Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

3-468 Vol. 2
INSTRUCTION SET REFERENCE, A-M
REAL-ADDRESS-MODE:
IF ((vector_number ∗ 4) + 3) is not within IDT limit
THEN #GP; FI;
IF stack not large enough for a 6-byte return information
THEN #SS; FI;
Push (EFLAGS[15:0]);
IF ← 0; (* Clear interrupt flag *)
TF ← 0; (* Clear trap flag *)
AC ← 0; (* Clear AC flag *)
Push(CS);
Push(IP);
(* No error codes are pushed *)
CS ← IDT(Descriptor (vector_number ∗ 4), selector));
EIP ← IDT(Descriptor (vector_number ∗ 4), offset)); (* 16 bit offset AND 0000FFFFH *)
END;
PROTECTED-MODE:
IF ((vector_number ∗ 8) + 7) is not within IDT limits
or selected IDT descriptor is not an interrupt-, trap-, or task-gate type
THEN #GP((vector_number ∗ 8) + 2 + EXT); FI;
(* EXT is bit 0 in error code *)
IF software interrupt (* Generated by INT n, INT 3, or INTO *)
THEN
IF gate descriptor DPL < CPL
THEN #GP((vector_number ∗ 8) + 2 ); FI;
(* PE
= 1, DPL<CPL, software interrupt *)
FI;
IF gate not present
THEN #NP((vector_number ∗ 8) + 2 + EXT); FI;
IF task gate (* Specified in the selected interrupt table descriptor *)
THEN GOTO TASK-GATE;
ELSE GOTO TRAP-OR-INTERRUPT-GATE; (* PE = 1, trap/interrupt gate *)
FI;
END;
IA-32e-MODE:
IF ((vector_number ∗ 16) + 15) is not in IDT limits
or selected IDT descriptor is not an interrupt-, or trap-gate type
THEN #GP((vector_number ∗ 16) + 2 + EXT); FI;
(* EXT is bit 0 in error code *)
IF software interrupt (* Generated by INT n, INT 3, but not INTO *)
THEN
IF gate descriptor DPL < CPL
THEN #GP((vector_number ∗ 16) + 2 ); FI;
(* PE
= 1, DPL < CPL, software interrupt *)