/* * highmem.h: virtual kernel memory mappings for high memory * * PowerPC version, stolen from the i386 version. * * Used in CONFIG_HIGHMEM systems for memory pages which * are not addressable by direct kernel virtual addresses. * * Copyright (C) 1999 Gerhard Wichert, Siemens AG * Gerhard.Wichert@pdb.siemens.de * * * Redesigned the x86 32-bit VM architecture to deal with * up to 16 Terrabyte physical memory. With current x86 CPUs * we now support up to 64 Gigabytes physical RAM. * * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> */ #ifndef _ASM_HIGHMEM_H #define _ASM_HIGHMEM_H #ifdef __KERNEL__ #include <linux/init.h> #include <linux/interrupt.h> #include <asm/kmap_types.h> #include <asm/tlbflush.h> #include <asm/page.h> /* undef for production */ #define HIGHMEM_DEBUG 1 extern pte_t *kmap_pte; extern pgprot_t kmap_prot; extern pte_t *pkmap_page_table; /* * Right now we initialize only a single pte table. It can be extended * easily, subsequent pte tables have to be allocated in one physical * chunk of RAM. */ #define PKMAP_BASE CONFIG_HIGHMEM_START #define LAST_PKMAP (1 << PTE_SHIFT) #define LAST_PKMAP_MASK (LAST_PKMAP-1) #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) #define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL) extern void *kmap_high(struct page *page); extern void kunmap_high(struct page *page); static inline void *kmap(struct page *page) { might_sleep(); if (!PageHighMem(page)) return page_address(page); return kmap_high(page); } static inline void kunmap(struct page *page) { BUG_ON(in_interrupt()); if (!PageHighMem(page)) return; kunmap_high(page); } /* * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap * gives a more generic (and caching) interface. But kmap_atomic can * be used in IRQ contexts, so in some (very limited) cases we need * it. */ static inline void *kmap_atomic(struct page *page, enum km_type type) { unsigned int idx; unsigned long vaddr; /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ inc_preempt_count(); if (!PageHighMem(page)) return page_address(page); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE; #ifdef HIGHMEM_DEBUG BUG_ON(!pte_none(*(kmap_pte+idx))); #endif set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot)); flush_tlb_page(NULL, vaddr); return (void*) vaddr; } static inline void kunmap_atomic(void *kvaddr, enum km_type type) { #ifdef HIGHMEM_DEBUG unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; unsigned int idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < KMAP_FIX_BEGIN) { // FIXME dec_preempt_count(); preempt_check_resched(); return; } BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE); /* * force other mappings to Oops if they'll try to access * this pte without first remap it */ pte_clear(&init_mm, vaddr, kmap_pte+idx); flush_tlb_page(NULL, vaddr); #endif dec_preempt_count(); preempt_check_resched(); } static inline struct page *kmap_atomic_to_page(void *ptr) { unsigned long idx, vaddr = (unsigned long) ptr; if (vaddr < KMAP_FIX_BEGIN) return virt_to_page(ptr); idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT; return pte_page(kmap_pte[idx]); } #define flush_cache_kmaps() flush_cache_all() #endif /* __KERNEL__ */ #endif /* _ASM_HIGHMEM_H */