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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/arch/arm/mm/highmem.c
..
..
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+// SPDX-License-Identifier: GPL-2.0-only
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+/*
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+ * arch/arm/mm/highmem.c -- ARM highmem support
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+ *
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+ * Author:	Nicolas Pitre
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+ * Created:	september 8, 2008
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+ * Copyright:	Marvell Semiconductors Inc.
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/highmem.h>
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+#include <linux/interrupt.h>
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+#include <asm/fixmap.h>
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+#include <asm/cacheflush.h>
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+#include <asm/tlbflush.h>
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+#include "mm.h"
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+
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+static inline void set_fixmap_pte(int idx, pte_t pte)
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+{
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+	unsigned long vaddr = __fix_to_virt(idx);
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+	pte_t *ptep = virt_to_kpte(vaddr);
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+
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+	set_pte_ext(ptep, pte, 0);
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+	local_flush_tlb_kernel_page(vaddr);
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+}
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+
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+static inline pte_t get_fixmap_pte(unsigned long vaddr)
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+{
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+	pte_t *ptep = virt_to_kpte(vaddr);
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+
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+	return *ptep;
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+}
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+
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+void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
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+{
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+	unsigned int idx;
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+	unsigned long vaddr;
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+	void *kmap;
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+	int type;
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+
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+	/*
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+	 * There is no cache coherency issue when non VIVT, so force the
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+	 * dedicated kmap usage for better debugging purposes in that case.
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+	 */
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+	if (!cache_is_vivt())
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+		kmap = NULL;
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+	else
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+#endif
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+		kmap = kmap_high_get(page);
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+	if (kmap)
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+		return kmap;
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+
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+	type = kmap_atomic_idx_push();
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+
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+	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+	vaddr = __fix_to_virt(idx);
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+	/*
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+	 * With debugging enabled, kunmap_atomic forces that entry to 0.
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+	 * Make sure it was indeed properly unmapped.
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+	 */
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+	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
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+#endif
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+	/*
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+	 * When debugging is off, kunmap_atomic leaves the previous mapping
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+	 * in place, so the contained TLB flush ensures the TLB is updated
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+	 * with the new mapping.
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+	 */
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+	set_fixmap_pte(idx, mk_pte(page, prot));
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+
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+	return (void *)vaddr;
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+}
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+EXPORT_SYMBOL(kmap_atomic_high_prot);
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+
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+void kunmap_atomic_high(void *kvaddr)
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+{
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+	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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+	int idx, type;
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+
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+	if (kvaddr >= (void *)FIXADDR_START) {
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+		type = kmap_atomic_idx();
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+		idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+
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+		if (cache_is_vivt())
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+			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+		BUG_ON(vaddr != __fix_to_virt(idx));
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+		set_fixmap_pte(idx, __pte(0));
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+#else
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+		(void) idx;  /* to kill a warning */
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+#endif
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+		kmap_atomic_idx_pop();
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+	} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
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+		/* this address was obtained through kmap_high_get() */
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+		kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
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+	}
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+}
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+EXPORT_SYMBOL(kunmap_atomic_high);
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+
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+void *kmap_atomic_pfn(unsigned long pfn)
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+{
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+	unsigned long vaddr;
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+	int idx, type;
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+	struct page *page = pfn_to_page(pfn);
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+
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+	preempt_disable();
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+	pagefault_disable();
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+	if (!PageHighMem(page))
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+		return page_address(page);
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+
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+	type = kmap_atomic_idx_push();
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+	idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
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+	vaddr = __fix_to_virt(idx);
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+	BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
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+#endif
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+	set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
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+
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+	return (void *)vaddr;
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+}