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 <generated/vdso-offsets.h>
25
26 extern char vdso_start[], vdso_end[];
27
28 /* Kernel-provided data used by the VDSO. */
29 static union {
30 u8 page[PAGE_SIZE];
31 struct vdso_data data[CS_BASES];
32 } generic_vdso_data __page_aligned_data;
33
34 static union {
35 u8 page[LOONGARCH_VDSO_DATA_SIZE];
36 struct loongarch_vdso_data vdata;
37 } loongarch_vdso_data __page_aligned_data;
38
39 static struct page *vdso_pages[] = { NULL };
40 struct vdso_data *vdso_data = generic_vdso_data.data;
41 struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata;
42
vdso_mremap(const struct vm_special_mapping * sm,struct vm_area_struct * new_vma)43 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
44 {
45 current->mm->context.vdso = (void *)(new_vma->vm_start);
46
47 return 0;
48 }
49
vvar_fault(const struct vm_special_mapping * sm,struct vm_area_struct * vma,struct vm_fault * vmf)50 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
51 struct vm_area_struct *vma, struct vm_fault *vmf)
52 {
53 unsigned long pfn;
54 struct page *timens_page = find_timens_vvar_page(vma);
55
56 switch (vmf->pgoff) {
57 case VVAR_GENERIC_PAGE_OFFSET:
58 if (!timens_page)
59 pfn = sym_to_pfn(vdso_data);
60 else
61 pfn = page_to_pfn(timens_page);
62 break;
63 #ifdef CONFIG_TIME_NS
64 case VVAR_TIMENS_PAGE_OFFSET:
65 /*
66 * If a task belongs to a time namespace then a namespace specific
67 * VVAR is mapped with the VVAR_GENERIC_PAGE_OFFSET and the real
68 * VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET offset.
69 * See also the comment near timens_setup_vdso_data().
70 */
71 if (!timens_page)
72 return VM_FAULT_SIGBUS;
73 else
74 pfn = sym_to_pfn(vdso_data);
75 break;
76 #endif /* CONFIG_TIME_NS */
77 case VVAR_LOONGARCH_PAGES_START ... VVAR_LOONGARCH_PAGES_END:
78 pfn = sym_to_pfn(&loongarch_vdso_data) + vmf->pgoff - VVAR_LOONGARCH_PAGES_START;
79 break;
80 default:
81 return VM_FAULT_SIGBUS;
82 }
83
84 return vmf_insert_pfn(vma, vmf->address, pfn);
85 }
86
87 struct loongarch_vdso_info vdso_info = {
88 .vdso = vdso_start,
89 .size = PAGE_SIZE,
90 .code_mapping = {
91 .name = "[vdso]",
92 .pages = vdso_pages,
93 .mremap = vdso_mremap,
94 },
95 .data_mapping = {
96 .name = "[vvar]",
97 .fault = vvar_fault,
98 },
99 .offset_sigreturn = vdso_offset_sigreturn,
100 };
101
init_vdso(void)102 static int __init init_vdso(void)
103 {
104 unsigned long i, cpu, pfn;
105
106 BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
107 BUG_ON(!PAGE_ALIGNED(vdso_info.size));
108
109 for_each_possible_cpu(cpu)
110 vdso_pdata[cpu].node = cpu_to_node(cpu);
111
112 pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
113 for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
114 vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
115
116 return 0;
117 }
118 subsys_initcall(init_vdso);
119
120 #ifdef CONFIG_TIME_NS
arch_get_vdso_data(void * vvar_page)121 struct vdso_data *arch_get_vdso_data(void *vvar_page)
122 {
123 return (struct vdso_data *)(vvar_page);
124 }
125
126 /*
127 * The vvar mapping contains data for a specific time namespace, so when a
128 * task changes namespace we must unmap its vvar data for the old namespace.
129 * Subsequent faults will map in data for the new namespace.
130 *
131 * For more details see timens_setup_vdso_data().
132 */
vdso_join_timens(struct task_struct * task,struct time_namespace * ns)133 int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
134 {
135 struct mm_struct *mm = task->mm;
136 struct vm_area_struct *vma;
137
138 VMA_ITERATOR(vmi, mm, 0);
139
140 mmap_read_lock(mm);
141 for_each_vma(vmi, vma) {
142 if (vma_is_special_mapping(vma, &vdso_info.data_mapping))
143 zap_vma_pages(vma);
144 }
145 mmap_read_unlock(mm);
146
147 return 0;
148 }
149 #endif
150
vdso_base(void)151 static unsigned long vdso_base(void)
152 {
153 unsigned long base = STACK_TOP;
154
155 if (current->flags & PF_RANDOMIZE) {
156 base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
157 base = PAGE_ALIGN(base);
158 }
159
160 return base;
161 }
162
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)163 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
164 {
165 int ret;
166 unsigned long size, data_addr, vdso_addr;
167 struct mm_struct *mm = current->mm;
168 struct vm_area_struct *vma;
169 struct loongarch_vdso_info *info = current->thread.vdso;
170
171 if (mmap_write_lock_killable(mm))
172 return -EINTR;
173
174 /*
175 * Determine total area size. This includes the VDSO data itself
176 * and the data pages.
177 */
178 size = VVAR_SIZE + info->size;
179
180 data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
181 if (IS_ERR_VALUE(data_addr)) {
182 ret = data_addr;
183 goto out;
184 }
185
186 vma = _install_special_mapping(mm, data_addr, VVAR_SIZE,
187 VM_READ | VM_MAYREAD | VM_PFNMAP,
188 &info->data_mapping);
189 if (IS_ERR(vma)) {
190 ret = PTR_ERR(vma);
191 goto out;
192 }
193
194 vdso_addr = data_addr + VVAR_SIZE;
195 vma = _install_special_mapping(mm, vdso_addr, info->size,
196 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
197 &info->code_mapping);
198 if (IS_ERR(vma)) {
199 ret = PTR_ERR(vma);
200 goto out;
201 }
202
203 mm->context.vdso = (void *)vdso_addr;
204 ret = 0;
205
206 out:
207 mmap_write_unlock(mm);
208 return ret;
209 }
210