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/*

 *  include/asm-s390/pgtable.h

 *

 *  S390 version

 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation

 *    Author(s): Hartmut Penner (hp@de.ibm.com)

 *               Ulrich Weigand (weigand@de.ibm.com)

 *               Martin Schwidefsky (schwidefsky@de.ibm.com)

 *

 *  Derived from "include/asm-i386/pgtable.h"

 */

#ifndef _ASM_S390_PGTABLE_H

#define _ASM_S390_PGTABLE_H

/*

 * The Linux memory management assumes a three-level page table setup. On

 * the S390, we use that, but "fold" the mid level into the top-level page

 * table, so that we physically have the same two-level page table as the

 * S390 mmu expects.

 *

 * The "pgd_xxx()" functions are trivial for a folded two-level

 * setup: the pgd is never bad, and a pmd always exists (as it's folded

 * into the pgd entry)

 *

 * This file contains the functions and defines necessary to modify and use

 * the S390 page table tree.

 */

#ifndef __ASSEMBLY__

#include <asm/processor.h>

#include <linux/threads.h>

extern pgd_t swapper_pg_dir[] __attribute__ ((aligned (4096)));

extern void paging_init(void);

/* Caches aren't brain-dead on S390. */

#define flush_cache_all()                       do { } while (0)

#define flush_cache_mm(mm)                      do { } while (0)

#define flush_cache_range(mm, start, end)       do { } while (0)

#define flush_cache_page(vma, vmaddr)           do { } while (0)

#define flush_page_to_ram(page)                 do { } while (0)

#define flush_dcache_page(page)                 do { } while (0)

#define flush_icache_range(start, end)          do { } while (0)

#define flush_icache_page(vma,pg)               do { } while (0)

#define flush_icache_user_range(vma,pg,adr,len) do { } while (0)

/*

 * The S390 doesn't have any external MMU info: the kernel page

 * tables contain all the necessary information.

 */

#define update_mmu_cache(vma, address, pte)     do { } while (0)

/*

 * ZERO_PAGE is a global shared page that is always zero: used

 * for zero-mapped memory areas etc..

 */

extern char empty_zero_page[PAGE_SIZE];

#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))

#endif /* !__ASSEMBLY__ */

/*

 * PMD_SHIFT determines the size of the area a second-level page

 * table can map

 */

#define PMD_SHIFT       22

#define PMD_SIZE        (1UL << PMD_SHIFT)

#define PMD_MASK        (~(PMD_SIZE-1))

/* PGDIR_SHIFT determines what a third-level page table entry can map */

#define PGDIR_SHIFT     22

#define PGDIR_SIZE      (1UL << PGDIR_SHIFT)

#define PGDIR_MASK      (~(PGDIR_SIZE-1))

/*

 * entries per page directory level: the S390 is two-level, so

 * we don't really have any PMD directory physically.

 * for S390 segment-table entries are combined to one PGD

 * that leads to 1024 pte per pgd

 */

#define PTRS_PER_PTE    1024

#define PTRS_PER_PMD    1

#define PTRS_PER_PGD    512

/*

 * pgd entries used up by user/kernel:

 */

#define USER_PTRS_PER_PGD  512

#define USER_PGD_PTRS      512

#define KERNEL_PGD_PTRS    512

#define FIRST_USER_PGD_NR  0

#define pte_ERROR(e) \

        printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))

#define pmd_ERROR(e) \

        printk("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))

#define pgd_ERROR(e) \

        printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))

#ifndef __ASSEMBLY__

/*

 * Just any arbitrary offset to the start of the vmalloc VM area: the

 * current 8MB value just means that there will be a 8MB "hole" after the

 * physical memory until the kernel virtual memory starts.  That means that

 * any out-of-bounds memory accesses will hopefully be caught.

 * The vmalloc() routines leaves a hole of 4kB between each vmalloced

 * area for the same reason. ;)

 */

#define VMALLOC_OFFSET  (8*1024*1024)

#define VMALLOC_START   (((unsigned long) high_memory + VMALLOC_OFFSET) \

                         & ~(VMALLOC_OFFSET-1))

#define VMALLOC_VMADDR(x) ((unsigned long)(x))

#define VMALLOC_END     (0x7fffffffL)

/*

 * A pagetable entry of S390 has following format:

 *  |   PFRA          |    |  OS  |

 * 0                   0IP0

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

 * I Page-Invalid Bit:    Page is not available for address-translation

 * P Page-Protection Bit: Store access not possible for page

 *

 * A segmenttable entry of S390 has following format:

 *  |   P-table origin      |  |PTL

 * 0                         IC

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

 * I Segment-Invalid Bit:    Segment is not available for address-translation

 * C Common-Segment Bit:     Segment is not private (PoP 3-30)

 * PTL Page-Table-Length:    Page-table length (PTL+1*16 entries -> up to 256)

 *

 * The segmenttable origin of S390 has following format:

 *

 *  |S-table origin   |     | STL |

 * X                   **GPS

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 *

 * X Space-Switch event:

 * G Segment-Invalid Bit:     *

 * P Private-Space Bit:       Segment is not private (PoP 3-30)

 * S Storage-Alteration:

 * STL Segment-Table-Length:  Segment-table length (STL+1*16 entries -> up to 2048)

 *

 * A storage key has the following format:

 * | ACC |F|R|C|0|

 *  0   3 4 5 6 7

 * ACC: access key

 * F  : fetch protection bit

 * R  : referenced bit

 * C  : changed bit

 */

/* Bits in the page table entry */

#define _PAGE_PRESENT   0x001          /* Software                         */

#define _PAGE_ISCLEAN   0x004          /* Software                         */

#define _PAGE_RO        0x200          /* HW read-only                     */

#define _PAGE_INVALID   0x400          /* HW invalid                       */

/* Bits in the segment table entry */

#define _PAGE_TABLE_LEN 0xf            /* only full page-tables            */

#define _PAGE_TABLE_COM 0x10           /* common page-table                */

#define _PAGE_TABLE_INV 0x20           /* invalid page-table               */

#define _SEG_PRESENT    0x001          /* Software (overlap with PTL)      */

/* Bits int the storage key */

#define _PAGE_CHANGED    0x02          /* HW changed bit                   */

#define _PAGE_REFERENCED 0x04          /* HW referenced bit                */

#define _USER_SEG_TABLE_LEN    0x7f    /* user-segment-table up to 2 GB    */

#define _KERNEL_SEG_TABLE_LEN  0x7f    /* kernel-segment-table up to 2 GB  */

/*

 * User and Kernel pagetables are identical

 */

#define _PAGE_TABLE     (_PAGE_TABLE_LEN )

#define _KERNPG_TABLE   (_PAGE_TABLE_LEN )

/*

 * The Kernel segment-tables includes the User segment-table

 */

#define _SEGMENT_TABLE  (_USER_SEG_TABLE_LEN|0x80000000|0x100)

#define _KERNSEG_TABLE  (_KERNEL_SEG_TABLE_LEN)

/*

 * No mapping available

 */

#define PAGE_INVALID      __pgprot(_PAGE_INVALID)

#define PAGE_NONE_SHARED  __pgprot(_PAGE_PRESENT|_PAGE_INVALID)

#define PAGE_NONE_PRIVATE __pgprot(_PAGE_PRESENT|_PAGE_INVALID|_PAGE_ISCLEAN)

#define PAGE_RO_SHARED    __pgprot(_PAGE_PRESENT|_PAGE_RO)

#define PAGE_RO_PRIVATE   __pgprot(_PAGE_PRESENT|_PAGE_RO|_PAGE_ISCLEAN)

#define PAGE_COPY         __pgprot(_PAGE_PRESENT|_PAGE_RO|_PAGE_ISCLEAN)

#define PAGE_SHARED       __pgprot(_PAGE_PRESENT)

#define PAGE_KERNEL       __pgprot(_PAGE_PRESENT)

/*

 * The S390 can't do page protection for execute, and considers that the

 * same are read. Also, write permissions imply read permissions. This is

 * the closest we can get..

 */

         /*xwr*/

#define __P000  PAGE_NONE_PRIVATE

#define __P001  PAGE_RO_PRIVATE

#define __P010  PAGE_COPY

#define __P011  PAGE_COPY

#define __P100  PAGE_RO_PRIVATE

#define __P101  PAGE_RO_PRIVATE

#define __P110  PAGE_COPY

#define __P111  PAGE_COPY

#define __S000  PAGE_NONE_SHARED

#define __S001  PAGE_RO_SHARED

#define __S010  PAGE_SHARED

#define __S011  PAGE_SHARED

#define __S100  PAGE_RO_SHARED

#define __S101  PAGE_RO_SHARED

#define __S110  PAGE_SHARED

#define __S111  PAGE_SHARED

/*

 * Certain architectures need to do special things when PTEs

 * within a page table are directly modified.  Thus, the following

 * hook is made available.

 */

extern inline void set_pte(pte_t *pteptr, pte_t pteval)

{

        *pteptr = pteval;

}

#define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))

/*

 * pgd/pmd/pte query functions

 */

extern inline int pgd_present(pgd_t pgd) { return 1; }

extern inline int pgd_none(pgd_t pgd)    { return 0; }

extern inline int pgd_bad(pgd_t pgd)     { return 0; }

extern inline int pmd_present(pmd_t pmd) { return pmd_val(pmd) & _SEG_PRESENT; }

extern inline int pmd_none(pmd_t pmd)    { return pmd_val(pmd) & _PAGE_TABLE_INV; }

extern inline int pmd_bad(pmd_t pmd)

{

        return (pmd_val(pmd) & (~PAGE_MASK & ~_PAGE_TABLE_INV)) != _PAGE_TABLE;

}

extern inline int pte_present(pte_t pte) { return pte_val(pte) & _PAGE_PRESENT; }

extern inline int pte_none(pte_t pte)

{

        return ((pte_val(pte) &

                (_PAGE_INVALID | _PAGE_RO | _PAGE_PRESENT)) == _PAGE_INVALID);

}

#define pte_same(a,b)   (pte_val(a) == pte_val(b))

/*

 * query functions pte_write/pte_dirty/pte_young only work if

 * pte_present() is true. Undefined behaviour if not..

 */

extern inline int pte_write(pte_t pte)

{

        return (pte_val(pte) & _PAGE_RO) == 0;

}

extern inline int pte_dirty(pte_t pte)

{

        int skey;

        if (pte_val(pte) & _PAGE_ISCLEAN)

                return 0;

        asm volatile ("iske %0,%1" : "=d" (skey) : "a" (pte_val(pte)));

        return skey & _PAGE_CHANGED;

}

extern inline int pte_young(pte_t pte)

{

        int skey;

        asm volatile ("iske %0,%1" : "=d" (skey) : "a" (pte_val(pte)));

        return skey & _PAGE_REFERENCED;

}

/*

 * pgd/pmd/pte modification functions

 */

extern inline void pgd_clear(pgd_t * pgdp)      { }

extern inline void pmd_clear(pmd_t * pmdp)

{

        pmd_val(pmdp[0]) = _PAGE_TABLE_INV;

        pmd_val(pmdp[1]) = _PAGE_TABLE_INV;

        pmd_val(pmdp[2]) = _PAGE_TABLE_INV;

        pmd_val(pmdp[3]) = _PAGE_TABLE_INV;

}

extern inline void pte_clear(pte_t *ptep)

{

        pte_val(*ptep) = _PAGE_INVALID;

}

#define PTE_INIT(x) pte_clear(x)

/*

 * The following pte modification functions only work if

 * pte_present() is true. Undefined behaviour if not..

 */

extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)

{

        pte_val(pte) &= PAGE_MASK | _PAGE_ISCLEAN;

        pte_val(pte) |= pgprot_val(newprot) & ~_PAGE_ISCLEAN;

        return pte;

}

extern inline pte_t pte_wrprotect(pte_t pte)

{

        pte_val(pte) |= _PAGE_RO;

        return pte;

}

extern inline pte_t pte_mkwrite(pte_t pte)

{

        pte_val(pte) &= ~(_PAGE_RO | _PAGE_ISCLEAN);

        return pte;

}

extern inline pte_t pte_mkclean(pte_t pte)

{

        /* The only user of pte_mkclean is the fork() code.

           We must *not* clear the *physical* page dirty bit

           just because fork() wants to clear the dirty bit in

           *one* of the page's mappings.  So we just do nothing. */

        return pte;

}

extern inline pte_t pte_mkdirty(pte_t pte)

{

        /* We do not explicitly set the dirty bit because the

         * sske instruction is slow. It is faster to let the

         * next instruction set the dirty bit.

         */

        pte_val(pte) &= ~_PAGE_ISCLEAN;

        return pte;

}

extern inline pte_t pte_mkold(pte_t pte)

{

        asm volatile ("rrbe 0,%0" : : "a" (pte_val(pte)) : "cc" );

        return pte;

}

extern inline pte_t pte_mkyoung(pte_t pte)

{

        /* To set the referenced bit we read the first word from the real

         * page with a special instruction: load using real address (lura).

         * Isn't S/390 a nice architecture ?! */

        asm volatile ("lura 0,%0" : : "a" (pte_val(pte) & PAGE_MASK) : "0" );

        return pte;

}

static inline int ptep_test_and_clear_young(pte_t *ptep)

{

        int ccode;

        asm volatile ("rrbe 0,%1\n\t"

                      "ipm  %0\n\t"

                      "srl  %0,28\n\t"

                      : "=d" (ccode) : "a" (pte_val(*ptep)) : "cc" );

        return ccode & 2;

}

static inline int ptep_test_and_clear_dirty(pte_t *ptep)

{

        int skey;

        if (pte_val(*ptep) & _PAGE_ISCLEAN)

                return 0;

        asm volatile ("iske %0,%1" : "=d" (skey) : "a" (*ptep));

        if ((skey & _PAGE_CHANGED) == 0)

                return 0;

        /* We can't clear the changed bit atomically. For now we

         * clear (!) the page referenced bit. */

        asm volatile ("sske %0,%1"

                      : : "d" (get_storage_key()), "a" (*ptep));

        return 1;

}

static inline pte_t ptep_get_and_clear(pte_t *ptep)

{

        pte_t pte = *ptep;

        pte_clear(ptep);

        return pte;

}

static inline void ptep_set_wrprotect(pte_t *ptep)

{

        pte_t old_pte = *ptep;

        set_pte(ptep, pte_wrprotect(old_pte));

}

static inline void ptep_mkdirty(pte_t *ptep)

{

        pte_mkdirty(*ptep);

}

/*

 * Conversion functions: convert a page and protection to a page entry,

 * and a page entry and page directory to the page they refer to.

 */

static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)

{

        pte_t __pte;

        pte_val(__pte) = physpage + pgprot_val(pgprot);

        return __pte;

}

#define mk_pte(pg, pgprot)                                                \

({                                                                        \

        struct page *__page = (pg);                                       \

        pgprot_t __pgprot = (pgprot);                                     \

        unsigned long __physpage = __pa((__page-mem_map) << PAGE_SHIFT);  \

        pte_t __pte = mk_pte_phys(__physpage, __pgprot);                  \

        __pte;                                                            \

})

#define arch_set_page_uptodate(__page)                                    \

        do {                                                              \

                asm volatile ("sske %0,%1" : : "d" (get_storage_key()),   \

                              "a" (__pa((__page-mem_map) << PAGE_SHIFT)));\

        } while (0)

#define pte_page(x) (mem_map+(unsigned long)((pte_val(x) >> PAGE_SHIFT)))

#define pmd_page(pmd) \

        ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))

/* to find an entry in a page-table-directory */

#define pgd_index(address) ((address >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))

#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))

/* to find an entry in a kernel page-table-directory */

#define pgd_offset_k(address) pgd_offset(&init_mm, address)

/* Find an entry in the second-level page table.. */

extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)

{

        return (pmd_t *) dir;

}

/* Find an entry in the third-level page table.. */

#define pte_offset(pmd, address) \

        ((pte_t *) (pmd_page(*pmd) + ((address>>10) & ((PTRS_PER_PTE-1)<<2))))

/*

 * A page-table entry has some bits we have to treat in a special way.

 * Bits 0, 20 and bit 23 have to be zero, otherwise an specification

 * exception will occur instead of a page translation exception. The

 * specifiation exception has the bad habit not to store necessary

 * information in the lowcore.

 * Bit 21 and bit 22 are the page invalid bit and the page protection

 * bit. We set both to indicate a swapped page.

 * Bit 31 is used as the software page present bit. If a page is

 * swapped this obviously has to be zero.

 * This leaves the bits 1-19 and bits 24-30 to store type and offset.

 * We use the 7 bits from 24-30 for the type and the 19 bits from 1-19

 * for the offset.

 * 0|     offset      |0110|type |0

 * 00000000001111111111222222222233

 * 01234567890123456789012345678901

 */

extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)

{

        pte_t pte;

        pte_val(pte) = (type << 1) | (offset << 12) | _PAGE_INVALID | _PAGE_RO;

        pte_val(pte) &= 0x7ffff6fe;  /* better to be paranoid */

        return pte;

}

#define SWP_TYPE(entry)         (((entry).val >> 1) & 0x3f)

#define SWP_OFFSET(entry)       (((entry).val >> 12) & 0x7FFFF )

#define SWP_ENTRY(type,offset)  ((swp_entry_t) { pte_val(mk_swap_pte((type),(offset))) })

#define pte_to_swp_entry(pte)   ((swp_entry_t) { pte_val(pte) })

#define swp_entry_to_pte(x)     ((pte_t) { (x).val })

#endif /* !__ASSEMBLY__ */

/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */

#define PageSkip(page)          (0)

#define kern_addr_valid(addr)   (1)

/*

 * No page table caches to initialise

 */

#define pgtable_cache_init()    do { } while (0)

#endif /* _S390_PAGE_H */