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>
---
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 --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 219ac88..f027941 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -182,6 +182,8 @@ 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 06e0bc0..16122d4 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -213,6 +213,13 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
#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 --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 01baef0..90aa4583 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -226,7 +226,6 @@ static inline pte_t *pmd_page_vaddr(pmd_t 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_struct *mm, unsigned long addr,
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 |
--
1.9.3
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