linux/include/asm-powerpc/pgtable-64k.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
3.6 KiB
C

#ifndef _ASM_POWERPC_PGTABLE_64K_H
#define _ASM_POWERPC_PGTABLE_64K_H
#ifdef __KERNEL__
#include <asm-generic/pgtable-nopud.h>
#define PTE_INDEX_SIZE 12
#define PMD_INDEX_SIZE 12
#define PUD_INDEX_SIZE 0
#define PGD_INDEX_SIZE 4
#define PTE_TABLE_SIZE (sizeof(real_pte_t) << PTE_INDEX_SIZE)
#define PMD_TABLE_SIZE (sizeof(pmd_t) << PMD_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_PGD (1 << PGD_INDEX_SIZE)
/* With 4k base page size, hugepage PTEs go at the PMD level */
#define MIN_HUGEPTE_SHIFT PAGE_SHIFT
/* 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))
/* PGDIR_SHIFT determines what a third-level page table entry can map */
#define PGDIR_SHIFT (PMD_SHIFT + PMD_INDEX_SIZE)
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/* Additional PTE bits (don't change without checking asm in hash_low.S) */
#define _PAGE_HPTE_SUB 0x0ffff000 /* combo only: sub pages HPTE bits */
#define _PAGE_HPTE_SUB0 0x08000000 /* combo only: first sub page */
#define _PAGE_COMBO 0x10000000 /* this is a combo 4k page */
#define _PAGE_F_SECOND 0x00008000 /* full page: hidx bits */
#define _PAGE_F_GIX 0x00007000 /* full page: hidx bits */
/* PTE flags to conserve for HPTE identification */
#define _PAGE_HPTEFLAGS (_PAGE_BUSY | _PAGE_HASHPTE | _PAGE_HPTE_SUB |\
_PAGE_COMBO)
/* Shift to put page number into pte.
*
* That gives us a max RPN of 32 bits, which means a max of 48 bits
* of addressable physical space.
* We could get 3 more bits here by setting PTE_RPN_SHIFT to 29 but
* 32 makes PTEs more readable for debugging for now :)
*/
#define PTE_RPN_SHIFT (32)
#define PTE_RPN_MAX (1UL << (64 - PTE_RPN_SHIFT))
#define PTE_RPN_MASK (~((1UL<<PTE_RPN_SHIFT)-1))
/* _PAGE_CHG_MASK masks of bits that are to be preserved accross
* pgprot changes
*/
#define _PAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
_PAGE_ACCESSED)
/* Bits to mask out from a PMD to get to the PTE page */
#define PMD_MASKED_BITS 0x1ff
/* Bits to mask out from a PGD/PUD to get to the PMD page */
#define PUD_MASKED_BITS 0x1ff
#ifndef __ASSEMBLY__
/* Manipulate "rpte" values */
#define __real_pte(e,p) ((real_pte_t) { \
(e), pte_val(*((p) + PTRS_PER_PTE)) })
#define __rpte_to_hidx(r,index) ((pte_val((r).pte) & _PAGE_COMBO) ? \
(((r).hidx >> ((index)<<2)) & 0xf) : ((pte_val((r).pte) >> 12) & 0xf))
#define __rpte_to_pte(r) ((r).pte)
#define __rpte_sub_valid(rpte, index) \
(pte_val(rpte.pte) & (_PAGE_HPTE_SUB0 >> (index)))
/* Trick: we set __end to va + 64k, which happens works for
* a 16M page as well as we want only one iteration
*/
#define pte_iterate_hashed_subpages(rpte, psize, va, index, shift) \
do { \
unsigned long __end = va + PAGE_SIZE; \
unsigned __split = (psize == MMU_PAGE_4K || \
psize == MMU_PAGE_64K_AP); \
shift = mmu_psize_defs[psize].shift; \
for (index = 0; va < __end; index++, va += (1 << shift)) { \
if (!__split || __rpte_sub_valid(rpte, index)) do { \
#define pte_iterate_hashed_end() } while(0); } } while(0)
#define pte_pagesize_index(pte) \
(((pte) & _PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K)
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_PGTABLE_64K_H */