Re: [PATCH v28 04/10] x86/cet/ibt: Disable IBT for ia32

[Andy Lutomirski]

On 7/22/21 1:57 PM, Yu-cheng Yu wrote:
> In a signal, a task's IBT status needs to be saved to the signal frame, and
> later restored in sigreturn.  For the purpose, previous versions of the
> series add a new struct to the signal frame.  However, a new signal frame
> format (or re-using a reserved space) introduces complex compatibility
> issues.
> 
> In the discussion (see link below), Andy Lutomirski proposed using a
> ucontext flag.  The approach is clean and eliminates most compatibility
> issues.
> 
> However, a legacy IA32 signal frame does not have ucontext and cannot
> support a uc flag.  Thus,
> 
> - Disable IBT for ia32.
> - In ia32 sigreturn, verify ibt is disabled.

Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>