Re: [PATCH v3 11/21] objtool: Allow empty alternatives

On Wed, May 13, 2026 at 09:37:11AM +0200, Peter Zijlstra wrote:
> On Tue, May 12, 2026 at 08:33:45PM -0700, Josh Poimboeuf wrote:
> > arm64 can have empty alternatives, which are effectively no-ops.  Ignore
> > them.  While at it, fix a memory leak.
> 
> How does this happen?

Yeah, that commit log sucks...

The case I stumbled on was the dcache_by_myline_op_nosync macro:

alternative_if ARM64_WORKAROUND_4311569
	.ifnc	\op, cvau
	mov	\start, \tmp
	mov	\tmp, xzr
	cbnz	\start, .Ldcache_op\@
	.endif
alternative_else_nop_endif

That's actually a bit weird, the .ifnc should probably be outside the
alternative_if.  Let me try fixing that instead.

-- 
Josh