1 files changed, 64 insertions, 0 deletions
diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
new file mode 100644
index 000000000..31811be38
--- /dev/null
+++ b/arch/arm/include/asm/highmem.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_HIGHMEM_H
+#define _ASM_HIGHMEM_H
+
+#include <asm/kmap_types.h>
+
+#define PKMAP_BASE		(PAGE_OFFSET - PMD_SIZE)
+#define LAST_PKMAP		PTRS_PER_PTE
+#define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
+#define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)
+#define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))
+
+#define flush_cache_kmaps() \
+	do { \
+		if (cache_is_vivt()) \
+			flush_cache_all(); \
+	} while (0)
+
+extern pte_t *pkmap_page_table;
+
+/*
+ * The reason for kmap_high_get() is to ensure that the currently kmap'd
+ * page usage count does not decrease to zero while we're using its
+ * existing virtual mapping in an atomic context.  With a VIVT cache this
+ * is essential to do, but with a VIPT cache this is only an optimization
+ * so not to pay the price of establishing a second mapping if an existing
+ * one can be used.  However, on platforms without hardware TLB maintenance
+ * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
+ * the locking involved must also disable IRQs which is incompatible with
+ * the IPI mechanism used by global TLB operations.
+ */
+#define ARCH_NEEDS_KMAP_HIGH_GET
+#if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
+#undef ARCH_NEEDS_KMAP_HIGH_GET
+#if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
+#error "The sum of features in your kernel config cannot be supported together"
+#endif
+#endif
+
+/*
+ * Needed to be able to broadcast the TLB invalidation for kmap.
+ */
+#ifdef CONFIG_ARM_ERRATA_798181
+#undef ARCH_NEEDS_KMAP_HIGH_GET
+#endif
+
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+extern void *kmap_high_get(struct page *page);
+#else
+static inline void *kmap_high_get(struct page *page)
+{
+	return NULL;
+}
+#endif
+
+/*
+ * The following functions are already defined by <linux/highmem.h>
+ * when CONFIG_HIGHMEM is not set.
+ */
+#ifdef CONFIG_HIGHMEM
+extern void *kmap_atomic_pfn(unsigned long pfn);
+#endif
+
+#endif