path: root/include/asm-s390/pgtable.h

/*
 *  include/asm-s390/pgtable.h
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Hartmut Penner
 *
 *  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.
 *
 * 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/tasks.h>

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

/* 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_icache_range(start, end)          do { } while (0)
#define flush_icache_page(vma,pg)               do { } while (0)

/*
 * ZERO_PAGE is a global shared page that is always zero: used
 * for zero-mapped memory areas etc..
 */
extern unsigned long empty_zero_page[1024];
#define ZERO_PAGE(vaddr) (mem_map + MAP_NR(empty_zero_page))
#endif /* !__ASSEMBLY__ */

/* Certain architectures need to do special things when PTEs
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
#define set_pte(pteptr, pteval) ((*(pteptr)) = (pteval))

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

/*
 * 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:  Length of Page-table (STL+1*16 entries -> up to 2048 entries)
 */

#define _PAGE_PRESENT   0x001          /* Software                         */
#define _PAGE_ACCESSED  0x002          /* Software accessed                */
#define _PAGE_DIRTY     0x004          /* Software dirty                   */
#define _PAGE_RO        0x200          /* HW read-only                     */
#define _PAGE_INVALID   0x400          /* HW invalid                       */

#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)      */

#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)
#define _KERNSEG_TABLE  (_KERNEL_SEG_TABLE_LEN)
/*
 * No mapping available
 */
#define PAGE_NONE       __pgprot(_PAGE_INVALID )

#define PAGE_SHARED     __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
#define PAGE_COPY       __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_RO)
#define PAGE_READONLY   __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_RO)
#define PAGE_KERNEL     __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY)

/*
 * 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..
 */
#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

/*
 * Define this if things work differently on an i386 and an i486:
 * it will (on an i486) warn about kernel memory accesses that are
 * done without a 'verify_area(VERIFY_WRITE,..)'
 *
 * Kernel and User memory-access are done equal, so we don't need verify
 */
#undef TEST_VERIFY_AREA

/* page table for 0-4MB for everybody */
extern unsigned long pg0[1024];

/* number of bits that fit into a memory pointer */
#define BITS_PER_PTR                    (8*sizeof(unsigned long))

/* to align the pointer to a pointer address */
#define PTR_MASK                        (~(sizeof(void*)-1))

/* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
/* 64-bit machines, beware!  SRB. */
#define SIZEOF_PTR_LOG2                 2

/* to find an entry in a page-table */
#define PAGE_PTR(address) \
((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)



/* 
 * CR 7 (SPST) and cr 13 (HPST) are set to the user pgdir. 
 * Kernel is running in its own, disjunct address space,
 * running in primary address space.
 * Copy to/from user is done via access register mode with
 * access registers set to 0 or 1. For that purpose we need 
 * set up CR 7 with the user pgd.  
 * 
 */

#define SET_PAGE_DIR(tsk,pgdir)                                              \
do {                                                                         \
        unsigned long __pgdir = (__pa(pgdir) & PAGE_MASK ) | _SEGMENT_TABLE; \
        (tsk)->thread.user_seg = __pgdir;                                    \
        if ((tsk) == current) {                                              \
                __asm__ __volatile__("lctl  7,7,%0": :"m" (__pgdir));        \
                __asm__ __volatile__("lctl  13,13,%0": :"m" (__pgdir));      \
        }                                                                    \
} while (0)

/* 
 * CR 7 (SPST) and cr 13 (HPST) are set to the user pgdir. 
 * Kernel is running in its own, disjunct address space,
 * running in primary address space.
 * Copy to/from user is done via access register mode with
 * access registers set to 0 or 1. For that purpose we need 
 * set up CR 7 with the user pgd.  
 * 
 */

#define SET_PAGE_DIR(tsk,pgdir)                                              \
do {                                                                         \
        unsigned long __pgdir = (__pa(pgdir) & PAGE_MASK ) | _SEGMENT_TABLE; \
        (tsk)->thread.user_seg = __pgdir;                                    \
        if ((tsk) == current) {                                              \
                __asm__ __volatile__("lctl  7,7,%0": :"m" (__pgdir));        \
                __asm__ __volatile__("lctl  13,13,%0": :"m" (__pgdir));      \
        }                                                                    \
} while (0)


extern inline int pte_none(pte_t pte)           { return ((pte_val(pte) & (_PAGE_INVALID | _PAGE_RO)) == _PAGE_INVALID); } 
extern inline int pte_present(pte_t pte)        { return pte_val(pte) & _PAGE_PRESENT; }
extern inline void pte_clear(pte_t *ptep)       { pte_val(*ptep) = _PAGE_INVALID; }
extern inline int pte_pagenr(pte_t pte)	        { return ((unsigned long)((pte_val(pte) >> PAGE_SHIFT))); }

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) == 0); }
extern inline int pmd_present(pmd_t pmd)        { return pmd_val(pmd) & _SEG_PRESENT; }
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;
                                                }

/*
 * The "pgd_xxx()" functions here 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)
 */
extern inline int pgd_none(pgd_t pgd)           { return 0; }
extern inline int pgd_bad(pgd_t pgd)            { return 0; }
extern inline int pgd_present(pgd_t pgd)        { return 1; }
extern inline void pgd_clear(pgd_t * pgdp)      { }


/*
 * The following 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); }
extern inline int pte_dirty(pte_t pte)          { return pte_val(pte) & _PAGE_DIRTY; }
extern inline int pte_young(pte_t pte)          { return pte_val(pte) & _PAGE_ACCESSED; }

/* who needs that
extern inline int pte_read(pte_t pte)           { return !(pte_val(pte) & _PAGE_INVALID); }
extern inline int pte_exec(pte_t pte)           { return !(pte_val(pte) & _PAGE_INVALID); }
extern inline pte_t pte_rdprotect(pte_t pte)    { pte_val(pte) |= _PAGE_INVALID; return pte; }
extern inline pte_t pte_exprotect(pte_t pte)    { pte_val(pte) |= _PAGE_INVALID; return pte; }
extern inline pte_t pte_mkread(pte_t pte)       { pte_val(pte) &= _PAGE_INVALID; return pte; }
extern inline pte_t pte_mkexec(pte_t pte)       { pte_val(pte) &= _PAGE_INVALID; 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 ; return pte; }

extern inline pte_t pte_mkclean(pte_t pte)      { pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
extern inline pte_t pte_mkdirty(pte_t pte)      { pte_val(pte) |= _PAGE_DIRTY; return pte; }

extern inline pte_t pte_mkold(pte_t pte)        { pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
extern inline pte_t pte_mkyoung(pte_t pte)      { pte_val(pte) |= _PAGE_ACCESSED; return pte; }


/*
 * 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) \
({ pte_t __pte; pte_val(__pte) = __pa(((page)-mem_map)<<PAGE_SHIFT) + pgprot_val(pgprot); __pte; })

/* This takes a physical page address that is used by the remapping functions */
#define mk_pte_phys(physpage, pgprot) \
({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })

extern inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{ pte_val(pte) = (pte_val(pte) & PAGE_MASK) | pgprot_val(newprot); return pte; }

#define page_address(page) \
({ if (!(page)->virtual) BUG(); (page)->virtual; })
#define pte_page(x) (mem_map+pte_pagenr(x))

#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(address) pgd_index(address)

#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))))


/* We don't use pmd cache, so these are dummy routines */
extern __inline__ pmd_t *get_pmd_fast(void)
{
        return (pmd_t *)0;
}

extern __inline__ void free_pmd_fast(pmd_t *pmd)
{
}

extern __inline__ void free_pmd_slow(pmd_t *pmd)
{
}

extern void __handle_bad_pmd(pmd_t *pmd);
extern void __handle_bad_pmd_kernel(pmd_t *pmd);

/*
 * The S390 doesn't have any external MMU info: the kernel page
 * tables contain all the necessary information.
 */
extern inline void update_mmu_cache(struct vm_area_struct * vma,
        unsigned long address, pte_t pte)
{
}

/*
 * a page-table entry has only 19 bit for offset and 7 bit for type
 * if bits 0, 20 or 23 are set, a translation specification exceptions occures, and it's
 * hard to find out the failing address
 * therefor, we zero out this bits
 */

#define SWP_TYPE(entry) (((entry).val >> 1) & 0x3f)
#define SWP_OFFSET(entry) (((entry).val >> 12) & 0x7FFFF )
#define SWP_ENTRY(type,offset) ((swp_entry_t) { (((type) << 1) | \
                                                 ((offset) << 12) | \
                                                 _PAGE_INVALID | _PAGE_RO) \
                                                 & 0x7ffff6fe })

#define pte_to_swp_entry(pte)           ((swp_entry_t) { pte_val(pte) })
#define swp_entry_to_pte(x)             ((pte_t) { (x).val })

#define module_map      vmalloc
#define module_unmap    vfree

#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)

#endif /* _S390_PAGE_H */