Re: [PATCH] objtool: Fix SYSCALL instruction handling and INSN_CONTEXT_SWITCH

[Peter Zijlstra]

On Fri, Apr 04, 2025 at 07:46:52AM -0700, Josh Poimboeuf wrote:
> On Fri, Apr 04, 2025 at 12:49:38PM +0200, Peter Zijlstra wrote:
> > On Thu, Apr 03, 2025 at 11:48:13AM -0700, Josh Poimboeuf wrote:
> > 
> > > The real problem here is that INSN_CONTEXT_SWITCH is ambiguous.  It can
> > > represent both call semantics (SYSCALL, SYSENTER) and return semantics
> > > (SYSRET, IRET, RETS, RETU).  Those differ significantly: calls preserve
> > > control flow whereas returns terminate it.
> > 
> > Does that not rather suggest we should perhaps have INSN_SYSCALL /
> > INSN_SYSRET to replace the single ambiguous thing?
> 
> Is there any reason to have INSN_SYSCALL in the first place?

This xen hyperclal thing?