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795c230604
The VDSO is part of the kernel image and therefore the struct pages are marked as reserved during boot. As we install a special mapping, the actual struct pages will never be exposed to MM via the page tables. We can therefore leave the pages marked as reserved. Link: http://lkml.kernel.org/r/20190114125903.24845-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Palmer Dabbelt <palmer@sifive.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Tobias Klauser <tklauser@distanz.ch> Cc: Michal Hocko <mhocko@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
125 lines
3.0 KiB
C
125 lines
3.0 KiB
C
/*
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* Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
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* <benh@kernel.crashing.org>
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* Copyright (C) 2012 ARM Limited
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* Copyright (C) 2015 Regents of the University of California
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/binfmts.h>
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#include <linux/err.h>
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#include <asm/vdso.h>
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extern char vdso_start[], vdso_end[];
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static unsigned int vdso_pages;
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static struct page **vdso_pagelist;
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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;
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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 __init vdso_init(void)
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{
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unsigned int i;
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vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
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vdso_pagelist =
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kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
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if (unlikely(vdso_pagelist == NULL)) {
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pr_err("vdso: pagelist allocation failed\n");
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return -ENOMEM;
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}
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for (i = 0; i < vdso_pages; i++) {
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struct page *pg;
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pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
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vdso_pagelist[i] = pg;
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}
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vdso_pagelist[i] = virt_to_page(vdso_data);
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return 0;
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}
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arch_initcall(vdso_init);
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int arch_setup_additional_pages(struct linux_binprm *bprm,
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int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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unsigned long vdso_base, vdso_len;
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int ret;
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vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
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down_write(&mm->mmap_sem);
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vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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ret = vdso_base;
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goto end;
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}
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/*
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* Put vDSO base into mm struct. We need to do this before calling
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* install_special_mapping or the perf counter mmap tracking code
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* will fail to recognise it as a vDSO (since arch_vma_name fails).
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*/
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mm->context.vdso = (void *)vdso_base;
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ret = install_special_mapping(mm, vdso_base, vdso_len,
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(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
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vdso_pagelist);
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if (unlikely(ret))
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mm->context.vdso = NULL;
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end:
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up_write(&mm->mmap_sem);
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return ret;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
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return "[vdso]";
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return NULL;
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}
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/*
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* Function stubs to prevent linker errors when AT_SYSINFO_EHDR is defined
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*/
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int in_gate_area_no_mm(unsigned long addr)
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{
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return 0;
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}
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int in_gate_area(struct mm_struct *mm, unsigned long addr)
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{
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return 0;
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}
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struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
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{
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return NULL;
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}
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