Intel 64 and IA-32 Architectures Software Developers Manual Volume 2B, Instruction Set Reference, N-Z

4-256 Vol. 2B
INSTRUCTION SET REFERENCE, N-Z
IF OperandSize
= 32
THEN
IF second doubleword on stack is not within stack limits
THEN #SS(0); FI;
ELSE (* OperandSize
= 16 *)
IF second word on stack is not within stack limits
THEN #SS(0); FI;
FI;
IF return code segment selector is NULL
THEN #GP(0); FI;
IF return code segment selector addresses descriptor beyond descriptor table limit
THEN #GP(selector); FI;
Obtain descriptor to which return code segment selector points from descriptor table;
IF return code segment descriptor is not a code segment
THEN #GP(selector); FI;
IF return code segment selector RPL < CPL
THEN #GP(selector); FI;
IF return code segment descriptor is conforming
and return code segment DPL > return code segment selector RPL
THEN #GP(selector); FI;
IF return code segment descriptor is non-conforming and return code
segment DPL
≠ return code segment selector RPL
THEN #GP(selector); FI;
IF return code segment descriptor is not present
THEN #NP(selector); FI:
IF return code segment selector RPL > CPL
THEN GOTO RETURN-OUTER-PRIVILEGE-LEVEL;
ELSE GOTO RETURN-TO-SAME-PRIVILEGE-LEVEL;
FI;
FI;
RETURN-SAME-PRIVILEGE-LEVEL:
IF the return instruction pointer is not within ther return code segment limit
THEN #GP(0); FI;
IF OperandSize
= 32
THEN
EIP ← Pop();
CS ← Pop(); (* 32-bit pop, high-order 16 bits discarded *)
ESP ← ESP + SRC; (* Release parameters from stack *)
ELSE (* OperandSize
= 16 *)
EIP ← Pop();
EIP ← EIP AND 0000FFFFH;
CS ← Pop(); (* 16-bit pop *)
ESP ← ESP + SRC; (* Release parameters from stack *)