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186 lines · 4.6 KiB

1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2015 Imagination Technologies
4 * Author: Alex Smith <[email protected]>
5 */
6
7#include <linux/binfmts.h>
8#include <linux/elf.h>
9#include <linux/err.h>
10#include <linux/init.h>
11#include <linux/ioport.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/mman.h>
15#include <linux/random.h>
16#include <linux/sched.h>
17#include <linux/slab.h>
18#include <linux/vdso_datastore.h>
19
20#include <asm/abi.h>
21#include <asm/mips-cps.h>
22#include <asm/page.h>
23#include <asm/vdso.h>
24#include <asm/vdso/vdso.h>
25#include <vdso/helpers.h>
26#include <vdso/vsyscall.h>
27
28static_assert(VDSO_NR_PAGES == __VDSO_PAGES);
29
30static void __init init_vdso_image(struct mips_vdso_image *image)
31{
32 unsigned long num_pages, i;
33 unsigned long data_pfn;
34
35 BUG_ON(!PAGE_ALIGNED(image->data));
36 BUG_ON(!PAGE_ALIGNED(image->size));
37
38 num_pages = image->size / PAGE_SIZE;
39
40 data_pfn = __phys_to_pfn(__pa_symbol(image->data));
41 for (i = 0; i < num_pages; i++)
42 image->mapping.pages[i] = pfn_to_page(data_pfn + i);
43}
44
45static int __init init_vdso(void)
46{
47 init_vdso_image(&vdso_image);
48
49#ifdef CONFIG_MIPS32_O32
50 init_vdso_image(&vdso_image_o32);
51#endif
52
53#ifdef CONFIG_MIPS32_N32
54 init_vdso_image(&vdso_image_n32);
55#endif
56
57 return 0;
58}
59subsys_initcall(init_vdso);
60
61static unsigned long vdso_base(void)
62{
63 unsigned long base = STACK_TOP;
64
65 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
66 /* Skip the delay slot emulation page */
67 base += PAGE_SIZE;
68 }
69
70 if (current->flags & PF_RANDOMIZE) {
71 base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
72 base = PAGE_ALIGN(base);
73 }
74
75 return base;
76}
77
78int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
79{
80 struct mips_vdso_image *image = current->thread.abi->vdso;
81 struct mm_struct *mm = current->mm;
82 unsigned long gic_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base;
83 struct vm_area_struct *vma;
84 int ret;
85
86 if (mmap_write_lock_killable(mm))
87 return -EINTR;
88
89 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
90 unsigned long unused;
91
92 /* Map delay slot emulation page */
93 base = do_mmap(NULL, STACK_TOP, PAGE_SIZE, PROT_READ | PROT_EXEC,
94 MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED,
95 EMPTY_VMA_FLAGS, 0, &unused, NULL);
96 if (IS_ERR_VALUE(base)) {
97 ret = base;
98 goto out;
99 }
100 }
101
102 /*
103 * Determine total area size. This includes the VDSO data itself, the
104 * data page, and the GIC user page if present. Always create a mapping
105 * for the GIC user area if the GIC is present regardless of whether it
106 * is the current clocksource, in case it comes into use later on. We
107 * only map a page even though the total area is 64K, as we only need
108 * the counter registers at the start.
109 */
110 gic_size = mips_gic_present() ? PAGE_SIZE : 0;
111 size = gic_size + VDSO_NR_PAGES * PAGE_SIZE + image->size;
112
113 /*
114 * Find a region that's large enough for us to perform the
115 * colour-matching alignment below.
116 */
117 if (cpu_has_dc_aliases)
118 size += shm_align_mask + 1;
119
120 base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
121 if (IS_ERR_VALUE(base)) {
122 ret = base;
123 goto out;
124 }
125
126 /*
127 * If we suffer from dcache aliasing, ensure that the VDSO data page
128 * mapping is coloured the same as the kernel's mapping of that memory.
129 * This ensures that when the kernel updates the VDSO data userland
130 * will observe it without requiring cache invalidations.
131 */
132 if (cpu_has_dc_aliases && IS_ENABLED(CONFIG_MIPS_GENERIC_GETTIMEOFDAY)) {
133 base = __ALIGN_MASK(base, shm_align_mask);
134 base += ((unsigned long)vdso_k_time_data - gic_size) & shm_align_mask;
135 }
136
137 data_addr = base + gic_size;
138 vdso_addr = data_addr + VDSO_NR_PAGES * PAGE_SIZE;
139
140 if (IS_ENABLED(CONFIG_MIPS_GENERIC_GETTIMEOFDAY)) {
141 vma = vdso_install_vvar_mapping(mm, data_addr);
142 if (IS_ERR(vma)) {
143 ret = PTR_ERR(vma);
144 goto out;
145 }
146 }
147
148 /* Map GIC user page. */
149 if (gic_size) {
150 gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
151 gic_pfn = PFN_DOWN(__pa(gic_base));
152 static const struct vm_special_mapping gic_mapping = {
153 .name = "[gic]",
154 .pages = (struct page **) { NULL },
155 };
156
157 vma = _install_special_mapping(mm, base, gic_size, VM_READ | VM_MAYREAD,
158 &gic_mapping);
159 if (IS_ERR(vma)) {
160 ret = PTR_ERR(vma);
161 goto out;
162 }
163
164 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
165 pgprot_noncached(vma->vm_page_prot));
166 if (ret)
167 goto out;
168 }
169
170 /* Map VDSO image. */
171 vma = _install_special_mapping(mm, vdso_addr, image->size,
172 VM_READ | VM_EXEC |
173 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
174 &image->mapping);
175 if (IS_ERR(vma)) {
176 ret = PTR_ERR(vma);
177 goto out;
178 }
179
180 mm->context.vdso = (void *)vdso_addr;
181 ret = 0;
182
183out:
184 mmap_write_unlock(mm);
185 return ret;
186}