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