Intel 64 and IA-32 Architectures Software Developers Manual Volume 1, Basic Architecture

Vol. 1 6-19
PROCEDURE CALLS, INTERRUPTS, AND EXCEPTIONS
exception (#MF); when an SSE/SSE2/SSE3 instruction generates a floating-point
exception, it in turn generates SIMD floating-point exception (#XF).
See the following sections for further descriptions of the floating-point exceptions,
how they are generated, and how they are handled:
• Section 4.9.1, “Floating-Point Exception Conditions,” and Section 4.9.3, “Typical
Actions of a Floating-Point Exception Handler”
• Section 8.4, “x87 FPU Floating-Point Exception Handling,” and Section 8.5, “x87
FPU Floating-Point Exception Conditions”
• Section 11.5.1, “SIMD Floating-Point Exceptions”
• Interrupt Behavior
6.4.6 Interrupt and Exception Behavior in 64-Bit Mode
64-bit extensions expand the legacy IA-32 interrupt-processing and exception-
processing mechanism to allow support for 64-bit operating systems and applica-
tions. Changes include:
• All interrupt handlers pointed to by the IDT are 64-bit code (does not apply to the
SMI handler).
• The size of interrupt-stack pushes is fixed at 64 bits. The processor uses 8-byte,
zero extended stores.
• The stack pointer (SS:RSP) is pushed unconditionally on interrupts. In legacy
environments, this push is conditional and based on a change in current privilege
level (CPL).
• The new SS is set to NULL if there is a change in CPL.
• IRET behavior changes.
• There is a new interrupt stack-switch mechanism.
• The alignment of interrupt stack frame is different.
6.5 PROCEDURE CALLS FOR BLOCK-STRUCTURED
LANGUAGES
The IA-32 architecture supports an alternate method of performing procedure calls
with the ENTER (enter procedure) and LEAVE (leave procedure) instructions. These
instructions automatically create and release, respectively, stack frames for called
procedures. The stack frames have predefined spaces for local variables and the
necessary pointers to allow coherent returns from called procedures. They also allow
scope rules to be implemented so that procedures can access their own local vari-
ables and some number of other variables located in other stack frames.