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Patch "ARM: 8108/1: mm: Introduce {pte,pmd}_isset and {pte,pmd}_isclear" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Apr 26, 2015

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

    ARM: 8108/1: mm: Introduce {pte,pmd}_isset and {pte,pmd}_isclear

to the 3.14-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:

     arm-8108-1-mm-introduce-pte-pmd-_isset-and-pte-pmd-_isclear.patch

and it can be found in the queue-3.14 subdirectory.

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

Quoted 1 line

From f2950706871c4b6e8c0f0d7c3f62d35930b8de63 Mon Sep 17 00:00:00 2001

From: Steven Capper <[email protected]>
Date: Fri, 18 Jul 2014 16:15:27 +0100
Subject: ARM: 8108/1: mm: Introduce {pte,pmd}_isset and {pte,pmd}_isclear

From: Steven Capper <[email protected]>

commit f2950706871c4b6e8c0f0d7c3f62d35930b8de63 upstream.

Long descriptors on ARM are 64 bits, and some pte functions such as pte_dirty return a bitwise-and of a flag with the pte value. If the flag to be tested resides in the upper 32 bits of the pte, then we run into the danger of the result being dropped if downcast.

For example:

	gather_stats(page, md, pte_dirty(*pte), 1);

where pte_dirty(*pte) is downcast to an int.

This patch introduces a new macro pte_isset which performs the bitwise and, then performs a double logical invert (where needed) to ensure predictable downcasting. The logical inverse pte_isclear is also introduced.

Equivalent pmd functions for Transparent HugePages have also been added.

Signed-off-by Steve Capper <[email protected]>
Reviewed-by Will Deacon <[email protected]>
Signed-off-by Russell King <[email protected]>

[hpy: Backported to 3.14
- adjust the context ]

Signed-off-by Hou Pengyang <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm/include/asm/pgtable-3level.h |   12 ++++++++----
 arch/arm/include/asm/pgtable.h        |   14 +++++++++-----
 2 files changed, 17 insertions(+), 9 deletions(-)
arch/arm/include/asm/pgtable-3level.h +8 -4
@@ -207,17 +207,21 @@ static inline pmd_t *pmd_offset(pud_t *p
 #define pte_huge(pte)		(pte_val(pte) && !(pte_val(pte) & PTE_TABLE_BIT))
 #define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))
 
-#define pmd_young(pmd)		(pmd_val(pmd) & PMD_SECT_AF)
+#define pmd_isset(pmd, val)	((u32)(val) == (val) ? pmd_val(pmd) & (val) \
+						: !!(pmd_val(pmd) & (val)))
+#define pmd_isclear(pmd, val)	(!(pmd_val(pmd) & (val)))
+
+#define pmd_young(pmd)		(pmd_isset((pmd), PMD_SECT_AF))
 
 #define __HAVE_ARCH_PMD_WRITE
-#define pmd_write(pmd)		(!(pmd_val(pmd) & PMD_SECT_RDONLY))
+#define pmd_write(pmd)		(pmd_isclear((pmd), PMD_SECT_RDONLY))
 
 #define pmd_hugewillfault(pmd)	(!pmd_young(pmd) || !pmd_write(pmd))
 #define pmd_thp_or_huge(pmd)	(pmd_huge(pmd) || pmd_trans_huge(pmd))
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
-#define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING)
+#define pmd_trans_huge(pmd)	(pmd_val(pmd) && !pmd_table(pmd))
+#define pmd_trans_splitting(pmd) (pmd_isset((pmd), PMD_SECT_SPLITTING))
 #endif
 
 #define PMD_BIT_FUNC(fn,op) \
arch/arm/include/asm/pgtable.h +9 -5
@@ -214,12 +214,16 @@ static inline pte_t *pmd_page_vaddr(pmd_
 
 #define pte_clear(mm,addr,ptep)	set_pte_ext(ptep, __pte(0), 0)
 
+#define pte_isset(pte, val)	((u32)(val) == (val) ? pte_val(pte) & (val) \
+						: !!(pte_val(pte) & (val)))
+#define pte_isclear(pte, val)	(!(pte_val(pte) & (val)))
+
 #define pte_none(pte)		(!pte_val(pte))
-#define pte_present(pte)	(pte_val(pte) & L_PTE_PRESENT)
-#define pte_write(pte)		(!(pte_val(pte) & L_PTE_RDONLY))
-#define pte_dirty(pte)		(pte_val(pte) & L_PTE_DIRTY)
-#define pte_young(pte)		(pte_val(pte) & L_PTE_YOUNG)
-#define pte_exec(pte)		(!(pte_val(pte) & L_PTE_XN))
+#define pte_present(pte)	(pte_isset((pte), L_PTE_PRESENT))
+#define pte_write(pte)		(pte_isclear((pte), L_PTE_RDONLY))
+#define pte_dirty(pte)		(pte_isset((pte), L_PTE_DIRTY))
+#define pte_young(pte)		(pte_isset((pte), L_PTE_YOUNG))
+#define pte_exec(pte)		(pte_isclear((pte), L_PTE_XN))
 #define pte_special(pte)	(0)
 
 #define pte_present_user(pte)  (pte_present(pte) && (pte_val(pte) & L_PTE_USER))

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

queue-3.14/arm-8109-1-mm-modify-pte_write-and-pmd_write-logic-for-lpae.patch queue-3.14/arm-8108-1-mm-introduce-pte-pmd-_isset-and-pte-pmd-_isclear.patch