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 unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
54 unsigned long vdso_size;
56 /* without VVAR page */
57 vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;
59 if (vdso_size != new_size)
62 current->mm->context.vdso = new_vma->vm_start;
67 static struct vm_special_mapping vdso_text_mapping __ro_after_init = {
69 .mremap = vdso_mremap,
73 Elf32_Ehdr *hdr; /* ptr to ELF */
74 Elf32_Sym *dynsym; /* ptr to .dynsym section */
75 unsigned long dynsymsize; /* size of .dynsym section */
76 char *dynstr; /* ptr to .dynstr section */
79 /* Cached result of boot-time check for whether the arch timer exists,
80 * and if so, whether the virtual counter is useable.
82 bool cntvct_ok __ro_after_init;
84 static bool __init cntvct_functional(void)
86 struct device_node *np;
89 if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
92 /* The arm_arch_timer core should export
93 * arch_timer_use_virtual or similar so we don't have to do
96 np = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
98 np = of_find_compatible_node(NULL, NULL, "arm,armv8-timer");
102 if (of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
113 static void * __init find_section(Elf32_Ehdr *ehdr, const char *name,
120 /* Grab section headers and strings so we can tell who is who */
121 sechdrs = (void *)ehdr + ehdr->e_shoff;
122 secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset;
124 /* Find the section they want */
125 for (i = 1; i < ehdr->e_shnum; i++) {
126 if (strcmp(secnames + sechdrs[i].sh_name, name) == 0) {
128 *size = sechdrs[i].sh_size;
129 return (void *)ehdr + sechdrs[i].sh_offset;
138 static Elf32_Sym * __init find_symbol(struct elfinfo *lib, const char *symname)
142 for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) {
143 char name[MAX_SYMNAME], *c;
145 if (lib->dynsym[i].st_name == 0)
147 strlcpy(name, lib->dynstr + lib->dynsym[i].st_name,
149 c = strchr(name, '@');
152 if (strcmp(symname, name) == 0)
153 return &lib->dynsym[i];
158 static void __init vdso_nullpatch_one(struct elfinfo *lib, const char *symname)
162 sym = find_symbol(lib, symname);
169 static void __init patch_vdso(void *ehdr)
171 struct elfinfo einfo;
173 einfo = (struct elfinfo) {
177 einfo.dynsym = find_section(einfo.hdr, ".dynsym", &einfo.dynsymsize);
178 einfo.dynstr = find_section(einfo.hdr, ".dynstr", NULL);
180 /* If the virtual counter is absent or non-functional we don't
181 * want programs to incur the slight additional overhead of
182 * dispatching through the VDSO only to fall back to syscalls.
185 vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
186 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
187 vdso_nullpatch_one(&einfo, "__vdso_clock_gettime64");
191 static int __init vdso_init(void)
193 unsigned int text_pages;
196 if (memcmp(vdso_start, "\177ELF", 4)) {
197 pr_err("VDSO is not a valid ELF object!\n");
201 text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
203 /* Allocate the VDSO text pagelist */
204 vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
206 if (vdso_text_pagelist == NULL)
209 /* Grab the VDSO data page. */
210 vdso_data_page = virt_to_page(vdso_data);
212 /* Grab the VDSO text pages. */
213 for (i = 0; i < text_pages; i++) {
216 page = virt_to_page(vdso_start + i * PAGE_SIZE);
217 vdso_text_pagelist[i] = page;
220 vdso_text_mapping.pages = vdso_text_pagelist;
222 vdso_total_pages = 1; /* for the data/vvar page */
223 vdso_total_pages += text_pages;
225 cntvct_ok = cntvct_functional();
227 patch_vdso(vdso_start);
231 arch_initcall(vdso_init);
233 static int install_vvar(struct mm_struct *mm, unsigned long addr)
235 struct vm_area_struct *vma;
237 vma = _install_special_mapping(mm, addr, PAGE_SIZE,
238 VM_READ | VM_MAYREAD,
241 return PTR_ERR_OR_ZERO(vma);
244 /* assumes mmap_lock is write-locked */
245 void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
247 struct vm_area_struct *vma;
250 mm->context.vdso = 0;
252 if (vdso_text_pagelist == NULL)
255 if (install_vvar(mm, addr))
258 /* Account for vvar page. */
260 len = (vdso_total_pages - 1) << PAGE_SHIFT;
262 vma = _install_special_mapping(mm, addr, len,
263 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
267 mm->context.vdso = addr;