433 lines
9.6 KiB
C
433 lines
9.6 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* VDSO implementations.
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*
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* Copyright (C) 2012 ARM Limited
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*
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* Author: Will Deacon <will.deacon@arm.com>
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*/
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#include <linux/cache.h>
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#include <linux/clocksource.h>
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#include <linux/elf.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/signal.h>
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#include <linux/slab.h>
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#include <linux/timekeeper_internal.h>
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#include <linux/vmalloc.h>
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#include <vdso/datapage.h>
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#include <vdso/helpers.h>
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#include <vdso/vsyscall.h>
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#include <asm/cacheflush.h>
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#include <asm/signal32.h>
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#include <asm/vdso.h>
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extern char vdso_start[], vdso_end[];
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#ifdef CONFIG_COMPAT_VDSO
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extern char vdso32_start[], vdso32_end[];
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#endif /* CONFIG_COMPAT_VDSO */
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/* vdso_lookup arch_index */
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enum arch_vdso_type {
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ARM64_VDSO = 0,
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#ifdef CONFIG_COMPAT_VDSO
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ARM64_VDSO32 = 1,
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#endif /* CONFIG_COMPAT_VDSO */
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};
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#ifdef CONFIG_COMPAT_VDSO
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#define VDSO_TYPES (ARM64_VDSO32 + 1)
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#else
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#define VDSO_TYPES (ARM64_VDSO + 1)
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#endif /* CONFIG_COMPAT_VDSO */
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struct __vdso_abi {
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const char *name;
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const char *vdso_code_start;
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const char *vdso_code_end;
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unsigned long vdso_pages;
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/* Data Mapping */
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struct vm_special_mapping *dm;
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/* Code Mapping */
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struct vm_special_mapping *cm;
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};
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static struct __vdso_abi vdso_lookup[VDSO_TYPES] __ro_after_init = {
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{
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.name = "vdso",
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.vdso_code_start = vdso_start,
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.vdso_code_end = vdso_end,
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},
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#ifdef CONFIG_COMPAT_VDSO
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{
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.name = "vdso32",
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.vdso_code_start = vdso32_start,
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.vdso_code_end = vdso32_end,
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},
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#endif /* CONFIG_COMPAT_VDSO */
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};
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/*
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* The vDSO data page.
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*/
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static union {
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struct vdso_data data[CS_BASES];
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u8 page[PAGE_SIZE];
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} vdso_data_store __page_aligned_data;
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struct vdso_data *vdso_data = vdso_data_store.data;
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static int __vdso_remap(enum arch_vdso_type arch_index,
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const struct vm_special_mapping *sm,
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struct vm_area_struct *new_vma)
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{
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unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
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unsigned long vdso_size = vdso_lookup[arch_index].vdso_code_end -
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vdso_lookup[arch_index].vdso_code_start;
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if (vdso_size != new_size)
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return -EINVAL;
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current->mm->context.vdso = (void *)new_vma->vm_start;
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return 0;
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}
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static int __vdso_init(enum arch_vdso_type arch_index)
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{
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int i;
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struct page **vdso_pagelist;
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unsigned long pfn;
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if (memcmp(vdso_lookup[arch_index].vdso_code_start, "\177ELF", 4)) {
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pr_err("vDSO is not a valid ELF object!\n");
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return -EINVAL;
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}
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vdso_lookup[arch_index].vdso_pages = (
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vdso_lookup[arch_index].vdso_code_end -
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vdso_lookup[arch_index].vdso_code_start) >>
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PAGE_SHIFT;
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/* Allocate the vDSO pagelist, plus a page for the data. */
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vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1,
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sizeof(struct page *),
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GFP_KERNEL);
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if (vdso_pagelist == NULL)
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return -ENOMEM;
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/* Grab the vDSO data page. */
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vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
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/* Grab the vDSO code pages. */
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pfn = sym_to_pfn(vdso_lookup[arch_index].vdso_code_start);
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for (i = 0; i < vdso_lookup[arch_index].vdso_pages; i++)
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vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
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vdso_lookup[arch_index].dm->pages = &vdso_pagelist[0];
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vdso_lookup[arch_index].cm->pages = &vdso_pagelist[1];
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return 0;
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}
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static int __setup_additional_pages(enum arch_vdso_type arch_index,
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struct mm_struct *mm,
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struct linux_binprm *bprm,
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int uses_interp)
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{
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unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
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void *ret;
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vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;
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/* Be sure to map the data page */
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vdso_mapping_len = vdso_text_len + PAGE_SIZE;
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vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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ret = ERR_PTR(vdso_base);
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goto up_fail;
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}
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ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
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VM_READ|VM_MAYREAD,
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vdso_lookup[arch_index].dm);
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if (IS_ERR(ret))
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goto up_fail;
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vdso_base += PAGE_SIZE;
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mm->context.vdso = (void *)vdso_base;
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ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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vdso_lookup[arch_index].cm);
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if (IS_ERR(ret))
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goto up_fail;
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return 0;
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up_fail:
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mm->context.vdso = NULL;
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return PTR_ERR(ret);
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}
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#ifdef CONFIG_COMPAT
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/*
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* Create and map the vectors page for AArch32 tasks.
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*/
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#ifdef CONFIG_COMPAT_VDSO
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static int aarch32_vdso_mremap(const struct vm_special_mapping *sm,
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struct vm_area_struct *new_vma)
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{
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return __vdso_remap(ARM64_VDSO32, sm, new_vma);
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}
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#endif /* CONFIG_COMPAT_VDSO */
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/*
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* aarch32_vdso_pages:
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* 0 - kuser helpers
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* 1 - sigreturn code
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* or (CONFIG_COMPAT_VDSO):
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* 0 - kuser helpers
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* 1 - vdso data
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* 2 - vdso code
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*/
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#define C_VECTORS 0
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#ifdef CONFIG_COMPAT_VDSO
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#define C_VVAR 1
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#define C_VDSO 2
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#define C_PAGES (C_VDSO + 1)
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#else
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#define C_SIGPAGE 1
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#define C_PAGES (C_SIGPAGE + 1)
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#endif /* CONFIG_COMPAT_VDSO */
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static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init;
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static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
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{
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.name = "[vectors]", /* ABI */
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.pages = &aarch32_vdso_pages[C_VECTORS],
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},
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#ifdef CONFIG_COMPAT_VDSO
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{
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.name = "[vvar]",
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},
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{
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.name = "[vdso]",
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.mremap = aarch32_vdso_mremap,
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},
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#else
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{
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.name = "[sigpage]", /* ABI */
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.pages = &aarch32_vdso_pages[C_SIGPAGE],
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},
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#endif /* CONFIG_COMPAT_VDSO */
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};
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static int aarch32_alloc_kuser_vdso_page(void)
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{
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extern char __kuser_helper_start[], __kuser_helper_end[];
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int kuser_sz = __kuser_helper_end - __kuser_helper_start;
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unsigned long vdso_page;
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
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return 0;
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vdso_page = get_zeroed_page(GFP_ATOMIC);
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if (!vdso_page)
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return -ENOMEM;
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memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start,
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kuser_sz);
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aarch32_vdso_pages[C_VECTORS] = virt_to_page(vdso_page);
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flush_dcache_page(aarch32_vdso_pages[C_VECTORS]);
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return 0;
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}
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#ifdef CONFIG_COMPAT_VDSO
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static int __aarch32_alloc_vdso_pages(void)
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{
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int ret;
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vdso_lookup[ARM64_VDSO32].dm = &aarch32_vdso_spec[C_VVAR];
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vdso_lookup[ARM64_VDSO32].cm = &aarch32_vdso_spec[C_VDSO];
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ret = __vdso_init(ARM64_VDSO32);
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if (ret)
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return ret;
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ret = aarch32_alloc_kuser_vdso_page();
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if (ret) {
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unsigned long c_vvar =
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(unsigned long)page_to_virt(aarch32_vdso_pages[C_VVAR]);
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unsigned long c_vdso =
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(unsigned long)page_to_virt(aarch32_vdso_pages[C_VDSO]);
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free_page(c_vvar);
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free_page(c_vdso);
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}
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return ret;
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}
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#else
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static int __aarch32_alloc_vdso_pages(void)
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{
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extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
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int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
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unsigned long sigpage;
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int ret;
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sigpage = get_zeroed_page(GFP_ATOMIC);
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if (!sigpage)
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return -ENOMEM;
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memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz);
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aarch32_vdso_pages[C_SIGPAGE] = virt_to_page(sigpage);
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flush_dcache_page(aarch32_vdso_pages[C_SIGPAGE]);
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ret = aarch32_alloc_kuser_vdso_page();
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if (ret)
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free_page(sigpage);
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return ret;
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}
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#endif /* CONFIG_COMPAT_VDSO */
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static int __init aarch32_alloc_vdso_pages(void)
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{
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return __aarch32_alloc_vdso_pages();
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}
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arch_initcall(aarch32_alloc_vdso_pages);
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static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
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{
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void *ret;
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if (!IS_ENABLED(CONFIG_KUSER_HELPERS))
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return 0;
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/*
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* Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's
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* not safe to CoW the page containing the CPU exception vectors.
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*/
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ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE,
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VM_READ | VM_EXEC |
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VM_MAYREAD | VM_MAYEXEC,
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&aarch32_vdso_spec[C_VECTORS]);
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return PTR_ERR_OR_ZERO(ret);
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}
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#ifndef CONFIG_COMPAT_VDSO
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static int aarch32_sigreturn_setup(struct mm_struct *mm)
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{
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unsigned long addr;
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void *ret;
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(addr)) {
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ret = ERR_PTR(addr);
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goto out;
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}
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/*
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* VM_MAYWRITE is required to allow gdb to Copy-on-Write and
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* set breakpoints.
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*/
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ret = _install_special_mapping(mm, addr, PAGE_SIZE,
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VM_READ | VM_EXEC | VM_MAYREAD |
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VM_MAYWRITE | VM_MAYEXEC,
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&aarch32_vdso_spec[C_SIGPAGE]);
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if (IS_ERR(ret))
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goto out;
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mm->context.vdso = (void *)addr;
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out:
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return PTR_ERR_OR_ZERO(ret);
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}
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#endif /* !CONFIG_COMPAT_VDSO */
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int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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int ret;
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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ret = aarch32_kuser_helpers_setup(mm);
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if (ret)
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goto out;
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#ifdef CONFIG_COMPAT_VDSO
|
||
|
|
ret = __setup_additional_pages(ARM64_VDSO32,
|
||
|
|
mm,
|
||
|
|
bprm,
|
||
|
|
uses_interp);
|
||
|
|
#else
|
||
|
|
ret = aarch32_sigreturn_setup(mm);
|
||
|
|
#endif /* CONFIG_COMPAT_VDSO */
|
||
|
|
|
||
|
|
out:
|
||
|
|
up_write(&mm->mmap_sem);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
#endif /* CONFIG_COMPAT */
|
||
|
|
|
||
|
|
static int vdso_mremap(const struct vm_special_mapping *sm,
|
||
|
|
struct vm_area_struct *new_vma)
|
||
|
|
{
|
||
|
|
return __vdso_remap(ARM64_VDSO, sm, new_vma);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* aarch64_vdso_pages:
|
||
|
|
* 0 - vvar
|
||
|
|
* 1 - vdso
|
||
|
|
*/
|
||
|
|
#define A_VVAR 0
|
||
|
|
#define A_VDSO 1
|
||
|
|
#define A_PAGES (A_VDSO + 1)
|
||
|
|
static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = {
|
||
|
|
{
|
||
|
|
.name = "[vvar]",
|
||
|
|
},
|
||
|
|
{
|
||
|
|
.name = "[vdso]",
|
||
|
|
.mremap = vdso_mremap,
|
||
|
|
},
|
||
|
|
};
|
||
|
|
|
||
|
|
static int __init vdso_init(void)
|
||
|
|
{
|
||
|
|
vdso_lookup[ARM64_VDSO].dm = &vdso_spec[A_VVAR];
|
||
|
|
vdso_lookup[ARM64_VDSO].cm = &vdso_spec[A_VDSO];
|
||
|
|
|
||
|
|
return __vdso_init(ARM64_VDSO);
|
||
|
|
}
|
||
|
|
arch_initcall(vdso_init);
|
||
|
|
|
||
|
|
int arch_setup_additional_pages(struct linux_binprm *bprm,
|
||
|
|
int uses_interp)
|
||
|
|
{
|
||
|
|
struct mm_struct *mm = current->mm;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
if (down_write_killable(&mm->mmap_sem))
|
||
|
|
return -EINTR;
|
||
|
|
|
||
|
|
ret = __setup_additional_pages(ARM64_VDSO,
|
||
|
|
mm,
|
||
|
|
bprm,
|
||
|
|
uses_interp);
|
||
|
|
|
||
|
|
up_write(&mm->mmap_sem);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|