_per_cpu_data *) page_frame;
165 vd->cpu_nr = lowcore->cpu_nr;
166 vd->node_id = cpu_to_node(vd->cpu_nr);
168 /* Set up access register mode page table */
169 clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
170 PAGE_SIZE << SEGMENT_ORDER);
171 clear_table((unsigned long *) page_table, _PAGE_INVALID,
172 256*sizeof(unsigned long));
174 *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
175 *(unsigned long *) page_table = _PAGE_PROTECT + page_frame;
177 psal = (u32 *) (page_table + 256*sizeof(unsigned long));
178 aste = psal + 32;
180 for (i = 4; i < 32; i += 4)
181 psal[i] = 0x80000000;
183 lowcore->paste[4] = (u32)(addr_t) psal;
184 psal[0] = 0x02000000;
185 psal[2] = (u32)(addr_t) aste;
186 *(unsigned long *) (aste + 2) = segment_table +
187 _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
188 aste[4] = (u32)(addr_t) psal;
189 lowcore->vdso_per_cpu_data = page_frame;
191 return 0;
193 out:
194 free_page(page_frame);
195 free_page(page_table);
196 free_pages(segment_table, SEGMENT_ORDER);
197 return -ENOMEM;
200 void vdso_free_per_cpu(struct lowcore *lowcore)
202 unsigned long segment_table, page_table, page_frame;
203 u32 *psal, *aste;
205 if (!vdso_enabled)
206 return;
208 psal = (u32 *)(addr_t) lowcore->paste[4];
209 aste = (u32 *)(addr_t) psal[2];
210 segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
211 page_table = *(unsigned long *) segment_table;
212 page_frame = *(unsigned long *) page_table;
214 free_page(page_frame);
215 free_page(page_table);
216 free_pages(segment_table, SEGMENT_ORDER);
219 static void vdso_init_cr5(void)
221 unsigned long cr5;
223 if (!vdso_enabled)
224 return;
225 cr5 = offsetof(struct lowcore, paste);
226 __ctl_load(cr5, 5, 5);
230 * This is called from binfmt_elf, we create the special vma for the
231 * vDSO and insert it into the mm struct tree
233 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
235 struct mm_struct *mm = current->mm;
236 struct vm_area_struct *vma;
237 unsigned long vdso_pages;
238 unsigned long vdso_base;
239 int rc;
241 if (!vdso_enabled)
242 return 0;
244 * Only map the vdso for dynamically linked elf binaries.
246 if (!uses_interp)
247 return 0;
249 vdso_pages = vdso64_pages;
250 #ifdef CONFIG_COMPAT
251 if (is_compat_task())
252 vdso_pages = vdso32_pages;
253 #endif
255 * vDSO has a problem and was disabled, just don't "enable" it for
256 * the process
258 if (vdso_pages == 0)
259 return 0;
262 * pick a base address for the vDSO in process space. We try to put
263 * it at vdso_base which is the "natural" base for it, but we might
264 * fail and end up putting it elsewhere.
266 if (down_write_killable(&mm->mmap_sem))
267 return -EINTR;
268 vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
269 if (IS_ERR_VALUE(vdso_base)) {
270 rc = vdso_base;
271 goto out_up;
275 * our vma flags don't have VM_WRITE so by default, the process
276 * isn't allowed to write those pages.
277 * gdb can break that with ptrace interface, and thus trigger COW
278 * on those pages but it's then your responsibility to never do that
279 * on the "data" page of the vDSO or you'll stop getting kernel
280 * updates and your nice userland gettimeofday will be totally dead.
281 * It's fine to use that for setting breakpoints in the vDSO code
282 * pages though.
284 vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
285 VM_READ|VM_EXEC|
286 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
287 &vdso_mapping);
288 if (IS_ERR(vma)) {
289 rc = PTR_ERR(vma);
290 goto out_up;
293 current->mm->context.vdso_base = vdso_base;
294 rc = 0;
296 out_up:
297 up_write(&mm->mmap_sem);
298 return rc;
301 static int __init vdso_init(void)
303 int i;
305 if (!vdso_enabled)
306 return 0;
307 vdso_init_data(vdso_data);
308 #ifdef CONFIG_COMPAT
309 /* Calculate the size of the 32 bit vDSO */
310 vdso32_pages = ((&vdso32_end - &vdso32_start
311 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
313 /* Make sure pages are in the correct state */
314 vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
315 GFP_KERNEL);
316 BUG_ON(vdso32_pagelist == NULL);
317 for (i = 0; i < vdso32_pages - 1; i++) {
318 struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
319 ClearPageReserved(pg);
320 get_page(pg);
321 vdso32_pagelist[i] = pg;
323 vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
324 vdso32_pagelist[vdso32_pages] = NULL;
325 #endif
327 /* Calculate the size of the 64 bit vDSO */
328 vdso64_pages = ((&vdso64_end - &vdso64_start
329 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
331 /* Make sure pages are in the correct state */
332 vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
333 GFP_KERNEL);
334 BUG_ON(vdso64_pagelist == NULL);
335 for (i = 0; i < vdso64_pages - 1; i++) {
336 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
337 ClearPageReserved(pg);
338 get_page(pg);
339 vdso64_pagelist[i] = pg;
341 vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
342 vdso64_pagelist[vdso64_pages] = NULL;
343 if (vdso_alloc_per_cpu(&S390_lowcore))
344 BUG();
345 vdso_init_cr5();
347 get_page(virt_to_page(vdso_data));
349 return 0;
351 early_initcall(vdso_init);