nios2: Page table management

This patch adds support for page table management.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

4 files changed, 505 insertions, 0 deletions

diff --git a/arch/nios2/include/asm/pgalloc.h b/arch/nios2/include/asm/pgalloc.h
new file mode 100644
index 000000000000..6e2985e0a7b9
--- /dev/null
+++ b/arch/nios2/include/asm/pgalloc.h
@@ -0,0 +1,86 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1994 - 2001, 2003 by Ralf Baechle
+ * Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
+ */
+
+#ifndef _ASM_NIOS2_PGALLOC_H
+#define _ASM_NIOS2_PGALLOC_H
+
+#include <linux/mm.h>
+
+static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
+        pte_t *pte)
+{
+        set_pmd(pmd, __pmd((unsigned long)pte));
+}
+
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
+        pgtable_t pte)
+{
+        set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
+}
+#define pmd_pgtable(pmd) pmd_page(pmd)
+
+/*
+ * Initialize a new pmd table with invalid pointers.
+ */
+extern void pmd_init(unsigned long page, unsigned long pagetable);
+
+extern pgd_t *pgd_alloc(struct mm_struct *mm);
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+        free_pages((unsigned long)pgd, PGD_ORDER);
+}
+
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
+        unsigned long address)
+{
+        pte_t *pte;
+
+        pte = (pte_t *) __get_free_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO,
+                                        PTE_ORDER);
+
+        return pte;
+}
+
+static inline pgtable_t pte_alloc_one(struct mm_struct *mm,
+        unsigned long address)
+{
+        struct page *pte;
+
+        pte = alloc_pages(GFP_KERNEL | __GFP_REPEAT, PTE_ORDER);
+        if (pte) {
+                if (!pgtable_page_ctor(pte)) {
+                        __free_page(pte);
+                        return NULL;
+                }
+                clear_highpage(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, struct page *pte)
+{
+        pgtable_page_dtor(pte);
+        __free_pages(pte, PTE_ORDER);
+}
+
+#define __pte_free_tlb(tlb, pte, addr)                          \
+        do {                                                    \
+                pgtable_page_dtor(pte);                         \
+                tlb_remove_page((tlb), (pte));                  \
+        } while (0)
+
+#define check_pgt_cache()       do { } while (0)
+
+#endif /* _ASM_NIOS2_PGALLOC_H */
diff --git a/arch/nios2/include/asm/pgtable-bits.h b/arch/nios2/include/asm/pgtable-bits.h
new file mode 100644
index 000000000000..ce9e7069aa96
--- /dev/null
+++ b/arch/nios2/include/asm/pgtable-bits.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009 Wind River Systems Inc
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_PGTABLE_BITS_H
+#define _ASM_NIOS2_PGTABLE_BITS_H
+
+/*
+ * These are actual hardware defined protection bits in the tlbacc register
+ * which looks like this:
+ *
+ * 31 30 ... 26 25 24 23 22 21 20 19 18 ...  1  0
+ * ignored........  C  R  W  X  G PFN............
+ */
+#define _PAGE_GLOBAL    (1<<20)
+#define _PAGE_EXEC      (1<<21)
+#define _PAGE_WRITE     (1<<22)
+#define _PAGE_READ      (1<<23)
+#define _PAGE_CACHED    (1<<24) /* C: data access cacheable */
+
+/*
+ * Software defined bits. They are ignored by the hardware and always read back
+ * as zero, but can be written as non-zero.
+ */
+#define _PAGE_PRESENT   (1<<25) /* PTE contains a translation */
+#define _PAGE_ACCESSED  (1<<26) /* page referenced */
+#define _PAGE_DIRTY     (1<<27) /* dirty page */
+#define _PAGE_FILE      (1<<28) /* PTE used for file mapping or swap */
+
+#endif /* _ASM_NIOS2_PGTABLE_BITS_H */
diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
new file mode 100644
index 000000000000..ccbaffd47671
--- /dev/null
+++ b/arch/nios2/include/asm/pgtable.h
@@ -0,0 +1,310 @@
+/*
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009 Wind River Systems Inc
+ *
+ * Based on asm/pgtable-32.h from mips which is:
+ *
+ * Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 2003 Ralf Baechle
+ * Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_PGTABLE_H
+#define _ASM_NIOS2_PGTABLE_H
+
+#include <linux/io.h>
+#include <linux/bug.h>
+#include <asm/page.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+#include <asm/pgtable-bits.h>
+#include <asm-generic/pgtable-nopmd.h>
+
+#define FIRST_USER_ADDRESS      0
+
+#define VMALLOC_START           CONFIG_NIOS2_KERNEL_MMU_REGION_BASE
+#define VMALLOC_END             (CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
+
+struct mm_struct;
+
+/* Helper macro */
+#define MKP(x, w, r) __pgprot(_PAGE_PRESENT | _PAGE_CACHED |            \
+                                ((x) ? _PAGE_EXEC : 0) |                \
+                                ((r) ? _PAGE_READ : 0) |                \
+                                ((w) ? _PAGE_WRITE : 0))
+/*
+ * These are the macros that generic kernel code needs
+ * (to populate protection_map[])
+ */
+
+/* Remove W bit on private pages for COW support */
+#define __P000  MKP(0, 0, 0)
+#define __P001  MKP(0, 0, 1)
+#define __P010  MKP(0, 0, 0)    /* COW */
+#define __P011  MKP(0, 0, 1)    /* COW */
+#define __P100  MKP(1, 0, 0)
+#define __P101  MKP(1, 0, 1)
+#define __P110  MKP(1, 0, 0)    /* COW */
+#define __P111  MKP(1, 0, 1)    /* COW */
+
+/* Shared pages can have exact HW mapping */
+#define __S000  MKP(0, 0, 0)
+#define __S001  MKP(0, 0, 1)
+#define __S010  MKP(0, 1, 0)
+#define __S011  MKP(0, 1, 1)
+#define __S100  MKP(1, 0, 0)
+#define __S101  MKP(1, 0, 1)
+#define __S110  MKP(1, 1, 0)
+#define __S111  MKP(1, 1, 1)
+
+/* Used all over the kernel */
+#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_CACHED | _PAGE_READ | \
+                             _PAGE_WRITE | _PAGE_EXEC | _PAGE_GLOBAL)
+
+#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_CACHED | _PAGE_READ | \
+                             _PAGE_WRITE | _PAGE_ACCESSED)
+
+#define PAGE_COPY MKP(0, 0, 1)
+
+#define PGD_ORDER       0
+#define PTE_ORDER       0
+
+#define PTRS_PER_PGD    ((PAGE_SIZE << PGD_ORDER) / sizeof(pgd_t))
+#define PTRS_PER_PTE    ((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
+
+#define USER_PTRS_PER_PGD       \
+        (CONFIG_NIOS2_KERNEL_MMU_REGION_BASE / PGDIR_SIZE)
+
+#define PGDIR_SHIFT     22
+#define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
+#define PGDIR_MASK      (~(PGDIR_SIZE-1))
+
+/*
+ * ZERO_PAGE is a global shared page that is always zero: used
+ * for zero-mapped memory areas etc..
+ */
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr)        (virt_to_page(empty_zero_page))
+
+extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
+extern pte_t invalid_pte_table[PAGE_SIZE/sizeof(pte_t)];
+
+/*
+ * (pmds are folded into puds so this doesn't get actually called,
+ * but the define is needed for a generic inline function.)
+ */
+static inline void set_pmd(pmd_t *pmdptr, pmd_t pmdval)
+{
+        pmdptr->pud.pgd.pgd = pmdval.pud.pgd.pgd;
+}
+
+/* to find an entry in a page-table-directory */
+#define pgd_index(addr)         (((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
+#define pgd_offset(mm, addr)    ((mm)->pgd + pgd_index(addr))
+
+static inline int pte_write(pte_t pte)          \
+        { return pte_val(pte) & _PAGE_WRITE; }
+static inline int pte_dirty(pte_t pte)          \
+        { return pte_val(pte) & _PAGE_DIRTY; }
+static inline int pte_young(pte_t pte)          \
+        { return pte_val(pte) & _PAGE_ACCESSED; }
+static inline int pte_file(pte_t pte)           \
+        { return pte_val(pte) & _PAGE_FILE; }
+static inline int pte_special(pte_t pte)        { return 0; }
+
+#define pgprot_noncached pgprot_noncached
+
+static inline pgprot_t pgprot_noncached(pgprot_t _prot)
+{
+        unsigned long prot = pgprot_val(_prot);
+
+        prot &= ~_PAGE_CACHED;
+
+        return __pgprot(prot);
+}
+
+static inline int pte_none(pte_t pte)
+{
+        return !(pte_val(pte) & ~(_PAGE_GLOBAL|0xf));
+}
+
+static inline int pte_present(pte_t pte)        \
+        { return pte_val(pte) & _PAGE_PRESENT; }
+
+/*
+ * The following only work if pte_present() is true.
+ * Undefined behaviour if not..
+ */
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+        pte_val(pte) &= ~_PAGE_WRITE;
+        return pte;
+}
+
+static inline pte_t pte_mkclean(pte_t pte)
+{
+        pte_val(pte) &= ~_PAGE_DIRTY;
+        return pte;
+}
+
+static inline pte_t pte_mkold(pte_t pte)
+{
+        pte_val(pte) &= ~_PAGE_ACCESSED;
+        return pte;
+}
+
+static inline pte_t pte_mkwrite(pte_t pte)
+{
+        pte_val(pte) |= _PAGE_WRITE;
+        return pte;
+}
+
+static inline pte_t pte_mkdirty(pte_t pte)
+{
+        pte_val(pte) |= _PAGE_DIRTY;
+        return pte;
+}
+
+static inline pte_t pte_mkspecial(pte_t pte)    { return pte; }
+
+static inline pte_t pte_mkyoung(pte_t pte)
+{
+        pte_val(pte) |= _PAGE_ACCESSED;
+        return pte;
+}
+
+static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
+{
+        const unsigned long mask = _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC;
+
+        pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
+        return pte;
+}
+
+static inline int pmd_present(pmd_t pmd)
+{
+        return (pmd_val(pmd) != (unsigned long) invalid_pte_table)
+                        && (pmd_val(pmd) != 0UL);
+}
+
+static inline void pmd_clear(pmd_t *pmdp)
+{
+        pmd_val(*pmdp) = (unsigned long) invalid_pte_table;
+}
+
+#define pte_pfn(pte)            (pte_val(pte) & 0xfffff)
+#define pfn_pte(pfn, prot)      (__pte(pfn | pgprot_val(prot)))
+#define pte_page(pte)           (pfn_to_page(pte_pfn(pte)))
+
+/*
+ * Store a linux PTE into the linux page table.
+ */
+static inline void set_pte(pte_t *ptep, pte_t pteval)
+{
+        *ptep = pteval;
+}
+
+static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
+                              pte_t *ptep, pte_t pteval)
+{
+        unsigned long paddr = page_to_virt(pte_page(pteval));
+
+        flush_dcache_range(paddr, paddr + PAGE_SIZE);
+        set_pte(ptep, pteval);
+}
+
+static inline int pmd_none(pmd_t pmd)
+{
+        return (pmd_val(pmd) ==
+                (unsigned long) invalid_pte_table) || (pmd_val(pmd) == 0UL);
+}
+
+#define pmd_bad(pmd)    (pmd_val(pmd) & ~PAGE_MASK)
+
+static inline void pte_clear(struct mm_struct *mm,
+                                unsigned long addr, pte_t *ptep)
+{
+        pte_t null;
+
+        pte_val(null) = (addr >> PAGE_SHIFT) & 0xf;
+
+        set_pte_at(mm, addr, ptep, null);
+        flush_tlb_one(addr);
+}
+
+/*
+ * 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, prot)      (pfn_pte(page_to_pfn(page), prot))
+
+#define pte_unmap(pte)  do { } while (0)
+
+/*
+ * 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 pmd_phys(pmd)           virt_to_phys((void *)pmd_val(pmd))
+#define pmd_page(pmd)           (pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
+#define pmd_page_vaddr(pmd)     pmd_val(pmd)
+
+#define pte_offset_map(dir, addr)                       \
+        ((pte_t *) page_address(pmd_page(*dir)) +       \
+         (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
+
+/* to find an entry in a kernel page-table-directory */
+#define pgd_offset_k(addr)      pgd_offset(&init_mm, addr)
+
+/* Get the address to the PTE for a vaddr in specific directory */
+#define pte_offset_kernel(dir, addr)                    \
+        ((pte_t *) pmd_page_vaddr(*(dir)) +             \
+         (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
+
+#define pte_ERROR(e) \
+        pr_err("%s:%d: bad pte %08lx.\n", \
+                __FILE__, __LINE__, pte_val(e))
+#define pgd_ERROR(e) \
+        pr_err("%s:%d: bad pgd %08lx.\n", \
+                __FILE__, __LINE__, pgd_val(e))
+
+/*
+ * Encode and decode a swap entry (must be !pte_none(pte) && !pte_present(pte)
+ * && !pte_file(pte)):
+ *
+ * 31 30 29 28 27 26 25 24 23 22 21 20 19 18 ...  1  0
+ *  0  0  0  0 type.  0  0  0  0  0  0 offset.........
+ *
+ * This gives us up to 2**2 = 4 swap files and 2**20 * 4K = 4G per swap file.
+ *
+ * Note that the offset field is always non-zero, thus !pte_none(pte) is always
+ * true.
+ */
+#define __swp_type(swp)         (((swp).val >> 26) & 0x3)
+#define __swp_offset(swp)       ((swp).val & 0xfffff)
+#define __swp_entry(type, off)  ((swp_entry_t) { (((type) & 0x3) << 26) \
+                                                 | ((off) & 0xfffff) })
+#define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
+#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
+
+/* Encode and decode a nonlinear file mapping entry */
+#define PTE_FILE_MAX_BITS       25
+#define pte_to_pgoff(pte)       (pte_val(pte) & 0x1ffffff)
+#define pgoff_to_pte(off)       __pte(((off) & 0x1ffffff) | _PAGE_FILE)
+
+#define kern_addr_valid(addr)           (1)
+
+#include <asm-generic/pgtable.h>
+
+#define pgtable_cache_init()            do { } while (0)
+
+extern void __init paging_init(void);
+extern void __init mmu_init(void);
+
+extern void update_mmu_cache(struct vm_area_struct *vma,
+                             unsigned long address, pte_t *pte);
+
+#endif /* _ASM_NIOS2_PGTABLE_H */
diff --git a/arch/nios2/mm/pgtable.c b/arch/nios2/mm/pgtable.c
new file mode 100644
index 000000000000..61e24a25f71a
--- /dev/null
+++ b/arch/nios2/mm/pgtable.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2009 Wind River Systems Inc
+ *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+
+#include <asm/pgtable.h>
+#include <asm/cpuinfo.h>
+
+/* pteaddr:
+ *   ptbase | vpn* | zero
+ *   31-22  | 21-2 | 1-0
+ *
+ *   *vpn is preserved on double fault
+ *
+ * tlbacc:
+ *   IG   |*flags| pfn
+ *   31-25|24-20 | 19-0
+ *
+ *   *crwxg
+ *
+ * tlbmisc:
+ *   resv  |way   |rd | we|pid |dbl|bad|perm|d
+ *   31-24 |23-20 |19 | 20|17-4|3  |2  |1   |0
+ *
+ */
+
+/*
+ * Initialize a new pgd / pmd table with invalid pointers.
+ */
+static void pgd_init(pgd_t *pgd)
+{
+        unsigned long *p = (unsigned long *) pgd;
+        int i;
+
+        for (i = 0; i < USER_PTRS_PER_PGD; i += 8) {
+                p[i + 0] = (unsigned long) invalid_pte_table;
+                p[i + 1] = (unsigned long) invalid_pte_table;
+                p[i + 2] = (unsigned long) invalid_pte_table;
+                p[i + 3] = (unsigned long) invalid_pte_table;
+                p[i + 4] = (unsigned long) invalid_pte_table;
+                p[i + 5] = (unsigned long) invalid_pte_table;
+                p[i + 6] = (unsigned long) invalid_pte_table;
+                p[i + 7] = (unsigned long) invalid_pte_table;
+        }
+}
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+        pgd_t *ret, *init;
+
+        ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER);
+        if (ret) {
+                init = pgd_offset(&init_mm, 0UL);
+                pgd_init(ret);
+                memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
+                       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+        }
+
+        return ret;
+}
+
+void __init pagetable_init(void)
+{
+        /* Initialize the entire pgd.  */
+        pgd_init(swapper_pg_dir);
+        pgd_init(swapper_pg_dir + USER_PTRS_PER_PGD);
+}