riscv: mm: add THP support on 64-bit

Bring Transparent HugePage support to riscv. A
transparent huge page is always represented as a pmd.
Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -103,6 +103,7 @@ config RISCV
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select UACCESS_MEMCPY if !MMU
+	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT

arch/riscv/include/asm/pgtable.h

@@ -172,10 +172,23 @@ extern pgd_t swapper_pg_dir[];
 #define __S110	PAGE_SHARED_EXEC
 #define __S111	PAGE_SHARED_EXEC
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_present(pmd_t pmd)
+{
+	/*
+	 * Checking for _PAGE_LEAF is needed too because:
+	 * When splitting a THP, split_huge_page() will temporarily clear
+	 * the present bit, in this situation, pmd_present() and
+	 * pmd_trans_huge() still needs to return true.
+	 */
+	return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE | _PAGE_LEAF));
+}
+#else
 static inline int pmd_present(pmd_t pmd)
 {
 	return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE));
 }
+#endif
 
 static inline int pmd_none(pmd_t pmd)
 {
@@ -369,6 +382,14 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
 	local_flush_tlb_page(address);
 }
 
+static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
+		unsigned long address, pmd_t *pmdp)
+{
+	pte_t *ptep = (pte_t *)pmdp;
+
+	update_mmu_cache(vma, address, ptep);
+}
+
 #define __HAVE_ARCH_PTE_SAME
 static inline int pte_same(pte_t pte_a, pte_t pte_b)
 {
@@ -462,6 +483,141 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 	return ptep_test_and_clear_young(vma, address, ptep);
 }
 
+/*
+ * THP functions
+ */
+static inline pmd_t pte_pmd(pte_t pte)
+{
+	return __pmd(pte_val(pte));
+}
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	return pmd;
+}
+
+static inline pmd_t pmd_mkinvalid(pmd_t pmd)
+{
+	return __pmd(pmd_val(pmd) & ~(_PAGE_PRESENT|_PAGE_PROT_NONE));
+}
+
+#define __pmd_to_phys(pmd)  (pmd_val(pmd) >> _PAGE_PFN_SHIFT << PAGE_SHIFT)
+
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	return ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT);
+}
+
+static inline pmd_t mk_pmd(struct page *page, pgprot_t prot)
+{
+	return pfn_pmd(page_to_pfn(page), prot);
+}
+
+static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
+{
+	return pte_pmd(pte_modify(pmd_pte(pmd), newprot));
+}
+
+#define pmd_write pmd_write
+static inline int pmd_write(pmd_t pmd)
+{
+	return pte_write(pmd_pte(pmd));
+}
+
+static inline int pmd_dirty(pmd_t pmd)
+{
+	return pte_dirty(pmd_pte(pmd));
+}
+
+static inline int pmd_young(pmd_t pmd)
+{
+	return pte_young(pmd_pte(pmd));
+}
+
+static inline pmd_t pmd_mkold(pmd_t pmd)
+{
+	return pte_pmd(pte_mkold(pmd_pte(pmd)));
+}
+
+static inline pmd_t pmd_mkyoung(pmd_t pmd)
+{
+	return pte_pmd(pte_mkyoung(pmd_pte(pmd)));
+}
+
+static inline pmd_t pmd_mkwrite(pmd_t pmd)
+{
+	return pte_pmd(pte_mkwrite(pmd_pte(pmd)));
+}
+
+static inline pmd_t pmd_wrprotect(pmd_t pmd)
+{
+	return pte_pmd(pte_wrprotect(pmd_pte(pmd)));
+}
+
+static inline pmd_t pmd_mkclean(pmd_t pmd)
+{
+	return pte_pmd(pte_mkclean(pmd_pte(pmd)));
+}
+
+static inline pmd_t pmd_mkdirty(pmd_t pmd)
+{
+	return pte_pmd(pte_mkdirty(pmd_pte(pmd)));
+}
+
+static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+				pmd_t *pmdp, pmd_t pmd)
+{
+	return set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_trans_huge(pmd_t pmd)
+{
+	return pmd_leaf(pmd);
+}
+
+#define __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
+					unsigned long address, pmd_t *pmdp,
+					pmd_t entry, int dirty)
+{
+	return ptep_set_access_flags(vma, address, (pte_t *)pmdp, pmd_pte(entry), dirty);
+}
+
+#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
+static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+					unsigned long address, pmd_t *pmdp)
+{
+	return ptep_test_and_clear_young(vma, address, (pte_t *)pmdp);
+}
+
+#define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
+static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
+					unsigned long address, pmd_t *pmdp)
+{
+	return pte_pmd(ptep_get_and_clear(mm, address, (pte_t *)pmdp));
+}
+
+#define __HAVE_ARCH_PMDP_SET_WRPROTECT
+static inline void pmdp_set_wrprotect(struct mm_struct *mm,
+					unsigned long address, pmd_t *pmdp)
+{
+	ptep_set_wrprotect(mm, address, (pte_t *)pmdp);
+}
+
+#define pmdp_establish pmdp_establish
+static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
+				unsigned long address, pmd_t *pmdp, pmd_t pmd)
+{
+	return __pmd(atomic_long_xchg((atomic_long_t *)pmdp, pmd_val(pmd)));
+}
+
+#define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
+void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
+			unsigned long end);
+
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
 /*
  * Encode and decode a swap entry
  *

arch/riscv/mm/tlbflush.c

@@ -54,3 +54,10 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 {
 	__sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), start, end - start, PAGE_SIZE);
 }
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
+			unsigned long end)
+{
+	__sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), start, end - start, PMD_SIZE);
+}
+#endif