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-Speculation-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-Speculation-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.