There is definitely something wrong here ;-) According to the "Principles of Operations" ISA document, opcode 0xEC54 is the RNSBG instruction (ROTATE THEN AND SELECTED BITS). But op_rosbg() apparently currently handles 0xEC55, 0xEC56 and 0xEC57. 0xEC55 seems wrong there, since this opcode should be handled by op_risbg() instead (according to target/s390x/insn-data.def). So the "case 0x55" seems to be a typo. Does it work if you replace "case 0x55" with "case 0x54" ?
There is definitely something wrong here ;-) According to the "Principles of Operations" ISA document, opcode 0xEC54 is the RNSBG instruction (ROTATE THEN AND SELECTED BITS). But op_rosbg() apparently currently handles 0xEC55, 0xEC56 and 0xEC57. 0xEC55 seems wrong there, since this opcode should be handled by op_risbg() instead (according to target/ s390x/insn- data.def) . So the "case 0x55" seems to be a typo. Does it work if you replace "case 0x55" with "case 0x54" ?