1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Author: Huacai Chen <chenhuacai@loongson.cn>
4 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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/time_namespace.h>
18 #include <linux/timekeeper_internal.h>
19
20 #include <asm/page.h>
21 #include <asm/vdso.h>
22 #include <vdso/helpers.h>
23 #include <vdso/vsyscall.h>
24 #include <vdso/datapage.h>
25 #include <generated/vdso-offsets.h>
26
27 extern char vdso_start[], vdso_end[];
28
29 /* Kernel-provided data used by the VDSO. */
30 static union vdso_data_store generic_vdso_data __page_aligned_data;
31
32 static union {
33 u8 page[LOONGARCH_VDSO_DATA_SIZE];
34 struct loongarch_vdso_data vdata;
35 } loongarch_vdso_data __page_aligned_data;
36
37 static struct page *vdso_pages[] = { NULL };
38 struct vdso_data *vdso_data = generic_vdso_data.data;
39 struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata;
40
41 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
42 {
43 current->mm->context.vdso = (void *)(new_vma->vm_start);
44
45 return 0;
46 }
47
48 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
49 struct vm_area_struct *vma, struct vm_fault *vmf)
50 {
51 unsigned long pfn;
52 struct page *timens_page = find_timens_vvar_page(vma);
53
54 switch (vmf->pgoff) {
55 case VVAR_GENERIC_PAGE_OFFSET:
56 if (!timens_page)
57 pfn = sym_to_pfn(vdso_data);
58 else
59 pfn = page_to_pfn(timens_page);
60 break;
61 #ifdef CONFIG_TIME_NS
62 case VVAR_TIMENS_PAGE_OFFSET:
63 /*
64 * If a task belongs to a time namespace then a namespace specific
65 * VVAR is mapped with the VVAR_GENERIC_PAGE_OFFSET and the real
66 * VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET offset.
67 * See also the comment near timens_setup_vdso_data().
68 */
69 if (!timens_page)
70 return VM_FAULT_SIGBUS;
71 else
72 pfn = sym_to_pfn(vdso_data);
73 break;
74 #endif /* CONFIG_TIME_NS */
75 case VVAR_LOONGARCH_PAGES_START ... VVAR_LOONGARCH_PAGES_END:
76 pfn = sym_to_pfn(&loongarch_vdso_data) + vmf->pgoff - VVAR_LOONGARCH_PAGES_START;
77 break;
78 default:
79 return VM_FAULT_SIGBUS;
80 }
81
82 return vmf_insert_pfn(vma, vmf->address, pfn);
83 }
84
85 struct loongarch_vdso_info vdso_info = {
86 .vdso = vdso_start,
87 .size = PAGE_SIZE,
88 .code_mapping = {
89 .name = "[vdso]",
90 .pages = vdso_pages,
91 .mremap = vdso_mremap,
92 },
93 .data_mapping = {
94 .name = "[vvar]",
95 .fault = vvar_fault,
96 },
97 .offset_sigreturn = vdso_offset_sigreturn,
98 };
99
100 static int __init init_vdso(void)
101 {
102 unsigned long i, cpu, pfn;
103
104 BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
105 BUG_ON(!PAGE_ALIGNED(vdso_info.size));
106
107 for_each_possible_cpu(cpu)
108 vdso_pdata[cpu].node = cpu_to_node(cpu);
109
110 pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
111 for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
112 vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
113
114 return 0;
115 }
116 subsys_initcall(init_vdso);
117
118 #ifdef CONFIG_TIME_NS
119 struct vdso_data *arch_get_vdso_data(void *vvar_page)
120 {
121 return (struct vdso_data *)(vvar_page);
122 }
123
124 /*
125 * The vvar mapping contains data for a specific time namespace, so when a
126 * task changes namespace we must unmap its vvar data for the old namespace.
127 * Subsequent faults will map in data for the new namespace.
128 *
129 * For more details see timens_setup_vdso_data().
130 */
131 int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
132 {
133 struct mm_struct *mm = task->mm;
134 struct vm_area_struct *vma;
135
136 VMA_ITERATOR(vmi, mm, 0);
137
138 mmap_read_lock(mm);
139 for_each_vma(vmi, vma) {
140 if (vma_is_special_mapping(vma, &vdso_info.data_mapping))
141 zap_vma_pages(vma);
142 }
143 mmap_read_unlock(mm);
144
145 return 0;
146 }
147 #endif
148
149 static unsigned long vdso_base(void)
150 {
151 unsigned long base = STACK_TOP;
152
153 if (current->flags & PF_RANDOMIZE) {
154 base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
155 base = PAGE_ALIGN(base);
156 }
157
158 return base;
159 }
160
161 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
162 {
163 int ret;
164 unsigned long size, data_addr, vdso_addr;
165 struct mm_struct *mm = current->mm;
166 struct vm_area_struct *vma;
167 struct loongarch_vdso_info *info = current->thread.vdso;
168
169 if (mmap_write_lock_killable(mm))
170 return -EINTR;
171
172 /*
173 * Determine total area size. This includes the VDSO data itself
174 * and the data pages.
175 */
176 size = VVAR_SIZE + info->size;
177
178 data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
179 if (IS_ERR_VALUE(data_addr)) {
180 ret = data_addr;
181 goto out;
182 }
183
184 vma = _install_special_mapping(mm, data_addr, VVAR_SIZE,
185 VM_READ | VM_MAYREAD | VM_PFNMAP,
186 &info->data_mapping);
187 if (IS_ERR(vma)) {
188 ret = PTR_ERR(vma);
189 goto out;
190 }
191
192 vdso_addr = data_addr + VVAR_SIZE;
193 vma = _install_special_mapping(mm, vdso_addr, info->size,
194 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
195 &info->code_mapping);
196 if (IS_ERR(vma)) {
197 ret = PTR_ERR(vma);
198 goto out;
199 }
200
201 mm->context.vdso = (void *)vdso_addr;
202 ret = 0;
203
204 out:
205 mmap_write_unlock(mm);
206 return ret;
207 }
208
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