1 // SPDX-License-Identifier: GPL-2.0
3 * highmem.c: virtual kernel memory mappings for high memory
5 * PowerPC version, stolen from the i386 version.
7 * Used in CONFIG_HIGHMEM systems for memory pages which
8 * are not addressable by direct kernel virtual addresses.
10 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
11 * Gerhard.Wichert@pdb.siemens.de
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.
18 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
20 * Reworked for PowerPC by various contributors. Moved from
21 * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
24 #include <linux/highmem.h>
25 #include <linux/module.h>
27 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
32 type = kmap_atomic_idx_push();
33 idx = type + KM_TYPE_NR*smp_processor_id();
34 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
35 WARN_ON(IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !pte_none(*(kmap_pte - idx)));
36 __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
37 local_flush_tlb_page(NULL, vaddr);
41 EXPORT_SYMBOL(kmap_atomic_high_prot);
43 void kunmap_atomic_high(void *kvaddr)
45 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
47 if (vaddr < __fix_to_virt(FIX_KMAP_END))
50 if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
51 int type = kmap_atomic_idx();
54 idx = type + KM_TYPE_NR * smp_processor_id();
55 WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
58 * force other mappings to Oops if they'll try to access
59 * this pte without first remap it
61 pte_clear(&init_mm, vaddr, kmap_pte-idx);
62 local_flush_tlb_page(NULL, vaddr);
65 kmap_atomic_idx_pop();
67 EXPORT_SYMBOL(kunmap_atomic_high);