pgtable.h

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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
 *
 *  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_dcache_page(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) (virt_to_page(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