/* * 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 */