FreeBSD/Linux Kernel Cross Reference
sys/mips/include/pte.h

     /*-
      * Copyright (c) 2004-2010 Juli Mallett <jmallett@FreeBSD.org>
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
     *
     * $FreeBSD$
     */
    
    #ifndef _MACHINE_PTE_H_
    #define _MACHINE_PTE_H_
    
    #ifndef _LOCORE
    #if defined(__mips_n64) || defined(__mips_n32) /*  PHYSADDR_64_BIT */
    typedef uint64_t pt_entry_t;
    #else
    typedef uint32_t pt_entry_t;
    #endif
    typedef pt_entry_t *pd_entry_t;
    #endif
    
    /*
     * TLB and PTE management.  Most things operate within the context of
     * EntryLo0,1, and begin with TLBLO_.  Things which work with EntryHi
     * start with TLBHI_.  PTE bits begin with PTE_.
     *
     * Note that we use the same size VM and TLB pages.
     */
    #define TLB_PAGE_SHIFT  (PAGE_SHIFT)
    #define TLB_PAGE_SIZE   (1 << TLB_PAGE_SHIFT)
    #define TLB_PAGE_MASK   (TLB_PAGE_SIZE - 1)
    
    /*
     * TLB PageMask register.  Has mask bits set above the default, 4K, page mask.
     */
    #define TLBMASK_SHIFT   (13)
    #define TLBMASK_MASK    ((PAGE_MASK >> TLBMASK_SHIFT) << TLBMASK_SHIFT)
    
    /*
     * FreeBSD/mips page-table entries take a near-identical format to MIPS TLB
     * entries, each consisting of two 32-bit or 64-bit values ("EntryHi" and
     * "EntryLo").  MIPS4k and MIPS64 both define certain bits in TLB entries as
     * reserved, and these must be zero-filled by software.  We overload these
     * bits in PTE entries to hold  PTE_ flags such as RO, W, and MANAGED.
     * However, we must mask these out when writing to TLB entries to ensure that
     * they do not become visible to hardware -- especially on MIPS64r2 which has
     * an extended physical memory space.
     *
     * When using n64 and n32, shift software-defined bits into the MIPS64r2
     * reserved range, which runs from bit 55 ... 63.  In other configurations
     * (32-bit MIPS4k and compatible), shift them out to bits 29 ... 31.
     *
     * NOTE: This means that for 32-bit use of CP0, we aren't able to set the top
     * bit of PFN to a non-zero value, as software is using it!  This physical
     * memory size limit may not be sufficiently enforced elsewhere.
     */
    #if defined(__mips_n64) || defined(__mips_n32) /*  PHYSADDR_64_BIT */
    #define TLBLO_SWBITS_SHIFT      (55)
    #define TLBLO_SWBITS_CLEAR_SHIFT        (9)
    #define TLBLO_PFN_MASK          0x3FFFFFFC0ULL
    #else
    #define TLBLO_SWBITS_SHIFT      (29)
    #define TLBLO_SWBITS_CLEAR_SHIFT        (3)
    #define TLBLO_PFN_MASK          (0x1FFFFFC0)
    #endif
    #define TLBLO_PFN_SHIFT         (6)
    #define TLBLO_SWBITS_MASK       ((pt_entry_t)0x7 << TLBLO_SWBITS_SHIFT)
    #define TLBLO_PA_TO_PFN(pa)     ((((pa) >> TLB_PAGE_SHIFT) << TLBLO_PFN_SHIFT) & TLBLO_PFN_MASK)
    #define TLBLO_PFN_TO_PA(pfn)    ((vm_paddr_t)((pfn) >> TLBLO_PFN_SHIFT) << TLB_PAGE_SHIFT)
    #define TLBLO_PTE_TO_PFN(pte)   ((pte) & TLBLO_PFN_MASK)
    #define TLBLO_PTE_TO_PA(pte)    (TLBLO_PFN_TO_PA(TLBLO_PTE_TO_PFN((pte))))
    
    /*
     * XXX This comment is not correct for anything more modern than R4K.
     *
     * VPN for EntryHi register.  Upper two bits select user, supervisor,
     * or kernel.  Bits 61 to 40 copy bit 63.  VPN2 is bits 39 and down to
     * as low as 13, down to PAGE_SHIFT, to index 2 TLB pages*.  From bit 12
     * to bit 8 there is a 5-bit 0 field.  Low byte is ASID.
     *
    * XXX This comment is not correct for FreeBSD.
    * Note that in FreeBSD, we map 2 TLB pages is equal to 1 VM page.
    */
   #define TLBHI_ASID_MASK         (0xff)
   #if defined(__mips_n64)
   #define TLBHI_R_SHIFT           62
   #define TLBHI_R_USER            (0x00UL << TLBHI_R_SHIFT)
   #define TLBHI_R_SUPERVISOR      (0x01UL << TLBHI_R_SHIFT)
   #define TLBHI_R_KERNEL          (0x03UL << TLBHI_R_SHIFT)
   #define TLBHI_R_MASK            (0x03UL << TLBHI_R_SHIFT)
   #define TLBHI_VA_R(va)          ((va) & TLBHI_R_MASK)
   #define TLBHI_FILL_SHIFT        40
   #define TLBHI_VPN2_SHIFT        (TLB_PAGE_SHIFT + 1)
   #define TLBHI_VPN2_MASK         (((~((1UL << TLBHI_VPN2_SHIFT) - 1)) << (63 - TLBHI_FILL_SHIFT)) >> (63 - TLBHI_FILL_SHIFT))
   #define TLBHI_VA_TO_VPN2(va)    ((va) & TLBHI_VPN2_MASK)
   #define TLBHI_ENTRY(va, asid)   ((TLBHI_VA_R((va))) /* Region. */ | \
                                    (TLBHI_VA_TO_VPN2((va))) /* VPN2. */ | \
                                    ((asid) & TLBHI_ASID_MASK))
   #else /* !defined(__mips_n64) */
   #define TLBHI_PAGE_MASK         (2 * PAGE_SIZE - 1)
   #define TLBHI_ENTRY(va, asid)   (((va) & ~TLBHI_PAGE_MASK) | ((asid) & TLBHI_ASID_MASK))
   #endif /* defined(__mips_n64) */
   
   /*
    * TLB flags managed in hardware:
    *      C:      Cache attribute.
    *      D:      Dirty bit.  This means a page is writable.  It is not
    *              set at first, and a write is trapped, and the dirty
    *              bit is set.  See also PTE_RO.
    *      V:      Valid bit.  Obvious, isn't it?
    *      G:      Global bit.  This means that this mapping is present
    *              in EVERY address space, and to ignore the ASID when
    *              it is matched.
    */
   #define PTE_C(attr)             ((attr & 0x07) << 3)
   #define PTE_C_UNCACHED          (PTE_C(MIPS_CCA_UNCACHED))
   #define PTE_C_CACHE             (PTE_C(MIPS_CCA_CACHED))
   #define PTE_D                   0x04
   #define PTE_V                   0x02
   #define PTE_G                   0x01
   
   /*
    * VM flags managed in software:
    *      RO:     Read only.  Never set PTE_D on this page, and don't
    *              listen to requests to write to it.
    *      W:      Wired.  ???
    *      MANAGED:Managed.  This PTE maps a managed page.
    *
    * These bits should not be written into the TLB, so must first be masked out
    * explicitly in C, or using CLEAR_PTE_SWBITS() in assembly.
    */
   #define PTE_RO                  ((pt_entry_t)0x01 << TLBLO_SWBITS_SHIFT)
   #define PTE_W                   ((pt_entry_t)0x02 << TLBLO_SWBITS_SHIFT)
   #define PTE_MANAGED             ((pt_entry_t)0x04 << TLBLO_SWBITS_SHIFT)
   
   /*
    * PTE management functions for bits defined above.
    */
   #define pte_clear(pte, bit)     (*(pte) &= ~(bit))
   #define pte_set(pte, bit)       (*(pte) |= (bit))
   #define pte_test(pte, bit)      ((*(pte) & (bit)) == (bit))
   
   /* Assembly support for PTE access*/
   #ifdef LOCORE
   #if defined(__mips_n64) || defined(__mips_n32) /*  PHYSADDR_64_BIT */
   #define PTESHIFT                3
   #define PTE2MASK                0xff0   /* for the 2-page lo0/lo1 */
   #define PTEMASK                 0xff8
   #define PTESIZE                 8
   #define PTE_L                   ld
   #define PTE_MTC0                dmtc0
   #define CLEAR_PTE_SWBITS(pr)
   #else
   #define PTESHIFT                2
   #define PTE2MASK                0xff8   /* for the 2-page lo0/lo1 */
   #define PTEMASK                 0xffc
   #define PTESIZE                 4
   #define PTE_L                   lw
   #define PTE_MTC0                mtc0
   #define CLEAR_PTE_SWBITS(r)     LONG_SLL r, TLBLO_SWBITS_CLEAR_SHIFT; LONG_SRL r, TLBLO_SWBITS_CLEAR_SHIFT /* remove swbits */
   #endif /* defined(__mips_n64) || defined(__mips_n32) */
   
   #if defined(__mips_n64)
   #define PTRSHIFT                3
   #define PDEPTRMASK              0xff8
   #else
   #define PTRSHIFT                2
   #define PDEPTRMASK              0xffc
   #endif
   
   #endif /* LOCORE */
   #endif /* !_MACHINE_PTE_H_ */

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