Re: [PATCH] drm/vmwgfx: Silence RBP clobber warnings

[Peter Zijlstra]

On Fri, Jun 02, 2023 at 07:56:34AM -0700, Josh Poimboeuf wrote:
> VMware hypercalls take the RBP register as input.  This breaks basic
> frame pointer convention, as RBP should never be clobbered.
> 
> So frame pointer unwinding is broken for the instructions surrounding
> the hypercall with the clobbered RBP.  There's nothing that can be done
> about that.  Just tell objtool to ignore it.
> 

That's a pretty horrific ABI, one that violates the oldest x86 calling
convention in existence.

VMware folks, shame!!