[PATCH v4 RESEND 8/11] x86/mm: Fix gup_huge_p?d() to handle large PAT bit

From: Toshi Kani
Date: Thu Sep 17 2015 - 14:40:16 EST


gup_huge_pud() and gup_huge_pmd() cast *pud and *pmd to *pte,
and use pte_xxx() interfaces to obtain the flags and PFN.
However, the pte_xxx() interface does not handle the large
PAT bit properly for PUD/PMD.

Fix gup_huge_pud() and gup_huge_pmd() to use pud_xxx() and
pmd_xxx() interfaces according to their type.

Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/gup.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 81bf3d2..ae9a37b 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -118,21 +118,20 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long mask;
- pte_t pte = *(pte_t *)&pmd;
struct page *head, *page;
int refs;

mask = _PAGE_PRESENT|_PAGE_USER;
if (write)
mask |= _PAGE_RW;
- if ((pte_flags(pte) & mask) != mask)
+ if ((pmd_flags(pmd) & mask) != mask)
return 0;
/* hugepages are never "special" */
- VM_BUG_ON(pte_flags(pte) & _PAGE_SPECIAL);
- VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+ VM_BUG_ON(pmd_flags(pmd) & _PAGE_SPECIAL);
+ VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));

refs = 0;
- head = pte_page(pte);
+ head = pmd_page(pmd);
page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
do {
VM_BUG_ON_PAGE(compound_head(page) != head, page);
@@ -195,21 +194,20 @@ static noinline int gup_huge_pud(pud_t pud, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long mask;
- pte_t pte = *(pte_t *)&pud;
struct page *head, *page;
int refs;

mask = _PAGE_PRESENT|_PAGE_USER;
if (write)
mask |= _PAGE_RW;
- if ((pte_flags(pte) & mask) != mask)
+ if ((pud_flags(pud) & mask) != mask)
return 0;
/* hugepages are never "special" */
- VM_BUG_ON(pte_flags(pte) & _PAGE_SPECIAL);
- VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
+ VM_BUG_ON(pud_flags(pud) & _PAGE_SPECIAL);
+ VM_BUG_ON(!pfn_valid(pud_pfn(pud)));

refs = 0;
- head = pte_page(pte);
+ head = pud_page(pud);
page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
do {
VM_BUG_ON_PAGE(compound_head(page) != head, page);
--
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