2f569afd9c
Background: I've implemented 1K/2K page tables for s390. These sub-page page tables are required to properly support the s390 virtualization instruction with KVM. The SIE instruction requires that the page tables have 256 page table entries (pte) followed by 256 page status table entries (pgste). The pgstes are only required if the process is using the SIE instruction. The pgstes are updated by the hardware and by the hypervisor for a number of reasons, one of them is dirty and reference bit tracking. To avoid wasting memory the standard pte table allocation should return 1K/2K (31/64 bit) and 2K/4K if the process is using SIE. Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means the s390 version for pte_alloc_one cannot return a pointer to a struct page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one cannot return a pointer to a pte either, since that would require more than 32 bit for the return value of pte_alloc_one (and the pte * would not be accessible since its not kmapped). Solution: The only solution I found to this dilemma is a new typedef: a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a later patch. For everybody else it will be a (struct page *). The additional problem with the initialization of the ptl lock and the NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and a destructor pgtable_page_dtor. The page table allocation and free functions need to call these two whenever a page table page is allocated or freed. pmd_populate will get a pgtable_t instead of a struct page pointer. To get the pgtable_t back from a pmd entry that has been installed with pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page call in free_pte_range and apply_to_pte_range. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
109 lines
2.4 KiB
C
109 lines
2.4 KiB
C
#ifndef _ASM_X86_PAGE_32_H
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#define _ASM_X86_PAGE_32_H
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/*
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* This handles the memory map.
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*
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* A __PAGE_OFFSET of 0xC0000000 means that the kernel has
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* a virtual address space of one gigabyte, which limits the
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* amount of physical memory you can use to about 950MB.
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*
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* If you want more physical memory than this then see the CONFIG_HIGHMEM4G
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* and CONFIG_HIGHMEM64G options in the kernel configuration.
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*/
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#define __PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
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#ifdef CONFIG_X86_PAE
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#define __PHYSICAL_MASK_SHIFT 36
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#define __VIRTUAL_MASK_SHIFT 32
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#define PAGETABLE_LEVELS 3
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#ifndef __ASSEMBLY__
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typedef u64 pteval_t;
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typedef u64 pmdval_t;
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typedef u64 pudval_t;
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typedef u64 pgdval_t;
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typedef u64 pgprotval_t;
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typedef u64 phys_addr_t;
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typedef union {
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struct {
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unsigned long pte_low, pte_high;
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};
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pteval_t pte;
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} pte_t;
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#endif /* __ASSEMBLY__
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*/
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#else /* !CONFIG_X86_PAE */
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#define __PHYSICAL_MASK_SHIFT 32
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#define __VIRTUAL_MASK_SHIFT 32
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#define PAGETABLE_LEVELS 2
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#ifndef __ASSEMBLY__
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typedef unsigned long pteval_t;
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typedef unsigned long pmdval_t;
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typedef unsigned long pudval_t;
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typedef unsigned long pgdval_t;
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typedef unsigned long pgprotval_t;
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typedef unsigned long phys_addr_t;
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typedef union { pteval_t pte, pte_low; } pte_t;
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typedef pte_t boot_pte_t;
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typedef struct page *pgtable_t;
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_X86_PAE */
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#ifdef CONFIG_HUGETLB_PAGE
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#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
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#endif
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#ifndef __ASSEMBLY__
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#define __phys_addr(x) ((x)-PAGE_OFFSET)
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#define __phys_reloc_hide(x) RELOC_HIDE((x), 0)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn) ((pfn) < max_mapnr)
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#endif /* CONFIG_FLATMEM */
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extern int nx_enabled;
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/*
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* This much address space is reserved for vmalloc() and iomap()
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* as well as fixmap mappings.
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*/
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extern unsigned int __VMALLOC_RESERVE;
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extern int sysctl_legacy_va_layout;
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#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
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#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE)
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#ifdef CONFIG_X86_USE_3DNOW
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#include <asm/mmx.h>
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static inline void clear_page(void *page)
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{
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mmx_clear_page(page);
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}
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static inline void copy_page(void *to, void *from)
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{
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mmx_copy_page(to, from);
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}
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#else /* !CONFIG_X86_USE_3DNOW */
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#include <linux/string.h>
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static inline void clear_page(void *page)
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{
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memset(page, 0, PAGE_SIZE);
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}
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static inline void copy_page(void *to, void *from)
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{
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memcpy(to, from, PAGE_SIZE);
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}
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#endif /* CONFIG_X86_3DNOW */
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PAGE_32_H */
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