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20#include <linux/cache.h>
21#include <linux/elf.h>
22#include <linux/err.h>
23#include <linux/kernel.h>
24#include <linux/mm.h>
25#include <linux/of.h>
26#include <linux/printk.h>
27#include <linux/slab.h>
28#include <linux/timekeeper_internal.h>
29#include <linux/vmalloc.h>
30#include <asm/arch_timer.h>
31#include <asm/barrier.h>
32#include <asm/cacheflush.h>
33#include <asm/page.h>
34#include <asm/vdso.h>
35#include <asm/vdso_datapage.h>
36#include <clocksource/arm_arch_timer.h>
37
38#define MAX_SYMNAME 64
39
40static struct page **vdso_text_pagelist;
41
42
43unsigned int vdso_total_pages __ro_after_init;
44
45
46
47
48static union vdso_data_store vdso_data_store __page_aligned_data;
49static struct vdso_data *vdso_data = &vdso_data_store.data;
50
51static struct page *vdso_data_page __ro_after_init;
52static const struct vm_special_mapping vdso_data_mapping = {
53 .name = "[vvar]",
54 .pages = &vdso_data_page,
55};
56
57static int vdso_mremap(const struct vm_special_mapping *sm,
58 struct vm_area_struct *new_vma)
59{
60 unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
61 unsigned long vdso_size;
62
63
64 vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;
65
66 if (vdso_size != new_size)
67 return -EINVAL;
68
69 current->mm->context.vdso = new_vma->vm_start;
70
71 return 0;
72}
73
74static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
75 .name = "[vdso]",
76 .mremap = vdso_mremap,
77};
78
79struct elfinfo {
80 Elf32_Ehdr *hdr;
81 Elf32_Sym *dynsym;
82 unsigned long dynsymsize;
83 char *dynstr;
84};
85
86
87
88
89static bool cntvct_ok __ro_after_init;
90
91static bool __init cntvct_functional(void)
92{
93 struct device_node *np;
94 bool ret = false;
95
96 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
97 goto out;
98
99
100
101
102
103 np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
104 if (!np)
105 goto out_put;
106
107 if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
108 goto out_put;
109
110 ret = true;
111
112out_put:
113 of_node_put(np);
114out:
115 return ret;
116}
117
118static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
119 unsigned long *size)
120{
121 Elf32_Shdr *sechdrs;
122 unsigned int i;
123 char *secnames;
124
125
126 sechdrs = (void *)ehdr + ehdr->e_shoff;
127 secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
128
129
130 for (i = 1; i < ehdr->e_shnum; i++) {
131 if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
132 if (size)
133 *size = sechdrs[i].sh_size;
134 return (void *)ehdr + sechdrs[i].sh_offset;
135 }
136 }
137
138 if (size)
139 *size = 0;
140 return NULL;
141}
142
143static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
144{
145 unsigned int i;
146
147 for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
148 char name[MAX_SYMNAME], *c;
149
150 if (lib->dynsym[i].st_name == 0)
151 continue;
152 strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
153 MAX_SYMNAME);
154 c = strchr(name, '@');
155 if (c)
156 *c = 0;
157 if (strcmp(symname, name) == 0)
158 return &lib->dynsym[i];
159 }
160 return NULL;
161}
162
163static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
164{
165 Elf32_Sym *sym;
166
167 sym = find_symbol(lib, symname);
168 if (!sym)
169 return;
170
171 sym->st_name = 0;
172}
173
174static void __init patch_vdso(void *ehdr)
175{
176 struct elfinfo einfo;
177
178 einfo = (struct elfinfo) {
179 .hdr = ehdr,
180 };
181
182 einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
183 einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
184
185
186
187
188
189 if (!cntvct_ok) {
190 vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
191 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
192 }
193}
194
195static int __init vdso_init(void)
196{
197 unsigned int text_pages;
198 int i;
199
200 if (memcmp(&vdso_start, "\177ELF", 4)) {
201 pr_err("VDSO is not a valid ELF object!\n");
202 return -ENOEXEC;
203 }
204
205 text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
206 pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
207
208
209 vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
210 GFP_KERNEL);
211 if (vdso_text_pagelist == NULL)
212 return -ENOMEM;
213
214
215 vdso_data_page = virt_to_page(vdso_data);
216
217
218 for (i = 0; i < text_pages; i++) {
219 struct page *page;
220
221 page = virt_to_page(&vdso_start + i * PAGE_SIZE);
222 vdso_text_pagelist[i] = page;
223 }
224
225 vdso_text_mapping.pages = vdso_text_pagelist;
226
227 vdso_total_pages = 1;
228 vdso_total_pages += text_pages;
229
230 cntvct_ok = cntvct_functional();
231
232 patch_vdso(&vdso_start);
233
234 return 0;
235}
236arch_initcall(vdso_init);
237
238static int install_vvar(struct mm_struct *mm, unsigned long addr)
239{
240 struct vm_area_struct *vma;
241
242 vma = _install_special_mapping(mm, addr, PAGE_SIZE,
243 VM_READ | VM_MAYREAD,
244 &vdso_data_mapping);
245
246 return PTR_ERR_OR_ZERO(vma);
247}
248
249
250void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
251{
252 struct vm_area_struct *vma;
253 unsigned long len;
254
255 mm->context.vdso = 0;
256
257 if (vdso_text_pagelist == NULL)
258 return;
259
260 if (install_vvar(mm, addr))
261 return;
262
263
264 addr += PAGE_SIZE;
265 len = (vdso_total_pages - 1) << PAGE_SHIFT;
266
267 vma = _install_special_mapping(mm, addr, len,
268 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
269 &vdso_text_mapping);
270
271 if (!IS_ERR(vma))
272 mm->context.vdso = addr;
273}
274
275static void vdso_write_begin(struct vdso_data *vdata)
276{
277 ++vdso_data->seq_count;
278 smp_wmb();
279}
280
281static void vdso_write_end(struct vdso_data *vdata)
282{
283 smp_wmb();
284 ++vdso_data->seq_count;
285}
286
287static bool tk_is_cntvct(const struct timekeeper *tk)
288{
289 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
290 return false;
291
292 if (!tk->tkr_mono.clock->archdata.vdso_direct)
293 return false;
294
295 return true;
296}
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315
316void update_vsyscall(struct timekeeper *tk)
317{
318 struct timespec64 *wtm = &tk->wall_to_monotonic;
319
320 if (!cntvct_ok) {
321
322
323
324 return;
325 }
326
327 vdso_write_begin(vdso_data);
328
329 vdso_data->tk_is_cntvct = tk_is_cntvct(tk);
330 vdso_data->xtime_coarse_sec = tk->xtime_sec;
331 vdso_data->xtime_coarse_nsec = (u32)(tk->tkr_mono.xtime_nsec >>
332 tk->tkr_mono.shift);
333 vdso_data->wtm_clock_sec = wtm->tv_sec;
334 vdso_data->wtm_clock_nsec = wtm->tv_nsec;
335
336 if (vdso_data->tk_is_cntvct) {
337 vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
338 vdso_data->xtime_clock_sec = tk->xtime_sec;
339 vdso_data->xtime_clock_snsec = tk->tkr_mono.xtime_nsec;
340 vdso_data->cs_mult = tk->tkr_mono.mult;
341 vdso_data->cs_shift = tk->tkr_mono.shift;
342 vdso_data->cs_mask = tk->tkr_mono.mask;
343 }
344
345 vdso_write_end(vdso_data);
346
347 flush_dcache_page(virt_to_page(vdso_data));
348}
349
350void update_vsyscall_tz(void)
351{
352 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
353 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
354 flush_dcache_page(virt_to_page(vdso_data));
355}
356