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1/*
2 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
3 * <benh@kernel.crashing.org>
4 * Copyright (C) 2012 ARM Limited
5 * Copyright (C) 2015 Regents of the University of California
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 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19
20#include <linux/mm.h>
21#include <linux/slab.h>
22#include <linux/binfmts.h>
23#include <linux/err.h>
24
25#include <asm/vdso.h>
26
27extern char vdso_start[], vdso_end[];
28
29static unsigned int vdso_pages;
30static struct page **vdso_pagelist;
31
32/*
33 * The vDSO data page.
34 */
35static union {
36 struct vdso_data data;
37 u8 page[PAGE_SIZE];
38} vdso_data_store __page_aligned_data;
39struct vdso_data *vdso_data = &vdso_data_store.data;
40
41static int __init vdso_init(void)
42{
43 unsigned int i;
44
45 vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
46 vdso_pagelist =
47 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
48 if (unlikely(vdso_pagelist == NULL)) {
49 pr_err("vdso: pagelist allocation failed\n");
50 return -ENOMEM;
51 }
52
53 for (i = 0; i < vdso_pages; i++) {
54 struct page *pg;
55
56 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
57 ClearPageReserved(pg);
58 vdso_pagelist[i] = pg;
59 }
60 vdso_pagelist[i] = virt_to_page(vdso_data);
61
62 return 0;
63}
64arch_initcall(vdso_init);
65
66int arch_setup_additional_pages(struct linux_binprm *bprm,
67 int uses_interp)
68{
69 struct mm_struct *mm = current->mm;
70 unsigned long vdso_base, vdso_len;
71 int ret;
72
73 vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
74
75 down_write(&mm->mmap_sem);
76 vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
77 if (IS_ERR_VALUE(vdso_base)) {
78 ret = vdso_base;
79 goto end;
80 }
81
82 /*
83 * Put vDSO base into mm struct. We need to do this before calling
84 * install_special_mapping or the perf counter mmap tracking code
85 * will fail to recognise it as a vDSO (since arch_vma_name fails).
86 */
87 mm->context.vdso = (void *)vdso_base;
88
89 ret = install_special_mapping(mm, vdso_base, vdso_len,
90 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
91 vdso_pagelist);
92
93 if (unlikely(ret))
94 mm->context.vdso = NULL;
95
96end:
97 up_write(&mm->mmap_sem);
98 return ret;
99}
100
101const char *arch_vma_name(struct vm_area_struct *vma)
102{
103 if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
104 return "[vdso]";
105 return NULL;
106}
107
108/*
109 * Function stubs to prevent linker errors when AT_SYSINFO_EHDR is defined
110 */
111
112int in_gate_area_no_mm(unsigned long addr)
113{
114 return 0;
115}
116
117int in_gate_area(struct mm_struct *mm, unsigned long addr)
118{
119 return 0;
120}
121
122struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
123{
124 return NULL;
125}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
4 * <benh@kernel.crashing.org>
5 * Copyright (C) 2012 ARM Limited
6 * Copyright (C) 2015 Regents of the University of California
7 */
8
9#include <linux/elf.h>
10#include <linux/mm.h>
11#include <linux/slab.h>
12#include <linux/binfmts.h>
13#include <linux/err.h>
14#include <asm/page.h>
15#include <asm/vdso.h>
16#include <linux/time_namespace.h>
17#include <vdso/datapage.h>
18#include <vdso/vsyscall.h>
19
20enum vvar_pages {
21 VVAR_DATA_PAGE_OFFSET,
22 VVAR_TIMENS_PAGE_OFFSET,
23 VVAR_NR_PAGES,
24};
25
26#define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT)
27
28static union vdso_data_store vdso_data_store __page_aligned_data;
29struct vdso_data *vdso_data = vdso_data_store.data;
30
31struct __vdso_info {
32 const char *name;
33 const char *vdso_code_start;
34 const char *vdso_code_end;
35 unsigned long vdso_pages;
36 /* Code Mapping */
37 struct vm_special_mapping *cm;
38};
39
40static struct __vdso_info vdso_info;
41#ifdef CONFIG_COMPAT
42static struct __vdso_info compat_vdso_info;
43#endif
44
45static int vdso_mremap(const struct vm_special_mapping *sm,
46 struct vm_area_struct *new_vma)
47{
48 current->mm->context.vdso = (void *)new_vma->vm_start;
49
50 return 0;
51}
52
53static void __init __vdso_init(struct __vdso_info *vdso_info)
54{
55 unsigned int i;
56 struct page **vdso_pagelist;
57 unsigned long pfn;
58
59 if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
60 panic("vDSO is not a valid ELF object!\n");
61
62 vdso_info->vdso_pages = (
63 vdso_info->vdso_code_end -
64 vdso_info->vdso_code_start) >>
65 PAGE_SHIFT;
66
67 vdso_pagelist = kcalloc(vdso_info->vdso_pages,
68 sizeof(struct page *),
69 GFP_KERNEL);
70 if (vdso_pagelist == NULL)
71 panic("vDSO kcalloc failed!\n");
72
73 /* Grab the vDSO code pages. */
74 pfn = sym_to_pfn(vdso_info->vdso_code_start);
75
76 for (i = 0; i < vdso_info->vdso_pages; i++)
77 vdso_pagelist[i] = pfn_to_page(pfn + i);
78
79 vdso_info->cm->pages = vdso_pagelist;
80}
81
82#ifdef CONFIG_TIME_NS
83struct vdso_data *arch_get_vdso_data(void *vvar_page)
84{
85 return (struct vdso_data *)(vvar_page);
86}
87
88static const struct vm_special_mapping rv_vvar_map;
89
90/*
91 * The vvar mapping contains data for a specific time namespace, so when a task
92 * changes namespace we must unmap its vvar data for the old namespace.
93 * Subsequent faults will map in data for the new namespace.
94 *
95 * For more details see timens_setup_vdso_data().
96 */
97int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
98{
99 struct mm_struct *mm = task->mm;
100 struct vm_area_struct *vma;
101 VMA_ITERATOR(vmi, mm, 0);
102
103 mmap_read_lock(mm);
104
105 for_each_vma(vmi, vma) {
106 if (vma_is_special_mapping(vma, &rv_vvar_map))
107 zap_vma_pages(vma);
108 }
109
110 mmap_read_unlock(mm);
111 return 0;
112}
113#endif
114
115static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
116 struct vm_area_struct *vma, struct vm_fault *vmf)
117{
118 struct page *timens_page = find_timens_vvar_page(vma);
119 unsigned long pfn;
120
121 switch (vmf->pgoff) {
122 case VVAR_DATA_PAGE_OFFSET:
123 if (timens_page)
124 pfn = page_to_pfn(timens_page);
125 else
126 pfn = sym_to_pfn(vdso_data);
127 break;
128#ifdef CONFIG_TIME_NS
129 case VVAR_TIMENS_PAGE_OFFSET:
130 /*
131 * If a task belongs to a time namespace then a namespace
132 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
133 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
134 * offset.
135 * See also the comment near timens_setup_vdso_data().
136 */
137 if (!timens_page)
138 return VM_FAULT_SIGBUS;
139 pfn = sym_to_pfn(vdso_data);
140 break;
141#endif /* CONFIG_TIME_NS */
142 default:
143 return VM_FAULT_SIGBUS;
144 }
145
146 return vmf_insert_pfn(vma, vmf->address, pfn);
147}
148
149static const struct vm_special_mapping rv_vvar_map = {
150 .name = "[vvar]",
151 .fault = vvar_fault,
152};
153
154static struct vm_special_mapping rv_vdso_map __ro_after_init = {
155 .name = "[vdso]",
156 .mremap = vdso_mremap,
157};
158
159static struct __vdso_info vdso_info __ro_after_init = {
160 .name = "vdso",
161 .vdso_code_start = vdso_start,
162 .vdso_code_end = vdso_end,
163 .cm = &rv_vdso_map,
164};
165
166#ifdef CONFIG_COMPAT
167static struct vm_special_mapping rv_compat_vdso_map __ro_after_init = {
168 .name = "[vdso]",
169 .mremap = vdso_mremap,
170};
171
172static struct __vdso_info compat_vdso_info __ro_after_init = {
173 .name = "compat_vdso",
174 .vdso_code_start = compat_vdso_start,
175 .vdso_code_end = compat_vdso_end,
176 .cm = &rv_compat_vdso_map,
177};
178#endif
179
180static int __init vdso_init(void)
181{
182 __vdso_init(&vdso_info);
183#ifdef CONFIG_COMPAT
184 __vdso_init(&compat_vdso_info);
185#endif
186
187 return 0;
188}
189arch_initcall(vdso_init);
190
191static int __setup_additional_pages(struct mm_struct *mm,
192 struct linux_binprm *bprm,
193 int uses_interp,
194 struct __vdso_info *vdso_info)
195{
196 unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
197 void *ret;
198
199 BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);
200
201 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
202 /* Be sure to map the data page */
203 vdso_mapping_len = vdso_text_len + VVAR_SIZE;
204
205 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
206 if (IS_ERR_VALUE(vdso_base)) {
207 ret = ERR_PTR(vdso_base);
208 goto up_fail;
209 }
210
211 ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
212 (VM_READ | VM_MAYREAD | VM_PFNMAP), &rv_vvar_map);
213 if (IS_ERR(ret))
214 goto up_fail;
215
216 vdso_base += VVAR_SIZE;
217 mm->context.vdso = (void *)vdso_base;
218
219 ret =
220 _install_special_mapping(mm, vdso_base, vdso_text_len,
221 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
222 vdso_info->cm);
223
224 if (IS_ERR(ret))
225 goto up_fail;
226
227 return 0;
228
229up_fail:
230 mm->context.vdso = NULL;
231 return PTR_ERR(ret);
232}
233
234#ifdef CONFIG_COMPAT
235int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
236 int uses_interp)
237{
238 struct mm_struct *mm = current->mm;
239 int ret;
240
241 if (mmap_write_lock_killable(mm))
242 return -EINTR;
243
244 ret = __setup_additional_pages(mm, bprm, uses_interp,
245 &compat_vdso_info);
246 mmap_write_unlock(mm);
247
248 return ret;
249}
250#endif
251
252int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
253{
254 struct mm_struct *mm = current->mm;
255 int ret;
256
257 if (mmap_write_lock_killable(mm))
258 return -EINTR;
259
260 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
261 mmap_write_unlock(mm);
262
263 return ret;
264}