1 // SPDX-License-Identifier: GPL-2.0-only
3 * Adapted from arm64 version.
5 * Copyright (C) 2012 ARM Limited
6 * Copyright (C) 2015 Mentor Graphics Corporation.
9 #include <linux/cache.h>
10 #include <linux/elf.h>
11 #include <linux/err.h>
12 #include <linux/kernel.h>
15 #include <linux/printk.h>
16 #include <linux/slab.h>
17 #include <linux/timekeeper_internal.h>
18 #include <linux/vmalloc.h>
19 #include <asm/arch_timer.h>
20 #include <asm/barrier.h>
21 #include <asm/cacheflush.h>
24 #include <asm/vdso_datapage.h>
25 #include <clocksource/arm_arch_timer.h>
26 #include <vdso/helpers.h>
27 #include <vdso/vsyscall.h>
29 #define MAX_SYMNAME 64
31 static struct page **vdso_text_pagelist;
33 extern char vdso_start[], vdso_end[];
35 /* Total number of pages needed for the data and text portions of the VDSO. */
36 unsigned int vdso_total_pages __ro_after_init;
41 static union vdso_data_store vdso_data_store __page_aligned_data;
42 struct vdso_data *vdso_data = vdso_data_store.data;
44 static struct page *vdso_data_page __ro_after_init;
45 static const struct vm_special_mapping vdso_data_mapping = {
47 .pages = &vdso_data_page,
50 static int vdso_mremap(const struct vm_special_mapping *sm,
51 struct vm_area_struct *new_vma)
53 current->mm->context.vdso = new_vma->vm_start;
58 static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
60 .mremap = vdso_mremap,
64 Elf32_Ehdr *hdr; /* ptr to ELF */
65 Elf32_Sym *dynsym; /* ptr to .dynsym section */
66 unsigned long dynsymsize; /* size of .dynsym section */
67 char *dynstr; /* ptr to .dynstr section */
70 /* Cached result of boot-time check for whether the arch timer exists,
71 * and if so, whether the virtual counter is useable.
73 bool cntvct_ok __ro_after_init;
75 static bool __init cntvct_functional(void)
77 struct device_node *np;
80 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
83 /* The arm_arch_timer core should export
84 * arch_timer_use_virtual or similar so we don't have to do
87 np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
89 np = of_find_compatible_node(NULL, NULL, "arm,armv8-timer");
93 if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
104 static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
111 /* Grab section headers and strings so we can tell who is who */
112 sechdrs = (void *)ehdr + ehdr->e_shoff;
113 secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
115 /* Find the section they want */
116 for (i = 1; i < ehdr->e_shnum; i++) {
117 if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
119 *size = sechdrs[i].sh_size;
120 return (void *)ehdr + sechdrs[i].sh_offset;
129 static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
133 for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
134 char name[MAX_SYMNAME], *c;
136 if (lib->dynsym[i].st_name == 0)
138 strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
140 c = strchr(name, '@');
143 if (strcmp(symname, name) == 0)
144 return &lib->dynsym[i];
149 static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
153 sym = find_symbol(lib, symname);
160 static void __init patch_vdso(void *ehdr)
162 struct elfinfo einfo;
164 einfo = (struct elfinfo) {
168 einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
169 einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
171 /* If the virtual counter is absent or non-functional we don't
172 * want programs to incur the slight additional overhead of
173 * dispatching through the VDSO only to fall back to syscalls.
176 vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
177 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
178 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
182 static int __init vdso_init(void)
184 unsigned int text_pages;
187 if (memcmp(vdso_start, "\177ELF", 4)) {
188 pr_err("VDSO is not a valid ELF object!\n");
192 text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
194 /* Allocate the VDSO text pagelist */
195 vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
197 if (vdso_text_pagelist == NULL)
200 /* Grab the VDSO data page. */
201 vdso_data_page = virt_to_page(vdso_data);
203 /* Grab the VDSO text pages. */
204 for (i = 0; i < text_pages; i++) {
207 page = virt_to_page(vdso_start + i * PAGE_SIZE);
208 vdso_text_pagelist[i] = page;
211 vdso_text_mapping.pages = vdso_text_pagelist;
213 vdso_total_pages = 1; /* for the data/vvar page */
214 vdso_total_pages += text_pages;
216 cntvct_ok = cntvct_functional();
218 patch_vdso(vdso_start);
222 arch_initcall(vdso_init);
224 static int install_vvar(struct mm_struct *mm, unsigned long addr)
226 struct vm_area_struct *vma;
228 vma = _install_special_mapping(mm, addr, PAGE_SIZE,
229 VM_READ | VM_MAYREAD,
232 return PTR_ERR_OR_ZERO(vma);
235 /* assumes mmap_lock is write-locked */
236 void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
238 struct vm_area_struct *vma;
241 mm->context.vdso = 0;
243 if (vdso_text_pagelist == NULL)
246 if (install_vvar(mm, addr))
249 /* Account for vvar page. */
251 len = (vdso_total_pages - 1) << PAGE_SHIFT;
253 vma = _install_special_mapping(mm, addr, len,
254 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
258 mm->context.vdso = addr;