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path: root/drivers/acpi/executer/exfldio.c
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-rw-r--r--drivers/acpi/executer/exfldio.c71
1 files changed, 55 insertions, 16 deletions
diff --git a/drivers/acpi/executer/exfldio.c b/drivers/acpi/executer/exfldio.c
index 051053f7cccb..40f0bee6faa5 100644
--- a/drivers/acpi/executer/exfldio.c
+++ b/drivers/acpi/executer/exfldio.c
@@ -727,11 +727,23 @@ acpi_ex_extract_from_field(union acpi_operand_object *obj_desc,
727 return_ACPI_STATUS(status); 727 return_ACPI_STATUS(status);
728 } 728 }
729 729
730 /* Merge with previous datum if necessary */ 730 /*
731 731 * Merge with previous datum if necessary.
732 merged_datum |= raw_datum << 732 *
733 (obj_desc->common_field.access_bit_width - 733 * Note: Before the shift, check if the shift value will be larger than
734 obj_desc->common_field.start_field_bit_offset); 734 * the integer size. If so, there is no need to perform the operation.
735 * This avoids the differences in behavior between different compilers
736 * concerning shift values larger than the target data width.
737 */
738 if ((obj_desc->common_field.access_bit_width -
739 obj_desc->common_field.start_field_bit_offset) <
740 ACPI_INTEGER_BIT_SIZE) {
741 merged_datum |=
742 raw_datum << (obj_desc->common_field.
743 access_bit_width -
744 obj_desc->common_field.
745 start_field_bit_offset);
746 }
735 747
736 if (i == datum_count) { 748 if (i == datum_count) {
737 break; 749 break;
@@ -808,13 +820,23 @@ acpi_ex_insert_into_field(union acpi_operand_object *obj_desc,
808 return_ACPI_STATUS(AE_BUFFER_OVERFLOW); 820 return_ACPI_STATUS(AE_BUFFER_OVERFLOW);
809 } 821 }
810 822
811 /* Compute the number of datums (access width data items) */ 823 /*
824 * Create the bitmasks used for bit insertion.
825 * Note: This if/else is used to bypass compiler differences with the
826 * shift operator
827 */
828 if (obj_desc->common_field.access_bit_width == ACPI_INTEGER_BIT_SIZE) {
829 width_mask = ACPI_INTEGER_MAX;
830 } else {
831 width_mask =
832 ACPI_MASK_BITS_ABOVE(obj_desc->common_field.
833 access_bit_width);
834 }
812 835
813 width_mask = 836 mask = width_mask &
814 ACPI_MASK_BITS_ABOVE(obj_desc->common_field.access_bit_width); 837 ACPI_MASK_BITS_BELOW(obj_desc->common_field.start_field_bit_offset);
815 mask = 838
816 width_mask & ACPI_MASK_BITS_BELOW(obj_desc->common_field. 839 /* Compute the number of datums (access width data items) */
817 start_field_bit_offset);
818 840
819 datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length, 841 datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
820 obj_desc->common_field.access_bit_width); 842 obj_desc->common_field.access_bit_width);
@@ -848,12 +870,29 @@ acpi_ex_insert_into_field(union acpi_operand_object *obj_desc,
848 return_ACPI_STATUS(status); 870 return_ACPI_STATUS(status);
849 } 871 }
850 872
851 /* Start new output datum by merging with previous input datum */
852
853 field_offset += obj_desc->common_field.access_byte_width; 873 field_offset += obj_desc->common_field.access_byte_width;
854 merged_datum = raw_datum >> 874
855 (obj_desc->common_field.access_bit_width - 875 /*
856 obj_desc->common_field.start_field_bit_offset); 876 * Start new output datum by merging with previous input datum
877 * if necessary.
878 *
879 * Note: Before the shift, check if the shift value will be larger than
880 * the integer size. If so, there is no need to perform the operation.
881 * This avoids the differences in behavior between different compilers
882 * concerning shift values larger than the target data width.
883 */
884 if ((obj_desc->common_field.access_bit_width -
885 obj_desc->common_field.start_field_bit_offset) <
886 ACPI_INTEGER_BIT_SIZE) {
887 merged_datum =
888 raw_datum >> (obj_desc->common_field.
889 access_bit_width -
890 obj_desc->common_field.
891 start_field_bit_offset);
892 } else {
893 merged_datum = 0;
894 }
895
857 mask = width_mask; 896 mask = width_mask;
858 897
859 if (i == datum_count) { 898 if (i == datum_count) {