1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * highmem.c: 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 * Reworked for PowerPC by various contributors. Moved from
21 * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
22 */
23
24#include <linux/highmem.h>
25#include <linux/module.h>
26
27void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
28{
29	unsigned long vaddr;
30	int idx, type;
31
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);
38
39	return (void*) vaddr;
40}
41EXPORT_SYMBOL(kmap_atomic_high_prot);
42
43void kunmap_atomic_high(void *kvaddr)
44{
45	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
46
47	if (vaddr < __fix_to_virt(FIX_KMAP_END))
48		return;
49
50	if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
51		int type = kmap_atomic_idx();
52		unsigned int idx;
53
54		idx = type + KM_TYPE_NR * smp_processor_id();
55		WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
56
57		/*
58		 * force other mappings to Oops if they'll try to access
59		 * this pte without first remap it
60		 */
61		pte_clear(&init_mm, vaddr, kmap_pte-idx);
62		local_flush_tlb_page(NULL, vaddr);
63	}
64
65	kmap_atomic_idx_pop();
66}
67EXPORT_SYMBOL(kunmap_atomic_high);