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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * VDSO implementations.
4 *
5 * Copyright (C) 2012 ARM Limited
6 *
7 * Author: Will Deacon <[email protected]>
8 */
9
10#include <linux/cache.h>
11#include <linux/clocksource.h>
12#include <linux/elf.h>
13#include <linux/err.h>
14#include <linux/errno.h>
15#include <linux/gfp.h>
16#include <linux/kernel.h>
17#include <linux/mm.h>
18#include <linux/sched.h>
19#include <linux/signal.h>
20#include <linux/slab.h>
21#include <linux/vdso_datastore.h>
22#include <linux/vmalloc.h>
23#include <vdso/datapage.h>
24#include <vdso/helpers.h>
25#include <vdso/vsyscall.h>
26
27#include <asm/cacheflush.h>
28#include <asm/signal32.h>
29#include <asm/vdso.h>
30
31enum vdso_abi {
32 VDSO_ABI_AA64,
33 VDSO_ABI_AA32,
34};
35
36struct vdso_abi_info {
37 const char *name;
38 const char *vdso_code_start;
39 const char *vdso_code_end;
40 unsigned long vdso_pages;
41 /* Code Mapping */
42 struct vm_special_mapping *cm;
43};
44
45static struct vdso_abi_info vdso_info[] __ro_after_init = {
46 [VDSO_ABI_AA64] = {
47 .name = "vdso",
48 .vdso_code_start = vdso_start,
49 .vdso_code_end = vdso_end,
50 },
51#ifdef CONFIG_COMPAT_VDSO
52 [VDSO_ABI_AA32] = {
53 .name = "vdso32",
54 .vdso_code_start = vdso32_start,
55 .vdso_code_end = vdso32_end,
56 },
57#endif /* CONFIG_COMPAT_VDSO */
58};
59
60static int vdso_mremap(const struct vm_special_mapping *sm,
61 struct vm_area_struct *new_vma)
62{
63 current->mm->context.vdso = (void *)new_vma->vm_start;
64
65 return 0;
66}
67
68static int __init __vdso_init(enum vdso_abi abi)
69{
70 int i;
71 struct page **vdso_pagelist;
72 unsigned long pfn;
73
74 if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) {
75 pr_err("vDSO is not a valid ELF object!\n");
76 return -EINVAL;
77 }
78
79 vdso_info[abi].vdso_pages = (
80 vdso_info[abi].vdso_code_end -
81 vdso_info[abi].vdso_code_start) >>
82 PAGE_SHIFT;
83
84 vdso_pagelist = kzalloc_objs(struct page *, vdso_info[abi].vdso_pages);
85 if (vdso_pagelist == NULL)
86 return -ENOMEM;
87
88 /* Grab the vDSO code pages. */
89 pfn = sym_to_pfn(vdso_info[abi].vdso_code_start);
90
91 for (i = 0; i < vdso_info[abi].vdso_pages; i++)
92 vdso_pagelist[i] = pfn_to_page(pfn + i);
93
94 vdso_info[abi].cm->pages = vdso_pagelist;
95
96 return 0;
97}
98
99static int __setup_additional_pages(enum vdso_abi abi,
100 struct mm_struct *mm,
101 struct linux_binprm *bprm,
102 int uses_interp)
103{
104 unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
105 unsigned long gp_flags = 0;
106 void *ret;
107
108 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);
109
110 vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT;
111 /* Be sure to map the data page */
112 vdso_mapping_len = vdso_text_len + VDSO_NR_PAGES * PAGE_SIZE;
113
114 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
115 if (IS_ERR_VALUE(vdso_base)) {
116 ret = ERR_PTR(vdso_base);
117 goto up_fail;
118 }
119
120 ret = vdso_install_vvar_mapping(mm, vdso_base);
121 if (IS_ERR(ret))
122 goto up_fail;
123
124 if (system_supports_bti_kernel())
125 gp_flags = VM_ARM64_BTI;
126
127 vdso_base += VDSO_NR_PAGES * PAGE_SIZE;
128 mm->context.vdso = (void *)vdso_base;
129 ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
130 VM_READ|VM_EXEC|gp_flags|
131 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
132 VM_SEALED_SYSMAP,
133 vdso_info[abi].cm);
134 if (IS_ERR(ret))
135 goto up_fail;
136
137 return 0;
138
139up_fail:
140 mm->context.vdso = NULL;
141 return PTR_ERR(ret);
142}
143
144#ifdef CONFIG_COMPAT
145/*
146 * Create and map the vectors page for AArch32 tasks.
147 */
148enum aarch32_map {
149 AA32_MAP_VECTORS, /* kuser helpers */
150 AA32_MAP_SIGPAGE,
151 AA32_MAP_VDSO,
152};
153
154static struct page *aarch32_vectors_page __ro_after_init;
155static struct page *aarch32_sig_page __ro_after_init;
156
157static int aarch32_sigpage_mremap(const struct vm_special_mapping *sm,
158 struct vm_area_struct *new_vma)
159{
160 current->mm->context.sigpage = (void *)new_vma->vm_start;
161
162 return 0;
163}
164
165static struct vm_special_mapping aarch32_vdso_maps[] = {
166 [AA32_MAP_VECTORS] = {
167 .name = "[vectors]", /* ABI */
168 .pages = &aarch32_vectors_page,
169 },
170 [AA32_MAP_SIGPAGE] = {
171 .name = "[sigpage]", /* ABI */
172 .pages = &aarch32_sig_page,
173 .mremap = aarch32_sigpage_mremap,
174 },
175 [AA32_MAP_VDSO] = {
176 .name = "[vdso]",
177 .mremap = vdso_mremap,
178 },
179};
180
181static int aarch32_alloc_kuser_vdso_page(void)
182{
183 extern char __kuser_helper_start[], __kuser_helper_end[];
184 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
185 unsigned long vdso_page;
186
187 if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
188 return 0;
189
190 vdso_page = get_zeroed_page(GFP_KERNEL);
191 if (!vdso_page)
192 return -ENOMEM;
193
194 memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start,
195 kuser_sz);
196 aarch32_vectors_page = virt_to_page((void *)vdso_page);
197 return 0;
198}
199
200#define COMPAT_SIGPAGE_POISON_WORD 0xe7fddef1
201static int aarch32_alloc_sigpage(void)
202{
203 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
204 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
205 __le32 poison = cpu_to_le32(COMPAT_SIGPAGE_POISON_WORD);
206 void *sigpage;
207
208 sigpage = (void *)__get_free_page(GFP_KERNEL);
209 if (!sigpage)
210 return -ENOMEM;
211
212 memset32(sigpage, (__force u32)poison, PAGE_SIZE / sizeof(poison));
213 memcpy(sigpage, __aarch32_sigret_code_start, sigret_sz);
214 aarch32_sig_page = virt_to_page(sigpage);
215 return 0;
216}
217
218static int __init __aarch32_alloc_vdso_pages(void)
219{
220
221 if (!IS_ENABLED(CONFIG_COMPAT_VDSO))
222 return 0;
223
224 vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO];
225
226 return __vdso_init(VDSO_ABI_AA32);
227}
228
229static int __init aarch32_alloc_vdso_pages(void)
230{
231 int ret;
232
233 ret = __aarch32_alloc_vdso_pages();
234 if (ret)
235 return ret;
236
237 ret = aarch32_alloc_sigpage();
238 if (ret)
239 return ret;
240
241 return aarch32_alloc_kuser_vdso_page();
242}
243arch_initcall(aarch32_alloc_vdso_pages);
244
245static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
246{
247 void *ret;
248
249 if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
250 return 0;
251
252 /*
253 * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's
254 * not safe to CoW the page containing the CPU exception vectors.
255 */
256 ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE,
257 VM_READ | VM_EXEC |
258 VM_MAYREAD | VM_MAYEXEC |
259 VM_SEALED_SYSMAP,
260 &aarch32_vdso_maps[AA32_MAP_VECTORS]);
261
262 return PTR_ERR_OR_ZERO(ret);
263}
264
265static int aarch32_sigreturn_setup(struct mm_struct *mm)
266{
267 unsigned long addr;
268 void *ret;
269
270 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
271 if (IS_ERR_VALUE(addr)) {
272 ret = ERR_PTR(addr);
273 goto out;
274 }
275
276 /*
277 * VM_MAYWRITE is required to allow gdb to Copy-on-Write and
278 * set breakpoints.
279 */
280 ret = _install_special_mapping(mm, addr, PAGE_SIZE,
281 VM_READ | VM_EXEC | VM_MAYREAD |
282 VM_MAYWRITE | VM_MAYEXEC |
283 VM_SEALED_SYSMAP,
284 &aarch32_vdso_maps[AA32_MAP_SIGPAGE]);
285 if (IS_ERR(ret))
286 goto out;
287
288 mm->context.sigpage = (void *)addr;
289
290out:
291 return PTR_ERR_OR_ZERO(ret);
292}
293
294int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
295{
296 struct mm_struct *mm = current->mm;
297 int ret;
298
299 if (mmap_write_lock_killable(mm))
300 return -EINTR;
301
302 ret = aarch32_kuser_helpers_setup(mm);
303 if (ret)
304 goto out;
305
306 if (IS_ENABLED(CONFIG_COMPAT_VDSO)) {
307 ret = __setup_additional_pages(VDSO_ABI_AA32, mm, bprm,
308 uses_interp);
309 if (ret)
310 goto out;
311 }
312
313 ret = aarch32_sigreturn_setup(mm);
314out:
315 mmap_write_unlock(mm);
316 return ret;
317}
318#endif /* CONFIG_COMPAT */
319
320static struct vm_special_mapping aarch64_vdso_map __ro_after_init = {
321 .name = "[vdso]",
322 .mremap = vdso_mremap,
323};
324
325static int __init vdso_init(void)
326{
327 vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_map;
328
329 return __vdso_init(VDSO_ABI_AA64);
330}
331arch_initcall(vdso_init);
332
333int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
334{
335 struct mm_struct *mm = current->mm;
336 int ret;
337
338 if (mmap_write_lock_killable(mm))
339 return -EINTR;
340
341 ret = __setup_additional_pages(VDSO_ABI_AA64, mm, bprm, uses_interp);
342 mmap_write_unlock(mm);
343
344 return ret;
345}