arm64/scs: Fix handling of advance_loc4

DW_CFA_advance_loc4 is defined but no handler is implemented. Its
CFA opcode defaults to EDYNSCS_INVALID_CFA_OPCODE triggering an
error which wrongfully prevents modules from loading.

Link: https://bugs.gentoo.org/971060
Signed-off-by: Pepper Gray <hello@peppergray.xyz>
Signed-off-by: Will Deacon <will@kernel.org>

Author: peppergrayxyz

arch/arm64/kernel/pi/patch-scs.c

@@ -192,6 +192,14 @@ static int scs_handle_fde_frame(const struct eh_frame *frame,
 			size -= 2;
 			break;
 
+		case DW_CFA_advance_loc4:
+			loc += *opcode++ * code_alignment_factor;
+			loc += (*opcode++ << 8) * code_alignment_factor;
+			loc += (*opcode++ << 16) * code_alignment_factor;
+			loc += (*opcode++ << 24) * code_alignment_factor;
+			size -= 4;
+		break;
+
 		case DW_CFA_def_cfa:
 		case DW_CFA_offset_extended:
 			size = skip_xleb128(&opcode, size);