Merge branch 'highmem' into devel

Documentation/arm/memory.txt

@@ -29,7 +29,14 @@ ffff0000	ffff0fff	CPU vector page.
 				CPU supports vector relocation (control
 				register V bit.)
 
-ffc00000	fffeffff	DMA memory mapping region.  Memory returned
+fffe0000	fffeffff	XScale cache flush area.  This is used
+				in proc-xscale.S to flush the whole data
+				cache.  Free for other usage on non-XScale.
+
+fff00000	fffdffff	Fixmap mapping region.  Addresses provided
+				by fix_to_virt() will be located here.
+
+ffc00000	ffefffff	DMA memory mapping region.  Memory returned
 				by the dma_alloc_xxx functions will be
 				dynamically mapped here.
 

arch/arm/Kconfig

@@ -939,6 +939,23 @@ config NODES_SHIFT
 	default "2"
 	depends on NEED_MULTIPLE_NODES
 
+config HIGHMEM
+	bool "High Memory Support (EXPERIMENTAL)"
+	depends on MMU && EXPERIMENTAL
+	help
+	  The address space of ARM processors is only 4 Gigabytes large
+	  and it has to accommodate user address space, kernel address
+	  space as well as some memory mapped IO. That means that, if you
+	  have a large amount of physical memory and/or IO, not all of the
+	  memory can be "permanently mapped" by the kernel. The physical
+	  memory that is not permanently mapped is called "high memory".
+
+	  Depending on the selected kernel/user memory split, minimum
+	  vmalloc space and actual amount of RAM, you may not need this
+	  option which should result in a slightly faster kernel.
+
+	  If unsure, say n.
+
 source "mm/Kconfig"
 
 config LEDS

arch/arm/common/dmabounce.c

@@ -25,6 +25,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/page-flags.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
@@ -349,6 +350,12 @@ dma_addr_t dma_map_page(struct device *dev, struct page *page,
 
 	BUG_ON(!valid_dma_direction(dir));
 
+	if (PageHighMem(page)) {
+		dev_err(dev, "DMA buffer bouncing of HIGHMEM pages "
+			     "is not supported\n");
+		return ~0;
+	}
+
 	return map_single(dev, page_address(page) + offset, size, dir);
 }
 EXPORT_SYMBOL(dma_map_page);

arch/arm/include/asm/dma-mapping.h

@@ -15,10 +15,20 @@
  * must not be used by drivers.
  */
 #ifndef __arch_page_to_dma
+
+#if !defined(CONFIG_HIGHMEM)
 static inline dma_addr_t page_to_dma(struct device *dev, struct page *page)
 {
 	return (dma_addr_t)__virt_to_bus((unsigned long)page_address(page));
 }
+#elif defined(__pfn_to_bus)
+static inline dma_addr_t page_to_dma(struct device *dev, struct page *page)
+{
+	return (dma_addr_t)__pfn_to_bus(page_to_pfn(page));
+}
+#else
+#error "this machine class needs to define __arch_page_to_dma to use HIGHMEM"
+#endif
 
 static inline void *dma_to_virt(struct device *dev, dma_addr_t addr)
 {
@@ -57,6 +67,8 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
  */
 extern void dma_cache_maint(const void *kaddr, size_t size, int rw);
+extern void dma_cache_maint_page(struct page *page, unsigned long offset,
+				 size_t size, int rw);
 
 /*
  * Return whether the given device DMA address mask can be supported
@@ -316,7 +328,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
 	BUG_ON(!valid_dma_direction(dir));
 
 	if (!arch_is_coherent())
-		dma_cache_maint(page_address(page) + offset, size, dir);
+		dma_cache_maint_page(page, offset, size, dir);
 
 	return page_to_dma(dev, page) + offset;
 }

arch/arm/include/asm/fixmap.h

+#ifndef _ASM_FIXMAP_H
+#define _ASM_FIXMAP_H
+
+/*
+ * Nothing too fancy for now.
+ *
+ * On ARM we already have well known fixed virtual addresses imposed by
+ * the architecture such as the vector page which is located at 0xffff0000,
+ * therefore a second level page table is already allocated covering
+ * 0xfff00000 upwards.
+ *
+ * The cache flushing code in proc-xscale.S uses the virtual area between
+ * 0xfffe0000 and 0xfffeffff.
+ */
+
+#define FIXADDR_START		0xfff00000UL
+#define FIXADDR_TOP		0xfffe0000UL
+#define FIXADDR_SIZE		(FIXADDR_TOP - FIXADDR_START)
+
+#define FIX_KMAP_BEGIN		0
+#define FIX_KMAP_END		(FIXADDR_SIZE >> PAGE_SHIFT)
+
+#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
+#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
+
+extern void __this_fixmap_does_not_exist(void);
+
+static inline unsigned long fix_to_virt(const unsigned int idx)
+{
+	if (idx >= FIX_KMAP_END)
+		__this_fixmap_does_not_exist();
+	return __fix_to_virt(idx);
+}
+
+static inline unsigned int virt_to_fix(const unsigned long vaddr)
+{
+	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
+	return __virt_to_fix(vaddr);
+}
+
+#endif

arch/arm/include/asm/highmem.h

+#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 kmap_prot		PAGE_KERNEL
+
+#define flush_cache_kmaps()	flush_cache_all()
+
+extern pte_t *pkmap_page_table;
+
+#define ARCH_NEEDS_KMAP_HIGH_GET
+
+extern void *kmap_high(struct page *page);
+extern void *kmap_high_get(struct page *page);
+extern void kunmap_high(struct page *page);
+
+extern void *kmap(struct page *page);
+extern void kunmap(struct page *page);
+extern void *kmap_atomic(struct page *page, enum km_type type);
+extern void kunmap_atomic(void *kvaddr, enum km_type type);
+extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
+extern struct page *kmap_atomic_to_page(const void *ptr);
+
+#endif

arch/arm/include/asm/kmap_types.h

@@ -18,6 +18,7 @@ enum km_type {
 	KM_IRQ1,
 	KM_SOFTIRQ0,
 	KM_SOFTIRQ1,
+	KM_L2_CACHE,
 	KM_TYPE_NR
 };
 

arch/arm/include/asm/memory.h

@@ -44,13 +44,20 @@
  * The module space lives between the addresses given by TASK_SIZE
  * and PAGE_OFFSET - it must be within 32MB of the kernel text.
  */
-#define MODULES_END		(PAGE_OFFSET)
-#define MODULES_VADDR		(MODULES_END - 16*1048576)
-
+#define MODULES_VADDR		(PAGE_OFFSET - 16*1024*1024)
 #if TASK_SIZE > MODULES_VADDR
 #error Top of user space clashes with start of module space
 #endif
 
+/*
+ * The highmem pkmap virtual space shares the end of the module area.
+ */
+#ifdef CONFIG_HIGHMEM
+#define MODULES_END		(PAGE_OFFSET - PMD_SIZE)
+#else
+#define MODULES_END		(PAGE_OFFSET)
+#endif
+
 /*
  * The XIP kernel gets mapped at the bottom of the module vm area.
  * Since we use sections to map it, this macro replaces the physical address
@@ -181,6 +188,7 @@ static inline void *phys_to_virt(unsigned long x)
 #ifndef __virt_to_bus
 #define __virt_to_bus	__virt_to_phys
 #define __bus_to_virt	__phys_to_virt
+#define __pfn_to_bus(x)	((x) << PAGE_SHIFT)
 #endif
 
 static inline __deprecated unsigned long virt_to_bus(void *x)

arch/arm/mach-iop13xx/include/mach/memory.h

@@ -59,7 +59,10 @@ static inline unsigned long __lbus_to_virt(dma_addr_t x)
 	})
 
 #define __arch_page_to_dma(dev, page)					\
-	__arch_virt_to_dma(dev, page_address(page))
+	({								\
+		/* __is_lbus_virt() can never be true for RAM pages */	\
+		(dma_addr_t)page_to_phys(page);				\
+	})
 
 #endif /* CONFIG_ARCH_IOP13XX */
 #endif /* !ASSEMBLY */

arch/arm/mach-ks8695/include/mach/memory.h

@@ -35,7 +35,11 @@ extern struct bus_type platform_bus_type;
 					__phys_to_virt(x) : __bus_to_virt(x)); })
 #define __arch_virt_to_dma(dev, x)	({ is_lbus_device(dev) ? \
 					(dma_addr_t)__virt_to_phys(x) : (dma_addr_t)__virt_to_bus(x); })
-#define __arch_page_to_dma(dev, x)	__arch_virt_to_dma(dev, page_address(x))
+#define __arch_page_to_dma(dev, x)	\
+	({ dma_addr_t __dma = page_to_phys(page); \
+	   if (!is_lbus_device(dev)) \
+		__dma = __dma - PHYS_OFFSET + KS8695_PCIMEM_PA; \
+	   __dma; })
 
 #endif
 

arch/arm/mm/Makefile

@@ -16,6 +16,7 @@ obj-$(CONFIG_MODULES)		+= proc-syms.o
 
 obj-$(CONFIG_ALIGNMENT_TRAP)	+= alignment.o
 obj-$(CONFIG_DISCONTIGMEM)	+= discontig.o
+obj-$(CONFIG_HIGHMEM)		+= highmem.o
 
 obj-$(CONFIG_CPU_ABRT_NOMMU)	+= abort-nommu.o
 obj-$(CONFIG_CPU_ABRT_EV4)	+= abort-ev4.o

arch/arm/mm/cache-feroceon-l2.c

@@ -14,8 +14,12 @@
 
 #include <linux/init.h>
 #include <asm/cacheflush.h>
+#include <asm/kmap_types.h>
+#include <asm/fixmap.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
 #include <plat/cache-feroceon-l2.h>
-
+#include "mm.h"
 
 /*
  * Low-level cache maintenance operations.
@@ -34,14 +38,36 @@
  * The range operations require two successive cp15 writes, in
  * between which we don't want to be preempted.
  */
+
+static inline unsigned long l2_start_va(unsigned long paddr)
+{
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * Let's do our own fixmap stuff in a minimal way here.
+	 * Because range ops can't be done on physical addresses,
+	 * we simply install a virtual mapping for it only for the
+	 * TLB lookup to occur, hence no need to flush the untouched
+	 * memory mapping.  This is protected with the disabling of
+	 * interrupts by the caller.
+	 */
+	unsigned long idx = KM_L2_CACHE + KM_TYPE_NR * smp_processor_id();
+	unsigned long vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+	set_pte_ext(TOP_PTE(vaddr), pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL), 0);
+	local_flush_tlb_kernel_page(vaddr);
+	return vaddr + (paddr & ~PAGE_MASK);
+#else
+	return __phys_to_virt(paddr);
+#endif
+}
+
 static inline void l2_clean_pa(unsigned long addr)
 {
 	__asm__("mcr p15, 1, %0, c15, c9, 3" : : "r" (addr));
 }
 
-static inline void l2_clean_mva_range(unsigned long start, unsigned long end)
+static inline void l2_clean_pa_range(unsigned long start, unsigned long end)
 {
-	unsigned long flags;
+	unsigned long va_start, va_end, flags;
 
 	/*
 	 * Make sure 'start' and 'end' reference the same page, as
@@ -51,17 +77,14 @@ static inline void l2_clean_mva_range(unsigned long start, unsigned long end)
 	BUG_ON((start ^ end) >> PAGE_SHIFT);
 
 	raw_local_irq_save(flags);
+	va_start = l2_start_va(start);
+	va_end = va_start + (end - start);
 	__asm__("mcr p15, 1, %0, c15, c9, 4\n\t"
 		"mcr p15, 1, %1, c15, c9, 5"
-		: : "r" (start), "r" (end));
+		: : "r" (va_start), "r" (va_end));
 	raw_local_irq_restore(flags);
 }
 
-static inline void l2_clean_pa_range(unsigned long start, unsigned long end)
-{
-	l2_clean_mva_range(__phys_to_virt(start), __phys_to_virt(end));
-}
-
 static inline void l2_clean_inv_pa(unsigned long addr)
 {
 	__asm__("mcr p15, 1, %0, c15, c10, 3" : : "r" (addr));
@@ -72,9 +95,9 @@ static inline void l2_inv_pa(unsigned long addr)
 	__asm__("mcr p15, 1, %0, c15, c11, 3" : : "r" (addr));
 }
 
-static inline void l2_inv_mva_range(unsigned long start, unsigned long end)
+static inline void l2_inv_pa_range(unsigned long start, unsigned long end)
 {
-	unsigned long flags;
+	unsigned long va_start, va_end, flags;
 
 	/*
 	 * Make sure 'start' and 'end' reference the same page, as
@@ -84,17 +107,14 @@ static inline void l2_inv_mva_range(unsigned long start, unsigned long end)
 	BUG_ON((start ^ end) >> PAGE_SHIFT);
 
 	raw_local_irq_save(flags);
+	va_start = l2_start_va(start);
+	va_end = va_start + (end - start);
 	__asm__("mcr p15, 1, %0, c15, c11, 4\n\t"
 		"mcr p15, 1, %1, c15, c11, 5"
-		: : "r" (start), "r" (end));
+		: : "r" (va_start), "r" (va_end));
 	raw_local_irq_restore(flags);
 }
 
-static inline void l2_inv_pa_range(unsigned long start, unsigned long end)
-{
-	l2_inv_mva_range(__phys_to_virt(start), __phys_to_virt(end));
-}
-
 
 /*
  * Linux primitives.

arch/arm/mm/cache-xsc3l2.c

@@ -17,12 +17,14 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  */
 #include <linux/init.h>
-#include <linux/spinlock.h>
-#include <linux/io.h>
-
 #include <asm/system.h>
 #include <asm/cputype.h>
 #include <asm/cacheflush.h>
+#include <asm/kmap_types.h>
+#include <asm/fixmap.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include "mm.h"
 
 #define CR_L2	(1 << 26)
 
@@ -47,21 +49,11 @@ static inline void xsc3_l2_clean_mva(unsigned long addr)
 	__asm__("mcr p15, 1, %0, c7, c11, 1" : : "r" (addr));
 }
 
-static inline void xsc3_l2_clean_pa(unsigned long addr)
-{
-	xsc3_l2_clean_mva(__phys_to_virt(addr));
-}
-
 static inline void xsc3_l2_inv_mva(unsigned long addr)
 {
 	__asm__("mcr p15, 1, %0, c7, c7, 1" : : "r" (addr));
 }
 
-static inline void xsc3_l2_inv_pa(unsigned long addr)
-{
-	xsc3_l2_inv_mva(__phys_to_virt(addr));
-}
-
 static inline void xsc3_l2_inv_all(void)
 {
 	unsigned long l2ctype, set_way;
@@ -79,50 +71,103 @@ static inline void xsc3_l2_inv_all(void)
 	dsb();
 }
 
+#ifdef CONFIG_HIGHMEM
+#define l2_map_save_flags(x)		raw_local_save_flags(x)
+#define l2_map_restore_flags(x)		raw_local_irq_restore(x)
+#else
+#define l2_map_save_flags(x)		((x) = 0)
+#define l2_map_restore_flags(x)		((void)(x))
+#endif
+
+static inline unsigned long l2_map_va(unsigned long pa, unsigned long prev_va,
+				      unsigned long flags)
+{
+#ifdef CONFIG_HIGHMEM
+	unsigned long va = prev_va & PAGE_MASK;
+	unsigned long pa_offset = pa << (32 - PAGE_SHIFT);
+	if (unlikely(pa_offset < (prev_va << (32 - PAGE_SHIFT)))) {
+		/*
+		 * Switching to a new page.  Because cache ops are
+		 * using virtual addresses only, we must put a mapping
+		 * in place for it.  We also enable interrupts for a
+		 * short while and disable them again to protect this
+		 * mapping.
+		 */
+		unsigned long idx;
+		raw_local_irq_restore(flags);
+		idx = KM_L2_CACHE + KM_TYPE_NR * smp_processor_id();
+		va = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+		raw_local_irq_restore(flags | PSR_I_BIT);
+		set_pte_ext(TOP_PTE(va), pfn_pte(pa >> PAGE_SHIFT, PAGE_KERNEL), 0);
+		local_flush_tlb_kernel_page(va);
+	}
+	return va + (pa_offset >> (32 - PAGE_SHIFT));
+#else
+	return __phys_to_virt(pa);
+#endif
+}
+
 static void xsc3_l2_inv_range(unsigned long start, unsigned long end)
 {
+	unsigned long vaddr, flags;
+
 	if (start == 0 && end == -1ul) {
 		xsc3_l2_inv_all();
 		return;
 	}
 
+	vaddr = -1;  /* to force the first mapping */
+	l2_map_save_flags(flags);
+
 	/*
 	 * Clean and invalidate partial first cache line.
 	 */
 	if (start & (CACHE_LINE_SIZE - 1)) {
-		xsc3_l2_clean_pa(start & ~(CACHE_LINE_SIZE - 1));
-		xsc3_l2_inv_pa(start & ~(CACHE_LINE_SIZE - 1));
+		vaddr = l2_map_va(start & ~(CACHE_LINE_SIZE - 1), vaddr, flags);
+		xsc3_l2_clean_mva(vaddr);
+		xsc3_l2_inv_mva(vaddr);
 		start = (start | (CACHE_LINE_SIZE - 1)) + 1;
 	}
 
 	/*
-	 * Clean and invalidate partial last cache line.
+	 * Invalidate all full cache lines between 'start' and 'end'.
 	 */
-	if (start < end && (end & (CACHE_LINE_SIZE - 1))) {
-		xsc3_l2_clean_pa(end & ~(CACHE_LINE_SIZE - 1));
-		xsc3_l2_inv_pa(end & ~(CACHE_LINE_SIZE - 1));
-		end &= ~(CACHE_LINE_SIZE - 1);
+	while (start < (end & ~(CACHE_LINE_SIZE - 1))) {
+		vaddr = l2_map_va(start, vaddr, flags);
+		xsc3_l2_inv_mva(vaddr);
+		start += CACHE_LINE_SIZE;
 	}
 
 	/*
-	 * Invalidate all full cache lines between 'start' and 'end'.
+	 * Clean and invalidate partial last cache line.
 	 */
-	while (start < end) {
-		xsc3_l2_inv_pa(start);
-		start += CACHE_LINE_SIZE;
+	if (start < end) {
+		vaddr = l2_map_va(start, vaddr, flags);
+		xsc3_l2_clean_mva(vaddr);
+		xsc3_l2_inv_mva(vaddr);
 	}
 
+	l2_map_restore_flags(flags);
+
 	dsb();
 }
 
 static void xsc3_l2_clean_range(unsigned long start, unsigned long end)
 {
+	unsigned long vaddr, flags;
+
+	vaddr = -1;  /* to force the first mapping */
+	l2_map_save_flags(flags);
+
 	start &= ~(CACHE_LINE_SIZE - 1);
 	while (start < end) {
-		xsc3_l2_clean_pa(start);
+		vaddr = l2_map_va(start, vaddr, flags);
+		xsc3_l2_clean_mva(vaddr);
 		start += CACHE_LINE_SIZE;
 	}
 
+	l2_map_restore_flags(flags);
+
 	dsb();
 }
 
@@ -148,18 +193,26 @@ static inline void xsc3_l2_flush_all(void)
 
 static void xsc3_l2_flush_range(unsigned long start, unsigned long end)
 {
+	unsigned long vaddr, flags;
+
 	if (start == 0 && end == -1ul) {
 		xsc3_l2_flush_all();
 		return;
 	}
 
+	vaddr = -1;  /* to force the first mapping */
+	l2_map_save_flags(flags);
+
 	start &= ~(CACHE_LINE_SIZE - 1);
 	while (start < end) {
-		xsc3_l2_clean_pa(start);
-		xsc3_l2_inv_pa(start);
+		vaddr = l2_map_va(start, vaddr, flags);
+		xsc3_l2_clean_mva(vaddr);
+		xsc3_l2_inv_mva(vaddr);
 		start += CACHE_LINE_SIZE;
 	}
 
+	l2_map_restore_flags(flags);
+
 	dsb();
 }
 

arch/arm/mm/dma-mapping.c

@@ -19,6 +19,7 @@
 #include <linux/dma-mapping.h>
 
 #include <asm/memory.h>
+#include <asm/highmem.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/sizes.h>
@@ -490,29 +491,101 @@ core_initcall(consistent_init);
  */
 void dma_cache_maint(const void *start, size_t size, int direction)
 {
-	const void *end = start + size;
+	void (*inner_op)(const void *, const void *);
+	void (*outer_op)(unsigned long, unsigned long);
 
-	BUG_ON(!virt_addr_valid(start) || !virt_addr_valid(end - 1));
+	BUG_ON(!virt_addr_valid(start) || !virt_addr_valid(start + size - 1));
 
 	switch (direction) {
 	case DMA_FROM_DEVICE:		/* invalidate only */
-		dmac_inv_range(start, end);
-		outer_inv_range(__pa(start), __pa(end));
+		inner_op = dmac_inv_range;
+		outer_op = outer_inv_range;
 		break;
 	case DMA_TO_DEVICE:		/* writeback only */
-		dmac_clean_range(start, end);
-		outer_clean_range(__pa(start), __pa(end));
+		inner_op = dmac_clean_range;
+		outer_op = outer_clean_range;
 		break;
 	case DMA_BIDIRECTIONAL:		/* writeback and invalidate */
-		dmac_flush_range(start, end);
-		outer_flush_range(__pa(start), __pa(end));
+		inner_op = dmac_flush_range;
+		outer_op = outer_flush_range;
 		break;
 	default:
 		BUG();
 	}
+
+	inner_op(start, start + size);
+	outer_op(__pa(start), __pa(start) + size);
 }
 EXPORT_SYMBOL(dma_cache_maint);
 
+static void dma_cache_maint_contiguous(struct page *page, unsigned long offset,
+				       size_t size, int direction)
+{
+	void *vaddr;
+	unsigned long paddr;
+	void (*inner_op)(const void *, const void *);
+	void (*outer_op)(unsigned long, unsigned long);
+
+	switch (direction) {
+	case DMA_FROM_DEVICE:		/* invalidate only */
+		inner_op = dmac_inv_range;
+		outer_op = outer_inv_range;
+		break;
+	case DMA_TO_DEVICE:		/* writeback only */
+		inner_op = dmac_clean_range;
+		outer_op = outer_clean_range;
+		break;
+	case DMA_BIDIRECTIONAL:		/* writeback and invalidate */
+		inner_op = dmac_flush_range;
+		outer_op = outer_flush_range;
+		break;
+	default:
+		BUG();
+	}
+
+	if (!PageHighMem(page)) {
+		vaddr = page_address(page) + offset;
+		inner_op(vaddr, vaddr + size);
+	} else {
+		vaddr = kmap_high_get(page);
+		if (vaddr) {
+			vaddr += offset;
+			inner_op(vaddr, vaddr + size);
+			kunmap_high(page);
+		}
+	}
+
+	paddr = page_to_phys(page) + offset;
+	outer_op(paddr, paddr + size);
+}
+
+void dma_cache_maint_page(struct page *page, unsigned long offset,
+			  size_t size, int dir)
+{
+	/*
+	 * A single sg entry may refer to multiple physically contiguous
+	 * pages.  But we still need to process highmem pages individually.
+	 * If highmem is not configured then the bulk of this loop gets
+	 * optimized out.
+	 */
+	size_t left = size;
+	do {
+		size_t len = left;
+		if (PageHighMem(page) && len + offset > PAGE_SIZE) {
+			if (offset >= PAGE_SIZE) {
+				page += offset / PAGE_SIZE;
+				offset %= PAGE_SIZE;
+			}
+			len = PAGE_SIZE - offset;
+		}
+		dma_cache_maint_contiguous(page, offset, len, dir);
+		offset = 0;
+		page++;
+		left -= len;
+	} while (left);
+}
+EXPORT_SYMBOL(dma_cache_maint_page);
+
 /**
  * dma_map_sg - map a set of SG buffers for streaming mode DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -610,7 +683,8 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 			continue;
 
 		if (!arch_is_coherent())
-			dma_cache_maint(sg_virt(s), s->length, dir);
+			dma_cache_maint_page(sg_page(s), s->offset,
+					     s->length, dir);
 	}
 }
 EXPORT_SYMBOL(dma_sync_sg_for_device);

arch/arm/mm/flush.c

@@ -192,7 +192,7 @@ void flush_dcache_page(struct page *page)
 	struct address_space *mapping = page_mapping(page);
 
 #ifndef CONFIG_SMP
-	if (mapping && !mapping_mapped(mapping))
+	if (!PageHighMem(page) && mapping && !mapping_mapped(mapping))
 		set_bit(PG_dcache_dirty, &page->flags);
 	else
 #endif

arch/arm/mm/highmem.c

+/*
+ * arch/arm/mm/highmem.c -- ARM highmem support
+ *
+ * Author:	Nicolas Pitre
+ * Created:	september 8, 2008
+ * Copyright:	Marvell Semiconductors Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/highmem.h>
+#include <linux/interrupt.h>
+#include <asm/fixmap.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include "mm.h"
+
+void *kmap(struct page *page)
+{
+	might_sleep();
+	if (!PageHighMem(page))
+		return page_address(page);
+	return kmap_high(page);
+}
+EXPORT_SYMBOL(kmap);
+
+void kunmap(struct page *page)
+{
+	BUG_ON(in_interrupt());
+	if (!PageHighMem(page))
+		return;
+	kunmap_high(page);
+}
+EXPORT_SYMBOL(kunmap);
+
+void *kmap_atomic(struct page *page, enum km_type type)
+{
+	unsigned int idx;
+	unsigned long vaddr;
+
+	pagefault_disable();
+	if (!PageHighMem(page))
+		return page_address(page);
+
+	idx = type + KM_TYPE_NR * smp_processor_id();
+	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+	/*
+	 * With debugging enabled, kunmap_atomic forces that entry to 0.
+	 * Make sure it was indeed properly unmapped.
+	 */
+	BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
+#endif
+	set_pte_ext(TOP_PTE(vaddr), mk_pte(page, kmap_prot), 0);
+	/*
+	 * When debugging is off, kunmap_atomic leaves the previous mapping
+	 * in place, so this TLB flush ensures the TLB is updated with the
+	 * new mapping.
+	 */
+	local_flush_tlb_kernel_page(vaddr);
+
+	return (void *)vaddr;
+}
+EXPORT_SYMBOL(kmap_atomic);
+
+void kunmap_atomic(void *kvaddr, enum km_type type)
+{
+	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
+	unsigned int idx = type + KM_TYPE_NR * smp_processor_id();
+
+	if (kvaddr >= (void *)FIXADDR_START) {
+		__cpuc_flush_dcache_page((void *)vaddr);
+#ifdef CONFIG_DEBUG_HIGHMEM
+		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+		set_pte_ext(TOP_PTE(vaddr), __pte(0), 0);
+		local_flush_tlb_kernel_page(vaddr);
+#else
+		(void) idx;  /* to kill a warning */
+#endif
+	}
+	pagefault_enable();
+}
+EXPORT_SYMBOL(kunmap_atomic);
+
+void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
+{
+	unsigned int idx;
+	unsigned long vaddr;
+
+	pagefault_disable();
+
+	idx = type + KM_TYPE_NR * smp_processor_id();
+	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+#ifdef CONFIG_DEBUG_HIGHMEM
+	BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
+#endif
+	set_pte_ext(TOP_PTE(vaddr), pfn_pte(pfn, kmap_prot), 0);
+	local_flush_tlb_kernel_page(vaddr);
+
+	return (void *)vaddr;
+}
+
+struct page *kmap_atomic_to_page(const void *ptr)
+{
+	unsigned long vaddr = (unsigned long)ptr;
+	pte_t *pte;
+
+	if (vaddr < FIXADDR_START)
+		return virt_to_page(ptr);
+
+	pte = TOP_PTE(vaddr);
+	return pte_page(*pte);
+}

arch/arm/mm/init.c

@@ -15,6 +15,7 @@
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/initrd.h>
+#include <linux/highmem.h>
 
 #include <asm/mach-types.h>
 #include <asm/sections.h>
@@ -382,7 +383,7 @@ void __init bootmem_init(void)
 	for_each_node(node)
 		bootmem_free_node(node, mi);
 
-	high_memory = __va(memend_pfn << PAGE_SHIFT);
+	high_memory = __va((memend_pfn << PAGE_SHIFT) - 1) + 1;
 
 	/*
 	 * This doesn't seem to be used by the Linux memory manager any
@@ -485,7 +486,7 @@ void __init mem_init(void)
 	int i, node;
 
 #ifndef CONFIG_DISCONTIGMEM
-	max_mapnr   = virt_to_page(high_memory) - mem_map;
+	max_mapnr   = pfn_to_page(max_pfn + PHYS_PFN_OFFSET) - mem_map;
 #endif
 
 	/* this will put all unused low memory onto the freelists */
@@ -504,6 +505,19 @@ void __init mem_init(void)
 				    __phys_to_pfn(__pa(swapper_pg_dir)), NULL);
 #endif
 
+#ifdef CONFIG_HIGHMEM
+	/* set highmem page free */
+	for_each_online_node(node) {
+		for_each_nodebank (i, &meminfo, node) {
+			unsigned long start = bank_pfn_start(&meminfo.bank[i]);
+			unsigned long end = bank_pfn_end(&meminfo.bank[i]);
+			if (start >= max_low_pfn + PHYS_PFN_OFFSET)
+				totalhigh_pages += free_area(start, end, NULL);
+		}
+	}
+	totalram_pages += totalhigh_pages;
+#endif
+
 	/*
 	 * Since our memory may not be contiguous, calculate the
 	 * real number of pages we have in this system
@@ -521,9 +535,10 @@ void __init mem_init(void)
 	initsize = __init_end - __init_begin;
 
 	printk(KERN_NOTICE "Memory: %luKB available (%dK code, "
-		"%dK data, %dK init)\n",
+		"%dK data, %dK init, %luK highmem)\n",
 		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
-		codesize >> 10, datasize >> 10, initsize >> 10);
+		codesize >> 10, datasize >> 10, initsize >> 10,
+		(unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)));
 
 	if (PAGE_SIZE >= 16384 && num_physpages <= 128) {
 		extern int sysctl_overcommit_memory;

arch/arm/mm/mm.h

-/* the upper-most page table pointer */
-
 #ifdef CONFIG_MMU
 
+/* the upper-most page table pointer */
 extern pmd_t *top_pmd;
 
 #define TOP_PTE(x)	pte_offset_kernel(top_pmd, x)

arch/arm/mm/mmap.c

@@ -124,7 +124,7 @@ int valid_phys_addr_range(unsigned long addr, size_t size)
 {
 	if (addr < PHYS_OFFSET)
 		return 0;
-	if (addr + size > __pa(high_memory))
+	if (addr + size >= __pa(high_memory - 1))
 		return 0;
 
 	return 1;

arch/arm/mm/mmu.c

@@ -18,9 +18,11 @@
 #include <asm/cputype.h>
 #include <asm/mach-types.h>
 #include <asm/sections.h>
+#include <asm/cachetype.h>
 #include <asm/setup.h>
 #include <asm/sizes.h>
 #include <asm/tlb.h>
+#include <asm/highmem.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
@@ -700,6 +702,10 @@ static void __init sanity_check_meminfo(void)
 			if (meminfo.nr_banks >= NR_BANKS) {
 				printk(KERN_CRIT "NR_BANKS too low, "
 						 "ignoring high memory\n");
+			} else if (cache_is_vipt_aliasing()) {
+				printk(KERN_CRIT "HIGHMEM is not yet supported "
+						 "with VIPT aliasing cache, "
+						 "ignoring high memory\n");
 			} else {
 				memmove(bank + 1, bank,
 					(meminfo.nr_banks - i) * sizeof(*bank));
@@ -918,6 +924,17 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
 	flush_cache_all();
 }
 
+static void __init kmap_init(void)
+{
+#ifdef CONFIG_HIGHMEM
+	pmd_t *pmd = pmd_off_k(PKMAP_BASE);
+	pte_t *pte = alloc_bootmem_low_pages(2 * PTRS_PER_PTE * sizeof(pte_t));
+	BUG_ON(!pmd_none(*pmd) || !pte);
+	__pmd_populate(pmd, __pa(pte) | _PAGE_KERNEL_TABLE);
+	pkmap_page_table = pte + PTRS_PER_PTE;
+#endif
+}
+
 /*
  * paging_init() sets up the page tables, initialises the zone memory
  * maps, and sets up the zero page, bad page and bad page tables.
@@ -931,6 +948,7 @@ void __init paging_init(struct machine_desc *mdesc)
 	prepare_page_table();
 	bootmem_init();
 	devicemaps_init(mdesc);
+	kmap_init();
 
 	top_pmd = pmd_off_k(0xffff0000);
 

arch/arm/plat-omap/include/mach/memory.h

@@ -61,9 +61,11 @@
 #define lbus_to_virt(x)		((x) - OMAP1510_LB_OFFSET + PAGE_OFFSET)
 #define is_lbus_device(dev)	(cpu_is_omap15xx() && dev && (strncmp(dev_name(dev), "ohci", 4) == 0))
 
-#define __arch_page_to_dma(dev, page)	({is_lbus_device(dev) ? \
-					(dma_addr_t)virt_to_lbus(page_address(page)) : \
-					(dma_addr_t)__virt_to_phys(page_address(page));})
+#define __arch_page_to_dma(dev, page)	\
+	({ dma_addr_t __dma = page_to_phys(page); \
+	   if (is_lbus_device(dev)) \
+		__dma = __dma - PHYS_OFFSET + OMAP1510_LB_OFFSET; \
+	   __dma; })
 
 #define __arch_dma_to_virt(dev, addr)	({ (void *) (is_lbus_device(dev) ? \
 						lbus_to_virt(addr) : \

mm/highmem.c

@@ -67,6 +67,25 @@ pte_t * pkmap_page_table;
 
 static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
 
+/*
+ * Most architectures have no use for kmap_high_get(), so let's abstract
+ * the disabling of IRQ out of the locking in that case to save on a
+ * potential useless overhead.
+ */
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+#define lock_kmap()             spin_lock_irq(&kmap_lock)
+#define unlock_kmap()           spin_unlock_irq(&kmap_lock)
+#define lock_kmap_any(flags)    spin_lock_irqsave(&kmap_lock, flags)
+#define unlock_kmap_any(flags)  spin_unlock_irqrestore(&kmap_lock, flags)
+#else
+#define lock_kmap()             spin_lock(&kmap_lock)
+#define unlock_kmap()           spin_unlock(&kmap_lock)
+#define lock_kmap_any(flags)    \
+		do { spin_lock(&kmap_lock); (void)(flags); } while (0)
+#define unlock_kmap_any(flags)  \
+		do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
+#endif
+
 static void flush_all_zero_pkmaps(void)
 {
 	int i;
@@ -113,9 +132,9 @@ static void flush_all_zero_pkmaps(void)
  */
 void kmap_flush_unused(void)
 {
-	spin_lock(&kmap_lock);
+	lock_kmap();
 	flush_all_zero_pkmaps();
-	spin_unlock(&kmap_lock);
+	unlock_kmap();
 }
 
 static inline unsigned long map_new_virtual(struct page *page)
@@ -145,10 +164,10 @@ start:
 
 			__set_current_state(TASK_UNINTERRUPTIBLE);
 			add_wait_queue(&pkmap_map_wait, &wait);
-			spin_unlock(&kmap_lock);
+			unlock_kmap();
 			schedule();
 			remove_wait_queue(&pkmap_map_wait, &wait);
-			spin_lock(&kmap_lock);
+			lock_kmap();
 
 			/* Somebody else might have mapped it while we slept */
 			if (page_address(page))
@@ -184,29 +203,59 @@ void *kmap_high(struct page *page)
 	 * For highmem pages, we can't trust "virtual" until
 	 * after we have the lock.
 	 */
-	spin_lock(&kmap_lock);
+	lock_kmap();
 	vaddr = (unsigned long)page_address(page);
 	if (!vaddr)
 		vaddr = map_new_virtual(page);
 	pkmap_count[PKMAP_NR(vaddr)]++;
 	BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 2);
-	spin_unlock(&kmap_lock);
+	unlock_kmap();
 	return (void*) vaddr;
 }
 
 EXPORT_SYMBOL(kmap_high);
 
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+/**
+ * kmap_high_get - pin a highmem page into memory
+ * @page: &struct page to pin
+ *
+ * Returns the page's current virtual memory address, or NULL if no mapping
+ * exists.  When and only when a non null address is returned then a
+ * matching call to kunmap_high() is necessary.
+ *
+ * This can be called from any context.
+ */
+void *kmap_high_get(struct page *page)
+{
+	unsigned long vaddr, flags;
+
+	lock_kmap_any(flags);
+	vaddr = (unsigned long)page_address(page);
+	if (vaddr) {
+		BUG_ON(pkmap_count[PKMAP_NR(vaddr)] < 1);
+		pkmap_count[PKMAP_NR(vaddr)]++;
+	}
+	unlock_kmap_any(flags);
+	return (void*) vaddr;
+}
+#endif
+
 /**
  * kunmap_high - map a highmem page into memory
  * @page: &struct page to unmap
+ *
+ * If ARCH_NEEDS_KMAP_HIGH_GET is not defined then this may be called
+ * only from user context.
  */
 void kunmap_high(struct page *page)
 {
 	unsigned long vaddr;
 	unsigned long nr;
+	unsigned long flags;
 	int need_wakeup;
 
-	spin_lock(&kmap_lock);
+	lock_kmap_any(flags);
 	vaddr = (unsigned long)page_address(page);
 	BUG_ON(!vaddr);
 	nr = PKMAP_NR(vaddr);
@@ -232,7 +281,7 @@ void kunmap_high(struct page *page)
 		 */
 		need_wakeup = waitqueue_active(&pkmap_map_wait);
 	}
-	spin_unlock(&kmap_lock);
+	unlock_kmap_any(flags);
 
 	/* do wake-up, if needed, race-free outside of the spin lock */
 	if (need_wakeup)