csky: MMU and page table management

This patch adds files related to memory management and here is our
memory-layout:

   Fixmap       : 0xffc02000 – 0xfffff000       (4 MB - 12KB)
   Pkmap        : 0xff800000 – 0xffc00000       (4 MB)
   Vmalloc      : 0xf0200000 – 0xff000000       (238 MB)
   Lowmem       : 0x80000000 – 0xc0000000       (1GB)

abiv1 CPU (CK610) is VIPT cache and it doesn't support highmem.
abiv2 CPUs are all PIPT cache and they could support highmem.

Lowmem is directly mapped by msa0 & msa1 reg, and we needn't setup
memory page table for it.

Link:https://lore.kernel.org/lkml/20180518215548.GH17671@n2100.armlinux.org.uk/
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

9 files changed, 655 insertions, 0 deletions

diff --git a/arch/csky/include/asm/addrspace.h b/arch/csky/include/asm/addrspace.h
new file mode 100644
index 000000000000..d1c2ede692ed
--- /dev/null
+++ b/arch/csky/include/asm/addrspace.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_ADDRSPACE_H
+#define __ASM_CSKY_ADDRSPACE_H
+
+#define KSEG0		0x80000000ul
+#define KSEG0ADDR(a)	(((unsigned long)a & 0x1fffffff) | KSEG0)
+
+#endif /* __ASM_CSKY_ADDRSPACE_H */
diff --git a/arch/csky/include/asm/fixmap.h b/arch/csky/include/asm/fixmap.h
new file mode 100644
index 000000000000..380ff0a307df
--- /dev/null
+++ b/arch/csky/include/asm/fixmap.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_FIXMAP_H
+#define __ASM_CSKY_FIXMAP_H
+
+#include <asm/page.h>
+#ifdef CONFIG_HIGHMEM
+#include <linux/threads.h>
+#include <asm/kmap_types.h>
+#endif
+
+enum fixed_addresses {
+#ifdef CONFIG_HIGHMEM
+	FIX_KMAP_BEGIN,
+	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
+#endif
+	__end_of_fixed_addresses
+};
+
+#define FIXADDR_TOP	0xffffc000
+#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
+#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
+
+#include <asm-generic/fixmap.h>
+
+#endif /* __ASM_CSKY_FIXMAP_H */
diff --git a/arch/csky/include/asm/highmem.h b/arch/csky/include/asm/highmem.h
new file mode 100644
index 000000000000..a345a2f2c22e
--- /dev/null
+++ b/arch/csky/include/asm/highmem.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_HIGHMEM_H
+#define __ASM_CSKY_HIGHMEM_H
+
+#ifdef __KERNEL__
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/uaccess.h>
+#include <asm/kmap_types.h>
+#include <asm/cache.h>
+
+/* undef for production */
+#define HIGHMEM_DEBUG 1
+
+/* declarations for highmem.c */
+extern unsigned long highstart_pfn, highend_pfn;
+
+extern pte_t *pkmap_page_table;
+
+/*
+ * Right now we initialize only a single pte table. It can be extended
+ * easily, subsequent pte tables have to be allocated in one physical
+ * chunk of RAM.
+ */
+#define LAST_PKMAP 1024
+#define LAST_PKMAP_MASK (LAST_PKMAP-1)
+#define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
+#define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
+
+extern void *kmap_high(struct page *page);
+extern void kunmap_high(struct page *page);
+
+extern void *kmap(struct page *page);
+extern void kunmap(struct page *page);
+extern void *kmap_atomic(struct page *page);
+extern void __kunmap_atomic(void *kvaddr);
+extern void *kmap_atomic_pfn(unsigned long pfn);
+extern struct page *kmap_atomic_to_page(void *ptr);
+
+#define flush_cache_kmaps() do {} while (0)
+
+extern void kmap_init(void);
+
+#define kmap_prot PAGE_KERNEL
+
+#endif /* __KERNEL__ */
+
+#endif /* __ASM_CSKY_HIGHMEM_H */
diff --git a/arch/csky/include/asm/mmu.h b/arch/csky/include/asm/mmu.h
new file mode 100644
index 000000000000..cb344675ccc4
--- /dev/null
+++ b/arch/csky/include/asm/mmu.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_MMU_H
+#define __ASM_CSKY_MMU_H
+
+typedef struct {
+	unsigned long asid[NR_CPUS];
+	void *vdso;
+} mm_context_t;
+
+#endif /* __ASM_CSKY_MMU_H */
diff --git a/arch/csky/include/asm/page.h b/arch/csky/include/asm/page.h
new file mode 100644
index 000000000000..73cf2bd66a13
--- /dev/null
+++ b/arch/csky/include/asm/page.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_CSKY_PAGE_H
+#define __ASM_CSKY_PAGE_H
+
+#include <asm/setup.h>
+#include <asm/cache.h>
+#include <linux/const.h>
+
+/*
+ * PAGE_SHIFT determines the page size
+ */
+#define PAGE_SHIFT	12
+#define PAGE_SIZE	(_AC(1, UL) << PAGE_SHIFT)
+#define PAGE_MASK	(~(PAGE_SIZE - 1))
+#define THREAD_SIZE	(PAGE_SIZE * 2)
+#define THREAD_MASK	(~(THREAD_SIZE - 1))
+#define THREAD_SHIFT	(PAGE_SHIFT + 1)
+
+/*
+ * NOTE: virtual isn't really correct, actually it should be the offset into the
+ * memory node, but we have no highmem, so that works for now.
+ * TODO: implement (fast) pfn<->pgdat_idx conversion functions, this makes lots
+ * of the shifts unnecessary.
+ */
+
+#ifndef __ASSEMBLY__
+
+#include <linux/pfn.h>
+
+#define virt_to_pfn(kaddr)      (__pa(kaddr) >> PAGE_SHIFT)
+#define pfn_to_virt(pfn)        __va((pfn) << PAGE_SHIFT)
+
+#define virt_addr_valid(kaddr)  ((void *)(kaddr) >= (void *)PAGE_OFFSET && \
+			(void *)(kaddr) < high_memory)
+#define pfn_valid(pfn)		((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
+
+extern void *memset(void *dest, int c, size_t l);
+extern void *memcpy(void *to, const void *from, size_t l);
+
+#define clear_page(page)	memset((page), 0, PAGE_SIZE)
+#define copy_page(to, from)	memcpy((to), (from), PAGE_SIZE)
+
+#define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)
+#define phys_to_page(paddr)	(pfn_to_page(PFN_DOWN(paddr)))
+
+struct page;
+
+#include <abi/page.h>
+
+struct vm_area_struct;
+
+/*
+ * These are used to make use of C type-checking..
+ */
+typedef struct { unsigned long pte_low; } pte_t;
+#define pte_val(x)	((x).pte_low)
+
+typedef struct { unsigned long pgd; } pgd_t;
+typedef struct { unsigned long pgprot; } pgprot_t;
+typedef struct page *pgtable_t;
+
+#define pgd_val(x)	((x).pgd)
+#define pgprot_val(x)	((x).pgprot)
+
+#define ptep_buddy(x)	((pte_t *)((unsigned long)(x) ^ sizeof(pte_t)))
+
+#define __pte(x)	((pte_t) { (x) })
+#define __pgd(x)	((pgd_t) { (x) })
+#define __pgprot(x)	((pgprot_t) { (x) })
+
+#endif /* !__ASSEMBLY__ */
+
+#define PHYS_OFFSET		(CONFIG_RAM_BASE & ~(LOWMEM_LIMIT - 1))
+#define PHYS_OFFSET_OFFSET	(CONFIG_RAM_BASE & (LOWMEM_LIMIT - 1))
+#define ARCH_PFN_OFFSET		PFN_DOWN(CONFIG_RAM_BASE)
+
+#define	PAGE_OFFSET	0x80000000
+#define LOWMEM_LIMIT	0x40000000
+
+#define __pa(x)		((unsigned long)(x) - PAGE_OFFSET + PHYS_OFFSET)
+#define __va(x)		((void *)((unsigned long)(x) + PAGE_OFFSET - \
+				  PHYS_OFFSET))
+#define __pa_symbol(x)	__pa(RELOC_HIDE((unsigned long)(x), 0))
+
+#define MAP_NR(x)	PFN_DOWN((unsigned long)(x) - PAGE_OFFSET - \
+				 PHYS_OFFSET_OFFSET)
+#define virt_to_page(x)	(mem_map + MAP_NR(x))
+
+#define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | VM_EXEC | \
+				VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
+
+/*
+ * main RAM and kernel working space are coincident at 0x80000000, but to make
+ * life more interesting, there's also an uncached virtual shadow at 0xb0000000
+ * - these mappings are fixed in the MMU
+ */
+
+#define pfn_to_kaddr(x)	__va(PFN_PHYS(x))
+
+#include <asm-generic/memory_model.h>
+#include <asm-generic/getorder.h>
+
+#endif /* __ASM_CSKY_PAGE_H */
diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
new file mode 100644
index 000000000000..bf4f4a0e140e
--- /dev/null
+++ b/arch/csky/include/asm/pgalloc.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_PGALLOC_H
+#define __ASM_CSKY_PGALLOC_H
+
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+
+static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
+					pte_t *pte)
+{
+	set_pmd(pmd, __pmd(__pa(pte)));
+}
+
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
+					pgtable_t pte)
+{
+	set_pmd(pmd, __pmd(__pa(page_address(pte))));
+}
+
+#define pmd_pgtable(pmd) pmd_page(pmd)
+
+extern void pgd_init(unsigned long *p);
+
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
+					unsigned long address)
+{
+	pte_t *pte;
+	unsigned long *kaddr, i;
+
+	pte = (pte_t *) __get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL,
+					 PTE_ORDER);
+	kaddr = (unsigned long *)pte;
+	if (address & 0x80000000)
+		for (i = 0; i < (PAGE_SIZE/4); i++)
+			*(kaddr + i) = 0x1;
+	else
+		clear_page(kaddr);
+
+	return pte;
+}
+
+static inline struct page *pte_alloc_one(struct mm_struct *mm,
+						unsigned long address)
+{
+	struct page *pte;
+	unsigned long *kaddr, i;
+
+	pte = alloc_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, PTE_ORDER);
+	if (pte) {
+		kaddr = kmap_atomic(pte);
+		if (address & 0x80000000) {
+			for (i = 0; i < (PAGE_SIZE/4); i++)
+				*(kaddr + i) = 0x1;
+		} else
+			clear_page(kaddr);
+		kunmap_atomic(kaddr);
+		pgtable_page_ctor(pte);
+	}
+	return pte;
+}
+
+static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+	free_pages((unsigned long)pte, PTE_ORDER);
+}
+
+static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
+{
+	pgtable_page_dtor(pte);
+	__free_pages(pte, PTE_ORDER);
+}
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+	free_pages((unsigned long)pgd, PGD_ORDER);
+}
+
+static inline pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *ret;
+	pgd_t *init;
+
+	ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER);
+	if (ret) {
+		init = pgd_offset(&init_mm, 0UL);
+		pgd_init((unsigned long *)ret);
+		memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
+			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+		/* prevent out of order excute */
+		smp_mb();
+#ifdef CONFIG_CPU_NEED_TLBSYNC
+		dcache_wb_range((unsigned int)ret,
+				(unsigned int)(ret + PTRS_PER_PGD));
+#endif
+	}
+
+	return ret;
+}
+
+#define __pte_free_tlb(tlb, pte, address)		\
+do {							\
+	pgtable_page_dtor(pte);				\
+	tlb_remove_page(tlb, pte);			\
+} while (0)
+
+#define check_pgt_cache()	do {} while (0)
+
+extern void pagetable_init(void);
+extern void pre_mmu_init(void);
+extern void pre_trap_init(void);
+
+#endif /* __ASM_CSKY_PGALLOC_H */
diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
new file mode 100644
index 000000000000..edfcbb25fd9f
--- /dev/null
+++ b/arch/csky/include/asm/pgtable.h
@@ -0,0 +1,306 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_PGTABLE_H
+#define __ASM_CSKY_PGTABLE_H
+
+#include <asm/fixmap.h>
+#include <asm/addrspace.h>
+#include <abi/pgtable-bits.h>
+#include <asm-generic/pgtable-nopmd.h>
+
+#define PGDIR_SHIFT		22
+#define PGDIR_SIZE		(1UL << PGDIR_SHIFT)
+#define PGDIR_MASK		(~(PGDIR_SIZE-1))
+
+#define USER_PTRS_PER_PGD	(0x80000000UL/PGDIR_SIZE)
+#define FIRST_USER_ADDRESS	0UL
+
+#define PKMAP_BASE		(0xff800000)
+
+#define VMALLOC_START		(0xc0008000)
+#define VMALLOC_END		(PKMAP_BASE - 2*PAGE_SIZE)
+
+/*
+ * C-SKY is two-level paging structure:
+ */
+#define PGD_ORDER	0
+#define PTE_ORDER	0
+
+#define PTRS_PER_PGD	((PAGE_SIZE << PGD_ORDER) / sizeof(pgd_t))
+#define PTRS_PER_PMD	1
+#define PTRS_PER_PTE	((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
+
+#define pte_ERROR(e) \
+	pr_err("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, (e).pte_low)
+#define pgd_ERROR(e) \
+	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
+
+/* Find an entry in the third-level page table.. */
+#define __pte_offset_t(address) \
+	(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
+#define pte_offset_kernel(dir, address) \
+	(pmd_page_vaddr(*(dir)) + __pte_offset_t(address))
+#define pte_offset_map(dir, address) \
+	((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset_t(address))
+#define pmd_page(pmd)	(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
+#define pte_clear(mm, addr, ptep)	set_pte((ptep), \
+			(((unsigned int)addr&0x80000000)?__pte(1):__pte(0)))
+#define pte_none(pte)	(!(pte_val(pte)&0xfffffffe))
+#define pte_present(pte)	(pte_val(pte) & _PAGE_PRESENT)
+#define pte_pfn(x)	((unsigned long)((x).pte_low >> PAGE_SHIFT))
+#define pfn_pte(pfn, prot) __pte(((unsigned long long)(pfn) << PAGE_SHIFT) \
+				| pgprot_val(prot))
+
+#define __READABLE	(_PAGE_READ | _PAGE_VALID | _PAGE_ACCESSED)
+#define __WRITEABLE	(_PAGE_WRITE | _PAGE_DIRTY | _PAGE_MODIFIED)
+
+#define _PAGE_CHG_MASK	(PAGE_MASK | _PAGE_ACCESSED | _PAGE_MODIFIED | \
+			 _CACHE_MASK)
+
+#define pte_unmap(pte)	((void)(pte))
+
+#define __swp_type(x)			(((x).val >> 4) & 0xff)
+#define __swp_offset(x)			((x).val >> 12)
+#define __swp_entry(type, offset)	((swp_entry_t) {((type) << 4) | \
+					((offset) << 12) })
+#define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) })
+#define __swp_entry_to_pte(x)		((pte_t) { (x).val })
+
+#define pte_page(x)			pfn_to_page(pte_pfn(x))
+#define __mk_pte(page_nr, pgprot)	__pte(((page_nr) << PAGE_SHIFT) | \
+					pgprot_val(pgprot))
+
+/*
+ * CSKY can't do page protection for execute, and considers that the same like
+ * read. Also, write permissions imply read permissions. This is the closest
+ * we can get by reasonable means..
+ */
+#define PAGE_NONE	__pgprot(_PAGE_PRESENT | _CACHE_CACHED)
+#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+				_CACHE_CACHED)
+#define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_READ | _CACHE_CACHED)
+#define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_READ | _CACHE_CACHED)
+#define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
+				_PAGE_GLOBAL | _CACHE_CACHED)
+#define PAGE_USERIO	__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | \
+				_CACHE_CACHED)
+
+#define __P000	PAGE_NONE
+#define __P001	PAGE_READONLY
+#define __P010	PAGE_COPY
+#define __P011	PAGE_COPY
+#define __P100	PAGE_READONLY
+#define __P101	PAGE_READONLY
+#define __P110	PAGE_COPY
+#define __P111	PAGE_COPY
+
+#define __S000	PAGE_NONE
+#define __S001	PAGE_READONLY
+#define __S010	PAGE_SHARED
+#define __S011	PAGE_SHARED
+#define __S100	PAGE_READONLY
+#define __S101	PAGE_READONLY
+#define __S110	PAGE_SHARED
+#define __S111	PAGE_SHARED
+
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
+
+extern void load_pgd(unsigned long pg_dir);
+extern pte_t invalid_pte_table[PTRS_PER_PTE];
+
+static inline int pte_special(pte_t pte) { return 0; }
+static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
+
+static inline void set_pte(pte_t *p, pte_t pte)
+{
+	*p = pte;
+#if defined(CONFIG_CPU_NEED_TLBSYNC)
+	dcache_wb_line((u32)p);
+#endif
+	/* prevent out of order excution */
+	smp_mb();
+}
+#define set_pte_at(mm, addr, ptep, pteval) set_pte(ptep, pteval)
+
+static inline pte_t *pmd_page_vaddr(pmd_t pmd)
+{
+	unsigned long ptr;
+
+	ptr = pmd_val(pmd);
+
+	return __va(ptr);
+}
+
+#define pmd_phys(pmd) pmd_val(pmd)
+
+static inline void set_pmd(pmd_t *p, pmd_t pmd)
+{
+	*p = pmd;
+#if defined(CONFIG_CPU_NEED_TLBSYNC)
+	dcache_wb_line((u32)p);
+#endif
+	/* prevent specul excute */
+	smp_mb();
+}
+
+
+static inline int pmd_none(pmd_t pmd)
+{
+	return pmd_val(pmd) == __pa(invalid_pte_table);
+}
+
+#define pmd_bad(pmd)	(pmd_val(pmd) & ~PAGE_MASK)
+
+static inline int pmd_present(pmd_t pmd)
+{
+	return (pmd_val(pmd) != __pa(invalid_pte_table));
+}
+
+static inline void pmd_clear(pmd_t *p)
+{
+	pmd_val(*p) = (__pa(invalid_pte_table));
+#if defined(CONFIG_CPU_NEED_TLBSYNC)
+	dcache_wb_line((u32)p);
+#endif
+}
+
+/*
+ * The following only work if pte_present() is true.
+ * Undefined behaviour if not..
+ */
+static inline int pte_read(pte_t pte)
+{
+	return pte.pte_low & _PAGE_READ;
+}
+
+static inline int pte_write(pte_t pte)
+{
+	return (pte).pte_low & _PAGE_WRITE;
+}
+
+static inline int pte_dirty(pte_t pte)
+{
+	return (pte).pte_low & _PAGE_MODIFIED;
+}
+
+static inline int pte_young(pte_t pte)
+{
+	return (pte).pte_low & _PAGE_ACCESSED;
+}
+
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+	pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_DIRTY);
+	return pte;
+}
+
+static inline pte_t pte_mkclean(pte_t pte)
+{
+	pte_val(pte) &= ~(_PAGE_MODIFIED|_PAGE_DIRTY);
+	return pte;
+}
+
+static inline pte_t pte_mkold(pte_t pte)
+{
+	pte_val(pte) &= ~(_PAGE_ACCESSED|_PAGE_VALID);
+	return pte;
+}
+
+static inline pte_t pte_mkwrite(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_WRITE;
+	if (pte_val(pte) & _PAGE_MODIFIED)
+		pte_val(pte) |= _PAGE_DIRTY;
+	return pte;
+}
+
+static inline pte_t pte_mkdirty(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_MODIFIED;
+	if (pte_val(pte) & _PAGE_WRITE)
+		pte_val(pte) |= _PAGE_DIRTY;
+	return pte;
+}
+
+static inline pte_t pte_mkyoung(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_ACCESSED;
+	if (pte_val(pte) & _PAGE_READ)
+		pte_val(pte) |= _PAGE_VALID;
+	return pte;
+}
+
+#define __pgd_offset(address)	pgd_index(address)
+#define __pud_offset(address)	(((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
+#define __pmd_offset(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
+
+/* to find an entry in a kernel page-table-directory */
+#define pgd_offset_k(address)	pgd_offset(&init_mm, address)
+
+#define pgd_index(address)	((address) >> PGDIR_SHIFT)
+
+/*
+ * Macro to make mark a page protection value as "uncacheable".  Note
+ * that "protection" is really a misnomer here as the protection value
+ * contains the memory attribute bits, dirty bits, and various other
+ * bits as well.
+ */
+#define pgprot_noncached pgprot_noncached
+
+static inline pgprot_t pgprot_noncached(pgprot_t _prot)
+{
+	unsigned long prot = pgprot_val(_prot);
+
+	prot = (prot & ~_CACHE_MASK) | _CACHE_UNCACHED;
+
+	return __pgprot(prot);
+}
+
+/*
+ * Conversion functions: convert a page and protection to a page entry,
+ * and a page entry and page directory to the page they refer to.
+ */
+#define mk_pte(page, pgprot)    pfn_pte(page_to_pfn(page), (pgprot))
+static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
+{
+	return __pte((pte_val(pte) & _PAGE_CHG_MASK) |
+		     (pgprot_val(newprot)));
+}
+
+/* to find an entry in a page-table-directory */
+static inline pgd_t *pgd_offset(struct mm_struct *mm, unsigned long address)
+{
+	return mm->pgd + pgd_index(address);
+}
+
+/* Find an entry in the third-level page table.. */
+static inline pte_t *pte_offset(pmd_t *dir, unsigned long address)
+{
+	return (pte_t *) (pmd_page_vaddr(*dir)) +
+		((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
+}
+
+extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
+extern void paging_init(void);
+
+extern void show_jtlb_table(void);
+
+void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
+		      pte_t *pte);
+
+/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
+#define kern_addr_valid(addr)	(1)
+
+/*
+ * No page table caches to initialise
+ */
+#define pgtable_cache_init()	do {} while (0)
+
+#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
+	remap_pfn_range(vma, vaddr, pfn, size, prot)
+
+#include <asm-generic/pgtable.h>
+
+#endif /* __ASM_CSKY_PGTABLE_H */
diff --git a/arch/csky/include/asm/segment.h b/arch/csky/include/asm/segment.h
new file mode 100644
index 000000000000..ffdc4c47ff43
--- /dev/null
+++ b/arch/csky/include/asm/segment.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_SEGMENT_H
+#define __ASM_CSKY_SEGMENT_H
+
+typedef struct {
+	unsigned long seg;
+} mm_segment_t;
+
+#define KERNEL_DS		((mm_segment_t) { 0xFFFFFFFF })
+#define get_ds()		KERNEL_DS
+
+#define USER_DS			((mm_segment_t) { 0x80000000UL })
+#define get_fs()		(current_thread_info()->addr_limit)
+#define set_fs(x)		(current_thread_info()->addr_limit = (x))
+#define segment_eq(a, b)	((a).seg == (b).seg)
+
+#endif /* __ASM_CSKY_SEGMENT_H */
diff --git a/arch/csky/include/asm/shmparam.h b/arch/csky/include/asm/shmparam.h
new file mode 100644
index 000000000000..efafe4c79fed
--- /dev/null
+++ b/arch/csky/include/asm/shmparam.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_SHMPARAM_H
+#define __ASM_CSKY_SHMPARAM_H
+
+#define SHMLBA	(4 * PAGE_SIZE)
+
+#define __ARCH_FORCE_SHMLBA
+
+#endif /* __ASM_CSKY_SHMPARAM_H */