From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 21 Mar 2003 17:56:26 -0800 From: Andrew Morton Subject: arch changes for file-offset-in-pte's Message-Id: <20030321175626.2834819d.akpm@digeo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: "David S. Miller" , paulus@au.ibm.com, benh@kernel.crashing.org, rth@twiddle.net, davidm@hpl.hp.com, ralf@linux-mips.org, schwidefsky@de.ibm.com, Russell King , bjornw@axis.com, geert@linux-m68k.org, Matthew Wilcox , gniibe@m17n.org, linux-sh@m17n.org, jdike@karaya.com, uclinux-v850@lsi.nec.co.jp Cc: Ingo Molnar , linux-mm@kvack.org List-ID: hi, I'd like to submit Ingo's remap_file_pages() enhancements soon. His patch allows pages in "nonlinear" mappings to be reestablished by the kernel's pagefault handler. It does this by embedding the page's ->index into the pte which wants to map the page. This is arch-specific, and I only have ia32, ppc64 and x86_64 done. So if&when this hits the tree, it will break other architectures. It's a five-minute-fix. Four things need to be provided: pte_t pgoff_to_pte(unsigned long pgoff) Return a pte_t which contains as many of the lower bits of pgoff as you can feasibly pack into a pte. You'll probably need to reserve at least two bits - one for not-present and one to say "this is a pte_file pte". unsigned long pte_to_pgoff(pte_t pte) Extract the unsigned long from a pte. int pte_file(pte_t) Return true if the pte is a "file pte". This is where you'll need to use the magical reserved bit to distinguish this from a swapped out pte. PTE_FILE_MAX_BITS (a constant) Tells the kernel how many bits of the file offset the architecture is capable of placing in the pte, via pgoff_to_pte(). ia32 sets this to 29 in non-PAE mode, 32 in PAE mode (CONFIG_HIGHMEM64G) As an example, here is the x86_64 implementation (the comment next to _PAGE_FILE is wrong, btw. These are not swapcache pages) The ia32 version of this code is right at the start of the the main patch, at http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.5/2.5.65/2.5.65-mm3/broken-out/remap-file-pages-2.5.63-a1.patch Thanks. diff -puN include/asm-x86_64/pgtable.h~file-offset-in-pte-x86_64 include/asm-x86_64/pgtable.h --- 25/include/asm-x86_64/pgtable.h~file-offset-in-pte-x86_64 2003-03-13 04:45:57.000000000 -0800 +++ 25-akpm/include/asm-x86_64/pgtable.h 2003-03-13 04:45:57.000000000 -0800 @@ -151,6 +151,7 @@ static inline void set_pml4(pml4_t *dst, #define _PAGE_ACCESSED 0x020 #define _PAGE_DIRTY 0x040 #define _PAGE_PSE 0x080 /* 2MB page */ +#define _PAGE_FILE 0x040 /* pagecache or swap */ #define _PAGE_GLOBAL 0x100 /* Global TLB entry */ #define _PAGE_PROTNONE 0x080 /* If not present */ @@ -245,6 +246,7 @@ extern inline int pte_exec(pte_t pte) { extern inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; } extern inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; } extern inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_RW; } +static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE; } extern inline pte_t pte_rdprotect(pte_t pte) { set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; } extern inline pte_t pte_exprotect(pte_t pte) { set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_USER)); return pte; } @@ -330,6 +332,11 @@ static inline pgd_t *current_pgd_offset_ #define pmd_bad(x) ((pmd_val(x) & (~PTE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE ) #define pfn_pmd(nr,prot) (__pmd(((nr) << PAGE_SHIFT) | pgprot_val(prot))) + +#define pte_to_pgoff(pte) ((pte_val(pte) & PHYSICAL_PAGE_MASK) >> PAGE_SHIFT) +#define pgoff_to_pte(off) ((pte_t) { ((off) << PAGE_SHIFT) | _PAGE_FILE }) +#define PTE_FILE_MAX_BITS __PHYSICAL_MASK_SHIFT + /* PTE - Level 1 access. */ /* page, protection -> pte */ diff -puN include/asm-x86_64/page.h~file-offset-in-pte-x86_64 include/asm-x86_64/page.h --- 25/include/asm-x86_64/page.h~file-offset-in-pte-x86_64 2003-03-13 04:45:57.000000000 -0800 +++ 25-akpm/include/asm-x86_64/page.h 2003-03-13 04:48:53.000000000 -0800 @@ -69,8 +69,9 @@ typedef struct { unsigned long pgprot; } /* See Documentation/x86_64/mm.txt for a description of the memory map. */ #define __START_KERNEL 0xffffffff80100000 #define __START_KERNEL_map 0xffffffff80000000 -#define __PAGE_OFFSET 0x0000010000000000 -#define __PHYSICAL_MASK 0x000000ffffffffff +#define __PAGE_OFFSET 0x0000010000000000 /* 1 << 40 */ +#define __PHYSICAL_MASK_SHIFT 40 +#define __PHYSICAL_MASK ((1UL << __PHYSICAL_MASK_SHIFT) - 1) #define KERNEL_TEXT_SIZE (40UL*1024*1024) #define KERNEL_TEXT_START 0xffffffff80000000UL _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org