1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * highmem.h: virtual kernel memory mappings for high memory 4 * 5 * PowerPC version, stolen from the i386 version. 6 * 7 * Used in CONFIG_HIGHMEM systems for memory pages which 8 * are not addressable by direct kernel virtual addresses. 9 * 10 * Copyright (C) 1999 Gerhard Wichert, Siemens AG 11 * Gerhard.Wichert@pdb.siemens.de 12 * 13 * 14 * Redesigned the x86 32-bit VM architecture to deal with 15 * up to 16 Terrabyte physical memory. With current x86 CPUs 16 * we now support up to 64 Gigabytes physical RAM. 17 * 18 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> 19 */ 20 21 #ifndef _ASM_HIGHMEM_H 22 #define _ASM_HIGHMEM_H 23 24 #ifdef __KERNEL__ 25 26 #include <linux/interrupt.h> 27 #include <asm/kmap_types.h> 28 #include <asm/cacheflush.h> 29 #include <asm/page.h> 30 #include <asm/fixmap.h> 31 32 extern pte_t *kmap_pte; 33 extern pgprot_t kmap_prot; 34 extern pte_t *pkmap_page_table; 35 36 /* 37 * Right now we initialize only a single pte table. It can be extended 38 * easily, subsequent pte tables have to be allocated in one physical 39 * chunk of RAM. 40 */ 41 /* 42 * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte 43 * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP 44 * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP 45 * in case of 16K/64K/256K page sizes. 46 */ 47 #ifdef CONFIG_PPC_4K_PAGES 48 #define PKMAP_ORDER PTE_SHIFT 49 #else 50 #define PKMAP_ORDER 9 51 #endif 52 #define LAST_PKMAP (1 << PKMAP_ORDER) 53 #ifndef CONFIG_PPC_4K_PAGES 54 #define PKMAP_BASE (FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) 55 #else 56 #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK) 57 #endif 58 #define LAST_PKMAP_MASK (LAST_PKMAP-1) 59 #define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT) 60 #define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT)) 61 62 extern void *kmap_high(struct page *page); 63 extern void kunmap_high(struct page *page); 64 extern void *kmap_atomic_prot(struct page *page, pgprot_t prot); 65 extern void __kunmap_atomic(void *kvaddr); 66 67 static inline void *kmap(struct page *page) 68 { 69 might_sleep(); 70 if (!PageHighMem(page)) 71 return page_address(page); 72 return kmap_high(page); 73 } 74 75 static inline void kunmap(struct page *page) 76 { 77 BUG_ON(in_interrupt()); 78 if (!PageHighMem(page)) 79 return; 80 kunmap_high(page); 81 } 82 83 static inline void *kmap_atomic(struct page *page) 84 { 85 return kmap_atomic_prot(page, kmap_prot); 86 } 87 88 89 #define flush_cache_kmaps() flush_cache_all() 90 91 #endif /* __KERNEL__ */ 92 93 #endif /* _ASM_HIGHMEM_H */ 94