/* * arch/arm/include/asm/pgtable.h * * Copyright (C) 1995-2002 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #ifndef _ASMARM_PGTABLE_H #define _ASMARM_PGTABLE_H #include #include #ifndef CONFIG_MMU #include "pgtable-nommu.h" #else #include #include #include /* * Just any arbitrary offset to the start of the vmalloc VM area: the * current 8MB value just means that there will be a 8MB "hole" after the * physical memory until the kernel virtual memory starts. That means that * any out-of-bounds memory accesses will hopefully be caught. * The vmalloc() routines leaves a hole of 4kB between each vmalloced * area for the same reason. ;) * * Note that platforms may override VMALLOC_START, but they must provide * VMALLOC_END. VMALLOC_END defines the (exclusive) limit of this space, * which may not overlap IO space. */ #ifndef VMALLOC_START #define VMALLOC_OFFSET (8*1024*1024) #define VMALLOC_START (((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)) #endif /* * Hardware-wise, we have a two level page table structure, where the first * level has 4096 entries, and the second level has 256 entries. Each entry * is one 32-bit word. Most of the bits in the second level entry are used * by hardware, and there aren't any "accessed" and "dirty" bits. * * Linux on the other hand has a three level page table structure, which can * be wrapped to fit a two level page table structure easily - using the PGD * and PTE only. However, Linux also expects one "PTE" table per page, and * at least a "dirty" bit. * * Therefore, we tweak the implementation slightly - we tell Linux that we * have 2048 entries in the first level, each of which is 8 bytes (iow, two * hardware pointers to the second level.) The second level contains two * hardware PTE tables arranged contiguously, followed by Linux versions * which contain the state information Linux needs. We, therefore, end up * with 512 entries in the "PTE" level. * * This leads to the page tables having the following layout: * * pgd pte * | | * +--------+ +0 * | |-----> +------------+ +0 * +- - - - + +4 | h/w pt 0 | * | |-----> +------------+ +1024 * +--------+ +8 | h/w pt 1 | * | | +------------+ +2048 * +- - - - + | Linux pt 0 | * | | +------------+ +3072 * +--------+ | Linux pt 1 | * | | +------------+ +4096 * * See L_PTE_xxx below for definitions of bits in the "Linux pt", and * PTE_xxx for definitions of bits appearing in the "h/w pt". * * PMD_xxx definitions refer to bits in the first level page table. * * The "dirty" bit is emulated by only granting hardware write permission * iff the page is marked "writable" and "dirty" in the Linux PTE. This * means that a write to a clean page will cause a permission fault, and * the Linux MM layer will mark the page dirty via handle_pte_fault(). * For the hardware to notice the permission change, the TLB entry must * be flushed, and ptep_set_access_flags() does that for us. * * The "accessed" or "young" bit is emulated by a similar method; we only * allow accesses to the page if the "young" bit is set. Accesses to the * page will cause a fault, and handle_pte_fault() will set the young bit * for us as long as the page is marked present in the corresponding Linux * PTE entry. Again, ptep_set_access_flags() will ensure that the TLB is * up to date. * * However, when the "young" bit is cleared, we deny access to the page * by clearing the hardware PTE. Currently Linux does not flush the TLB * for us in this case, which means the TLB will retain the transation * until either the TLB entry is evicted under pressure, or a context * switch which changes the user space mapping occurs. */ #define PTRS_PER_PTE 512 #define PTRS_PER_PMD 1 #define PTRS_PER_PGD 2048 /* * PMD_SHIFT determines the size of the area a second-level page table can map * PGDIR_SHIFT determines what a third-level page table entry can map */ #define PMD_SHIFT 21 #define PGDIR_SHIFT 21 #define LIBRARY_TEXT_START 0x0c000000 #ifndef __ASSEMBLY__ extern void __pte_error(const char *file, int line, unsigned long val); extern void __pmd_error(const char *file, int line, unsigned long val); extern void __pgd_error(const char *file, int line, unsigned long val); #define pte_ERROR(pte) __pte_error(__FILE__, __LINE__, pte_val(pte)) #define pmd_ERROR(pmd) __pmd_error(__FILE__, __LINE__, pmd_val(pmd)) #define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd)) #endif /* !__ASSEMBLY__ */ #define PMD_SIZE (1UL << PMD_SHIFT) #define PMD_MASK (~(PMD_SIZE-1)) #define PGDIR_SIZE (1UL << PGDIR_SHIFT) #define PGDIR_MASK (~(PGDIR_SIZE-1)) /* * This is the lowest virtual address we can permit any user space * mapping to be mapped at. This is particularly important for * non-high vector CPUs. */ #define FIRST_USER_ADDRESS PAGE_SIZE #define FIRST_USER_PGD_NR 1 #define USER_PTRS_PER_PGD ((TASK_SIZE/PGDIR_SIZE) - FIRST_USER_PGD_NR) /* * section address mask and size definitions. */ #define SECTION_SHIFT 20 #define SECTION_SIZE (1UL << SECTION_SHIFT) #define SECTION_MASK (~(SECTION_SIZE-1)) /* * ARMv6 supersection address mask and size definitions. */ #define SUPERSECTION_SHIFT 24 #define SUPERSECTION_SIZE (1UL << SUPERSECTION_SHIFT) #define SUPERSECTION_MASK (~(SUPERSECTION_SIZE-1)) /* * "Linux" PTE definitions. * * We keep two sets of PTEs - the hardware and the linux version. * This allows greater flexibility in the way we map the Linux bits * onto the hardware tables, and allows us to have YOUNG and DIRTY * bits. * * The PTE table pointer refers to the hardware entries; the "Linux" * entries are stored 1024 bytes below. */ #define L_PTE_PRESENT (1 << 0) #define L_PTE_FILE (1 << 1) /* only when !PRESENT */ #define L_PTE_YOUNG (1 << 1) #define L_PTE_BUFFERABLE (1 << 2) /* obsolete, matches PTE */ #define L_PTE_CACHEABLE (1 << 3) /* obsolete, matches PTE */ #define L_PTE_DIRTY (1 << 6) #define L_PTE_WRITE (1 << 7) #define L_PTE_USER (1 << 8) #define L_PTE_EXEC (1 << 9) #define L_PTE_SHARED (1 << 10) /* shared(v6), coherent(xsc3) */ /* * These are the memory types, defined to be compatible with * pre-ARMv6 CPUs cacheable and bufferable bits: XXCB */ #define L_PTE_MT_UNCACHED (0x00 << 2) /* 0000 */ #define L_PTE_MT_BUFFERABLE (0x01 << 2) /* 0001 */ #define L_PTE_MT_WRITETHROUGH (0x02 << 2) /* 0010 */ #define L_PTE_MT_WRITEBACK (0x03 << 2) /* 0011 */ #define L_PTE_MT_MINICACHE (0x06 << 2) /* 0110 (sa1100, xscale) */ #define L_PTE_MT_WRITEALLOC (0x07 << 2) /* 0111 */ #define L_PTE_MT_DEV_SHARED (0x04 << 2) /* 0100 */ #define L_PTE_MT_DEV_NONSHARED (0x0c << 2) /* 1100 */ #define L_PTE_MT_DEV_IXP2000 (0x0d << 2) /* 1101 */ #define L_PTE_MT_DEV_WC (0x09 << 2) /* 1001 */ #define L_PTE_MT_DEV_CACHED (0x0b << 2) /* 1011 */ #define L_PTE_MT_MASK (0x0f << 2) #ifndef __ASSEMBLY__ /* * The pgprot_* and protection_map entries will be fixed up in runtime * to include the cachable and bufferable bits based on memory policy, * as well as any architecture dependent bits like global/ASID and SMP * shared mapping bits. */ #define _L_PTE_DEFAULT L_PTE_PRESENT | L_PTE_YOUNG #define _L_PTE_READ L_PTE_USER | L_PTE_EXEC extern pgprot_t pgprot_user; extern pgprot_t pgprot_kernel; #define PAGE_NONE pgprot_user #define PAGE_COPY __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ) #define PAGE_SHARED __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ | \ L_PTE_WRITE) #define PAGE_READONLY __pgprot(pgprot_val(pgprot_user) | _L_PTE_READ) #define PAGE_KERNEL pgprot_kernel #define __PAGE_NONE __pgprot(_L_PTE_DEFAULT) #define __PAGE_COPY __pgprot(_L_PTE_DEFAULT | _L_PTE_READ) #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | _L_PTE_READ | L_PTE_WRITE) #define __PAGE_READONLY __pgprot(_L_PTE_DEFAULT | _L_PTE_READ) #endif /* __ASSEMBLY__ */ /* * The table below defines the page protection levels that we insert into our * Linux page table version. These get translated into the best that the * architecture can perform. Note that on most ARM hardware: * 1) We cannot do execute protection * 2) If we could do execute protection, then read is implied * 3) write implies read permissions */ #define __P000 __PAGE_NONE #define __P001 __PAGE_READONLY #define __P010 __PAGE_COPY #define __P011 __PAGE_COPY #define __P100 __PAGE_READONLY #define __P101 __PAGE_READONLY #define __P110 __PAGE_COPY #define __P111 __PAGE_COPY #define __S000 __PAGE_NONE #define __S001 __PAGE_READONLY #define __S010 __PAGE_SHARED #define __S011 __PAGE_SHARED #define __S100 __PAGE_READONLY #define __S101 __PAGE_READONLY #define __S110 __PAGE_SHARED #define __S111 __PAGE_SHARED #ifndef __ASSEMBLY__ /* * ZERO_PAGE is a global shared page that is always zero: used * for zero-mapped memory areas etc.. */ extern struct page *empty_zero_page; #define ZERO_PAGE(vaddr) (empty_zero_page) #define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT) #define pfn_pte(pfn,prot) (__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))) #define pte_none(pte) (!pte_val(pte)) #define pte_clear(mm,addr,ptep) set_pte_ext(ptep, __pte(0), 0) #define pte_page(pte) (pfn_to_page(pte_pfn(pte))) #define pte_offset_kernel(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr)) #define pte_offset_map(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr)) #define pte_offset_map_nested(dir,addr) (pmd_page_vaddr(*(dir)) + __pte_index(addr)) #define pte_unmap(pte) do { } while (0) #define pte_unmap_nested(pte) do { } while (0) #define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext) #define set_pte_at(mm,addr,ptep,pteval) do { \ set_pte_ext(ptep, pteval, (addr) >= TASK_SIZE ? 0 : PTE_EXT_NG); \ } while (0) /* * The following only work if pte_present() is true. * Undefined behaviour if not.. */ #define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT) #define pte_write(pte) (pte_val(pte) & L_PTE_WRITE) #define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY) #define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG) #define pte_special(pte) (0) /* * The following only works if pte_present() is not true. */ #define pte_file(pte) (pte_val(pte) & L_PTE_FILE) #define pte_to_pgoff(x) (pte_val(x) >> 2) #define pgoff_to_pte(x) __pte(((x) << 2) | L_PTE_FILE) #define PTE_FILE_MAX_BITS 30 #define PTE_BIT_FUNC(fn,op) \ static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; } PTE_BIT_FUNC(wrprotect, &= ~L_PTE_WRITE); PTE_BIT_FUNC(mkwrite, |= L_PTE_WRITE); PTE_BIT_FUNC(mkclean, &= ~L_PTE_DIRTY); PTE_BIT_FUNC(mkdirty, |= L_PTE_DIRTY); PTE_BIT_FUNC(mkold, &= ~L_PTE_YOUNG); PTE_BIT_FUNC(mkyoung, |= L_PTE_YOUNG); static inline pte_t pte_mkspecial(pte_t pte) { return pte; } /* * Mark the prot value as uncacheable and unbufferable. */ #define pgprot_noncached(prot) \ __pgprot((pgprot_val(prot) & ~L_PTE_MT_MASK) | L_PTE_MT_UNCACHED) #define pgprot_writecombine(prot) \ __pgprot((pgprot_val(prot) & ~L_PTE_MT_MASK) | L_PTE_MT_BUFFERABLE) #define pmd_none(pmd) (!pmd_val(pmd)) #define pmd_present(pmd) (pmd_val(pmd)) #define pmd_bad(pmd) (pmd_val(pmd) & 2) #define copy_pmd(pmdpd,pmdps) \ do { \ pmdpd[0] = pmdps[0]; \ pmdpd[1] = pmdps[1]; \ flush_pmd_entry(pmdpd); \ } while (0) #define pmd_clear(pmdp) \ do { \ pmdp[0] = __pmd(0); \ pmdp[1] = __pmd(0); \ clean_pmd_entry(pmdp); \ } while (0) static inline pte_t *pmd_page_vaddr(pmd_t pmd) { unsigned long ptr; ptr = pmd_val(pmd) & ~(PTRS_PER_PTE * sizeof(void *) - 1); ptr += PTRS_PER_PTE * sizeof(void *); return __va(ptr); } #define pmd_page(pmd) virt_to_page(__va(pmd_val(pmd))) /* * Permanent address of a page. We never have highmem, so this is trivial. */ #define pages_to_mb(x) ((x) >> (20 - PAGE_SHIFT)) /* * Conversion functions: convert a page and protection to a page entry, * and a page entry and page directory to the page they refer to. */ #define mk_pte(page,prot) pfn_pte(page_to_pfn(page),prot) /* * The "pgd_xxx()" functions here are trivial for a folded two-level * setup: the pgd is never bad, and a pmd always exists (as it's folded * into the pgd entry) */ #define pgd_none(pgd) (0) #define pgd_bad(pgd) (0) #define pgd_present(pgd) (1) #define pgd_clear(pgdp) do { } while (0) #define set_pgd(pgd,pgdp) do { } while (0) /* to find an entry in a page-table-directory */ #define pgd_index(addr) ((addr) >> PGDIR_SHIFT) #define pgd_offset(mm, addr) ((mm)->pgd+pgd_index(addr)) /* to find an entry in a kernel page-table-directory */ #define pgd_offset_k(addr) pgd_offset(&init_mm, addr) /* Find an entry in the second-level page table.. */ #define pmd_offset(dir, addr) ((pmd_t *)(dir)) /* Find an entry in the third-level page table.. */ #define __pte_index(addr) (((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { const unsigned long mask = L_PTE_EXEC | L_PTE_WRITE | L_PTE_USER; pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask); return pte; } extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; /* Encode and decode a swap entry. * * We support up to 32GB of swap on 4k machines */ #define __swp_type(x) (((x).val >> 2) & 0x7f) #define __swp_offset(x) ((x).val >> 9) #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << 2) | ((offset) << 9) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(swp) ((pte_t) { (swp).val }) /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */ /* FIXME: this is not correct */ #define kern_addr_valid(addr) (1) #include /* * We provide our own arch_get_unmapped_area to cope with VIPT caches. */ #define HAVE_ARCH_UNMAPPED_AREA /* * remap a physical page `pfn' of size `size' with page protection `prot' * into virtual address `from' */ #define io_remap_pfn_range(vma,from,pfn,size,prot) \ remap_pfn_range(vma, from, pfn, size, prot) #define pgtable_cache_init() do { } while (0) #endif /* !__ASSEMBLY__ */ #endif /* CONFIG_MMU */ #endif /* _ASMARM_PGTABLE_H */