aboutsummaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/vdso.c
blob: c958cb84d75fd4c488d585a6bec5233aa839b21c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
/*
 * VDSO implementation for AArch64 and vector page setup for AArch32.
 *
 * Copyright (C) 2012 ARM Limited
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Author: Will Deacon <will.deacon@arm.com>
 */

#include <linux/kernel.h>
#include <linux/clocksource.h>
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>

#include <asm/cacheflush.h>
#include <asm/signal32.h>
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>

extern char vdso_start, vdso_end;
static unsigned long vdso_pages;
static struct page **vdso_pagelist;

/*
 * The vDSO data page.
 */
static union {
	struct vdso_data	data;
	u8			page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;

#ifdef CONFIG_COMPAT
/*
 * Create and map the vectors page for AArch32 tasks.
 */
static struct page *vectors_page[1];

static int alloc_vectors_page(void)
{
	extern char __kuser_helper_start[], __kuser_helper_end[];
	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
	unsigned long vpage;

	vpage = get_zeroed_page(GFP_ATOMIC);

	if (!vpage)
		return -ENOMEM;

	/* kuser helpers */
	memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
		kuser_sz);

	/* sigreturn code */
	memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
		aarch32_sigret_code, sizeof(aarch32_sigret_code));

	flush_icache_range(vpage, vpage + PAGE_SIZE);
	vectors_page[0] = virt_to_page(vpage);

	return 0;
}
arch_initcall(alloc_vectors_page);

int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
{
	struct mm_struct *mm = current->mm;
	unsigned long addr = AARCH32_VECTORS_BASE;
	int ret;

	down_write(&mm->mmap_sem);
	current->mm->context.vdso = (void *)addr;

	/* Map vectors page at the high address. */
	ret = install_special_mapping(mm, addr, PAGE_SIZE,
				      VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
				      vectors_page);

	up_write(&mm->mmap_sem);

	return ret;
}
#endif /* CONFIG_COMPAT */

static int __init vdso_init(void)
{
	struct page *pg;
	char *vbase;
	int i, ret = 0;

	vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
	pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n",
		vdso_pages + 1, vdso_pages, 1L, &vdso_start);

	/* Allocate the vDSO pagelist, plus a page for the data. */
	vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1),
				GFP_KERNEL);
	if (vdso_pagelist == NULL) {
		pr_err("Failed to allocate vDSO pagelist!\n");
		return -ENOMEM;
	}

	/* Grab the vDSO code pages. */
	for (i = 0; i < vdso_pages; i++) {
		pg = virt_to_page(&vdso_start + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
		vdso_pagelist[i] = pg;
	}

	/* Sanity check the shared object header. */
	vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL);
	if (vbase == NULL) {
		pr_err("Failed to map vDSO pagelist!\n");
		return -ENOMEM;
	} else if (memcmp(vbase, "\177ELF", 4)) {
		pr_err("vDSO is not a valid ELF object!\n");
		ret = -EINVAL;
		goto unmap;
	}

	/* Grab the vDSO data page. */
	pg = virt_to_page(vdso_data);
	get_page(pg);
	vdso_pagelist[i] = pg;

unmap:
	vunmap(vbase);
	return ret;
}
arch_initcall(vdso_init);

int arch_setup_additional_pages(struct linux_binprm *bprm,
				int uses_interp)
{
	struct mm_struct *mm = current->mm;
	unsigned long vdso_base, vdso_mapping_len;
	int ret;

	/* Be sure to map the data page */
	vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;

	down_write(&mm->mmap_sem);
	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
	if (IS_ERR_VALUE(vdso_base)) {
		ret = vdso_base;
		goto up_fail;
	}
	mm->context.vdso = (void *)vdso_base;

	ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,
				      VM_READ|VM_EXEC|
				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
				      vdso_pagelist);
	if (ret) {
		mm->context.vdso = NULL;
		goto up_fail;
	}

up_fail:
	up_write(&mm->mmap_sem);

	return ret;
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
	/*
	 * We can re-use the vdso pointer in mm_context_t for identifying
	 * the vectors page for compat applications. The vDSO will always
	 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about
	 * it conflicting with the vectors base.
	 */
	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) {
#ifdef CONFIG_COMPAT
		if (vma->vm_start == AARCH32_VECTORS_BASE)
			return "[vectors]";
#endif
		return "[vdso]";
	}

	return NULL;
}

/*
 * We define AT_SYSINFO_EHDR, so we need these function stubs to keep
 * Linux happy.
 */
int in_gate_area_no_mm(unsigned long addr)
{
	return 0;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
	return 0;
}

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
	return NULL;
}

/*
 * Update the vDSO data page to keep in sync with kernel timekeeping.
 */
void update_vsyscall(struct timekeeper *tk)
{
	struct timespec xtime_coarse;
	u32 use_syscall = strcmp(tk->clock->name, "arch_sys_counter");

	++vdso_data->tb_seq_count;
	smp_wmb();

	xtime_coarse = __current_kernel_time();
	vdso_data->use_syscall			= use_syscall;
	vdso_data->xtime_coarse_sec		= xtime_coarse.tv_sec;
	vdso_data->xtime_coarse_nsec		= xtime_coarse.tv_nsec;

	if (!use_syscall) {
		vdso_data->cs_cycle_last	= tk->clock->cycle_last;
		vdso_data->xtime_clock_sec	= tk->xtime_sec;
		vdso_data->xtime_clock_nsec	= tk->xtime_nsec;
		vdso_data->cs_mult		= tk->mult;
		vdso_data->cs_shift		= tk->shift;
		vdso_data->wtm_clock_sec	= tk->wall_to_monotonic.tv_sec;
		vdso_data->wtm_clock_nsec	= tk->wall_to_monotonic.tv_nsec;
	}

	smp_wmb();
	++vdso_data->tb_seq_count;
}

void update_vsyscall_tz(void)
{
	++vdso_data->tb_seq_count;
	smp_wmb();
	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;
	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;
	smp_wmb();
	++vdso_data->tb_seq_count;
}