[PATCH] x86/mm: Simplify p[g4um]d_page() macros

[Andi Kleen]

From: Tom Lendacky <thomas.lendacky@xxxxxxx>

[backport of fd7e315988b78 from mainline for stable to fix stable crashes
suggested by Michael Hocko. Should be applied to 4.9 and 4.4.]

Create a pgd_pfn() macro similar to the p[4um]d_pfn() macros and then
use the p[g4um]d_pfn() macros in the p[g4um]d_page() macros instead of
duplicating the code.

Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brijesh Singh <brijesh.singh@xxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Larry Woodman <lwoodman@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Toshimitsu Kani <toshi.kani@xxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-efi@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/e61eb533a6d0aac941db2723d8aa63ef6b882dee.1500319216.git.thomas.lendacky@xxxxxxx
[Backported to 4.9 stable by AK, suggested by Michael Hocko]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/pgtable.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 4de6c282c02a..68a55273ce0f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -173,6 +173,11 @@ static inline unsigned long pud_pfn(pud_t pud)
 	return (pfn & pud_pfn_mask(pud)) >> PAGE_SHIFT;
 }
 
+static inline unsigned long pgd_pfn(pgd_t pgd)
+{
+	return (pgd_val(pgd) & PTE_PFN_MASK) >> PAGE_SHIFT;
+}
+
 #define pte_page(pte)	pfn_to_page(pte_pfn(pte))
 
 static inline int pmd_large(pmd_t pte)
@@ -578,8 +583,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
  * Currently stuck as a macro due to indirect forward reference to
  * linux/mmzone.h's __section_mem_map_addr() definition:
  */
-#define pmd_page(pmd)		\
-	pfn_to_page((pmd_val(pmd) & pmd_pfn_mask(pmd)) >> PAGE_SHIFT)
+#define pmd_page(pmd)	pfn_to_page(pmd_pfn(pmd))
 
 /*
  * the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
@@ -647,8 +651,7 @@ static inline unsigned long pud_page_vaddr(pud_t pud)
  * Currently stuck as a macro due to indirect forward reference to
  * linux/mmzone.h's __section_mem_map_addr() definition:
  */
-#define pud_page(pud)		\
-	pfn_to_page((pud_val(pud) & pud_pfn_mask(pud)) >> PAGE_SHIFT)
+#define pud_page(pud)	pfn_to_page(pud_pfn(pud))
 
 /* Find an entry in the second-level page table.. */
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
@@ -688,7 +691,7 @@ static inline unsigned long pgd_page_vaddr(pgd_t pgd)
  * Currently stuck as a macro due to indirect forward reference to
  * linux/mmzone.h's __section_mem_map_addr() definition:
  */
-#define pgd_page(pgd)		pfn_to_page(pgd_val(pgd) >> PAGE_SHIFT)
+#define pgd_page(pgd)		pfn_to_page(pgd_pfn(pgd))
 
 /* to find an entry in a page-table-directory. */
 static inline unsigned long pud_index(unsigned long address)
-- 
2.17.1