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/random.h> |
15 | #include <linux/sched.h> |
16 | #include <linux/slab.h> |
17 | #include <linux/timekeeper_internal.h> |
18 | |
19 | #include <asm/abi.h> |
20 | #include <asm/mips-cps.h> |
21 | #include <asm/page.h> |
22 | #include <asm/vdso.h> |
23 | #include <vdso/helpers.h> |
24 | #include <vdso/vsyscall.h> |
25 | |
26 | /* Kernel-provided data used by the VDSO. */ |
27 | static union mips_vdso_data mips_vdso_data __page_aligned_data; |
28 | struct vdso_data *vdso_data = mips_vdso_data.data; |
29 | |
30 | /* |
31 | * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as |
32 | * what we map and where within the area they are mapped is determined at |
33 | * runtime. |
34 | */ |
35 | static struct page *no_pages[] = { NULL }; |
36 | static struct vm_special_mapping vdso_vvar_mapping = { |
37 | .name = "[vvar]" , |
38 | .pages = no_pages, |
39 | }; |
40 | |
41 | static void __init init_vdso_image(struct mips_vdso_image *image) |
42 | { |
43 | unsigned long num_pages, i; |
44 | unsigned long data_pfn; |
45 | |
46 | BUG_ON(!PAGE_ALIGNED(image->data)); |
47 | BUG_ON(!PAGE_ALIGNED(image->size)); |
48 | |
49 | num_pages = image->size / PAGE_SIZE; |
50 | |
51 | data_pfn = __phys_to_pfn(__pa_symbol(image->data)); |
52 | for (i = 0; i < num_pages; i++) |
53 | image->mapping.pages[i] = pfn_to_page(data_pfn + i); |
54 | } |
55 | |
56 | static int __init init_vdso(void) |
57 | { |
58 | init_vdso_image(image: &vdso_image); |
59 | |
60 | #ifdef CONFIG_MIPS32_O32 |
61 | init_vdso_image(&vdso_image_o32); |
62 | #endif |
63 | |
64 | #ifdef CONFIG_MIPS32_N32 |
65 | init_vdso_image(&vdso_image_n32); |
66 | #endif |
67 | |
68 | return 0; |
69 | } |
70 | subsys_initcall(init_vdso); |
71 | |
72 | static unsigned long vdso_base(void) |
73 | { |
74 | unsigned long base = STACK_TOP; |
75 | |
76 | if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { |
77 | /* Skip the delay slot emulation page */ |
78 | base += PAGE_SIZE; |
79 | } |
80 | |
81 | if (current->flags & PF_RANDOMIZE) { |
82 | base += get_random_u32_below(ceil: VDSO_RANDOMIZE_SIZE); |
83 | base = PAGE_ALIGN(base); |
84 | } |
85 | |
86 | return base; |
87 | } |
88 | |
89 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
90 | { |
91 | struct mips_vdso_image *image = current->thread.abi->vdso; |
92 | struct mm_struct *mm = current->mm; |
93 | unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base; |
94 | struct vm_area_struct *vma; |
95 | int ret; |
96 | |
97 | if (mmap_write_lock_killable(mm)) |
98 | return -EINTR; |
99 | |
100 | if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { |
101 | /* Map delay slot emulation page */ |
102 | base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, |
103 | VM_READ | VM_EXEC | |
104 | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, |
105 | pgoff: 0, NULL); |
106 | if (IS_ERR_VALUE(base)) { |
107 | ret = base; |
108 | goto out; |
109 | } |
110 | } |
111 | |
112 | /* |
113 | * Determine total area size. This includes the VDSO data itself, the |
114 | * data page, and the GIC user page if present. Always create a mapping |
115 | * for the GIC user area if the GIC is present regardless of whether it |
116 | * is the current clocksource, in case it comes into use later on. We |
117 | * only map a page even though the total area is 64K, as we only need |
118 | * the counter registers at the start. |
119 | */ |
120 | gic_size = mips_gic_present() ? PAGE_SIZE : 0; |
121 | vvar_size = gic_size + PAGE_SIZE; |
122 | size = vvar_size + image->size; |
123 | |
124 | /* |
125 | * Find a region that's large enough for us to perform the |
126 | * colour-matching alignment below. |
127 | */ |
128 | if (cpu_has_dc_aliases) |
129 | size += shm_align_mask + 1; |
130 | |
131 | base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); |
132 | if (IS_ERR_VALUE(base)) { |
133 | ret = base; |
134 | goto out; |
135 | } |
136 | |
137 | /* |
138 | * If we suffer from dcache aliasing, ensure that the VDSO data page |
139 | * mapping is coloured the same as the kernel's mapping of that memory. |
140 | * This ensures that when the kernel updates the VDSO data userland |
141 | * will observe it without requiring cache invalidations. |
142 | */ |
143 | if (cpu_has_dc_aliases) { |
144 | base = __ALIGN_MASK(base, shm_align_mask); |
145 | base += ((unsigned long)vdso_data - gic_size) & shm_align_mask; |
146 | } |
147 | |
148 | data_addr = base + gic_size; |
149 | vdso_addr = data_addr + PAGE_SIZE; |
150 | |
151 | vma = _install_special_mapping(mm, addr: base, len: vvar_size, |
152 | VM_READ | VM_MAYREAD, |
153 | spec: &vdso_vvar_mapping); |
154 | if (IS_ERR(ptr: vma)) { |
155 | ret = PTR_ERR(ptr: vma); |
156 | goto out; |
157 | } |
158 | |
159 | /* Map GIC user page. */ |
160 | if (gic_size) { |
161 | gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS; |
162 | gic_pfn = PFN_DOWN(__pa(gic_base)); |
163 | |
164 | ret = io_remap_pfn_range(vma, addr: base, pfn: gic_pfn, size: gic_size, |
165 | pgprot_noncached(vma->vm_page_prot)); |
166 | if (ret) |
167 | goto out; |
168 | } |
169 | |
170 | /* Map data page. */ |
171 | ret = remap_pfn_range(vma, addr: data_addr, |
172 | virt_to_phys(address: vdso_data) >> PAGE_SHIFT, |
173 | PAGE_SIZE, vma->vm_page_prot); |
174 | if (ret) |
175 | goto out; |
176 | |
177 | /* Map VDSO image. */ |
178 | vma = _install_special_mapping(mm, addr: vdso_addr, len: image->size, |
179 | VM_READ | VM_EXEC | |
180 | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, |
181 | spec: &image->mapping); |
182 | if (IS_ERR(ptr: vma)) { |
183 | ret = PTR_ERR(ptr: vma); |
184 | goto out; |
185 | } |
186 | |
187 | mm->context.vdso = (void *)vdso_addr; |
188 | ret = 0; |
189 | |
190 | out: |
191 | mmap_write_unlock(mm); |
192 | return ret; |
193 | } |
194 | |