1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * arch/arm/mm/highmem.c -- ARM highmem support
  4 *
  5 * Author:	Nicolas Pitre
  6 * Created:	september 8, 2008
  7 * Copyright:	Marvell Semiconductors Inc.
  8 */
  9
 10#include <linux/module.h>
 11#include <linux/highmem.h>
 12#include <linux/interrupt.h>
 13#include <asm/fixmap.h>
 14#include <asm/cacheflush.h>
 15#include <asm/tlbflush.h>
 16#include "mm.h"
 17
 18static inline void set_fixmap_pte(int idx, pte_t pte)
 19{
 20	unsigned long vaddr = __fix_to_virt(idx);
 21	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
 22
 23	set_pte_ext(ptep, pte, 0);
 24	local_flush_tlb_kernel_page(vaddr);
 25}
 26
 27static inline pte_t get_fixmap_pte(unsigned long vaddr)
 28{
 29	pte_t *ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
 30
 31	return *ptep;
 32}
 33
 34void *kmap(struct page *page)
 35{
 36	might_sleep();
 37	if (!PageHighMem(page))
 38		return page_address(page);
 39	return kmap_high(page);
 40}
 41EXPORT_SYMBOL(kmap);
 42
 43void kunmap(struct page *page)
 44{
 45	BUG_ON(in_interrupt());
 46	if (!PageHighMem(page))
 47		return;
 48	kunmap_high(page);
 49}
 50EXPORT_SYMBOL(kunmap);
 51
 52void *kmap_atomic(struct page *page)
 53{
 54	unsigned int idx;
 55	unsigned long vaddr;
 56	void *kmap;
 57	int type;
 58
 59	preempt_disable();
 60	pagefault_disable();
 61	if (!PageHighMem(page))
 62		return page_address(page);
 63
 64#ifdef CONFIG_DEBUG_HIGHMEM
 65	/*
 66	 * There is no cache coherency issue when non VIVT, so force the
 67	 * dedicated kmap usage for better debugging purposes in that case.
 68	 */
 69	if (!cache_is_vivt())
 70		kmap = NULL;
 71	else
 72#endif
 73		kmap = kmap_high_get(page);
 74	if (kmap)
 75		return kmap;
 76
 77	type = kmap_atomic_idx_push();
 78
 79	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
 80	vaddr = __fix_to_virt(idx);
 81#ifdef CONFIG_DEBUG_HIGHMEM
 82	/*
 83	 * With debugging enabled, kunmap_atomic forces that entry to 0.
 84	 * Make sure it was indeed properly unmapped.
 85	 */
 86	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
 87#endif
 88	/*
 89	 * When debugging is off, kunmap_atomic leaves the previous mapping
 90	 * in place, so the contained TLB flush ensures the TLB is updated
 91	 * with the new mapping.
 92	 */
 93	set_fixmap_pte(idx, mk_pte(page, kmap_prot));
 94
 95	return (void *)vaddr;
 96}
 97EXPORT_SYMBOL(kmap_atomic);
 98
 99void __kunmap_atomic(void *kvaddr)
100{
101	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
102	int idx, type;
103
104	if (kvaddr >= (void *)FIXADDR_START) {
105		type = kmap_atomic_idx();
106		idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
107
108		if (cache_is_vivt())
109			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
110#ifdef CONFIG_DEBUG_HIGHMEM
111		BUG_ON(vaddr != __fix_to_virt(idx));
112		set_fixmap_pte(idx, __pte(0));
113#else
114		(void) idx;  /* to kill a warning */
115#endif
116		kmap_atomic_idx_pop();
117	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
118		/* this address was obtained through kmap_high_get() */
119		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
120	}
121	pagefault_enable();
122	preempt_enable();
123}
124EXPORT_SYMBOL(__kunmap_atomic);
125
126void *kmap_atomic_pfn(unsigned long pfn)
127{
128	unsigned long vaddr;
129	int idx, type;
130	struct page *page = pfn_to_page(pfn);
131
132	preempt_disable();
133	pagefault_disable();
134	if (!PageHighMem(page))
135		return page_address(page);
136
137	type = kmap_atomic_idx_push();
138	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
139	vaddr = __fix_to_virt(idx);
140#ifdef CONFIG_DEBUG_HIGHMEM
141	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
142#endif
143	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
144
145	return (void *)vaddr;
146}