![Linus Torvalds](/assets/img/avatar_default.png)
Commit2c4541e24c
("mm: use vma_init() to initialize VMAs on stack and data segments") tried to initialize various left-over ad-hoc vma's "properly", but actually made things worse for the temporary vma's used for TLB flushing. vma_init() doesn't actually initialize all of the vma, just a few fields, so doing something like - struct vm_area_struct vma = { .vm_mm = tlb->mm, }; + struct vm_area_struct vma; + + vma_init(&vma, tlb->mm); was actually very bad: instead of having a nicely initialized vma with every field but "vm_mm" zeroed, you'd have an entirely uninitialized vma with only a couple of fields initialized. And they weren't even fields that the code in question mostly cared about. The flush_tlb_range() function takes a "struct vma" rather than a "struct mm_struct", because a few architectures actually care about what kind of range it is - being able to only do an ITLB flush if it's a range that doesn't have data accesses enabled, for example. And all the normal users already have the vma for doing the range invalidation. But a few people want to call flush_tlb_range() with a range they just made up, so they also end up using a made-up vma. x86 just has a special "flush_tlb_mm_range()" function for this, but other architectures (arm and ia64) do the "use fake vma" thing instead, and thus got caught up in the vma_init() changes. At the same time, the TLB flushing code really doesn't care about most other fields in the vma, so vma_init() is just unnecessary and pointless. This fixes things by having an explicit "this is just an initializer for the TLB flush" initializer macro, which is used by the arm/arm64/ia64 people who mis-use this interface with just a dummy vma. Fixes:2c4541e24c
("mm: use vma_init() to initialize VMAs on stack and data segments") Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
426 lines
9.9 KiB
C
426 lines
9.9 KiB
C
/*
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* arch/arm64/mm/hugetlbpage.c
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*
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* Copyright (C) 2013 Linaro Ltd.
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*
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* Based on arch/x86/mm/hugetlbpage.c.
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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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#include <linux/init.h>
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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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#include <asm/pgalloc.h>
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int pmd_huge(pmd_t pmd)
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{
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return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
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}
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int pud_huge(pud_t pud)
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{
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#ifndef __PAGETABLE_PMD_FOLDED
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return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
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#else
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return 0;
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#endif
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}
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/*
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* Select all bits except the pfn
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*/
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static inline pgprot_t pte_pgprot(pte_t pte)
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{
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unsigned long pfn = pte_pfn(pte);
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return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
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}
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static int find_num_contig(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, size_t *pgsize)
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{
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pgd_t *pgdp = pgd_offset(mm, addr);
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pud_t *pudp;
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pmd_t *pmdp;
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*pgsize = PAGE_SIZE;
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pudp = pud_offset(pgdp, addr);
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pmdp = pmd_offset(pudp, addr);
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if ((pte_t *)pmdp == ptep) {
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*pgsize = PMD_SIZE;
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return CONT_PMDS;
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}
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return CONT_PTES;
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}
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static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
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{
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int contig_ptes = 0;
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*pgsize = size;
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switch (size) {
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#ifdef CONFIG_ARM64_4K_PAGES
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case PUD_SIZE:
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#endif
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case PMD_SIZE:
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contig_ptes = 1;
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break;
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case CONT_PMD_SIZE:
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*pgsize = PMD_SIZE;
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contig_ptes = CONT_PMDS;
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break;
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case CONT_PTE_SIZE:
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*pgsize = PAGE_SIZE;
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contig_ptes = CONT_PTES;
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break;
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}
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return contig_ptes;
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}
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/*
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* Changing some bits of contiguous entries requires us to follow a
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* Break-Before-Make approach, breaking the whole contiguous set
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* before we can change any entries. See ARM DDI 0487A.k_iss10775,
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* "Misprogramming of the Contiguous bit", page D4-1762.
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*
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* This helper performs the break step.
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*/
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static pte_t get_clear_flush(struct mm_struct *mm,
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unsigned long addr,
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pte_t *ptep,
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unsigned long pgsize,
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unsigned long ncontig)
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{
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pte_t orig_pte = huge_ptep_get(ptep);
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bool valid = pte_valid(orig_pte);
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unsigned long i, saddr = addr;
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for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
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pte_t pte = ptep_get_and_clear(mm, addr, ptep);
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/*
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* If HW_AFDBM is enabled, then the HW could turn on
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* the dirty bit for any page in the set, so check
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* them all. All hugetlb entries are already young.
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*/
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if (pte_dirty(pte))
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orig_pte = pte_mkdirty(orig_pte);
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}
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if (valid) {
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struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
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flush_tlb_range(&vma, saddr, addr);
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}
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return orig_pte;
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}
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/*
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* Changing some bits of contiguous entries requires us to follow a
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* Break-Before-Make approach, breaking the whole contiguous set
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* before we can change any entries. See ARM DDI 0487A.k_iss10775,
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* "Misprogramming of the Contiguous bit", page D4-1762.
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*
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* This helper performs the break step for use cases where the
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* original pte is not needed.
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*/
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static void clear_flush(struct mm_struct *mm,
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unsigned long addr,
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pte_t *ptep,
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unsigned long pgsize,
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unsigned long ncontig)
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{
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struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
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unsigned long i, saddr = addr;
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for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
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pte_clear(mm, addr, ptep);
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flush_tlb_range(&vma, saddr, addr);
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}
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void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pte)
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{
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size_t pgsize;
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int i;
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int ncontig;
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unsigned long pfn, dpfn;
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pgprot_t hugeprot;
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/*
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* Code needs to be expanded to handle huge swap and migration
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* entries. Needed for HUGETLB and MEMORY_FAILURE.
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*/
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WARN_ON(!pte_present(pte));
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if (!pte_cont(pte)) {
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set_pte_at(mm, addr, ptep, pte);
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return;
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}
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ncontig = find_num_contig(mm, addr, ptep, &pgsize);
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pfn = pte_pfn(pte);
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dpfn = pgsize >> PAGE_SHIFT;
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hugeprot = pte_pgprot(pte);
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clear_flush(mm, addr, ptep, pgsize, ncontig);
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for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
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set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
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}
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void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pte, unsigned long sz)
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{
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int i, ncontig;
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size_t pgsize;
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ncontig = num_contig_ptes(sz, &pgsize);
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for (i = 0; i < ncontig; i++, ptep++)
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set_pte(ptep, pte);
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}
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pte_t *huge_pte_alloc(struct mm_struct *mm,
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unsigned long addr, unsigned long sz)
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{
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pgd_t *pgdp;
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pud_t *pudp;
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pmd_t *pmdp;
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pte_t *ptep = NULL;
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pgdp = pgd_offset(mm, addr);
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pudp = pud_alloc(mm, pgdp, addr);
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if (!pudp)
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return NULL;
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if (sz == PUD_SIZE) {
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ptep = (pte_t *)pudp;
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} else if (sz == (PAGE_SIZE * CONT_PTES)) {
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pmdp = pmd_alloc(mm, pudp, addr);
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WARN_ON(addr & (sz - 1));
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/*
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* Note that if this code were ever ported to the
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* 32-bit arm platform then it will cause trouble in
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* the case where CONFIG_HIGHPTE is set, since there
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* will be no pte_unmap() to correspond with this
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* pte_alloc_map().
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*/
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ptep = pte_alloc_map(mm, pmdp, addr);
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} else if (sz == PMD_SIZE) {
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if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
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pud_none(READ_ONCE(*pudp)))
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ptep = huge_pmd_share(mm, addr, pudp);
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else
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ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
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} else if (sz == (PMD_SIZE * CONT_PMDS)) {
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pmdp = pmd_alloc(mm, pudp, addr);
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WARN_ON(addr & (sz - 1));
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return (pte_t *)pmdp;
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}
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return ptep;
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}
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pte_t *huge_pte_offset(struct mm_struct *mm,
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unsigned long addr, unsigned long sz)
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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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pgdp = pgd_offset(mm, addr);
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if (!pgd_present(READ_ONCE(*pgdp)))
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return NULL;
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pudp = pud_offset(pgdp, addr);
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pud = READ_ONCE(*pudp);
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if (sz != PUD_SIZE && pud_none(pud))
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return NULL;
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/* hugepage or swap? */
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if (pud_huge(pud) || !pud_present(pud))
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return (pte_t *)pudp;
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/* table; check the next level */
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if (sz == CONT_PMD_SIZE)
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addr &= CONT_PMD_MASK;
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pmdp = pmd_offset(pudp, addr);
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pmd = READ_ONCE(*pmdp);
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if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
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pmd_none(pmd))
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return NULL;
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if (pmd_huge(pmd) || !pmd_present(pmd))
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return (pte_t *)pmdp;
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if (sz == CONT_PTE_SIZE)
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return pte_offset_kernel(pmdp, (addr & CONT_PTE_MASK));
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return NULL;
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}
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pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
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struct page *page, int writable)
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{
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size_t pagesize = huge_page_size(hstate_vma(vma));
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if (pagesize == CONT_PTE_SIZE) {
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entry = pte_mkcont(entry);
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} else if (pagesize == CONT_PMD_SIZE) {
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entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
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} else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
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pr_warn("%s: unrecognized huge page size 0x%lx\n",
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__func__, pagesize);
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}
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return entry;
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}
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void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, unsigned long sz)
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{
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int i, ncontig;
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size_t pgsize;
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ncontig = num_contig_ptes(sz, &pgsize);
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for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
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pte_clear(mm, addr, ptep);
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}
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pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
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unsigned long addr, pte_t *ptep)
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{
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int ncontig;
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size_t pgsize;
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pte_t orig_pte = huge_ptep_get(ptep);
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if (!pte_cont(orig_pte))
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return ptep_get_and_clear(mm, addr, ptep);
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ncontig = find_num_contig(mm, addr, ptep, &pgsize);
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return get_clear_flush(mm, addr, ptep, pgsize, ncontig);
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}
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int huge_ptep_set_access_flags(struct vm_area_struct *vma,
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unsigned long addr, pte_t *ptep,
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pte_t pte, int dirty)
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{
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int ncontig, i, changed = 0;
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size_t pgsize = 0;
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unsigned long pfn = pte_pfn(pte), dpfn;
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pgprot_t hugeprot;
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pte_t orig_pte;
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if (!pte_cont(pte))
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return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
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ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
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dpfn = pgsize >> PAGE_SHIFT;
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orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
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if (!pte_same(orig_pte, pte))
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changed = 1;
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/* Make sure we don't lose the dirty state */
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if (pte_dirty(orig_pte))
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pte = pte_mkdirty(pte);
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hugeprot = pte_pgprot(pte);
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for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
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set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));
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return changed;
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}
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void huge_ptep_set_wrprotect(struct mm_struct *mm,
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unsigned long addr, pte_t *ptep)
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{
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unsigned long pfn, dpfn;
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pgprot_t hugeprot;
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int ncontig, i;
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size_t pgsize;
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pte_t pte;
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if (!pte_cont(READ_ONCE(*ptep))) {
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ptep_set_wrprotect(mm, addr, ptep);
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return;
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}
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ncontig = find_num_contig(mm, addr, ptep, &pgsize);
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dpfn = pgsize >> PAGE_SHIFT;
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pte = get_clear_flush(mm, addr, ptep, pgsize, ncontig);
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pte = pte_wrprotect(pte);
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hugeprot = pte_pgprot(pte);
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pfn = pte_pfn(pte);
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for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
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set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
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}
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void huge_ptep_clear_flush(struct vm_area_struct *vma,
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unsigned long addr, pte_t *ptep)
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{
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size_t pgsize;
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int ncontig;
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if (!pte_cont(READ_ONCE(*ptep))) {
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ptep_clear_flush(vma, addr, ptep);
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return;
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}
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ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
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clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
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}
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static __init int setup_hugepagesz(char *opt)
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{
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unsigned long ps = memparse(opt, &opt);
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switch (ps) {
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#ifdef CONFIG_ARM64_4K_PAGES
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case PUD_SIZE:
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#endif
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case PMD_SIZE * CONT_PMDS:
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case PMD_SIZE:
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case PAGE_SIZE * CONT_PTES:
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hugetlb_add_hstate(ilog2(ps) - PAGE_SHIFT);
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return 1;
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}
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hugetlb_bad_size();
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pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
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return 0;
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}
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__setup("hugepagesz=", setup_hugepagesz);
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#ifdef CONFIG_ARM64_64K_PAGES
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static __init int add_default_hugepagesz(void)
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{
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if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
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hugetlb_add_hstate(CONT_PTE_SHIFT);
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return 0;
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}
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arch_initcall(add_default_hugepagesz);
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#endif
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