[PATCH v1 2/3] arm: mm: introduce L_PTE_SPECIAL

From: Minchan Kim
Date: Sun Sep 16 2018 - 20:47:22 EST


This patch introduces L_PTE_SPECIAL and pte functions for supporting
get_user_pages_fast.

Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Steve Capper <steve.capper@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
arch/arm/Kconfig | 2 +-
arch/arm/include/asm/pgtable-2level.h | 3 +--
arch/arm/include/asm/pgtable-3level.h | 6 ------
arch/arm/include/asm/pgtable.h | 13 +++++++++++++
4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e8cd55a5b04c..278cf22b5aa1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,7 +10,7 @@ config ARM
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KCOV
select ARCH_HAS_MEMBARRIER_SYNC_CORE
- select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
+ select ARCH_HAS_PTE_SPECIAL if (ARM_LPAE || CPU_V7 || CPU_V6 || CPUV6K)
select ARCH_HAS_PHYS_TO_DMA
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 514b13c27b43..378668420642 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -120,6 +120,7 @@
#define L_PTE_VALID (_AT(pteval_t, 1) << 0) /* Valid */
#define L_PTE_PRESENT (_AT(pteval_t, 1) << 0)
#define L_PTE_YOUNG (_AT(pteval_t, 1) << 1)
+#define L_PTE_SPECIAL (_AT(pteval_t, 1) << 5)
#define L_PTE_DIRTY (_AT(pteval_t, 1) << 6)
#define L_PTE_RDONLY (_AT(pteval_t, 1) << 7)
#define L_PTE_USER (_AT(pteval_t, 1) << 8)
@@ -224,8 +225,6 @@ 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 6d50a11d7793..b6f52e16b478 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -213,12 +213,6 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)

#define pmd_present(pmd) (pmd_isset((pmd), L_PMD_SECT_VALID))
#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 pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY))
#define pmd_dirty(pmd) (pmd_isset((pmd), L_PMD_SECT_DIRTY))
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index a757401129f9..6cc7ce0e423e 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -228,6 +228,11 @@ 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))
+#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
+#define pte_special(pte) (pte_isset((pte), L_PTE_SPECIAL))
+#else
+#define pte_special(pte) (0)
+#endif

#define pte_valid_user(pte) \
(pte_valid(pte) && pte_isset((pte), L_PTE_USER) && pte_young(pte))
@@ -318,6 +323,14 @@ static inline pte_t pte_mknexec(pte_t pte)
return set_pte_bit(pte, __pgprot(L_PTE_XN));
}

+#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
+static inline pte_t pte_mkspecial(pte_t pte)
+{
+ return set_pte_bit(pte, __pgprot(L_PTE_SPECIAL));
+}
+#else
+static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
+#endif
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 |
--
2.19.0.397.gdd90340f6a-goog