123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2022 Helge Deller <deller@gmx.de>
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*
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* based on arch/s390/kernel/vdso.c which is
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/elf.h>
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#include <linux/timekeeper_internal.h>
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#include <linux/compat.h>
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#include <linux/nsproxy.h>
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#include <linux/time_namespace.h>
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#include <linux/random.h>
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#include <asm/pgtable.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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#include <asm/vdso.h>
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#include <asm/cacheflush.h>
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extern char vdso32_start, vdso32_end;
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extern char vdso64_start, vdso64_end;
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static int vdso_mremap(const struct vm_special_mapping *sm,
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struct vm_area_struct *vma)
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{
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current->mm->context.vdso_base = vma->vm_start;
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return 0;
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}
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#ifdef CONFIG_64BIT
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static struct vm_special_mapping vdso64_mapping = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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};
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#endif
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static struct vm_special_mapping vdso32_mapping = {
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.name = "[vdso]",
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.mremap = vdso_mremap,
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};
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/*
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* This is called from binfmt_elf, we create the special vma for the
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* vDSO and insert it into the mm struct tree
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*/
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int arch_setup_additional_pages(struct linux_binprm *bprm,
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int executable_stack)
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{
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unsigned long vdso_text_start, vdso_text_len, map_base;
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struct vm_special_mapping *vdso_mapping;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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int rc;
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if (mmap_write_lock_killable(mm))
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return -EINTR;
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#ifdef CONFIG_64BIT
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if (!is_compat_task()) {
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vdso_text_len = &vdso64_end - &vdso64_start;
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vdso_mapping = &vdso64_mapping;
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} else
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#endif
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{
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vdso_text_len = &vdso32_end - &vdso32_start;
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vdso_mapping = &vdso32_mapping;
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}
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map_base = mm->mmap_base;
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if (current->flags & PF_RANDOMIZE)
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map_base -= get_random_u32_below(0x20) * PAGE_SIZE;
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vdso_text_start = get_unmapped_area(NULL, map_base, vdso_text_len, 0, 0);
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/* VM_MAYWRITE for COW so gdb can set breakpoints */
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vma = _install_special_mapping(mm, vdso_text_start, 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_mapping);
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if (IS_ERR(vma)) {
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do_munmap(mm, vdso_text_start, PAGE_SIZE, NULL);
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rc = PTR_ERR(vma);
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} else {
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current->mm->context.vdso_base = vdso_text_start;
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rc = 0;
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}
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mmap_write_unlock(mm);
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return rc;
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}
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static struct page ** __init vdso_setup_pages(void *start, void *end)
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{
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int pages = (end - start) >> PAGE_SHIFT;
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struct page **pagelist;
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int i;
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pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL);
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if (!pagelist)
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panic("%s: Cannot allocate page list for VDSO", __func__);
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for (i = 0; i < pages; i++)
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pagelist[i] = virt_to_page(start + i * PAGE_SIZE);
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return pagelist;
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}
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static int __init vdso_init(void)
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{
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#ifdef CONFIG_64BIT
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vdso64_mapping.pages = vdso_setup_pages(&vdso64_start, &vdso64_end);
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#endif
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if (IS_ENABLED(CONFIG_COMPAT) || !IS_ENABLED(CONFIG_64BIT))
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vdso32_mapping.pages = vdso_setup_pages(&vdso32_start, &vdso32_end);
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return 0;
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}
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arch_initcall(vdso_init);
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