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kernel/linux-rt-4.4.41/arch/powerpc/include/asm/pte-hash32.h 1.83 KB
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  #ifndef _ASM_POWERPC_PTE_HASH32_H
  #define _ASM_POWERPC_PTE_HASH32_H
  #ifdef __KERNEL__
  
  /*
   * The "classic" 32-bit implementation of the PowerPC MMU uses a hash
   * table containing PTEs, together with a set of 16 segment registers,
   * to define the virtual to physical address mapping.
   *
   * We use the hash table as an extended TLB, i.e. a cache of currently
   * active mappings.  We maintain a two-level page table tree, much
   * like that used by the i386, for the sake of the Linux memory
   * management code.  Low-level assembler code in hash_low_32.S
   * (procedure hash_page) is responsible for extracting ptes from the
   * tree and putting them into the hash table when necessary, and
   * updating the accessed and modified bits in the page table tree.
   */
  
  #define _PAGE_PRESENT	0x001	/* software: pte contains a translation */
  #define _PAGE_HASHPTE	0x002	/* hash_page has made an HPTE for this pte */
  #define _PAGE_USER	0x004	/* usermode access allowed */
  #define _PAGE_GUARDED	0x008	/* G: prohibit speculative access */
  #define _PAGE_COHERENT	0x010	/* M: enforce memory coherence (SMP systems) */
  #define _PAGE_NO_CACHE	0x020	/* I: cache inhibit */
  #define _PAGE_WRITETHRU	0x040	/* W: cache write-through */
  #define _PAGE_DIRTY	0x080	/* C: page changed */
  #define _PAGE_ACCESSED	0x100	/* R: page referenced */
  #define _PAGE_RW	0x400	/* software: user write access allowed */
  #define _PAGE_SPECIAL	0x800	/* software: Special page */
  
  #ifdef CONFIG_PTE_64BIT
  /* We never clear the high word of the pte */
  #define _PTE_NONE_MASK	(0xffffffff00000000ULL | _PAGE_HASHPTE)
  #else
  #define _PTE_NONE_MASK	_PAGE_HASHPTE
  #endif
  
  #define _PMD_PRESENT	0
  #define _PMD_PRESENT_MASK (PAGE_MASK)
  #define _PMD_BAD	(~PAGE_MASK)
  
  /* Hash table based platforms need atomic updates of the linux PTE */
  #define PTE_ATOMIC_UPDATES	1
  
  #endif /* __KERNEL__ */
  #endif /*  _ASM_POWERPC_PTE_HASH32_H */