Mitigate RSB underflow with call depth tracking
configname: CONFIG_MITIGATION_CALL_DEPTH_TRACKING
Linux Kernel Configuration
└─>Mitigations for CPU vulnerabilities
└─>Mitigate RSB underflow with call depth tracking
In linux kernel since version 4.19.314 (release Date: 2024-05-17)
Compile the kernel with call depth tracking to mitigate the Intel
SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
by default and needs to be enabled on the kernel command line via the
retbleed=stuff option. For non-affected systems the overhead of this
option is marginal as the call depth tracking is using run-time
generated call thunks in a compiler generated padding area and call
patching. This increases text size by ~5%. For non affected systems
this space is unused. On affected SKL systems this results in a
significant performance gain over the IBRS mitigation.
SKL Return-Stack-Buffer (RSB) underflow issue. The mitigation is off
by default and needs to be enabled on the kernel command line via the
retbleed=stuff option. For non-affected systems the overhead of this
option is marginal as the call depth tracking is using run-time
generated call thunks in a compiler generated padding area and call
patching. This increases text size by ~5%. For non affected systems
this space is unused. On affected SKL systems this results in a
significant performance gain over the IBRS mitigation.