Kernel Watch
Jon Masters summarises the latest happenings in the Linux kernel, so that you don’t have to.
Linus Torvalds announced the release of Linux 5.18, noting that there had been no “unexpected surprises” at the tail end of the development cycle. The new kernel includes support for Intel’s Indirect Branch Tracking (IBT), improved scheduling performance on AMD Zen processors, and switches to a more “modern” C language standard (C11) as a baseline (previously C89!). KernelNewbies.orgcontains the usual great detailed breakdown.
IBT comes to x86
Among the many other features landing in 5.18, comes support for Intel’s Indirect Branch Tracking feature that adds landing pads to the x86 architecture. The new ENDBR instruction can be inserted into code, particularly at the entry to functions that are intended to be called from other code. The new instruction on its own doesn’t do anything, but on suitably enabled hardware platforms it’ll prevent a function from being called unless it begins with such an instruction. If it doesn’t, this could indicate an attempted attack to hijack program flow.