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  • pgtable_32.h 3.10 KiB
    /* SPDX-License-Identifier: GPL-2.0 */
    #ifndef _ASM_X86_PGTABLE_32_H
    #define _ASM_X86_PGTABLE_32_H
    
    #include <asm/pgtable_32_types.h>
    
    /*
     * The Linux memory management assumes a three-level page table setup. On
     * the i386, 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
     * i386 mmu expects.
     *
     * This file contains the functions and defines necessary to modify and use
     * the i386 page table tree.
     */
    #ifndef __ASSEMBLY__
    #include <asm/processor.h>
    #include <linux/threads.h>
    #include <asm/paravirt.h>
    
    #include <linux/bitops.h>
    #include <linux/list.h>
    #include <linux/spinlock.h>
    
    struct mm_struct;
    struct vm_area_struct;
    
    extern pgd_t swapper_pg_dir[1024];
    extern pgd_t initial_page_table[1024];
    extern pmd_t initial_pg_pmd[];
    
    static inline void pgtable_cache_init(void) { }
    static inline void check_pgt_cache(void) { }
    void paging_init(void);
    void sync_initial_page_table(void);
    
    /*
     * 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 'access_ok(VERIFY_WRITE,..)'
     */
    #undef TEST_ACCESS_OK
    
    #ifdef CONFIG_X86_PAE
    # include <asm/pgtable-3level.h>
    #else
    # include <asm/pgtable-2level.h>
    #endif
    
    #if defined(CONFIG_HIGHPTE)
    #define pte_offset_map(dir, address)					\
    	((pte_t *)kmap_atomic(pmd_page(*(dir))) +		\
    	 pte_index((address)))
    #define pte_unmap(pte) kunmap_atomic((pte))
    #else
    #define pte_offset_map(dir, address)					\
    	((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
    #define pte_unmap(pte) do { } while (0)
    #endif
    
    /* Clear a kernel PTE and flush it from the TLB */
    #define kpte_clear_flush(ptep, vaddr)		\
    do {						\
    	pte_clear(&init_mm, (vaddr), (ptep));	\
    	__flush_tlb_one_kernel((vaddr));		\
    } while (0)
    
    #endif /* !__ASSEMBLY__ */
    
    /*
     * kern_addr_valid() is (1) for FLATMEM and (0) for
     * SPARSEMEM and DISCONTIGMEM
     */
    #ifdef CONFIG_FLATMEM
    #define kern_addr_valid(addr)	(1)
    #else
    #define kern_addr_valid(kaddr)	(0)
    #endif
    
    /*
     * This is how much memory in addition to the memory covered up to
     * and including _end we need mapped initially.
     * We need:
     *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
     *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
     *
     * Modulo rounding, each megabyte assigned here requires a kilobyte of
     * memory, which is currently unreclaimed.
     *
     * This should be a multiple of a page.
     *
     * KERNEL_IMAGE_SIZE should be greater than pa(_end)
     * and small than max_low_pfn, otherwise will waste some page table entries
     */
    #if PTRS_PER_PMD > 1
    #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
    #else
    #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
    #endif
    
    /*
     * Number of possible pages in the lowmem region.
     *
     * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
     * gas warning about overflowing shift count when gas has been compiled
     * with only a host target support using a 32-bit type for internal
     * representation.
     */
    #define LOWMEM_PAGES ((((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT))
    
    #endif /* _ASM_X86_PGTABLE_32_H */