* Yu, Yu-cheng <yu-cheng.yu@xxxxxxxxx> wrote: > On 3/16/2021 2:15 PM, Peter Zijlstra wrote: > > On Tue, Mar 16, 2021 at 08:10:26AM -0700, Yu-cheng Yu wrote: > > > Control-flow Enforcement (CET) is a new Intel processor feature that blocks > > > return/jump-oriented programming attacks. Details are in "Intel 64 and > > > IA-32 Architectures Software Developer's Manual" [1]. > > > > > > CET can protect applications and the kernel. This series enables only > > > application-level protection, and has three parts: > > > > > > - Shadow stack [2], > > > - Indirect branch tracking [3], and > > > - Selftests [4]. > > > > CET is marketing; afaict SS and IBT are 100% independent and there's no > > reason what so ever to have them share any code, let alone a Kconfig > > knob. > > We used to have shadow stack and ibt under separate Kconfig options, but in > a few places they actually share same code path, such as the XSAVES > supervisor states and ELF header for example. Anyways I will be happy to > make changes again if there is agreement. I was look at: x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states didn't see any IBT logic - it's essentially all shadow stack state. Which is not surprising, forward call edge integrity protection (IBT) requires very little state, does it? With IBT there's no nesting, no stack - the IBT state machine basically requires the next instruction to be and ENDBR instruction, and that's essentially it, right? Thanks, Ingo
