/* SPDX-License-Identifier: GPL-2.0 */ /* * highmem.h: virtual kernel memory mappings for high memory * * 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 Terabyte 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 <linux/uaccess.h> #include <asm/fixmap.h> extern pte_t *kmap_pte; 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. */ /* * We use one full pte table with 4K pages. And with 16K/64K/256K pages pte * table covers enough memory (32MB/512MB/2GB resp.), so that both FIXMAP * and PKMAP can be placed in a single pte table. We use 512 pages for PKMAP * in case of 16K/64K/256K page sizes. */ #define PKMAP_ORDER PTE_SHIFT #define LAST_PKMAP (1 << PKMAP_ORDER) #define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE * (LAST_PKMAP + 1)) \ & PMD_MASK) #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 flush_cache_kmaps() { flush_icache(); flush_dcache(); } #endif /* __KERNEL__ */ #endif /* _ASM_HIGHMEM_H */