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https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
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4574815abf
As very well explained in commit20a004e7b0("arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing page tables"), an architecture whose page table walker can modify the PTE in parallel must use READ_ONCE()/ WRITE_ONCE() macro to avoid any compiler transformation. So apply that to LoongArch which is such an architecture, in order to avoid potential problems. Similar to commitedf9556472("riscv: Use accessors to page table entries instead of direct dereference"). Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
66 lines
1.3 KiB
C
66 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*/
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/err.h>
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#include <linux/sysctl.h>
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#include <asm/mman.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned long addr, unsigned long sz)
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{
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pte_t *pte = NULL;
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pgd = pgd_offset(mm, addr);
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p4d = p4d_alloc(mm, pgd, addr);
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pud = pud_alloc(mm, p4d, addr);
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if (pud)
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pte = (pte_t *)pmd_alloc(mm, pud, addr);
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return pte;
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}
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pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
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unsigned long sz)
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{
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd = NULL;
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pgd = pgd_offset(mm, addr);
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if (pgd_present(pgdp_get(pgd))) {
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p4d = p4d_offset(pgd, addr);
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if (p4d_present(p4dp_get(p4d))) {
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pud = pud_offset(p4d, addr);
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if (pud_present(pudp_get(pud)))
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pmd = pmd_offset(pud, addr);
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}
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}
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return (pte_t *) pmd;
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}
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uint64_t pmd_to_entrylo(unsigned long pmd_val)
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{
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uint64_t val;
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/* PMD as PTE. Must be huge page */
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if (!pmd_leaf(__pmd(pmd_val)))
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panic("%s", __func__);
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val = pmd_val ^ _PAGE_HUGE;
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val |= ((val & _PAGE_HGLOBAL) >>
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(_PAGE_HGLOBAL_SHIFT - _PAGE_GLOBAL_SHIFT));
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return val;
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}
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