From bf72aeba2ffef599d1d386425c9e46b82be657cd Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 15 Jun 2006 10:45:18 +1000 Subject: 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 --- include/asm-powerpc/pgtable.h | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'include/asm-powerpc/pgtable.h') diff --git a/include/asm-powerpc/pgtable.h b/include/asm-powerpc/pgtable.h index e9f1f4627e6..260a0fabe97 100644 --- a/include/asm-powerpc/pgtable.h +++ b/include/asm-powerpc/pgtable.h @@ -47,8 +47,8 @@ struct mm_struct; /* * Define the address range of the vmalloc VM area. */ -#define VMALLOC_START (0xD000000000000000ul) -#define VMALLOC_SIZE (0x80000000000UL) +#define VMALLOC_START ASM_CONST(0xD000000000000000) +#define VMALLOC_SIZE ASM_CONST(0x80000000000) #define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE) /* @@ -413,12 +413,6 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, flush_tlb_pending(); } pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS); - -#ifdef CONFIG_PPC_64K_PAGES - if (mmu_virtual_psize != MMU_PAGE_64K) - pte = __pte(pte_val(pte) | _PAGE_COMBO); -#endif /* CONFIG_PPC_64K_PAGES */ - *ptep = pte; } -- cgit v1.2.3-70-g09d2