linux-kernel - Re: [PATCH] objtool: Fix SLS checks

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Date:   Mon, 2 May 2022 22:01:53 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] objtool: Fix SLS checks

On Mon, May 02, 2022 at 11:15:47AM -0700, Josh Poimboeuf wrote:
> On Sat, Apr 30, 2022 at 12:50:02PM +0200, Peter Zijlstra wrote:
> > 
> > Fix the SLS validation; not having a next instruction is also a fail
> > when the next instruction should be INSN_TRAP.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > ---
> >  tools/objtool/check.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 3f6785415894..3354101ffe34 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -3380,7 +3380,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
> >  
> >  		case INSN_RETURN:
> >  			if (sls && !insn->retpoline_safe &&
> > -			    next_insn && next_insn->type != INSN_TRAP) {
> > +			    (!next_insn || (next_insn && next_insn->type != INSN_TRAP))) {
> >  				WARN_FUNC("missing int3 after ret",
> >  					  insn->sec, insn->offset);
> >  			}
> > @@ -3428,7 +3428,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
> >  
> >  		case INSN_JUMP_DYNAMIC:
> >  			if (sls && !insn->retpoline_safe &&
> > -			    next_insn && next_insn->type != INSN_TRAP) {
> > +			    (!next_insn || (next_insn && next_insn->type != INSN_TRAP))) {
> >  				WARN_FUNC("missing int3 after indirect jump",
> >  					  insn->sec, insn->offset);
> >  			}
> 
> My SLS rewrite in tip/objtool/core already fixed this, FWIW.  But this
> could be good for -urgent.

Urgh, I should've looked at that indeed. This didn't find any new sites
though; so I don't think this needs to go through urgent.