linux-kernel - Re: [PATCH v3 26/26] objtool: Add STT

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Message-ID: <20200325164046.p2oxemcjnj2tnxbz@treble>
Date:   Wed, 25 Mar 2020 11:40:46 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org, x86@...nel.org,
        mhiramat@...nel.org, mbenes@...e.cz, brgerst@...il.com
Subject: Re: [PATCH v3 26/26] objtool: Add STT_NOTYPE noinstr validation

On Wed, Mar 25, 2020 at 04:53:48PM +0100, Peter Zijlstra wrote:
> On Wed, Mar 25, 2020 at 09:42:11AM -0500, Josh Poimboeuf wrote:
> > Sure, but couldn't validate_unwind_hints() and
> > validate_reachable_instructions() be changed to *only* run on
> > .noinstr.text, for the vmlinux case?  That might help converge the
> > vmlinux and !vmlinux paths.
> 
> You're thinking something like so then?

Not exactly.  But I don't want to keep churning this patch set.  I can
add more patches later, so don't worry about it.

But I was thinking it would eventually be good to have the top-level
check() be like

	sec = NULL;
	if (!validate_all)
		sec = find_section_by_name(file->elf, ".noinstr.text");

	ret = validate_functions(&file, sec);
	if (ret < 0)
		goto out;
	warnings += ret;

	ret = validate_unwind_hints(&file, sec);
	if (ret < 0)
		goto out;
	warnings += ret;

	if (!warnings) {
		ret = validate_reachable_instructions(&file, sec);
		if (ret < 0)
			goto out;
		warnings += ret;
	}

	if (!validate_all)
		goto out;

	ret = validate_retpoline(&file);
	....

that way the general flow is the same regardless...

-- 
Josh