1 files changed, 46 insertions, 18 deletions

diff --git a/drivers/acpi/acpica/exregion.c b/drivers/acpi/acpica/exregion.c
index d15a66de26c0..4914dbc44517 100644
--- a/drivers/acpi/acpica/exregion.c
+++ b/drivers/acpi/acpica/exregion.c
@@ -41,6 +41,7 @@ acpi_ex_system_memory_space_handler(u32 function,
 	acpi_status status = AE_OK;
 	void *logical_addr_ptr = NULL;
 	struct acpi_mem_space_context *mem_info = region_context;
+	struct acpi_mem_mapping *mm = mem_info->cur_mm;
 	u32 length;
 	acpi_size map_length;
 	acpi_size page_boundary_map_length;
@@ -96,20 +97,37 @@ acpi_ex_system_memory_space_handler(u32 function,
 	 * Is 1) Address below the current mapping? OR
 	 *    2) Address beyond the current mapping?
 	 */
-	if ((address < mem_info->mapped_physical_address) ||
-	    (((u64) address + length) > ((u64)
-					 mem_info->mapped_physical_address +
-					 mem_info->mapped_length))) {
+	if (!mm || (address < mm->physical_address) ||
+	    ((u64) address + length > (u64) mm->physical_address + mm->length)) {
 		/*
-		 * The request cannot be resolved by the current memory mapping;
-		 * Delete the existing mapping and create a new one.
+		 * The request cannot be resolved by the current memory mapping.
+		 *
+		 * Look for an existing saved mapping covering the address range
+		 * at hand.  If found, save it as the current one and carry out
+		 * the access.
 		 */
-		if (mem_info->mapped_length) {
+		for (mm = mem_info->first_mm; mm; mm = mm->next_mm) {
+			if (mm == mem_info->cur_mm)
+				continue;
+
+			if (address < mm->physical_address)
+				continue;
 
-			/* Valid mapping, delete it */
+			if ((u64) address + length >
+					(u64) mm->physical_address + mm->length)
+				continue;
 
-			acpi_os_unmap_memory(mem_info->mapped_logical_address,
-					     mem_info->mapped_length);
+			mem_info->cur_mm = mm;
+			goto access;
+		}
+
+		/* Create a new mappings list entry */
+		mm = ACPI_ALLOCATE_ZEROED(sizeof(*mm));
+		if (!mm) {
+			ACPI_ERROR((AE_INFO,
+				    "Unable to save memory mapping at 0x%8.8X%8.8X, size %u",
+				    ACPI_FORMAT_UINT64(address), length));
+			return_ACPI_STATUS(AE_NO_MEMORY);
 		}
 
 		/*
@@ -143,29 +161,39 @@ acpi_ex_system_memory_space_handler(u32 function,
 
 		/* Create a new mapping starting at the address given */
 
-		mem_info->mapped_logical_address =
-		    acpi_os_map_memory(address, map_length);
-		if (!mem_info->mapped_logical_address) {
+		logical_addr_ptr = acpi_os_map_memory(address, map_length);
+		if (!logical_addr_ptr) {
 			ACPI_ERROR((AE_INFO,
 				    "Could not map memory at 0x%8.8X%8.8X, size %u",
 				    ACPI_FORMAT_UINT64(address),
 				    (u32)map_length));
-			mem_info->mapped_length = 0;
+			ACPI_FREE(mm);
 			return_ACPI_STATUS(AE_NO_MEMORY);
 		}
 
 		/* Save the physical address and mapping size */
 
-		mem_info->mapped_physical_address = address;
-		mem_info->mapped_length = map_length;
+		mm->logical_address = logical_addr_ptr;
+		mm->physical_address = address;
+		mm->length = map_length;
+
+		/*
+		 * Add the new entry to the mappigs list and save it as the
+		 * current mapping.
+		 */
+		mm->next_mm = mem_info->first_mm;
+		mem_info->first_mm = mm;
+
+		mem_info->cur_mm = mm;
 	}
 
+access:
 	/*
 	 * Generate a logical pointer corresponding to the address we want to
 	 * access
 	 */
-	logical_addr_ptr = mem_info->mapped_logical_address +
-	    ((u64) address - (u64) mem_info->mapped_physical_address);
+	logical_addr_ptr = mm->logical_address +
+		((u64) address - (u64) mm->physical_address);
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 			  "System-Memory (width %u) R/W %u Address=%8.8X%8.8X\n",