IA32SYSENTERESP
IA32SYSENTERESP is a Model-Specific Register (MSR) in the IA-32 architecture used by the SYSENTER/SYSEXIT fast system call mechanism. It stores the address of the kernel-mode stack pointer (the top of the kernel stack) that the processor loads into the ESP register when a user-space thread executes SYSENTER to enter the kernel.
During a SYSENTER, the processor switches from user mode to ring 0, loading the kernel code segment
Access to this MSR is privileged; only ring-0 software can read or write it via RDMSR or
Relation and context: IA32_SYSENTER_ESP is one of a trio of MSRs (IA32_SYSENTER_CS, IA32_SYSENTER_ESP, IA32_SYSENTER_EIP) that configure
Security and correctness considerations: The kernel must ensure IA32SYSENTERESP points to a valid, properly aligned kernel