4 files changed, 41 insertions, 22 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index d7909091cf97..c135f6e37a00 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -564,14 +564,6 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 	if (mask < 0xffffffffULL)
 		gfp |= GFP_DMA;
 
-	/*
-	 * Following is a work-around (a.k.a. hack) to prevent pages
-	 * with __GFP_COMP being passed to split_page() which cannot
-	 * handle them.  The real problem is that this flag probably
-	 * should be 0 on ARM as it is not supported on this
-	 * platform; see CONFIG_HUGETLBFS.
-	 */
-	gfp &= ~(__GFP_COMP);
 	args.gfp = gfp;
 
 	*handle = DMA_MAPPING_ERROR;
@@ -1093,15 +1085,6 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
 		return __iommu_alloc_simple(dev, size, gfp, handle,
 					    coherent_flag, attrs);
 
-	/*
-	 * Following is a work-around (a.k.a. hack) to prevent pages
-	 * with __GFP_COMP being passed to split_page() which cannot
-	 * handle them.  The real problem is that this flag probably
-	 * should be 0 on ARM as it is not supported on this
-	 * platform; see CONFIG_HUGETLBFS.
-	 */
-	gfp &= ~(__GFP_COMP);
-
 	pages = __iommu_alloc_buffer(dev, size, gfp, attrs, coherent_flag);
 	if (!pages)
 		return NULL;
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 46cccd6bf705..de988cba9a4b 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -105,6 +105,19 @@ static inline bool is_write_fault(unsigned int fsr)
 	return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
 }
 
+static inline bool is_translation_fault(unsigned int fsr)
+{
+	int fs = fsr_fs(fsr);
+#ifdef CONFIG_ARM_LPAE
+	if ((fs & FS_MMU_NOLL_MASK) == FS_TRANS_NOLL)
+		return true;
+#else
+	if (fs == FS_L1_TRANS || fs == FS_L2_TRANS)
+		return true;
+#endif
+	return false;
+}
+
 static void die_kernel_fault(const char *msg, struct mm_struct *mm,
 			     unsigned long addr, unsigned int fsr,
 			     struct pt_regs *regs)
@@ -140,7 +153,8 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 	if (addr < PAGE_SIZE) {
 		msg = "NULL pointer dereference";
 	} else {
-		if (kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
+		if (is_translation_fault(fsr) &&
+		    kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
 			return;
 
 		msg = "paging request";
@@ -208,7 +222,7 @@ static inline bool is_permission_fault(unsigned int fsr)
 {
 	int fs = fsr_fs(fsr);
 #ifdef CONFIG_ARM_LPAE
-	if ((fs & FS_PERM_NOLL_MASK) == FS_PERM_NOLL)
+	if ((fs & FS_MMU_NOLL_MASK) == FS_PERM_NOLL)
 		return true;
 #else
 	if (fs == FS_L1_PERM || fs == FS_L2_PERM)
diff --git a/arch/arm/mm/fault.h b/arch/arm/mm/fault.h
index 83b5ab32d7a4..54927ba1fa6e 100644
--- a/arch/arm/mm/fault.h
+++ b/arch/arm/mm/fault.h
@@ -14,8 +14,9 @@
 
 #ifdef CONFIG_ARM_LPAE
 #define FSR_FS_AEA		17
+#define FS_TRANS_NOLL		0x4
 #define FS_PERM_NOLL		0xC
-#define FS_PERM_NOLL_MASK	0x3C
+#define FS_MMU_NOLL_MASK	0x3C
 
 static inline int fsr_fs(unsigned int fsr)
 {
@@ -23,8 +24,10 @@ static inline int fsr_fs(unsigned int fsr)
 }
 #else
 #define FSR_FS_AEA		22
-#define FS_L1_PERM             0xD
-#define FS_L2_PERM             0xF
+#define FS_L1_TRANS		0x5
+#define FS_L2_TRANS		0x7
+#define FS_L1_PERM		0xD
+#define FS_L2_PERM		0xF
 
 static inline int fsr_fs(unsigned int fsr)
 {
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index c42debaded95..c1494a4dee25 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -26,6 +26,13 @@
 
 unsigned long vectors_base;
 
+/*
+ * empty_zero_page is a special page that is used for
+ * zero-initialized data and COW.
+ */
+struct page *empty_zero_page;
+EXPORT_SYMBOL(empty_zero_page);
+
 #ifdef CONFIG_ARM_MPU
 struct mpu_rgn_info mpu_rgn_info;
 #endif
@@ -148,9 +155,21 @@ void __init adjust_lowmem_bounds(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
+	void *zero_page;
+
 	early_trap_init((void *)vectors_base);
 	mpu_setup();
+
+	/* allocate the zero page. */
+	zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+	if (!zero_page)
+		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+		      __func__, PAGE_SIZE, PAGE_SIZE);
+
 	bootmem_init();
+
+	empty_zero_page = virt_to_page(zero_page);
+	flush_dcache_page(empty_zero_page);
 }
 
 /*