1/*
2 * VDSO implementation for AArch64 and vector page setup for AArch32.
3 *
4 * Copyright (C) 2012 ARM Limited
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Will Deacon <will.deacon@arm.com>
19 */
20
21#include <linux/kernel.h>
22#include <linux/clocksource.h>
23#include <linux/elf.h>
24#include <linux/err.h>
25#include <linux/errno.h>
26#include <linux/gfp.h>
27#include <linux/mm.h>
28#include <linux/sched.h>
29#include <linux/signal.h>
30#include <linux/slab.h>
31#include <linux/timekeeper_internal.h>
32#include <linux/vmalloc.h>
33
34#include <asm/cacheflush.h>
35#include <asm/signal32.h>
36#include <asm/vdso.h>
37#include <asm/vdso_datapage.h>
38
39extern char vdso_start, vdso_end;
40static unsigned long vdso_pages;
41static struct page **vdso_pagelist;
42
43/*
44 * The vDSO data page.
45 */
46static union {
47	struct vdso_data	data;
48	u8			page[PAGE_SIZE];
49} vdso_data_store __page_aligned_data;
50struct vdso_data *vdso_data = &vdso_data_store.data;
51
52#ifdef CONFIG_COMPAT
53/*
54 * Create and map the vectors page for AArch32 tasks.
55 */
56static struct page *vectors_page[1];
57
58static int alloc_vectors_page(void)
59{
60	extern char __kuser_helper_start[], __kuser_helper_end[];
61	extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
62
63	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
64	int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
65	unsigned long vpage;
66
67	vpage = get_zeroed_page(GFP_ATOMIC);
68
69	if (!vpage)
70		return -ENOMEM;
71
72	/* kuser helpers */
73	memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start,
74		kuser_sz);
75
76	/* sigreturn code */
77	memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
78               __aarch32_sigret_code_start, sigret_sz);
79
80	flush_icache_range(vpage, vpage + PAGE_SIZE);
81	vectors_page[0] = virt_to_page(vpage);
82
83	return 0;
84}
85arch_initcall(alloc_vectors_page);
86
87int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
88{
89	struct mm_struct *mm = current->mm;
90	unsigned long addr = AARCH32_VECTORS_BASE;
91	static struct vm_special_mapping spec = {
92		.name	= "[vectors]",
93		.pages	= vectors_page,
94
95	};
96	void *ret;
97
98	down_write(&mm->mmap_sem);
99	current->mm->context.vdso = (void *)addr;
100
101	/* Map vectors page at the high address. */
102	ret = _install_special_mapping(mm, addr, PAGE_SIZE,
103				       VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
104				       &spec);
105
106	up_write(&mm->mmap_sem);
107
108	return PTR_ERR_OR_ZERO(ret);
109}
110#endif /* CONFIG_COMPAT */
111
112static struct vm_special_mapping vdso_spec[2];
113
114static int __init vdso_init(void)
115{
116	int i;
117
118	if (memcmp(&vdso_start, "\177ELF", 4)) {
119		pr_err("vDSO is not a valid ELF object!\n");
120		return -EINVAL;
121	}
122
123	vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
124	pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
125		vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
126
127	/* Allocate the vDSO pagelist, plus a page for the data. */
128	vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
129				GFP_KERNEL);
130	if (vdso_pagelist == NULL)
131		return -ENOMEM;
132
133	/* Grab the vDSO data page. */
134	vdso_pagelist[0] = virt_to_page(vdso_data);
135
136	/* Grab the vDSO code pages. */
137	for (i = 0; i < vdso_pages; i++)
138		vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE);
139
140	/* Populate the special mapping structures */
141	vdso_spec[0] = (struct vm_special_mapping) {
142		.name	= "[vvar]",
143		.pages	= vdso_pagelist,
144	};
145
146	vdso_spec[1] = (struct vm_special_mapping) {
147		.name	= "[vdso]",
148		.pages	= &vdso_pagelist[1],
149	};
150
151	return 0;
152}
153arch_initcall(vdso_init);
154
155int arch_setup_additional_pages(struct linux_binprm *bprm,
156				int uses_interp)
157{
158	struct mm_struct *mm = current->mm;
159	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
160	void *ret;
161
162	vdso_text_len = vdso_pages << PAGE_SHIFT;
163	/* Be sure to map the data page */
164	vdso_mapping_len = vdso_text_len + PAGE_SIZE;
165
166	down_write(&mm->mmap_sem);
167	vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
168	if (IS_ERR_VALUE(vdso_base)) {
169		ret = ERR_PTR(vdso_base);
170		goto up_fail;
171	}
172	ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
173				       VM_READ|VM_MAYREAD,
174				       &vdso_spec[0]);
175	if (IS_ERR(ret))
176		goto up_fail;
177
178	vdso_base += PAGE_SIZE;
179	mm->context.vdso = (void *)vdso_base;
180	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
181				       VM_READ|VM_EXEC|
182				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
183				       &vdso_spec[1]);
184	if (IS_ERR(ret))
185		goto up_fail;
186
187
188	up_write(&mm->mmap_sem);
189	return 0;
190
191up_fail:
192	mm->context.vdso = NULL;
193	up_write(&mm->mmap_sem);
194	return PTR_ERR(ret);
195}
196
197/*
198 * Update the vDSO data page to keep in sync with kernel timekeeping.
199 */
200void update_vsyscall(struct timekeeper *tk)
201{
202	u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter");
203
204	++vdso_data->tb_seq_count;
205	smp_wmb();
206
207	vdso_data->use_syscall			= use_syscall;
208	vdso_data->xtime_coarse_sec		= tk->xtime_sec;
209	vdso_data->xtime_coarse_nsec		= tk->tkr_mono.xtime_nsec >>
210							tk->tkr_mono.shift;
211	vdso_data->wtm_clock_sec		= tk->wall_to_monotonic.tv_sec;
212	vdso_data->wtm_clock_nsec		= tk->wall_to_monotonic.tv_nsec;
213
214	if (!use_syscall) {
215		vdso_data->cs_cycle_last	= tk->tkr_mono.cycle_last;
216		vdso_data->xtime_clock_sec	= tk->xtime_sec;
217		vdso_data->xtime_clock_nsec	= tk->tkr_mono.xtime_nsec;
218		vdso_data->cs_mult		= tk->tkr_mono.mult;
219		vdso_data->cs_shift		= tk->tkr_mono.shift;
220	}
221
222	smp_wmb();
223	++vdso_data->tb_seq_count;
224}
225
226void update_vsyscall_tz(void)
227{
228	vdso_data->tz_minuteswest	= sys_tz.tz_minuteswest;
229	vdso_data->tz_dsttime		= sys_tz.tz_dsttime;
230}
231