Patch "arm64: Ensure pmd_present() returns false after pmd_mknotpresent()" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

arm64: Ensure pmd_present() returns false after pmd_mknotpresent()

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-ensure-pmd_present-returns-false-after-pmd_mknotpresent.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Catalin Marinas <[email protected]>
Date: Thu, 5 May 2016 10:44:02 +0100
Subject: arm64: Ensure pmd_present() returns false after pmd_mknotpresent()

From: Catalin Marinas <[email protected]>

commit 5bb1cc0ff9a6b68871970737e6c4c16919928d8b upstream.

Currently, pmd_present() only checks for a non-zero value, returning true even after pmd_mknotpresent() (which only clears the type bits). This patch converts pmd_present() to using pte_present(), similar to the other pmd_*() checks. As a side effect, it will return true for PROT_NONE mappings, though they are not yet used by the kernel with transparent huge pages.

For consistency, also change pmd_mknotpresent() to only clear the PMD_SECT_VALID bit, even though the PMD_TABLE_BIT is already 0 for block mappings (no functional change). The unused PMD_SECT_PROT_NONE definition is removed as transparent huge pages use the pte page prot values.

---
 arch/arm64/include/asm/pgtable-hwdef.h |    1 -
 arch/arm64/include/asm/pgtable.h       |    4 ++--
 2 files changed, 2 insertions(+), 3 deletions(-)

@@ -133,7 +133,6 @@
  * Section
  */
 #define PMD_SECT_VALID		(_AT(pmdval_t, 1) << 0)
-#define PMD_SECT_PROT_NONE	(_AT(pmdval_t, 1) << 58)
 #define PMD_SECT_USER		(_AT(pmdval_t, 1) << 6)		/* AP[1] */
 #define PMD_SECT_RDONLY		(_AT(pmdval_t, 1) << 7)		/* AP[2] */
 #define PMD_SECT_S		(_AT(pmdval_t, 3) << 8)

@@ -280,6 +280,7 @@ static inline pgprot_t mk_sect_prot(pgpr
 #define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#define pmd_present(pmd)	pte_present(pmd_pte(pmd))
 #define pmd_dirty(pmd)		pte_dirty(pmd_pte(pmd))
 #define pmd_young(pmd)		pte_young(pmd_pte(pmd))
 #define pmd_wrprotect(pmd)	pte_pmd(pte_wrprotect(pmd_pte(pmd)))

@@ -288,7 +289,7 @@ static inline pgprot_t mk_sect_prot(pgpr
 #define pmd_mkclean(pmd)       pte_pmd(pte_mkclean(pmd_pte(pmd)))
 #define pmd_mkdirty(pmd)	pte_pmd(pte_mkdirty(pmd_pte(pmd)))
 #define pmd_mkyoung(pmd)	pte_pmd(pte_mkyoung(pmd_pte(pmd)))
-#define pmd_mknotpresent(pmd)	(__pmd(pmd_val(pmd) & ~PMD_TYPE_MASK))
+#define pmd_mknotpresent(pmd)	(__pmd(pmd_val(pmd) & ~PMD_SECT_VALID))
 
 #define __HAVE_ARCH_PMD_WRITE
 #define pmd_write(pmd)		pte_write(pmd_pte(pmd))

@@ -327,7 +328,6 @@ extern pgprot_t phys_mem_access_prot(str
 				     unsigned long size, pgprot_t vma_prot);
 
 #define pmd_none(pmd)		(!pmd_val(pmd))
-#define pmd_present(pmd)	(pmd_val(pmd))
 
 #define pmd_bad(pmd)		(!(pmd_val(pmd) & 2))
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/arm64-fix-typo-in-the-pmdp_huge_get_and_clear-definition.patch queue-4.6/arm64-implement-ptep_set_access_flags-for-hardware-af-dbm.patch queue-4.6/arm64-implement-pmdp_set_access_flags-for-hardware-af-dbm.patch queue-4.6/arm64-ensure-pmd_present-returns-false-after-pmd_mknotpresent.patch