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/timekeeper_internal.h>
18 
19 #include <asm/page.h>
20 #include <asm/vdso.h>
21 #include <vdso/helpers.h>
22 #include <vdso/vsyscall.h>
23 #include <generated/vdso-offsets.h>
24 
25 extern char vdso_start[], vdso_end[];
26 
27 /* Kernel-provided data used by the VDSO. */
28 static union {
29 	u8 page[VDSO_DATA_SIZE];
30 	struct loongarch_vdso_data vdata;
31 } loongarch_vdso_data __page_aligned_data;
32 
33 static struct page *vdso_pages[] = { NULL };
34 struct vdso_data *vdso_data = loongarch_vdso_data.vdata.data;
35 struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata;
36 
vdso_mremap(const struct vm_special_mapping * sm,struct vm_area_struct * new_vma)37 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
38 {
39 	current->mm->context.vdso = (void *)(new_vma->vm_start);
40 
41 	return 0;
42 }
43 
44 struct loongarch_vdso_info vdso_info = {
45 	.vdso = vdso_start,
46 	.size = PAGE_SIZE,
47 	.code_mapping = {
48 		.name = "[vdso]",
49 		.pages = vdso_pages,
50 		.mremap = vdso_mremap,
51 	},
52 	.data_mapping = {
53 		.name = "[vvar]",
54 	},
55 	.offset_sigreturn = vdso_offset_sigreturn,
56 };
57 
init_vdso(void)58 static int __init init_vdso(void)
59 {
60 	unsigned long i, cpu, pfn;
61 
62 	BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
63 	BUG_ON(!PAGE_ALIGNED(vdso_info.size));
64 
65 	for_each_possible_cpu(cpu)
66 		vdso_pdata[cpu].node = cpu_to_node(cpu);
67 
68 	pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
69 	for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
70 		vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
71 
72 	return 0;
73 }
74 subsys_initcall(init_vdso);
75 
vdso_base(void)76 static unsigned long vdso_base(void)
77 {
78 	unsigned long base = STACK_TOP;
79 
80 	if (current->flags & PF_RANDOMIZE) {
81 		base += get_random_u32_below(VDSO_RANDOMIZE_SIZE);
82 		base = PAGE_ALIGN(base);
83 	}
84 
85 	return base;
86 }
87 
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)88 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
89 {
90 	int ret;
91 	unsigned long vvar_size, size, data_addr, vdso_addr;
92 	struct mm_struct *mm = current->mm;
93 	struct vm_area_struct *vma;
94 	struct loongarch_vdso_info *info = current->thread.vdso;
95 
96 	if (mmap_write_lock_killable(mm))
97 		return -EINTR;
98 
99 	/*
100 	 * Determine total area size. This includes the VDSO data itself
101 	 * and the data pages.
102 	 */
103 	vvar_size = VDSO_DATA_SIZE;
104 	size = vvar_size + info->size;
105 
106 	data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
107 	if (IS_ERR_VALUE(data_addr)) {
108 		ret = data_addr;
109 		goto out;
110 	}
111 	vdso_addr = data_addr + VDSO_DATA_SIZE;
112 
113 	vma = _install_special_mapping(mm, data_addr, vvar_size,
114 				       VM_READ | VM_MAYREAD,
115 				       &info->data_mapping);
116 	if (IS_ERR(vma)) {
117 		ret = PTR_ERR(vma);
118 		goto out;
119 	}
120 
121 	/* Map VDSO data page. */
122 	ret = remap_pfn_range(vma, data_addr,
123 			      virt_to_phys(&loongarch_vdso_data) >> PAGE_SHIFT,
124 			      vvar_size, PAGE_READONLY);
125 	if (ret)
126 		goto out;
127 
128 	/* Map VDSO code page. */
129 	vma = _install_special_mapping(mm, vdso_addr, info->size,
130 				       VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
131 				       &info->code_mapping);
132 	if (IS_ERR(vma)) {
133 		ret = PTR_ERR(vma);
134 		goto out;
135 	}
136 
137 	mm->context.vdso = (void *)vdso_addr;
138 	ret = 0;
139 
140 out:
141 	mmap_write_unlock(mm);
142 	return ret;
143 }
144