Re: [PATCH 45/48] x86/Kconfig: Enable CONFIG_PREFIX_SYMBOLS for FineIBT

[Josh Poimboeuf]

On Tue, Apr 28, 2026 at 02:37:17AM +0100, David Laight wrote:
> >  static const struct option check_options[] = {
> >  	OPT_GROUP("Actions:"),
> > -	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
> >  	OPT_STRING_OPTARG('d',	 "disas", &opts.disas, "function-pattern", "disassemble functions", "*"),
> >  	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
> >  	OPT_BOOLEAN('i',	 "ibt", &opts.ibt, "validate and annotate IBT"),
> > @@ -84,7 +83,7 @@ static const struct option check_options[] = {
> >  	OPT_BOOLEAN('r',	 "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
> >  	OPT_BOOLEAN(0,		 "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
> >  	OPT_BOOLEAN(0,		 "unret", &opts.unret, "validate entry unret placement"),
> > -	OPT_INTEGER(0,		 "prefix", &opts.prefix, "generate prefix symbols"),
> > +	OPT_INTEGER(0,		 "prefix", &opts.prefix, "generate or grow prefix symbols for N-byte function padding"),
> >  	OPT_BOOLEAN('l',	 "sls", &opts.sls, "validate straight-line-speculation mitigations"),
> >  	OPT_BOOLEAN('s',	 "stackval", &opts.stackval, "validate frame pointer rules"),
> >  	OPT_BOOLEAN('t',	 "static-call", &opts.static_call, "annotate static calls"),
> > @@ -92,6 +91,7 @@ static const struct option check_options[] = {
> >  	OPT_CALLBACK_OPTARG(0,	 "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
> >  
> >  	OPT_GROUP("Options:"),
> > +	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "annotate and grow kCFI preamble symbols (use with --prefix)"),
> >  	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
> >  	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),
> >  	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
> > @@ -163,6 +163,11 @@ static bool opts_valid(void)
> >  		return false;
> >  	}
> >  
> > +	if (opts.cfi && !opts.prefix) {
> > +		ERROR("--cfi requires --prefix");
> > +		return false;
> > +	}
> > +
> 
> Wouldn't it be more friendly to have:
> 	opts.prefix |= opts.cfi;
> and change the help to (implies --prefix).

It would, if prefix didn't take an integer as an argument ;-)

-- 
Josh