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

Vol. 2B 4-131
INSTRUCTION SET REFERENCE, N-Z
IF DS, ES, FS, or GS is loaded with non-NULL selector;
THEN
IF segment selector index is outside descriptor table limits
or segment is not a data or readable code segment
or ((segment is a data or nonconforming code segment)
and (both RPL and CPL > DPL))
THEN #GP(selector);
FI;
IF segment not marked present
THEN #NP(selector);
ELSE
SegmentRegister ← segment selector;
SegmentRegister ← segment descriptor;
FI;
FI;
IF DS, ES, FS, or GS is loaded with a NULL selector
THEN
SegmentRegister ← segment selector;
SegmentRegister ← segment descriptor;
FI;
Flags Affected
None.
Protected Mode Exceptions
#GP(0) If attempt is made to load SS register with NULL segment
selector.
If the destination operand is in a non-writable segment.
If a memory operand effective address is outside the CS, DS,
ES, FS, or GS segment limit.
If the DS, ES, FS, or GS register is used to access memory and it
contains a NULL segment selector.
#GP(selector) If segment selector index is outside descriptor table limits.
If the SS register is being loaded and the segment selector's RPL
and the segment descriptor’s DPL are not equal to the CPL.
If the SS register is being loaded and the segment pointed to is a
non-writable data segment.