// SPDX-License-Identifier: GPL-2.0 /* * highmem.c: 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> * * Reworked for PowerPC by various contributors. Moved from * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp. */ #include <linux/export.h> #include <linux/highmem.h> /* * 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. */ #include <asm/tlbflush.h> void *kmap_atomic_prot(struct page *page, pgprot_t prot) { unsigned long vaddr; int idx, type; preempt_disable(); pagefault_disable(); if (!PageHighMem(page)) return page_address(page); type = kmap_atomic_idx_push(); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); #ifdef CONFIG_DEBUG_HIGHMEM BUG_ON(!pte_none(*(kmap_pte-idx))); #endif set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot)); local_flush_tlb_page(NULL, vaddr); return (void *) vaddr; } EXPORT_SYMBOL(kmap_atomic_prot); void __kunmap_atomic(void *kvaddr) { unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; int type; unsigned int idx; if (vaddr < __fix_to_virt(FIX_KMAP_END)) { pagefault_enable(); preempt_enable(); return; } type = kmap_atomic_idx(); idx = type + KM_TYPE_NR * smp_processor_id(); #ifdef CONFIG_DEBUG_HIGHMEM BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); #endif /* * 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); local_flush_tlb_page(NULL, vaddr); kmap_atomic_idx_pop(); pagefault_enable(); preempt_enable(); } EXPORT_SYMBOL(__kunmap_atomic);