linux/include/asm-powerpc/pgtable-4k.h
Paul Mackerras bf72aeba2f powerpc: Use 64k pages without needing cache-inhibited large pages
Some POWER5+ machines can do 64k hardware pages for normal memory but
not for cache-inhibited pages.  This patch lets us use 64k hardware
pages for most user processes on such machines (assuming the kernel
has been configured with CONFIG_PPC_64K_PAGES=y).  User processes
start out using 64k pages and get switched to 4k pages if they use any
non-cacheable mappings.

With this, we use 64k pages for the vmalloc region and 4k pages for
the imalloc region.  If anything creates a non-cacheable mapping in
the vmalloc region, the vmalloc region will get switched to 4k pages.
I don't know of any driver other than the DRM that would do this,
though, and these machines don't have AGP.

When a region gets switched from 64k pages to 4k pages, we do not have
to clear out all the 64k HPTEs from the hash table immediately.  We
use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page
was hashed in as a 64k page or a set of 4k pages.  If hash_page is
trying to insert a 4k page for a Linux PTE and it sees that it has
already been inserted as a 64k page, it first invalidates the 64k HPTE
before inserting the 4k HPTE.  The hash invalidation routines also use
the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a
set of 4k HPTEs to remove.  With those two changes, we can tolerate a
mix of 4k and 64k HPTEs in the hash table, and they will all get
removed when the address space is torn down.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 10:45:18 +10:00

99 lines
3.3 KiB
C

/*
* Entries per page directory level. The PTE level must use a 64b record
* for each page table entry. The PMD and PGD level use a 32b record for
* each entry by assuming that each entry is page aligned.
*/
#define PTE_INDEX_SIZE 9
#define PMD_INDEX_SIZE 7
#define PUD_INDEX_SIZE 7
#define PGD_INDEX_SIZE 9
#define PTE_TABLE_SIZE (sizeof(pte_t) << PTE_INDEX_SIZE)
#define PMD_TABLE_SIZE (sizeof(pmd_t) << PMD_INDEX_SIZE)
#define PUD_TABLE_SIZE (sizeof(pud_t) << PUD_INDEX_SIZE)
#define PGD_TABLE_SIZE (sizeof(pgd_t) << PGD_INDEX_SIZE)
#define PTRS_PER_PTE (1 << PTE_INDEX_SIZE)
#define PTRS_PER_PMD (1 << PMD_INDEX_SIZE)
#define PTRS_PER_PUD (1 << PMD_INDEX_SIZE)
#define PTRS_PER_PGD (1 << PGD_INDEX_SIZE)
/* PMD_SHIFT determines what a second-level page table entry can map */
#define PMD_SHIFT (PAGE_SHIFT + PTE_INDEX_SIZE)
#define PMD_SIZE (1UL << PMD_SHIFT)
#define PMD_MASK (~(PMD_SIZE-1))
/* With 4k base page size, hugepage PTEs go at the PMD level */
#define MIN_HUGEPTE_SHIFT PMD_SHIFT
/* PUD_SHIFT determines what a third-level page table entry can map */
#define PUD_SHIFT (PMD_SHIFT + PMD_INDEX_SIZE)
#define PUD_SIZE (1UL << PUD_SHIFT)
#define PUD_MASK (~(PUD_SIZE-1))
/* PGDIR_SHIFT determines what a fourth-level page table entry can map */
#define PGDIR_SHIFT (PUD_SHIFT + PUD_INDEX_SIZE)
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/* PTE bits */
#define _PAGE_SECONDARY 0x8000 /* software: HPTE is in secondary group */
#define _PAGE_GROUP_IX 0x7000 /* software: HPTE index within group */
#define _PAGE_F_SECOND _PAGE_SECONDARY
#define _PAGE_F_GIX _PAGE_GROUP_IX
/* PTE flags to conserve for HPTE identification */
#define _PAGE_HPTEFLAGS (_PAGE_BUSY | _PAGE_HASHPTE | \
_PAGE_SECONDARY | _PAGE_GROUP_IX)
/* PAGE_MASK gives the right answer below, but only by accident */
/* It should be preserving the high 48 bits and then specifically */
/* preserving _PAGE_SECONDARY | _PAGE_GROUP_IX */
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | \
_PAGE_HPTEFLAGS)
/* Bits to mask out from a PMD to get to the PTE page */
#define PMD_MASKED_BITS 0
/* Bits to mask out from a PUD to get to the PMD page */
#define PUD_MASKED_BITS 0
/* Bits to mask out from a PGD to get to the PUD page */
#define PGD_MASKED_BITS 0
/* shift to put page number into pte */
#define PTE_RPN_SHIFT (17)
#ifdef STRICT_MM_TYPECHECKS
#define __real_pte(e,p) ((real_pte_t){(e)})
#define __rpte_to_pte(r) ((r).pte)
#else
#define __real_pte(e,p) (e)
#define __rpte_to_pte(r) (__pte(r))
#endif
#define __rpte_to_hidx(r,index) (pte_val(__rpte_to_pte(r)) >> 12)
#define pte_iterate_hashed_subpages(rpte, psize, va, index, shift) \
do { \
index = 0; \
shift = mmu_psize_defs[psize].shift; \
#define pte_iterate_hashed_end() } while(0)
#define pte_pagesize_index(pte) MMU_PAGE_4K
/*
* 4-level page tables related bits
*/
#define pgd_none(pgd) (!pgd_val(pgd))
#define pgd_bad(pgd) (pgd_val(pgd) == 0)
#define pgd_present(pgd) (pgd_val(pgd) != 0)
#define pgd_clear(pgdp) (pgd_val(*(pgdp)) = 0)
#define pgd_page(pgd) (pgd_val(pgd) & ~PGD_MASKED_BITS)
#define pud_offset(pgdp, addr) \
(((pud_t *) pgd_page(*(pgdp))) + \
(((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1)))
#define pud_ERROR(e) \
printk("%s:%d: bad pud %08lx.\n", __FILE__, __LINE__, pud_val(e))