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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * vdso setup for s390
4 *
5 * Copyright IBM Corp. 2008
6 * Author(s): Martin Schwidefsky ([email protected])
7 */
8
9#include <linux/binfmts.h>
10#include <linux/elf.h>
11#include <linux/errno.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/mm.h>
16#include <linux/slab.h>
17#include <linux/smp.h>
18#include <linux/random.h>
19#include <linux/vdso_datastore.h>
20#include <vdso/datapage.h>
21#include <asm/vdso/vsyscall.h>
22#include <asm/alternative.h>
23#include <asm/vdso.h>
24
25extern char vdso_start[], vdso_end[];
26
27static int vdso_mremap(const struct vm_special_mapping *sm,
28 struct vm_area_struct *vma)
29{
30 current->mm->context.vdso_base = vma->vm_start;
31 return 0;
32}
33
34static struct vm_special_mapping vdso_mapping = {
35 .name = "[vdso]",
36 .mremap = vdso_mremap,
37};
38
39int vdso_getcpu_init(void)
40{
41 set_tod_programmable_field(smp_processor_id());
42 return 0;
43}
44early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
45
46static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
47{
48 unsigned long vvar_start, vdso_text_start, vdso_text_len;
49 struct mm_struct *mm = current->mm;
50 struct vm_area_struct *vma;
51 int rc;
52
53 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES);
54 if (mmap_write_lock_killable(mm))
55 return -EINTR;
56
57 vdso_text_len = vdso_end - vdso_start;
58 vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
59 rc = vvar_start;
60 if (IS_ERR_VALUE(vvar_start))
61 goto out;
62 vma = vdso_install_vvar_mapping(mm, vvar_start);
63 rc = PTR_ERR(vma);
64 if (IS_ERR(vma))
65 goto out;
66 vdso_text_start = vvar_start + VDSO_NR_PAGES * PAGE_SIZE;
67 /* VM_MAYWRITE for COW so gdb can set breakpoints */
68 vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
69 VM_READ|VM_EXEC|VM_SEALED_SYSMAP|
70 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
71 &vdso_mapping);
72 if (IS_ERR(vma)) {
73 do_munmap(mm, vvar_start, PAGE_SIZE, NULL);
74 rc = PTR_ERR(vma);
75 } else {
76 current->mm->context.vdso_base = vdso_text_start;
77 rc = 0;
78 }
79out:
80 mmap_write_unlock(mm);
81 return rc;
82}
83
84static unsigned long vdso_addr(unsigned long start, unsigned long len)
85{
86 unsigned long addr, end, offset;
87
88 /*
89 * Round up the start address. It can start out unaligned as a result
90 * of stack start randomization.
91 */
92 start = PAGE_ALIGN(start);
93
94 /* Round the lowest possible end address up to a PMD boundary. */
95 end = (start + len + PMD_SIZE - 1) & PMD_MASK;
96 if (end >= VDSO_BASE)
97 end = VDSO_BASE;
98 end -= len;
99
100 if (end > start) {
101 offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
102 addr = start + (offset << PAGE_SHIFT);
103 } else {
104 addr = start;
105 }
106 return addr;
107}
108
109unsigned long vdso_text_size(void)
110{
111 return PAGE_ALIGN(vdso_end - vdso_start);
112}
113
114unsigned long vdso_size(void)
115{
116 return vdso_text_size() + VDSO_NR_PAGES * PAGE_SIZE;
117}
118
119int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
120{
121 unsigned long addr = VDSO_BASE;
122 unsigned long size = vdso_size();
123
124 if (current->flags & PF_RANDOMIZE)
125 addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size);
126 return map_vdso(addr, size);
127}
128
129static struct page ** __init vdso_setup_pages(void *start, void *end)
130{
131 int pages = (end - start) >> PAGE_SHIFT;
132 struct page **pagelist;
133 int i;
134
135 pagelist = kzalloc_objs(struct page *, pages + 1);
136 if (!pagelist)
137 panic("%s: Cannot allocate page list for VDSO", __func__);
138 for (i = 0; i < pages; i++)
139 pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
140 return pagelist;
141}
142
143static void vdso_apply_alternatives(void)
144{
145 const struct elf64_shdr *alt, *shdr;
146 struct alt_instr *start, *end;
147 const struct elf64_hdr *hdr;
148
149 hdr = (struct elf64_hdr *)vdso_start;
150 shdr = (void *)hdr + hdr->e_shoff;
151 alt = find_section(hdr, shdr, ".altinstructions");
152 if (!alt)
153 return;
154 start = (void *)hdr + alt->sh_offset;
155 end = (void *)hdr + alt->sh_offset + alt->sh_size;
156 apply_alternatives(start, end);
157}
158
159static int __init vdso_init(void)
160{
161 vdso_apply_alternatives();
162 vdso_mapping.pages = vdso_setup_pages(vdso_start, vdso_end);
163 return 0;
164}
165arch_initcall(vdso_init);