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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/init.h>
10#include <linux/errno.h>
11#include <linux/sched.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/smp.h>
15#include <linux/stddef.h>
16#include <linux/unistd.h>
17#include <linux/slab.h>
18#include <linux/user.h>
19#include <linux/elf.h>
20#include <linux/security.h>
21#include <linux/memblock.h>
22#include <linux/compat.h>
23#include <asm/asm-offsets.h>
24#include <asm/pgtable.h>
25#include <asm/processor.h>
26#include <asm/mmu.h>
27#include <asm/mmu_context.h>
28#include <asm/sections.h>
29#include <asm/vdso.h>
30#include <asm/facility.h>
31
32#ifdef CONFIG_COMPAT_VDSO
33extern char vdso32_start, vdso32_end;
34static void *vdso32_kbase = &vdso32_start;
35static unsigned int vdso32_pages;
36static struct page **vdso32_pagelist;
37#endif
38
39extern char vdso64_start, vdso64_end;
40static void *vdso64_kbase = &vdso64_start;
41static unsigned int vdso64_pages;
42static struct page **vdso64_pagelist;
43
44/*
45 * Should the kernel map a VDSO page into processes and pass its
46 * address down to glibc upon exec()?
47 */
48unsigned int __read_mostly vdso_enabled = 1;
49
50static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
51 struct vm_area_struct *vma, struct vm_fault *vmf)
52{
53 struct page **vdso_pagelist;
54 unsigned long vdso_pages;
55
56 vdso_pagelist = vdso64_pagelist;
57 vdso_pages = vdso64_pages;
58#ifdef CONFIG_COMPAT_VDSO
59 if (vma->vm_mm->context.compat_mm) {
60 vdso_pagelist = vdso32_pagelist;
61 vdso_pages = vdso32_pages;
62 }
63#endif
64
65 if (vmf->pgoff >= vdso_pages)
66 return VM_FAULT_SIGBUS;
67
68 vmf->page = vdso_pagelist[vmf->pgoff];
69 get_page(vmf->page);
70 return 0;
71}
72
73static int vdso_mremap(const struct vm_special_mapping *sm,
74 struct vm_area_struct *vma)
75{
76 unsigned long vdso_pages;
77
78 vdso_pages = vdso64_pages;
79#ifdef CONFIG_COMPAT_VDSO
80 if (vma->vm_mm->context.compat_mm)
81 vdso_pages = vdso32_pages;
82#endif
83
84 if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
85 return -EINVAL;
86
87 if (WARN_ON_ONCE(current->mm != vma->vm_mm))
88 return -EFAULT;
89
90 current->mm->context.vdso_base = vma->vm_start;
91 return 0;
92}
93
94static const struct vm_special_mapping vdso_mapping = {
95 .name = "[vdso]",
96 .fault = vdso_fault,
97 .mremap = vdso_mremap,
98};
99
100static int __init vdso_setup(char *str)
101{
102 bool enabled;
103
104 if (!kstrtobool(str, &enabled))
105 vdso_enabled = enabled;
106 return 1;
107}
108__setup("vdso=", vdso_setup);
109
110/*
111 * The vdso data page
112 */
113static union {
114 struct vdso_data data;
115 u8 page[PAGE_SIZE];
116} vdso_data_store __page_aligned_data;
117struct vdso_data *vdso_data = &vdso_data_store.data;
118
119/*
120 * Setup vdso data page.
121 */
122static void __init vdso_init_data(struct vdso_data *vd)
123{
124 vd->ectg_available = test_facility(31);
125}
126
127/*
128 * Allocate/free per cpu vdso data.
129 */
130#define SEGMENT_ORDER 2
131
132/*
133 * The initial vdso_data structure for the boot CPU. Eventually
134 * it is replaced with a properly allocated structure in vdso_init.
135 * This is necessary because a valid S390_lowcore.vdso_per_cpu_data
136 * pointer is required to be able to return from an interrupt or
137 * program check. See the exit paths in entry.S.
138 */
139struct vdso_data boot_vdso_data __initdata;
140
141void __init vdso_alloc_boot_cpu(struct lowcore *lowcore)
142{
143 lowcore->vdso_per_cpu_data = (unsigned long) &boot_vdso_data;
144}
145
146int vdso_alloc_per_cpu(struct lowcore *lowcore)
147{
148 unsigned long segment_table, page_table, page_frame;
149 struct vdso_per_cpu_data *vd;
150
151 segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
152 page_table = get_zeroed_page(GFP_KERNEL);
153 page_frame = get_zeroed_page(GFP_KERNEL);
154 if (!segment_table || !page_table || !page_frame)
155 goto out;
156 arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
157 arch_set_page_dat(virt_to_page(page_table), 0);
158
159 /* Initialize per-cpu vdso data page */
160 vd = (struct vdso_per_cpu_data *) page_frame;
161 vd->cpu_nr = lowcore->cpu_nr;
162 vd->node_id = cpu_to_node(vd->cpu_nr);
163
164 /* Set up page table for the vdso address space */
165 memset64((u64 *)segment_table, _SEGMENT_ENTRY_EMPTY, _CRST_ENTRIES);
166 memset64((u64 *)page_table, _PAGE_INVALID, PTRS_PER_PTE);
167
168 *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
169 *(unsigned long *) page_table = _PAGE_PROTECT + page_frame;
170
171 lowcore->vdso_asce = segment_table +
172 _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
173 lowcore->vdso_per_cpu_data = page_frame;
174
175 return 0;
176
177out:
178 free_page(page_frame);
179 free_page(page_table);
180 free_pages(segment_table, SEGMENT_ORDER);
181 return -ENOMEM;
182}
183
184void vdso_free_per_cpu(struct lowcore *lowcore)
185{
186 unsigned long segment_table, page_table, page_frame;
187
188 segment_table = lowcore->vdso_asce & PAGE_MASK;
189 page_table = *(unsigned long *) segment_table;
190 page_frame = *(unsigned long *) page_table;
191
192 free_page(page_frame);
193 free_page(page_table);
194 free_pages(segment_table, SEGMENT_ORDER);
195}
196
197/*
198 * This is called from binfmt_elf, we create the special vma for the
199 * vDSO and insert it into the mm struct tree
200 */
201int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
202{
203 struct mm_struct *mm = current->mm;
204 struct vm_area_struct *vma;
205 unsigned long vdso_pages;
206 unsigned long vdso_base;
207 int rc;
208
209 if (!vdso_enabled)
210 return 0;
211
212 vdso_pages = vdso64_pages;
213#ifdef CONFIG_COMPAT_VDSO
214 mm->context.compat_mm = is_compat_task();
215 if (mm->context.compat_mm)
216 vdso_pages = vdso32_pages;
217#endif
218 /*
219 * vDSO has a problem and was disabled, just don't "enable" it for
220 * the process
221 */
222 if (vdso_pages == 0)
223 return 0;
224
225 /*
226 * pick a base address for the vDSO in process space. We try to put
227 * it at vdso_base which is the "natural" base for it, but we might
228 * fail and end up putting it elsewhere.
229 */
230 if (down_write_killable(&mm->mmap_sem))
231 return -EINTR;
232 vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
233 if (IS_ERR_VALUE(vdso_base)) {
234 rc = vdso_base;
235 goto out_up;
236 }
237
238 /*
239 * our vma flags don't have VM_WRITE so by default, the process
240 * isn't allowed to write those pages.
241 * gdb can break that with ptrace interface, and thus trigger COW
242 * on those pages but it's then your responsibility to never do that
243 * on the "data" page of the vDSO or you'll stop getting kernel
244 * updates and your nice userland gettimeofday will be totally dead.
245 * It's fine to use that for setting breakpoints in the vDSO code
246 * pages though.
247 */
248 vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
249 VM_READ|VM_EXEC|
250 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
251 &vdso_mapping);
252 if (IS_ERR(vma)) {
253 rc = PTR_ERR(vma);
254 goto out_up;
255 }
256
257 current->mm->context.vdso_base = vdso_base;
258 rc = 0;
259
260out_up:
261 up_write(&mm->mmap_sem);
262 return rc;
263}
264
265static int __init vdso_init(void)
266{
267 int i;
268
269 vdso_init_data(vdso_data);
270#ifdef CONFIG_COMPAT_VDSO
271 /* Calculate the size of the 32 bit vDSO */
272 vdso32_pages = ((&vdso32_end - &vdso32_start
273 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
274
275 /* Make sure pages are in the correct state */
276 vdso32_pagelist = kcalloc(vdso32_pages + 1, sizeof(struct page *),
277 GFP_KERNEL);
278 BUG_ON(vdso32_pagelist == NULL);
279 for (i = 0; i < vdso32_pages - 1; i++) {
280 struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
281 get_page(pg);
282 vdso32_pagelist[i] = pg;
283 }
284 vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
285 vdso32_pagelist[vdso32_pages] = NULL;
286#endif
287
288 /* Calculate the size of the 64 bit vDSO */
289 vdso64_pages = ((&vdso64_end - &vdso64_start
290 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
291
292 /* Make sure pages are in the correct state */
293 vdso64_pagelist = kcalloc(vdso64_pages + 1, sizeof(struct page *),
294 GFP_KERNEL);
295 BUG_ON(vdso64_pagelist == NULL);
296 for (i = 0; i < vdso64_pages - 1; i++) {
297 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
298 get_page(pg);
299 vdso64_pagelist[i] = pg;
300 }
301 vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
302 vdso64_pagelist[vdso64_pages] = NULL;
303 if (vdso_alloc_per_cpu(&S390_lowcore))
304 BUG();
305
306 get_page(virt_to_page(vdso_data));
307
308 return 0;
309}
310early_initcall(vdso_init);
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/init.h>
10#include <linux/errno.h>
11#include <linux/sched.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/smp.h>
15#include <linux/stddef.h>
16#include <linux/unistd.h>
17#include <linux/slab.h>
18#include <linux/user.h>
19#include <linux/elf.h>
20#include <linux/security.h>
21#include <linux/memblock.h>
22#include <linux/compat.h>
23#include <asm/asm-offsets.h>
24#include <asm/processor.h>
25#include <asm/mmu.h>
26#include <asm/mmu_context.h>
27#include <asm/sections.h>
28#include <asm/vdso.h>
29#include <asm/facility.h>
30
31extern char vdso64_start, vdso64_end;
32static void *vdso64_kbase = &vdso64_start;
33static unsigned int vdso64_pages;
34static struct page **vdso64_pagelist;
35
36/*
37 * Should the kernel map a VDSO page into processes and pass its
38 * address down to glibc upon exec()?
39 */
40unsigned int __read_mostly vdso_enabled = 1;
41
42static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
43 struct vm_area_struct *vma, struct vm_fault *vmf)
44{
45 struct page **vdso_pagelist;
46 unsigned long vdso_pages;
47
48 vdso_pagelist = vdso64_pagelist;
49 vdso_pages = vdso64_pages;
50
51 if (vmf->pgoff >= vdso_pages)
52 return VM_FAULT_SIGBUS;
53
54 vmf->page = vdso_pagelist[vmf->pgoff];
55 get_page(vmf->page);
56 return 0;
57}
58
59static int vdso_mremap(const struct vm_special_mapping *sm,
60 struct vm_area_struct *vma)
61{
62 unsigned long vdso_pages;
63
64 vdso_pages = vdso64_pages;
65
66 if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
67 return -EINVAL;
68
69 if (WARN_ON_ONCE(current->mm != vma->vm_mm))
70 return -EFAULT;
71
72 current->mm->context.vdso_base = vma->vm_start;
73 return 0;
74}
75
76static const struct vm_special_mapping vdso_mapping = {
77 .name = "[vdso]",
78 .fault = vdso_fault,
79 .mremap = vdso_mremap,
80};
81
82static int __init vdso_setup(char *str)
83{
84 bool enabled;
85
86 if (!kstrtobool(str, &enabled))
87 vdso_enabled = enabled;
88 return 1;
89}
90__setup("vdso=", vdso_setup);
91
92/*
93 * The vdso data page
94 */
95static union {
96 struct vdso_data data;
97 u8 page[PAGE_SIZE];
98} vdso_data_store __page_aligned_data;
99struct vdso_data *vdso_data = &vdso_data_store.data;
100
101/*
102 * Setup vdso data page.
103 */
104static void __init vdso_init_data(struct vdso_data *vd)
105{
106 vd->ectg_available = test_facility(31);
107}
108
109/*
110 * Allocate/free per cpu vdso data.
111 */
112#define SEGMENT_ORDER 2
113
114/*
115 * The initial vdso_data structure for the boot CPU. Eventually
116 * it is replaced with a properly allocated structure in vdso_init.
117 * This is necessary because a valid S390_lowcore.vdso_per_cpu_data
118 * pointer is required to be able to return from an interrupt or
119 * program check. See the exit paths in entry.S.
120 */
121struct vdso_data boot_vdso_data __initdata;
122
123void __init vdso_alloc_boot_cpu(struct lowcore *lowcore)
124{
125 lowcore->vdso_per_cpu_data = (unsigned long) &boot_vdso_data;
126}
127
128int vdso_alloc_per_cpu(struct lowcore *lowcore)
129{
130 unsigned long segment_table, page_table, page_frame;
131 struct vdso_per_cpu_data *vd;
132
133 segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
134 page_table = get_zeroed_page(GFP_KERNEL);
135 page_frame = get_zeroed_page(GFP_KERNEL);
136 if (!segment_table || !page_table || !page_frame)
137 goto out;
138 arch_set_page_dat(virt_to_page(segment_table), SEGMENT_ORDER);
139 arch_set_page_dat(virt_to_page(page_table), 0);
140
141 /* Initialize per-cpu vdso data page */
142 vd = (struct vdso_per_cpu_data *) page_frame;
143 vd->cpu_nr = lowcore->cpu_nr;
144 vd->node_id = cpu_to_node(vd->cpu_nr);
145
146 /* Set up page table for the vdso address space */
147 memset64((u64 *)segment_table, _SEGMENT_ENTRY_EMPTY, _CRST_ENTRIES);
148 memset64((u64 *)page_table, _PAGE_INVALID, PTRS_PER_PTE);
149
150 *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
151 *(unsigned long *) page_table = _PAGE_PROTECT + page_frame;
152
153 lowcore->vdso_asce = segment_table +
154 _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
155 lowcore->vdso_per_cpu_data = page_frame;
156
157 return 0;
158
159out:
160 free_page(page_frame);
161 free_page(page_table);
162 free_pages(segment_table, SEGMENT_ORDER);
163 return -ENOMEM;
164}
165
166void vdso_free_per_cpu(struct lowcore *lowcore)
167{
168 unsigned long segment_table, page_table, page_frame;
169
170 segment_table = lowcore->vdso_asce & PAGE_MASK;
171 page_table = *(unsigned long *) segment_table;
172 page_frame = *(unsigned long *) page_table;
173
174 free_page(page_frame);
175 free_page(page_table);
176 free_pages(segment_table, SEGMENT_ORDER);
177}
178
179/*
180 * This is called from binfmt_elf, we create the special vma for the
181 * vDSO and insert it into the mm struct tree
182 */
183int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
184{
185 struct mm_struct *mm = current->mm;
186 struct vm_area_struct *vma;
187 unsigned long vdso_pages;
188 unsigned long vdso_base;
189 int rc;
190
191 if (!vdso_enabled)
192 return 0;
193
194 if (is_compat_task())
195 return 0;
196
197 vdso_pages = vdso64_pages;
198 /*
199 * vDSO has a problem and was disabled, just don't "enable" it for
200 * the process
201 */
202 if (vdso_pages == 0)
203 return 0;
204
205 /*
206 * pick a base address for the vDSO in process space. We try to put
207 * it at vdso_base which is the "natural" base for it, but we might
208 * fail and end up putting it elsewhere.
209 */
210 if (mmap_write_lock_killable(mm))
211 return -EINTR;
212 vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
213 if (IS_ERR_VALUE(vdso_base)) {
214 rc = vdso_base;
215 goto out_up;
216 }
217
218 /*
219 * our vma flags don't have VM_WRITE so by default, the process
220 * isn't allowed to write those pages.
221 * gdb can break that with ptrace interface, and thus trigger COW
222 * on those pages but it's then your responsibility to never do that
223 * on the "data" page of the vDSO or you'll stop getting kernel
224 * updates and your nice userland gettimeofday will be totally dead.
225 * It's fine to use that for setting breakpoints in the vDSO code
226 * pages though.
227 */
228 vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
229 VM_READ|VM_EXEC|
230 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
231 &vdso_mapping);
232 if (IS_ERR(vma)) {
233 rc = PTR_ERR(vma);
234 goto out_up;
235 }
236
237 current->mm->context.vdso_base = vdso_base;
238 rc = 0;
239
240out_up:
241 mmap_write_unlock(mm);
242 return rc;
243}
244
245static int __init vdso_init(void)
246{
247 int i;
248
249 vdso_init_data(vdso_data);
250
251 /* Calculate the size of the 64 bit vDSO */
252 vdso64_pages = ((&vdso64_end - &vdso64_start
253 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
254
255 /* Make sure pages are in the correct state */
256 vdso64_pagelist = kcalloc(vdso64_pages + 1, sizeof(struct page *),
257 GFP_KERNEL);
258 BUG_ON(vdso64_pagelist == NULL);
259 for (i = 0; i < vdso64_pages - 1; i++) {
260 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
261 get_page(pg);
262 vdso64_pagelist[i] = pg;
263 }
264 vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
265 vdso64_pagelist[vdso64_pages] = NULL;
266 if (vdso_alloc_per_cpu(&S390_lowcore))
267 BUG();
268
269 get_page(virt_to_page(vdso_data));
270
271 return 0;
272}
273early_initcall(vdso_init);