188 lines
4.9 KiB
C
188 lines
4.9 KiB
C
/*
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* Copyright (c) 2014, The Linux Foundation. All rights reserved.
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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 and
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* only version 2 as 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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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/vmalloc.h>
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#include <asm/pgtable.h>
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#include <asm/set_memory.h>
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#include <asm/tlbflush.h>
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struct page_change_data {
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pgprot_t set_mask;
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pgprot_t clear_mask;
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};
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static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
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void *data)
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{
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struct page_change_data *cdata = data;
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pte_t pte = READ_ONCE(*ptep);
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pte = clear_pte_bit(pte, cdata->clear_mask);
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pte = set_pte_bit(pte, cdata->set_mask);
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set_pte(ptep, pte);
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return 0;
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}
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/*
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* This function assumes that the range is mapped with PAGE_SIZE pages.
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*/
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static int __change_memory_common(unsigned long start, unsigned long size,
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pgprot_t set_mask, pgprot_t clear_mask)
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{
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struct page_change_data data;
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int ret;
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data.set_mask = set_mask;
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data.clear_mask = clear_mask;
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ret = apply_to_page_range(&init_mm, start, size, change_page_range,
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&data);
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flush_tlb_kernel_range(start, start + size);
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return ret;
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}
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static int change_memory_common(unsigned long addr, int numpages,
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pgprot_t set_mask, pgprot_t clear_mask)
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{
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unsigned long start = addr;
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unsigned long size = PAGE_SIZE*numpages;
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unsigned long end = start + size;
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struct vm_struct *area;
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if (!PAGE_ALIGNED(addr)) {
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start &= PAGE_MASK;
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end = start + size;
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WARN_ON_ONCE(1);
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}
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/*
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* Kernel VA mappings are always live, and splitting live section
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* mappings into page mappings may cause TLB conflicts. This means
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* we have to ensure that changing the permission bits of the range
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* we are operating on does not result in such splitting.
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*
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* Let's restrict ourselves to mappings created by vmalloc (or vmap).
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* Those are guaranteed to consist entirely of page mappings, and
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* splitting is never needed.
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*
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* So check whether the [addr, addr + size) interval is entirely
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* covered by precisely one VM area that has the VM_ALLOC flag set.
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*/
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area = find_vm_area((void *)addr);
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if (!area ||
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end > (unsigned long)area->addr + area->size ||
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!(area->flags & VM_ALLOC))
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return -EINVAL;
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if (!numpages)
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return 0;
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return __change_memory_common(start, size, set_mask, clear_mask);
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}
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int set_memory_ro(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(PTE_RDONLY),
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__pgprot(PTE_WRITE));
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}
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int set_memory_rw(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(PTE_WRITE),
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__pgprot(PTE_RDONLY));
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}
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int set_memory_nx(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(PTE_PXN),
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__pgprot(0));
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}
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EXPORT_SYMBOL_GPL(set_memory_nx);
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int set_memory_x(unsigned long addr, int numpages)
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{
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return change_memory_common(addr, numpages,
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__pgprot(0),
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__pgprot(PTE_PXN));
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}
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EXPORT_SYMBOL_GPL(set_memory_x);
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int set_memory_valid(unsigned long addr, int numpages, int enable)
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{
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if (enable)
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return __change_memory_common(addr, PAGE_SIZE * numpages,
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__pgprot(PTE_VALID),
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__pgprot(0));
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else
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return __change_memory_common(addr, PAGE_SIZE * numpages,
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__pgprot(0),
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__pgprot(PTE_VALID));
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}
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#ifdef CONFIG_DEBUG_PAGEALLOC
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void __kernel_map_pages(struct page *page, int numpages, int enable)
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{
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set_memory_valid((unsigned long)page_address(page), numpages, enable);
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}
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#ifdef CONFIG_HIBERNATION
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/*
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* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
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* is used to determine if a linear map page has been marked as not-valid by
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* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
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* This is based on kern_addr_valid(), which almost does what we need.
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*
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* Because this is only called on the kernel linear map, p?d_sect() implies
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* p?d_present(). When debug_pagealloc is enabled, sections mappings are
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* disabled.
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*/
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bool kernel_page_present(struct page *page)
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{
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pgd_t *pgdp;
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pud_t *pudp, pud;
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pmd_t *pmdp, pmd;
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pte_t *ptep;
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unsigned long addr = (unsigned long)page_address(page);
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pgdp = pgd_offset_k(addr);
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if (pgd_none(READ_ONCE(*pgdp)))
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return false;
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pudp = pud_offset(pgdp, addr);
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pud = READ_ONCE(*pudp);
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if (pud_none(pud))
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return false;
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if (pud_sect(pud))
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return true;
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pmdp = pmd_offset(pudp, addr);
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pmd = READ_ONCE(*pmdp);
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if (pmd_none(pmd))
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return false;
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if (pmd_sect(pmd))
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return true;
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ptep = pte_offset_kernel(pmdp, addr);
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return pte_valid(READ_ONCE(*ptep));
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}
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#endif /* CONFIG_HIBERNATION */
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#endif /* CONFIG_DEBUG_PAGEALLOC */
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