source: mainline/kernel/arch/arm32/include/mm/page.h@ 82474ef

/*
 * Copyright (c) 2007 Pavel Jancik, Michal Kebrt
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup arm32mm 
 * @{
 */
/** @file
 *  @brief Paging related declarations.
 */

#ifndef KERN_arm32_PAGE_H_
#define KERN_arm32_PAGE_H_

#include <arch/mm/frame.h>
#include <mm/mm.h>
#include <arch/exception.h>

#define PAGE_WIDTH      FRAME_WIDTH
#define PAGE_SIZE       FRAME_SIZE

#ifndef __ASM__
#       define KA2PA(x) (((uintptr_t) (x)) - 0x80000000)
#       define PA2KA(x) (((uintptr_t) (x)) + 0x80000000)
#else
#       define KA2PA(x) ((x) - 0x80000000)
#       define PA2KA(x) ((x) + 0x80000000)
#endif

#ifdef KERNEL

/* Number of entries in each level. */
#define PTL0_ENTRIES_ARCH       (2 << 12)       /* 4096 */
#define PTL1_ENTRIES_ARCH       0
#define PTL2_ENTRIES_ARCH       0
/* coarse page tables used (256 * 4 = 1KB per page) */
#define PTL3_ENTRIES_ARCH       (2 << 8)        /* 256 */

/* Page table sizes for each level. */
#define PTL0_SIZE_ARCH          FOUR_FRAMES
#define PTL1_SIZE_ARCH          0
#define PTL2_SIZE_ARCH          0
#define PTL3_SIZE_ARCH          ONE_FRAME

/* Macros calculating indices into page tables for each level. */
#define PTL0_INDEX_ARCH(vaddr)  (((vaddr) >> 20) & 0xfff)
#define PTL1_INDEX_ARCH(vaddr)  0
#define PTL2_INDEX_ARCH(vaddr)  0
#define PTL3_INDEX_ARCH(vaddr)  (((vaddr) >> 12) & 0x0ff)

/* Get PTE address accessors for each level. */
#define GET_PTL1_ADDRESS_ARCH(ptl0, i) \
        ((pte_t *) ((((pte_t *)(ptl0))[(i)].l0).coarse_table_addr << 10))
#define GET_PTL2_ADDRESS_ARCH(ptl1, i) \
        (ptl1)
#define GET_PTL3_ADDRESS_ARCH(ptl2, i) \
        (ptl2)
#define GET_FRAME_ADDRESS_ARCH(ptl3, i) \
        ((uintptr_t) ((((pte_t *)(ptl3))[(i)].l1).frame_base_addr << 12))

/* Set PTE address accessors for each level. */
#define SET_PTL0_ADDRESS_ARCH(ptl0) \
        (set_ptl0_addr((pte_t *) (ptl0)))
#define SET_PTL1_ADDRESS_ARCH(ptl0, i, a) \
        (((pte_t *) (ptl0))[(i)].l0.coarse_table_addr = (a) >> 10)
#define SET_PTL2_ADDRESS_ARCH(ptl1, i, a)
#define SET_PTL3_ADDRESS_ARCH(ptl2, i, a)
#define SET_FRAME_ADDRESS_ARCH(ptl3, i, a) \
        (((pte_t *) (ptl3))[(i)].l1.frame_base_addr = (a) >> 12)

/* Get PTE flags accessors for each level. */
#define GET_PTL1_FLAGS_ARCH(ptl0, i) \
        get_pt_level0_flags((pte_t *) (ptl0), (size_t) (i))
#define GET_PTL2_FLAGS_ARCH(ptl1, i) \
        PAGE_PRESENT
#define GET_PTL3_FLAGS_ARCH(ptl2, i) \
        PAGE_PRESENT
#define GET_FRAME_FLAGS_ARCH(ptl3, i) \
        get_pt_level1_flags((pte_t *) (ptl3), (size_t) (i))

/* Set PTE flags accessors for each level. */
#define SET_PTL1_FLAGS_ARCH(ptl0, i, x) \
        set_pt_level0_flags((pte_t *) (ptl0), (size_t) (i), (x))
#define SET_PTL2_FLAGS_ARCH(ptl1, i, x)
#define SET_PTL3_FLAGS_ARCH(ptl2, i, x)
#define SET_FRAME_FLAGS_ARCH(ptl3, i, x) \
        set_pt_level1_flags((pte_t *) (ptl3), (size_t) (i), (x))

/* Macros for querying the last-level PTE entries. */
#define PTE_VALID_ARCH(pte) \
        (*((uint32_t *) (pte)) != 0)
#define PTE_PRESENT_ARCH(pte) \
        (((pte_t *) (pte))->l0.descriptor_type != 0)
#define PTE_GET_FRAME_ARCH(pte) \
        (((pte_t *) (pte))->l1.frame_base_addr << FRAME_WIDTH)
#define PTE_WRITABLE_ARCH(pte) \
        (((pte_t *) (pte))->l1.access_permission_0 == PTE_AP_USER_RW_KERNEL_RW)
#define PTE_EXECUTABLE_ARCH(pte) \
        1

#ifndef __ASM__

/** Level 0 page table entry. */
typedef struct {
        /* 0b01 for coarse tables, see below for details */
        unsigned descriptor_type : 2;
        unsigned impl_specific : 3;
        unsigned domain : 4;
        unsigned should_be_zero : 1;

        /* Pointer to the coarse 2nd level page table (holding entries for small
         * (4KB) or large (64KB) pages. ARM also supports fine 2nd level page
         * tables that may hold even tiny pages (1KB) but they are bigger (4KB
         * per table in comparison with 1KB per the coarse table)
         */
        unsigned coarse_table_addr : 22;
} ATTRIBUTE_PACKED pte_level0_t;

/** Level 1 page table entry (small (4KB) pages used). */
typedef struct {

        /* 0b10 for small pages */
        unsigned descriptor_type : 2;
        unsigned bufferable : 1;
        unsigned cacheable : 1;

        /* access permissions for each of 4 subparts of a page
         * (for each 1KB when small pages used */
        unsigned access_permission_0 : 2;
        unsigned access_permission_1 : 2;
        unsigned access_permission_2 : 2;
        unsigned access_permission_3 : 2;
        unsigned frame_base_addr : 20;
} ATTRIBUTE_PACKED pte_level1_t;

typedef union {
        pte_level0_t l0;
        pte_level1_t l1;
} pte_t;

/* Level 1 page tables access permissions */

/** User mode: no access, privileged mode: no access. */
#define PTE_AP_USER_NO_KERNEL_NO        0

/** User mode: no access, privileged mode: read/write. */
#define PTE_AP_USER_NO_KERNEL_RW        1

/** User mode: read only, privileged mode: read/write. */
#define PTE_AP_USER_RO_KERNEL_RW        2

/** User mode: read/write, privileged mode: read/write. */
#define PTE_AP_USER_RW_KERNEL_RW        3


/* pte_level0_t and pte_level1_t descriptor_type flags */

/** pte_level0_t and pte_level1_t "not present" flag (used in descriptor_type). */
#define PTE_DESCRIPTOR_NOT_PRESENT      0

/** pte_level0_t coarse page table flag (used in descriptor_type). */
#define PTE_DESCRIPTOR_COARSE_TABLE     1

/** pte_level1_t small page table flag (used in descriptor type). */
#define PTE_DESCRIPTOR_SMALL_PAGE       2


/** Sets the address of level 0 page table.
 *
 * @param pt    Pointer to the page table to set.
 */   
static inline void set_ptl0_addr(pte_t *pt)
{
        asm volatile (
                "mcr p15, 0, %[pt], c2, c0, 0\n"
                :: [pt] "r" (pt)
        );
}


/** Returns level 0 page table entry flags.
 *
 *  @param pt     Level 0 page table.
 *  @param i      Index of the entry to return.
 */
static inline int get_pt_level0_flags(pte_t *pt, size_t i)
{
        pte_level0_t *p = &pt[i].l0;
        int np = (p->descriptor_type == PTE_DESCRIPTOR_NOT_PRESENT);

        return (np << PAGE_PRESENT_SHIFT) | (1 << PAGE_USER_SHIFT) |
            (1 << PAGE_READ_SHIFT) | (1 << PAGE_WRITE_SHIFT) |
            (1 << PAGE_EXEC_SHIFT) | (1 << PAGE_CACHEABLE_SHIFT);
}

/** Returns level 1 page table entry flags.
 *
 *  @param pt     Level 1 page table.
 *  @param i      Index of the entry to return.
 */
static inline int get_pt_level1_flags(pte_t *pt, size_t i)
{
        pte_level1_t *p = &pt[i].l1;

        int dt = p->descriptor_type;
        int ap = p->access_permission_0;

        return ((dt == PTE_DESCRIPTOR_NOT_PRESENT) << PAGE_PRESENT_SHIFT) |
            ((ap == PTE_AP_USER_RO_KERNEL_RW) << PAGE_READ_SHIFT) |
            ((ap == PTE_AP_USER_RW_KERNEL_RW) << PAGE_READ_SHIFT) |
            ((ap == PTE_AP_USER_RW_KERNEL_RW) << PAGE_WRITE_SHIFT) |
            ((ap != PTE_AP_USER_NO_KERNEL_RW) << PAGE_USER_SHIFT) |
            ((ap == PTE_AP_USER_NO_KERNEL_RW) << PAGE_READ_SHIFT) |
            ((ap == PTE_AP_USER_NO_KERNEL_RW) << PAGE_WRITE_SHIFT) |
            (1 << PAGE_EXEC_SHIFT) |
            (p->bufferable << PAGE_CACHEABLE);
}


/** Sets flags of level 0 page table entry.
 *
 *  @param pt     level 0 page table
 *  @param i      index of the entry to be changed
 *  @param flags  new flags
 */
static inline void set_pt_level0_flags(pte_t *pt, size_t i, int flags)
{
        pte_level0_t *p = &pt[i].l0;

        if (flags & PAGE_NOT_PRESENT) {
                p->descriptor_type = PTE_DESCRIPTOR_NOT_PRESENT;
                /*
                 * Ensures that the entry will be recognized as valid when
                 * PTE_VALID_ARCH applied.
                 */
                p->should_be_zero = 1;
        } else {
                p->descriptor_type = PTE_DESCRIPTOR_COARSE_TABLE;
                p->should_be_zero = 0;
    }
}


/** Sets flags of level 1 page table entry.
 *
 *  We use same access rights for the whole page. When page is not preset we
 *  store 1 in acess_rigts_3 so that at least one bit is 1 (to mark correct
 *  page entry, see #PAGE_VALID_ARCH).
 *
 *  @param pt     Level 1 page table.
 *  @param i      Index of the entry to be changed.
 *  @param flags  New flags.
 */  
static inline void set_pt_level1_flags(pte_t *pt, size_t i, int flags)
{
        pte_level1_t *p = &pt[i].l1;
        
        if (flags & PAGE_NOT_PRESENT) {
                p->descriptor_type = PTE_DESCRIPTOR_NOT_PRESENT;
                p->access_permission_3 = 1;
        } else {
                p->descriptor_type = PTE_DESCRIPTOR_SMALL_PAGE;
                p->access_permission_3 = p->access_permission_0;
        }
  
        p->cacheable = p->bufferable = (flags & PAGE_CACHEABLE) != 0;

        /* default access permission */
        p->access_permission_0 = p->access_permission_1 = 
            p->access_permission_2 = p->access_permission_3 =
            PTE_AP_USER_NO_KERNEL_RW;

        if (flags & PAGE_USER)  {
                if (flags & PAGE_READ) {
                        p->access_permission_0 = p->access_permission_1 = 
                            p->access_permission_2 = p->access_permission_3 = 
                            PTE_AP_USER_RO_KERNEL_RW;
                }
                if (flags & PAGE_WRITE) {
                        p->access_permission_0 = p->access_permission_1 = 
                            p->access_permission_2 = p->access_permission_3 = 
                            PTE_AP_USER_RW_KERNEL_RW; 
                }
        }
}


extern void page_arch_init(void);


#endif /* __ASM__ */

#endif /* KERNEL */

#endif

/** @}
 */