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1/*
2 * Adapted from arm64 version.
3 *
4 * Copyright (C) 2012 ARM Limited
5 * Copyright (C) 2015 Mentor Graphics Corporation.
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/elf.h>
21#include <linux/err.h>
22#include <linux/kernel.h>
23#include <linux/mm.h>
24#include <linux/of.h>
25#include <linux/printk.h>
26#include <linux/slab.h>
27#include <linux/timekeeper_internal.h>
28#include <linux/vmalloc.h>
29#include <asm/arch_timer.h>
30#include <asm/barrier.h>
31#include <asm/cacheflush.h>
32#include <asm/page.h>
33#include <asm/vdso.h>
34#include <asm/vdso_datapage.h>
35#include <clocksource/arm_arch_timer.h>
36
37#define MAX_SYMNAME 64
38
39static struct page **vdso_text_pagelist;
40
41/* Total number of pages needed for the data and text portions of the VDSO. */
42unsigned int vdso_total_pages __read_mostly;
43
44/*
45 * The VDSO data page.
46 */
47static union vdso_data_store vdso_data_store __page_aligned_data;
48static struct vdso_data *vdso_data = &vdso_data_store.data;
49
50static struct page *vdso_data_page;
51static struct vm_special_mapping vdso_data_mapping = {
52 .name = "[vvar]",
53 .pages = &vdso_data_page,
54};
55
56static struct vm_special_mapping vdso_text_mapping = {
57 .name = "[vdso]",
58};
59
60struct elfinfo {
61 Elf32_Ehdr *hdr; /* ptr to ELF */
62 Elf32_Sym *dynsym; /* ptr to .dynsym section */
63 unsigned long dynsymsize; /* size of .dynsym section */
64 char *dynstr; /* ptr to .dynstr section */
65};
66
67/* Cached result of boot-time check for whether the arch timer exists,
68 * and if so, whether the virtual counter is useable.
69 */
70static bool cntvct_ok __read_mostly;
71
72static bool __init cntvct_functional(void)
73{
74 struct device_node *np;
75 bool ret = false;
76
77 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
78 goto out;
79
80 /* The arm_arch_timer core should export
81 * arch_timer_use_virtual or similar so we don't have to do
82 * this.
83 */
84 np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
85 if (!np)
86 goto out_put;
87
88 if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
89 goto out_put;
90
91 ret = true;
92
93out_put:
94 of_node_put(np);
95out:
96 return ret;
97}
98
99static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
100 unsigned long *size)
101{
102 Elf32_Shdr *sechdrs;
103 unsigned int i;
104 char *secnames;
105
106 /* Grab section headers and strings so we can tell who is who */
107 sechdrs = (void *)ehdr + ehdr->e_shoff;
108 secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
109
110 /* Find the section they want */
111 for (i = 1; i < ehdr->e_shnum; i++) {
112 if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
113 if (size)
114 *size = sechdrs[i].sh_size;
115 return (void *)ehdr + sechdrs[i].sh_offset;
116 }
117 }
118
119 if (size)
120 *size = 0;
121 return NULL;
122}
123
124static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
125{
126 unsigned int i;
127
128 for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
129 char name[MAX_SYMNAME], *c;
130
131 if (lib->dynsym[i].st_name == 0)
132 continue;
133 strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
134 MAX_SYMNAME);
135 c = strchr(name, '@');
136 if (c)
137 *c = 0;
138 if (strcmp(symname, name) == 0)
139 return &lib->dynsym[i];
140 }
141 return NULL;
142}
143
144static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
145{
146 Elf32_Sym *sym;
147
148 sym = find_symbol(lib, symname);
149 if (!sym)
150 return;
151
152 sym->st_name = 0;
153}
154
155static void __init patch_vdso(void *ehdr)
156{
157 struct elfinfo einfo;
158
159 einfo = (struct elfinfo) {
160 .hdr = ehdr,
161 };
162
163 einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
164 einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
165
166 /* If the virtual counter is absent or non-functional we don't
167 * want programs to incur the slight additional overhead of
168 * dispatching through the VDSO only to fall back to syscalls.
169 */
170 if (!cntvct_ok) {
171 vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
172 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
173 }
174}
175
176static int __init vdso_init(void)
177{
178 unsigned int text_pages;
179 int i;
180
181 if (memcmp(&vdso_start, "\177ELF", 4)) {
182 pr_err("VDSO is not a valid ELF object!\n");
183 return -ENOEXEC;
184 }
185
186 text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
187 pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
188
189 /* Allocate the VDSO text pagelist */
190 vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
191 GFP_KERNEL);
192 if (vdso_text_pagelist == NULL)
193 return -ENOMEM;
194
195 /* Grab the VDSO data page. */
196 vdso_data_page = virt_to_page(vdso_data);
197
198 /* Grab the VDSO text pages. */
199 for (i = 0; i < text_pages; i++) {
200 struct page *page;
201
202 page = virt_to_page(&vdso_start + i * PAGE_SIZE);
203 vdso_text_pagelist[i] = page;
204 }
205
206 vdso_text_mapping.pages = vdso_text_pagelist;
207
208 vdso_total_pages = 1; /* for the data/vvar page */
209 vdso_total_pages += text_pages;
210
211 cntvct_ok = cntvct_functional();
212
213 patch_vdso(&vdso_start);
214
215 return 0;
216}
217arch_initcall(vdso_init);
218
219static int install_vvar(struct mm_struct *mm, unsigned long addr)
220{
221 struct vm_area_struct *vma;
222
223 vma = _install_special_mapping(mm, addr, PAGE_SIZE,
224 VM_READ | VM_MAYREAD,
225 &vdso_data_mapping);
226
227 return PTR_ERR_OR_ZERO(vma);
228}
229
230/* assumes mmap_sem is write-locked */
231void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
232{
233 struct vm_area_struct *vma;
234 unsigned long len;
235
236 mm->context.vdso = 0;
237
238 if (vdso_text_pagelist == NULL)
239 return;
240
241 if (install_vvar(mm, addr))
242 return;
243
244 /* Account for vvar page. */
245 addr += PAGE_SIZE;
246 len = (vdso_total_pages - 1) << PAGE_SHIFT;
247
248 vma = _install_special_mapping(mm, addr, len,
249 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
250 &vdso_text_mapping);
251
252 if (!IS_ERR(vma))
253 mm->context.vdso = addr;
254}
255
256static void vdso_write_begin(struct vdso_data *vdata)
257{
258 ++vdso_data->seq_count;
259 smp_wmb(); /* Pairs with smp_rmb in vdso_read_retry */
260}
261
262static void vdso_write_end(struct vdso_data *vdata)
263{
264 smp_wmb(); /* Pairs with smp_rmb in vdso_read_begin */
265 ++vdso_data->seq_count;
266}
267
268static bool tk_is_cntvct(const struct timekeeper *tk)
269{
270 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
271 return false;
272
273 if (strcmp(tk->tkr_mono.clock->name, "arch_sys_counter") != 0)
274 return false;
275
276 return true;
277}
278
279/**
280 * update_vsyscall - update the vdso data page
281 *
282 * Increment the sequence counter, making it odd, indicating to
283 * userspace that an update is in progress. Update the fields used
284 * for coarse clocks and, if the architected system timer is in use,
285 * the fields used for high precision clocks. Increment the sequence
286 * counter again, making it even, indicating to userspace that the
287 * update is finished.
288 *
289 * Userspace is expected to sample seq_count before reading any other
290 * fields from the data page. If seq_count is odd, userspace is
291 * expected to wait until it becomes even. After copying data from
292 * the page, userspace must sample seq_count again; if it has changed
293 * from its previous value, userspace must retry the whole sequence.
294 *
295 * Calls to update_vsyscall are serialized by the timekeeping core.
296 */
297void update_vsyscall(struct timekeeper *tk)
298{
299 struct timespec64 *wtm = &tk->wall_to_monotonic;
300
301 if (!cntvct_ok) {
302 /* The entry points have been zeroed, so there is no
303 * point in updating the data page.
304 */
305 return;
306 }
307
308 vdso_write_begin(vdso_data);
309
310 vdso_data->tk_is_cntvct = tk_is_cntvct(tk);
311 vdso_data->xtime_coarse_sec = tk->xtime_sec;
312 vdso_data->xtime_coarse_nsec = (u32)(tk->tkr_mono.xtime_nsec >>
313 tk->tkr_mono.shift);
314 vdso_data->wtm_clock_sec = wtm->tv_sec;
315 vdso_data->wtm_clock_nsec = wtm->tv_nsec;
316
317 if (vdso_data->tk_is_cntvct) {
318 vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
319 vdso_data->xtime_clock_sec = tk->xtime_sec;
320 vdso_data->xtime_clock_snsec = tk->tkr_mono.xtime_nsec;
321 vdso_data->cs_mult = tk->tkr_mono.mult;
322 vdso_data->cs_shift = tk->tkr_mono.shift;
323 vdso_data->cs_mask = tk->tkr_mono.mask;
324 }
325
326 vdso_write_end(vdso_data);
327
328 flush_dcache_page(virt_to_page(vdso_data));
329}
330
331void update_vsyscall_tz(void)
332{
333 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
334 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
335 flush_dcache_page(virt_to_page(vdso_data));
336}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Adapted from arm64 version.
4 *
5 * Copyright (C) 2012 ARM Limited
6 * Copyright (C) 2015 Mentor Graphics Corporation.
7 */
8
9#include <linux/cache.h>
10#include <linux/elf.h>
11#include <linux/err.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/of.h>
15#include <linux/printk.h>
16#include <linux/slab.h>
17#include <linux/timekeeper_internal.h>
18#include <linux/vmalloc.h>
19#include <asm/arch_timer.h>
20#include <asm/barrier.h>
21#include <asm/cacheflush.h>
22#include <asm/page.h>
23#include <asm/vdso.h>
24#include <asm/vdso_datapage.h>
25#include <clocksource/arm_arch_timer.h>
26#include <vdso/helpers.h>
27#include <vdso/vsyscall.h>
28
29#define MAX_SYMNAME 64
30
31static struct page **vdso_text_pagelist;
32
33extern char vdso_start[], vdso_end[];
34
35/* Total number of pages needed for the data and text portions of the VDSO. */
36unsigned int vdso_total_pages __ro_after_init;
37
38/*
39 * The VDSO data page.
40 */
41static union vdso_data_store vdso_data_store __page_aligned_data;
42struct vdso_data *vdso_data = vdso_data_store.data;
43
44static struct page *vdso_data_page __ro_after_init;
45static const struct vm_special_mapping vdso_data_mapping = {
46 .name = "[vvar]",
47 .pages = &vdso_data_page,
48};
49
50static int vdso_mremap(const struct vm_special_mapping *sm,
51 struct vm_area_struct *new_vma)
52{
53 unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
54 unsigned long vdso_size;
55
56 /* without VVAR page */
57 vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;
58
59 if (vdso_size != new_size)
60 return -EINVAL;
61
62 current->mm->context.vdso = new_vma->vm_start;
63
64 return 0;
65}
66
67static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
68 .name = "[vdso]",
69 .mremap = vdso_mremap,
70};
71
72struct elfinfo {
73 Elf32_Ehdr *hdr; /* ptr to ELF */
74 Elf32_Sym *dynsym; /* ptr to .dynsym section */
75 unsigned long dynsymsize; /* size of .dynsym section */
76 char *dynstr; /* ptr to .dynstr section */
77};
78
79/* Cached result of boot-time check for whether the arch timer exists,
80 * and if so, whether the virtual counter is useable.
81 */
82bool cntvct_ok __ro_after_init;
83
84static bool __init cntvct_functional(void)
85{
86 struct device_node *np;
87 bool ret = false;
88
89 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
90 goto out;
91
92 /* The arm_arch_timer core should export
93 * arch_timer_use_virtual or similar so we don't have to do
94 * this.
95 */
96 np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
97 if (!np)
98 np = of_find_compatible_node(NULL, NULL, "arm,armv8-timer");
99 if (!np)
100 goto out_put;
101
102 if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
103 goto out_put;
104
105 ret = true;
106
107out_put:
108 of_node_put(np);
109out:
110 return ret;
111}
112
113static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
114 unsigned long *size)
115{
116 Elf32_Shdr *sechdrs;
117 unsigned int i;
118 char *secnames;
119
120 /* Grab section headers and strings so we can tell who is who */
121 sechdrs = (void *)ehdr + ehdr->e_shoff;
122 secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
123
124 /* Find the section they want */
125 for (i = 1; i < ehdr->e_shnum; i++) {
126 if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
127 if (size)
128 *size = sechdrs[i].sh_size;
129 return (void *)ehdr + sechdrs[i].sh_offset;
130 }
131 }
132
133 if (size)
134 *size = 0;
135 return NULL;
136}
137
138static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
139{
140 unsigned int i;
141
142 for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
143 char name[MAX_SYMNAME], *c;
144
145 if (lib->dynsym[i].st_name == 0)
146 continue;
147 strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
148 MAX_SYMNAME);
149 c = strchr(name, '@');
150 if (c)
151 *c = 0;
152 if (strcmp(symname, name) == 0)
153 return &lib->dynsym[i];
154 }
155 return NULL;
156}
157
158static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
159{
160 Elf32_Sym *sym;
161
162 sym = find_symbol(lib, symname);
163 if (!sym)
164 return;
165
166 sym->st_name = 0;
167}
168
169static void __init patch_vdso(void *ehdr)
170{
171 struct elfinfo einfo;
172
173 einfo = (struct elfinfo) {
174 .hdr = ehdr,
175 };
176
177 einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
178 einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
179
180 /* If the virtual counter is absent or non-functional we don't
181 * want programs to incur the slight additional overhead of
182 * dispatching through the VDSO only to fall back to syscalls.
183 */
184 if (!cntvct_ok) {
185 vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
186 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
187 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
188 }
189}
190
191static int __init vdso_init(void)
192{
193 unsigned int text_pages;
194 int i;
195
196 if (memcmp(vdso_start, "\177ELF", 4)) {
197 pr_err("VDSO is not a valid ELF object!\n");
198 return -ENOEXEC;
199 }
200
201 text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
202
203 /* Allocate the VDSO text pagelist */
204 vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
205 GFP_KERNEL);
206 if (vdso_text_pagelist == NULL)
207 return -ENOMEM;
208
209 /* Grab the VDSO data page. */
210 vdso_data_page = virt_to_page(vdso_data);
211
212 /* Grab the VDSO text pages. */
213 for (i = 0; i < text_pages; i++) {
214 struct page *page;
215
216 page = virt_to_page(vdso_start + i * PAGE_SIZE);
217 vdso_text_pagelist[i] = page;
218 }
219
220 vdso_text_mapping.pages = vdso_text_pagelist;
221
222 vdso_total_pages = 1; /* for the data/vvar page */
223 vdso_total_pages += text_pages;
224
225 cntvct_ok = cntvct_functional();
226
227 patch_vdso(vdso_start);
228
229 return 0;
230}
231arch_initcall(vdso_init);
232
233static int install_vvar(struct mm_struct *mm, unsigned long addr)
234{
235 struct vm_area_struct *vma;
236
237 vma = _install_special_mapping(mm, addr, PAGE_SIZE,
238 VM_READ | VM_MAYREAD,
239 &vdso_data_mapping);
240
241 return PTR_ERR_OR_ZERO(vma);
242}
243
244/* assumes mmap_lock is write-locked */
245void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
246{
247 struct vm_area_struct *vma;
248 unsigned long len;
249
250 mm->context.vdso = 0;
251
252 if (vdso_text_pagelist == NULL)
253 return;
254
255 if (install_vvar(mm, addr))
256 return;
257
258 /* Account for vvar page. */
259 addr += PAGE_SIZE;
260 len = (vdso_total_pages - 1) << PAGE_SHIFT;
261
262 vma = _install_special_mapping(mm, addr, len,
263 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
264 &vdso_text_mapping);
265
266 if (!IS_ERR(vma))
267 mm->context.vdso = addr;
268}
269