diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 18fce223b67b2746d08b1d5f64ee3c54e456989d..99d7e1494aaa62aceab0032d8dcb68734fafecd7 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -247,9 +247,11 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 
 
 /*
- * The linear kernel range starts at the bottom of the virtual address space.
+ * Check whether an arbitrary address is within the linear map, which
+ * lives in the [PAGE_OFFSET, PAGE_END) interval at the bottom of the
+ * kernel's TTBR1 address range.
  */
-#define __is_lm_address(addr)	(((u64)(addr) & ~PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
+#define __is_lm_address(addr)	(((u64)(addr) ^ PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index d4eac6d7e9fbc5659bc494402212d0d9eedca66e..2494138a6905ed105009894a8eb49ed2ee4ac4e6 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -1107,6 +1107,11 @@ static int nc_dma_get_range(struct device *dev, u64 *size)
 
 	ncomp = (struct acpi_iort_named_component *)node->node_data;
 
+	if (!ncomp->memory_address_limit) {
+		pr_warn(FW_BUG "Named component missing memory address limit\n");
+		return -EINVAL;
+	}
+
 	*size = ncomp->memory_address_limit >= 64 ? U64_MAX :
 			1ULL<<ncomp->memory_address_limit;
 
@@ -1126,6 +1131,11 @@ static int rc_dma_get_range(struct device *dev, u64 *size)
 
 	rc = (struct acpi_iort_root_complex *)node->node_data;
 
+	if (!rc->memory_address_limit) {
+		pr_warn(FW_BUG "Root complex missing memory address limit\n");
+		return -EINVAL;
+	}
+
 	*size = rc->memory_address_limit >= 64 ? U64_MAX :
 			1ULL<<rc->memory_address_limit;
 
@@ -1173,8 +1183,8 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 		end = dmaaddr + size - 1;
 		mask = DMA_BIT_MASK(ilog2(end) + 1);
 		dev->bus_dma_limit = end;
-		dev->coherent_dma_mask = mask;
-		*dev->dma_mask = mask;
+		dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
+		*dev->dma_mask = min(*dev->dma_mask, mask);
 	}
 
 	*dma_addr = dmaaddr;