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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)
36extern char vdso32_start, vdso32_end;
37static void *vdso32_kbase = &vdso32_start;
38static unsigned int vdso32_pages;
39static struct page **vdso32_pagelist;
40#endif
41
42#ifdef CONFIG_64BIT
43extern char vdso64_start, vdso64_end;
44static void *vdso64_kbase = &vdso64_start;
45static unsigned int vdso64_pages;
46static 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 */
53unsigned int __read_mostly vdso_enabled = 1;
54
55static 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 */
76static union {
77 struct vdso_data data;
78 u8 page[PAGE_SIZE];
79} vdso_data_store __page_aligned_data;
80struct vdso_data *vdso_data = &vdso_data_store.data;
81
82/*
83 * Setup vdso data page.
84 */
85static 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 */
94static 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
103int 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
145out:
146 free_page(page_frame);
147 free_page(page_table);
148 free_pages(segment_table, SEGMENT_ORDER);
149 return -ENOMEM;
150}
151
152void 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
171static 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
179static 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 */
190int 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;
270out_up:
271 up_write(&mm->mmap_sem);
272 return rc;
273}
274
275const 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
282static 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}
338arch_initcall(vdso_init);
339
340int in_gate_area_no_mm(unsigned long addr)
341{
342 return 0;
343}
344
345int in_gate_area(struct mm_struct *mm, unsigned long addr)
346{
347 return 0;
348}
349
350struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
351{
352 return NULL;
353}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * vdso setup for s390
4 *
5 * Copyright IBM Corp. 2008
6 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
7 */
8
9#include <linux/binfmts.h>
10#include <linux/compat.h>
11#include <linux/elf.h>
12#include <linux/errno.h>
13#include <linux/init.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/mm.h>
17#include <linux/slab.h>
18#include <linux/smp.h>
19#include <linux/time_namespace.h>
20#include <linux/random.h>
21#include <vdso/datapage.h>
22#include <asm/vdso/vsyscall.h>
23#include <asm/alternative.h>
24#include <asm/vdso.h>
25
26extern char vdso64_start[], vdso64_end[];
27extern char vdso32_start[], vdso32_end[];
28
29static struct vm_special_mapping vvar_mapping;
30
31static union vdso_data_store vdso_data_store __page_aligned_data;
32
33struct vdso_data *vdso_data = vdso_data_store.data;
34
35#ifdef CONFIG_TIME_NS
36struct vdso_data *arch_get_vdso_data(void *vvar_page)
37{
38 return (struct vdso_data *)(vvar_page);
39}
40
41/*
42 * The VVAR page layout depends on whether a task belongs to the root or
43 * non-root time namespace. Whenever a task changes its namespace, the VVAR
44 * page tables are cleared and then they will be re-faulted with a
45 * corresponding layout.
46 * See also the comment near timens_setup_vdso_data() for details.
47 */
48int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
49{
50 struct mm_struct *mm = task->mm;
51 VMA_ITERATOR(vmi, mm, 0);
52 struct vm_area_struct *vma;
53
54 mmap_read_lock(mm);
55 for_each_vma(vmi, vma) {
56 if (!vma_is_special_mapping(vma, &vvar_mapping))
57 continue;
58 zap_vma_pages(vma);
59 break;
60 }
61 mmap_read_unlock(mm);
62 return 0;
63}
64#endif
65
66static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
67 struct vm_area_struct *vma, struct vm_fault *vmf)
68{
69 struct page *timens_page = find_timens_vvar_page(vma);
70 unsigned long addr, pfn;
71 vm_fault_t err;
72
73 switch (vmf->pgoff) {
74 case VVAR_DATA_PAGE_OFFSET:
75 pfn = virt_to_pfn(vdso_data);
76 if (timens_page) {
77 /*
78 * Fault in VVAR page too, since it will be accessed
79 * to get clock data anyway.
80 */
81 addr = vmf->address + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE;
82 err = vmf_insert_pfn(vma, addr, pfn);
83 if (unlikely(err & VM_FAULT_ERROR))
84 return err;
85 pfn = page_to_pfn(timens_page);
86 }
87 break;
88#ifdef CONFIG_TIME_NS
89 case VVAR_TIMENS_PAGE_OFFSET:
90 /*
91 * If a task belongs to a time namespace then a namespace
92 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
93 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
94 * offset.
95 * See also the comment near timens_setup_vdso_data().
96 */
97 if (!timens_page)
98 return VM_FAULT_SIGBUS;
99 pfn = virt_to_pfn(vdso_data);
100 break;
101#endif /* CONFIG_TIME_NS */
102 default:
103 return VM_FAULT_SIGBUS;
104 }
105 return vmf_insert_pfn(vma, vmf->address, pfn);
106}
107
108static int vdso_mremap(const struct vm_special_mapping *sm,
109 struct vm_area_struct *vma)
110{
111 current->mm->context.vdso_base = vma->vm_start;
112 return 0;
113}
114
115static struct vm_special_mapping vvar_mapping = {
116 .name = "[vvar]",
117 .fault = vvar_fault,
118};
119
120static struct vm_special_mapping vdso64_mapping = {
121 .name = "[vdso]",
122 .mremap = vdso_mremap,
123};
124
125static struct vm_special_mapping vdso32_mapping = {
126 .name = "[vdso]",
127 .mremap = vdso_mremap,
128};
129
130int vdso_getcpu_init(void)
131{
132 set_tod_programmable_field(smp_processor_id());
133 return 0;
134}
135early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
136
137static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
138{
139 unsigned long vvar_start, vdso_text_start, vdso_text_len;
140 struct vm_special_mapping *vdso_mapping;
141 struct mm_struct *mm = current->mm;
142 struct vm_area_struct *vma;
143 int rc;
144
145 BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
146 if (mmap_write_lock_killable(mm))
147 return -EINTR;
148
149 if (is_compat_task()) {
150 vdso_text_len = vdso32_end - vdso32_start;
151 vdso_mapping = &vdso32_mapping;
152 } else {
153 vdso_text_len = vdso64_end - vdso64_start;
154 vdso_mapping = &vdso64_mapping;
155 }
156 vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
157 rc = vvar_start;
158 if (IS_ERR_VALUE(vvar_start))
159 goto out;
160 vma = _install_special_mapping(mm, vvar_start, VVAR_NR_PAGES*PAGE_SIZE,
161 VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
162 VM_PFNMAP,
163 &vvar_mapping);
164 rc = PTR_ERR(vma);
165 if (IS_ERR(vma))
166 goto out;
167 vdso_text_start = vvar_start + VVAR_NR_PAGES * PAGE_SIZE;
168 /* VM_MAYWRITE for COW so gdb can set breakpoints */
169 vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
170 VM_READ|VM_EXEC|
171 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
172 vdso_mapping);
173 if (IS_ERR(vma)) {
174 do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
175 rc = PTR_ERR(vma);
176 } else {
177 current->mm->context.vdso_base = vdso_text_start;
178 rc = 0;
179 }
180out:
181 mmap_write_unlock(mm);
182 return rc;
183}
184
185static unsigned long vdso_addr(unsigned long start, unsigned long len)
186{
187 unsigned long addr, end, offset;
188
189 /*
190 * Round up the start address. It can start out unaligned as a result
191 * of stack start randomization.
192 */
193 start = PAGE_ALIGN(start);
194
195 /* Round the lowest possible end address up to a PMD boundary. */
196 end = (start + len + PMD_SIZE - 1) & PMD_MASK;
197 if (end >= VDSO_BASE)
198 end = VDSO_BASE;
199 end -= len;
200
201 if (end > start) {
202 offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
203 addr = start + (offset << PAGE_SHIFT);
204 } else {
205 addr = start;
206 }
207 return addr;
208}
209
210unsigned long vdso_text_size(void)
211{
212 unsigned long size;
213
214 if (is_compat_task())
215 size = vdso32_end - vdso32_start;
216 else
217 size = vdso64_end - vdso64_start;
218 return PAGE_ALIGN(size);
219}
220
221unsigned long vdso_size(void)
222{
223 return vdso_text_size() + VVAR_NR_PAGES * PAGE_SIZE;
224}
225
226int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
227{
228 unsigned long addr = VDSO_BASE;
229 unsigned long size = vdso_size();
230
231 if (current->flags & PF_RANDOMIZE)
232 addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size);
233 return map_vdso(addr, size);
234}
235
236static struct page ** __init vdso_setup_pages(void *start, void *end)
237{
238 int pages = (end - start) >> PAGE_SHIFT;
239 struct page **pagelist;
240 int i;
241
242 pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL);
243 if (!pagelist)
244 panic("%s: Cannot allocate page list for VDSO", __func__);
245 for (i = 0; i < pages; i++)
246 pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
247 return pagelist;
248}
249
250static void vdso_apply_alternatives(void)
251{
252 const struct elf64_shdr *alt, *shdr;
253 struct alt_instr *start, *end;
254 const struct elf64_hdr *hdr;
255
256 hdr = (struct elf64_hdr *)vdso64_start;
257 shdr = (void *)hdr + hdr->e_shoff;
258 alt = find_section(hdr, shdr, ".altinstructions");
259 if (!alt)
260 return;
261 start = (void *)hdr + alt->sh_offset;
262 end = (void *)hdr + alt->sh_offset + alt->sh_size;
263 apply_alternatives(start, end);
264}
265
266static int __init vdso_init(void)
267{
268 vdso_apply_alternatives();
269 vdso64_mapping.pages = vdso_setup_pages(vdso64_start, vdso64_end);
270 if (IS_ENABLED(CONFIG_COMPAT))
271 vdso32_mapping.pages = vdso_setup_pages(vdso32_start, vdso32_end);
272 return 0;
273}
274arch_initcall(vdso_init);