linux_dsm_epyc7002/arch/mips/include/asm/hugetlb.h
David Daney ac53c4fca4 MIPS: Avoid mcheck by flushing page range in huge_ptep_set_access_flags()
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)
2012-12-04 16:57:54 +01:00

130 lines
2.7 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2008, 2009 Cavium Networks, Inc.
*/
#ifndef __ASM_HUGETLB_H
#define __ASM_HUGETLB_H
#include <asm/page.h>
static inline int is_hugepage_only_range(struct mm_struct *mm,
unsigned long addr,
unsigned long len)
{
return 0;
}
static inline int prepare_hugepage_range(struct file *file,
unsigned long addr,
unsigned long len)
{
unsigned long task_size = STACK_TOP;
struct hstate *h = hstate_file(file);
if (len & ~huge_page_mask(h))
return -EINVAL;
if (addr & ~huge_page_mask(h))
return -EINVAL;
if (len > task_size)
return -ENOMEM;
if (task_size - len < addr)
return -EINVAL;
return 0;
}
static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm)
{
}
static inline void hugetlb_free_pgd_range(struct mmu_gather *tlb,
unsigned long addr,
unsigned long end,
unsigned long floor,
unsigned long ceiling)
{
free_pgd_range(tlb, addr, end, floor, ceiling);
}
static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
set_pte_at(mm, addr, ptep, pte);
}
static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pte_t clear;
pte_t pte = *ptep;
pte_val(clear) = (unsigned long)invalid_pte_table;
set_pte_at(mm, addr, ptep, clear);
return pte;
}
static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
flush_tlb_page(vma, addr & huge_page_mask(hstate_vma(vma)));
}
static inline int huge_pte_none(pte_t pte)
{
unsigned long val = pte_val(pte) & ~_PAGE_GLOBAL;
return !val || (val == (unsigned long)invalid_pte_table);
}
static inline pte_t huge_pte_wrprotect(pte_t pte)
{
return pte_wrprotect(pte);
}
static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
ptep_set_wrprotect(mm, addr, ptep);
}
static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr,
pte_t *ptep, pte_t pte,
int dirty)
{
int changed = !pte_same(*ptep, pte);
if (changed) {
set_pte_at(vma->vm_mm, addr, ptep, pte);
/*
* There could be some standard sized pages in there,
* get them all.
*/
flush_tlb_range(vma, addr, addr + HPAGE_SIZE);
}
return changed;
}
static inline pte_t huge_ptep_get(pte_t *ptep)
{
return *ptep;
}
static inline int arch_prepare_hugepage(struct page *page)
{
return 0;
}
static inline void arch_release_hugepage(struct page *page)
{
}
static inline void arch_clear_hugepage_flags(struct page *page)
{
}
#endif /* __ASM_HUGETLB_H */