ac53c4fca4
Problem: 1) Huge page mapping of anonymous memory is initially invalid. Will be faulted in by copy-on-write mechanism. 2) Userspace attempts store at the end of the huge mapping. 3) TLB Refill exception handler fill TLB with a normal (4K sized) invalid page at the end of the huge mapping virtual address range. 4) Userspace restarted, and re-attempts the store at the end of the huge mapping. 5) Page from #3 is invalid, we get a fault and go to the hugepage fault handler. This tries to map a huge page and calls huge_ptep_set_access_flags() to install the mapping. 6) We just call the generic ptep_set_access_flags() to set up the page tables, but the flush there assumes a normal (4K sized) page and only tries to flush the first part of the huge page virtual address out of the TLB, since the existing entry from step #3 doesn't conflict, nothing is flushed. 7) We attempt to load the mapping into the TLB, but because it conflicts with the entry from step #3, we get a Machine Check exception. The fix: Flush the entire rage covered by the huge page in huge_ptep_set_access_flags(), and remove the optimization in local_flush_tlb_range() so that the flush actually does the correct thing. Signed-off-by: David Daney <david.daney@cavium.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: Hillf Danton <dhillf@gmail.com> Patchwork: https://patchwork.linux-mips.org/patch/4661/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit dd617f258cc39d36be26afee9912624a2d23112c)
129 lines
2.7 KiB
C
129 lines
2.7 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2008, 2009 Cavium Networks, Inc.
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*/
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#ifndef __ASM_HUGETLB_H
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#define __ASM_HUGETLB_H
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#include <asm/page.h>
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static inline int is_hugepage_only_range(struct mm_struct *mm,
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unsigned long addr,
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unsigned long len)
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{
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return 0;
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}
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static inline int prepare_hugepage_range(struct file *file,
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unsigned long addr,
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unsigned long len)
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{
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unsigned long task_size = STACK_TOP;
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struct hstate *h = hstate_file(file);
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if (len & ~huge_page_mask(h))
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return -EINVAL;
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if (addr & ~huge_page_mask(h))
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return -EINVAL;
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if (len > task_size)
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return -ENOMEM;
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if (task_size - len < addr)
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return -EINVAL;
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return 0;
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}
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static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm)
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{
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}
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static inline void hugetlb_free_pgd_range(struct mmu_gather *tlb,
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unsigned long addr,
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unsigned long end,
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unsigned long floor,
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unsigned long ceiling)
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{
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free_pgd_range(tlb, addr, end, floor, ceiling);
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}
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static inline 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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set_pte_at(mm, addr, ptep, pte);
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}
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static inline 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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pte_t clear;
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pte_t pte = *ptep;
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pte_val(clear) = (unsigned long)invalid_pte_table;
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set_pte_at(mm, addr, ptep, clear);
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return pte;
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}
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static inline 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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flush_tlb_page(vma, addr & huge_page_mask(hstate_vma(vma)));
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}
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static inline int huge_pte_none(pte_t pte)
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{
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unsigned long val = pte_val(pte) & ~_PAGE_GLOBAL;
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return !val || (val == (unsigned long)invalid_pte_table);
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}
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static inline pte_t huge_pte_wrprotect(pte_t pte)
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{
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return pte_wrprotect(pte);
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}
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static inline 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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ptep_set_wrprotect(mm, addr, ptep);
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}
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static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
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unsigned long addr,
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pte_t *ptep, pte_t pte,
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int dirty)
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{
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int changed = !pte_same(*ptep, pte);
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if (changed) {
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set_pte_at(vma->vm_mm, addr, ptep, pte);
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/*
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* There could be some standard sized pages in there,
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* get them all.
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*/
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flush_tlb_range(vma, addr, addr + HPAGE_SIZE);
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}
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return changed;
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}
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static inline pte_t huge_ptep_get(pte_t *ptep)
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{
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return *ptep;
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}
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static inline int arch_prepare_hugepage(struct page *page)
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{
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return 0;
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}
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static inline void arch_release_hugepage(struct page *page)
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{
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}
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static inline void arch_clear_hugepage_flags(struct page *page)
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{
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}
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#endif /* __ASM_HUGETLB_H */
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