disable FB

hc

2024-01-04 1543e317f1da31b75942316931e8f491a8920811

 kernel/arch/microblaze/mm/highmem.c
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..
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+// SPDX-License-Identifier: GPL-2.0
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+/*
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+ * highmem.c: virtual kernel memory mappings for high memory
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+ *
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+ * PowerPC version, stolen from the i386 version.
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+ *
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+ * Used in CONFIG_HIGHMEM systems for memory pages which
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+ * are not addressable by direct kernel virtual addresses.
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+ *
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+ * Copyright (C) 1999 Gerhard Wichert, Siemens AG
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+ *		      Gerhard.Wichert@pdb.siemens.de
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+ *
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+ *
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+ * Redesigned the x86 32-bit VM architecture to deal with
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+ * up to 16 Terrabyte physical memory. With current x86 CPUs
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+ * we now support up to 64 Gigabytes physical RAM.
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+ *
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+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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+ *
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+ * Reworked for PowerPC by various contributors. Moved from
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+ * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
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+ */
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+
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+#include <linux/export.h>
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+#include <linux/highmem.h>
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+
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+/*
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+ * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
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+ * gives a more generic (and caching) interface. But kmap_atomic can
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+ * be used in IRQ contexts, so in some (very limited) cases we need
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+ * it.
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+ */
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+#include <asm/tlbflush.h>
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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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+
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+	unsigned long vaddr;
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+	int idx, type;
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+
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+	type = kmap_atomic_idx_push();
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+	idx = type + KM_TYPE_NR*smp_processor_id();
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+	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+	BUG_ON(!pte_none(*(kmap_pte-idx)));
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+#endif
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+	set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
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+	local_flush_tlb_page(NULL, vaddr);
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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 type;
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+	unsigned int idx;
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+
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+	if (vaddr < __fix_to_virt(FIX_KMAP_END))
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+		return;
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+
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+	type = kmap_atomic_idx();
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+
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+	idx = type + KM_TYPE_NR * smp_processor_id();
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+#ifdef CONFIG_DEBUG_HIGHMEM
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+	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
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+#endif
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+	/*
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+	 * force other mappings to Oops if they'll try to access
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+	 * this pte without first remap it
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+	 */
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+	pte_clear(&init_mm, vaddr, kmap_pte-idx);
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+	local_flush_tlb_page(NULL, vaddr);
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+
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+	kmap_atomic_idx_pop();
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+}
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+EXPORT_SYMBOL(kunmap_atomic_high);