[PATCH 6/6] ARM: mm: Transparent huge page support for non-LPAE systems.

[Steve Capper <steve.capper@arm.com>]

Much of the required code for THP has been implemented in the
earlier non-LPAE HugeTLB patch.

One more domain bit is used (to store whether or not the THP is
splitting).

Some THP helper functions are defined; and we have to re-define
pmd_page such that it distinguishes between page tables and
sections.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm/Kconfig                      |    2 +-
 arch/arm/include/asm/pgtable-2level.h |   47 +++++++++++++++++++++++++++++++++
 arch/arm/include/asm/pgtable-3level.h |    2 ++
 arch/arm/include/asm/pgtable.h        |    7 +++--
 4 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7bee9b9..32e6aba 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1784,7 +1784,7 @@ config SYS_SUPPORTS_HUGETLBFS
 
 config HAVE_ARCH_TRANSPARENT_HUGEPAGE
        def_bool y
-       depends on ARM_LPAE
+       depends on SYS_SUPPORTS_HUGETLBFS
 
 source "mm/Kconfig"
 
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 7423ecf..e3b5ec2 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -207,6 +207,7 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
 #define PMD_DOMAIN_MASK		(_AT(pmdval_t, 0xF) << 5)
 #define PMD_DSECT_DIRTY		(_AT(pmdval_t, 1) << 5)
 #define PMD_DSECT_AF		(_AT(pmdval_t, 1) << 6)
+#define PMD_DSECT_SPLITTING	(_AT(pmdval_t, 1) << 7)
 
 #define PMD_BIT_FUNC(fn,op) \
 static inline pmd_t pmd_##fn(pmd_t pmd) { pmd_val(pmd) op; return pmd; }
@@ -285,6 +286,52 @@ PMD_BIT_FUNC(mknexec,	|= PMD_SECT_XN);
 #define HPAGE_SIZE 0
 #endif /* CONFIG_SYS_SUPPORTS_HUGETLBFS */
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmd_mkhuge(pmd)		(__pmd((pmd_val(pmd) & ~PMD_TYPE_MASK) | PMD_TYPE_SECT))
+
+PMD_BIT_FUNC(mksplitting, |= PMD_DSECT_SPLITTING);
+#define pmd_trans_splitting(pmd)	(pmd_val(pmd) & PMD_DSECT_SPLITTING)
+#define pmd_trans_huge(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
+
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	/*
+	 * for a section, we need to mask off more of the pmd
+	 * before looking up the pfn
+	 */
+	if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
+		return __phys_to_pfn(pmd_val(pmd) & HPAGE_MASK);
+	else
+		return __phys_to_pfn(pmd_val(pmd) & PHYS_MASK);
+}
+
+#define pfn_pmd(pfn,prot) pmd_modify(__pmd(__pfn_to_phys(pfn)),prot);
+#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot);
+
+static inline int has_transparent_hugepage(void)
+{
+	return 1;
+}
+
+#define _PMD_HUGE(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
+#define _PMD_HPAGE(pmd) (phys_to_page(pmd_val(pmd) & HPAGE_MASK))
+#else
+#define _PMD_HUGE(pmd) (0)
+#define _PMD_HPAGE(pmd) (0)
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+static inline struct page *pmd_page(pmd_t pmd)
+{
+	/*
+	 * for a section, we need to mask off more of the pmd
+	 * before looking up the page as it is a section descriptor.
+	 */
+	if (_PMD_HUGE(pmd))
+		return _PMD_HPAGE(pmd);
+
+	return phys_to_page(pmd_val(pmd) & PHYS_MASK);
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_PGTABLE_2LEVEL_H */
diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 1b0351d..cc16398 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -211,6 +211,8 @@ PMD_BIT_FUNC(mknotpresent, &= ~PMD_TYPE_MASK);
 #define pfn_pmd(pfn,prot)	(__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
 #define mk_pmd(page,prot)	pfn_pmd(page_to_pfn(page),prot)
 
+#define pmd_page(pmd)           pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
+
 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 {
 	const pmdval_t mask = PMD_SECT_USER | PMD_SECT_XN | PMD_SECT_RDONLY;
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index bb27451..850270c5 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -169,11 +169,14 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 
 static inline pte_t *pmd_page_vaddr(pmd_t pmd)
 {
+#ifdef SYS_SUPPORTS_HUGETLBFS
+	if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_SECT)
+		return __va(pmd_val(pmd) & HPAGE_MASK);
+#endif
+
 	return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
 }
 
-#define pmd_page(pmd)		pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
-
 #ifndef CONFIG_HIGHPTE
 #define __pte_map(pmd)		pmd_page_vaddr(*(pmd))
 #define __pte_unmap(pte)	do { } while (0)
-- 
1.7.9.5