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authorSteve Capper <steve.capper@linaro.org>2014-03-12 10:05:27 +0000
committerSteve Capper <steve.capper@linaro.org>2014-03-26 09:33:38 +0000
commit30d61053c52c39de917c90aa53119749f3eddb0b (patch)
tree53ee90b3d12ce4a48ded20b7d0fd1bee74e6dcf6
parente544abd61c026d766ecebd13a398033c4fbb335f (diff)
downloadlinux-30d61053c52c39de917c90aa53119749f3eddb0b.tar.gz
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@linaro.org>
-rw-r--r--arch/arm/include/asm/pgtable-2level.h2
-rw-r--r--arch/arm/include/asm/pgtable-3level.h8
-rw-r--r--arch/arm/include/asm/pgtable.h6
3 files changed, 12 insertions, 4 deletions
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index dfff709fda3..26d17423228 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -181,6 +181,8 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
#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 --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 85c60adc8b6..b286ba9539d 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -207,6 +207,14 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
#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 pte_special(pte) (!!(pte_val(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 pmd_young(pmd) (pmd_val(pmd) & PMD_SECT_AF)
#define __HAVE_ARCH_PMD_WRITE
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 7d59b524f2a..e6139e34066 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -220,7 +220,6 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
#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_special(pte) (0)
#define pte_present_user(pte) (pte_present(pte) && (pte_val(pte) & L_PTE_USER))
@@ -238,7 +237,8 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
unsigned long ext = 0;
if (addr < TASK_SIZE && pte_present_user(pteval)) {
- __sync_icache_dcache(pteval);
+ if (!pte_special(pteval))
+ __sync_icache_dcache(pteval);
ext |= PTE_EXT_NG;
}
@@ -257,8 +257,6 @@ 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 |