ACPI: Fix buffer/integer type mismatch

This is actually not a bug in the kernel, but rather Microsoft not conforming with the ACPI specification.
linux-surface · Sep 17, 2019 · 07db8ff · 07db8ff
1 parent 4d856f7
commit 07db8ff
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/drivers/acpi/acpica/dsopcode.c b/drivers/acpi/acpica/dsopcode.c
@@ -123,7 +123,7 @@ acpi_ds_init_buffer_field(u16 aml_opcode,
 
 		/* Offset is in bits, count is in bits */
 
-		field_flags = AML_FIELD_ACCESS_BYTE;
+		field_flags = AML_FIELD_ACCESS_BUFFER;
 		bit_offset = offset;
 		bit_count = (u32) length_desc->integer.value;
 

diff --git a/drivers/acpi/acpica/exfield.c b/drivers/acpi/acpica/exfield.c
@@ -109,6 +109,7 @@ acpi_ex_read_data_from_field(struct acpi_walk_state *walk_state,
 	union acpi_operand_object *buffer_desc;
 	void *buffer;
 	u32 buffer_length;
+	u8 field_flags;
 
 	ACPI_FUNCTION_TRACE_PTR(ex_read_data_from_field, obj_desc);
 
@@ -157,11 +158,16 @@ acpi_ex_read_data_from_field(struct acpi_walk_state *walk_state,
 	 * Note: Field.length is in bits.
 	 */
 	buffer_length =
-	    (acpi_size)ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->field.bit_length);
+	    (acpi_size)ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length);
+	field_flags = obj_desc->common_field.field_flags;
 
-	if (buffer_length > acpi_gbl_integer_byte_width) {
+	if (buffer_length > acpi_gbl_integer_byte_width ||
+	    (field_flags & AML_FIELD_ACCESS_TYPE_MASK) == AML_FIELD_ACCESS_BUFFER) {
 
-		/* Field is too large for an Integer, create a Buffer instead */
+		/*
+		 * Field is either too large for an Integer, or a actually of type
+		 * buffer, so create a Buffer.
+		 */
 
 		buffer_desc = acpi_ut_create_buffer_object(buffer_length);
 		if (!buffer_desc) {