The patch titled
Subject: arm: mm: introduce special ptes for LPAE
has been added to the -mm tree. Its filename is
arm-mm-introduce-special-ptes-for-lpae.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arm-mm-introduce-special-ptes-for-lpae.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arm-mm-introduce-special-ptes-for-lpae.patch
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From: Steve Capper <steve.capper@xxxxxxxxxx>
Subject: arm: mm: introduce special ptes for LPAE
We need a mechanism to tag ptes as being special, this indicates that no
attempt should be made to access the underlying struct page * associated
with the pte. This is used by the fast_gup when operating on ptes as it
has no means to access VMAs (that also contain this information)
locklessly.
The L_PTE_SPECIAL bit is already allocated for LPAE, this patch modifies
pte_special and pte_mkspecial to make use of it, and defines
__HAVE_ARCH_PTE_SPECIAL.
This patch also excludes special ptes from the icache/dcache sync logic.
Signed-off-by: Steve Capper <steve.capper@xxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dann Frazier <dann.frazier@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/pgtable-2level.h | 2 ++
arch/arm/include/asm/pgtable-3level.h | 7 +++++++
arch/arm/include/asm/pgtable.h | 6 ++----
3 files changed, 11 insertions(+), 4 deletions(-)
diff -puN arch/arm/include/asm/pgtable-2level.h~arm-mm-introduce-special-ptes-for-lpae arch/arm/include/asm/pgtable-2level.h
--- a/arch/arm/include/asm/pgtable-2level.h~arm-mm-introduce-special-ptes-for-lpae
+++ a/arch/arm/include/asm/pgtable-2level.h
@@ -182,6 +182,8 @@ static inline pmd_t *pmd_offset(pud_t *p
#define pmd_addr_end(addr,end) (end)
#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
+#define pte_special(pte) (0)
+static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
/*
* We don't have huge page support for short descriptors, for the moment
diff -puN arch/arm/include/asm/pgtable-3level.h~arm-mm-introduce-special-ptes-for-lpae arch/arm/include/asm/pgtable-3level.h
--- a/arch/arm/include/asm/pgtable-3level.h~arm-mm-introduce-special-ptes-for-lpae
+++ a/arch/arm/include/asm/pgtable-3level.h
@@ -213,6 +213,13 @@ static inline pmd_t *pmd_offset(pud_t *p
#define pmd_isclear(pmd, val) (!(pmd_val(pmd) & (val)))
#define pmd_young(pmd) (pmd_isset((pmd), PMD_SECT_AF))
+#define pte_special(pte) (pte_isset((pte), L_PTE_SPECIAL))
+static inline pte_t pte_mkspecial(pte_t pte)
+{
+ pte_val(pte) |= L_PTE_SPECIAL;
+ return pte;
+}
+#define __HAVE_ARCH_PTE_SPECIAL
#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY))
diff -puN arch/arm/include/asm/pgtable.h~arm-mm-introduce-special-ptes-for-lpae arch/arm/include/asm/pgtable.h
--- a/arch/arm/include/asm/pgtable.h~arm-mm-introduce-special-ptes-for-lpae
+++ a/arch/arm/include/asm/pgtable.h
@@ -226,7 +226,6 @@ static inline pte_t *pmd_page_vaddr(pmd_
#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_valid_user(pte) \
(pte_valid(pte) && pte_isset((pte), L_PTE_USER) && pte_young(pte))
@@ -245,7 +244,8 @@ static inline void set_pte_at(struct mm_
unsigned long ext = 0;
if (addr < TASK_SIZE && pte_valid_user(pteval)) {
- __sync_icache_dcache(pteval);
+ if (!pte_special(pteval))
+ __sync_icache_dcache(pteval);
ext |= PTE_EXT_NG;
}
@@ -264,8 +264,6 @@ PTE_BIT_FUNC(mkyoung, |= L_PTE_YOUNG);
PTE_BIT_FUNC(mkexec, &= ~L_PTE_XN);
PTE_BIT_FUNC(mknexec, |= L_PTE_XN);
-static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
-
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER |
_
Patches currently in -mm which might be from steve.capper@xxxxxxxxxx are
mm-introduce-a-general-rcu-get_user_pages_fast.patch
mm-introduce-a-general-rcu-get_user_pages_fast-fix.patch
arm-mm-introduce-special-ptes-for-lpae.patch
arm-mm-enable-have_rcu_table_free-logic.patch
arm-mm-enable-rcu-fast_gup.patch
arm64-mm-enable-have_rcu_table_free-logic.patch
arm64-mm-enable-rcu-fast_gup.patch
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