From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B583420298B for ; Fri, 14 Mar 2025 17:23:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741973020; cv=none; b=Hw7ck+GBWwxZS/hi0b9LK0ZiqfMKHh+tP6qLFqYTEV+1NPtL5GzmaogTcnqm3VhFiBKbRkJ+0ujDdrsxFvJNw95P6VS2xAF843krAuqoJTYpDMjwP9PM6tEY1YZ4w7B8nxP9kOINra69bzlGo0BMULMaV8BhBEm05tkjkZMzQYM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741973020; c=relaxed/simple; bh=ji7dAuqGQI3tg4wd37U2flJuKrm1sErZacCEBv8gbT8=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=NGpt+5OI8fAXPhCuBIYB4xsnRP3PTPJ/Z2XO/6aJAAoScp+jO6ceUZ1P4aRbvMERMBxqJVPS8oTxrW+omzVZck2RR9Lj6EftqqMSn8jz7dtFbm8oyvSE7fbipb39nkRwAcl9KNGmU8RLYo4RBYadWLNSlKSo4Xl+ZGw/oinIJKE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=HcESCXzj; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HcESCXzj" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=l3zw1XmUm3mGB3Pj7fKsZIT3INOpc7DOpB2p9k69ZiM=; b=HcESCXzjIkh3JrFaHqn1IjvSGn LdUMw7VUq8xxP8Npzf2rVnU3GxRgT/Ix14I6rEh2iSYIpa4LLrKnriiRDj6MXXqrMcjy+/liStjyb 4QUxE9nhlw+nyycskiSuRgVbEqt8zRKsMm62jUvxo5/tDun+Ni4hxQftNg5+k6Tuzyxdj/DNc9qmy yT/haUYebCS3VrO7KCmTKyH7pcLCaxhkISMiljgoPiH08YbWlqhCOfqZFkx9CafvcjtMBS0sA0T2h HGkE5VQ0rfMsBICbE/oK2VABkjbxlRvWVWdOUnfI7MXDqbpPlZS3m9/PuNmVhkokgfizsUyGt+zKf Q+LLaQwA==; Received: from [172.31.31.145] (helo=u09cd745991455d.ant.amazon.com) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tt8kd-00000002vR5-4BzO; Fri, 14 Mar 2025 17:23:16 +0000 Message-ID: Subject: Re: [PATCH v7 8/8] [DO NOT MERGE] x86/kexec: Add CFI type information to relocate_kernel() From: David Woodhouse To: Josh Poimboeuf Cc: kexec@lists.infradead.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , "Kirill A . Shutemov" , Kai Huang , Nikolay Borisov , linux-kernel@vger.kernel.org, Simon Horman , Dave Young , Peter Zijlstra , bsz@amazon.de Date: Fri, 14 Mar 2025 17:23:15 +0000 In-Reply-To: References: <20250312144257.2348250-1-dwmw2@infradead.org> <20250312144257.2348250-9-dwmw2@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-s61U3xegMYCIifdpMjrd" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html --=-s61U3xegMYCIifdpMjrd Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2025-03-14 at 09:07 -0700, Josh Poimboeuf wrote: > On Wed, Mar 12, 2025 at 02:34:20PM +0000, David Woodhouse wrote: > > From: David Woodhouse > >=20 > > A previous commit added __nocfi to machine_kexec() because it makes an > > indirect call to relocate_kernel() which lacked CFI type information, > > and caused the system to crash. > >=20 > > Use SYM_TYPED_FUNC_START() to ensure that the type information is > > present, and remove the __nocfi tag. > >=20 > > I still can't make objtool happy with this in both GCC and Clang builds > > at the same time, so not yet for merging; only included in this series > > to nerd-snipe the objtool maintainers. >=20 > Again, I'd recommend just compiling the code in .data..relocate_kernel. > Then objtool doesn't need to care. >=20 > Otherwise it would help to know what warnings you're getting with this > patch, and the corresponding .config. ISTR this version is OK with Clang and CONFIG_CFI_CLANG but with GCC I get this: vmlinux.o: warning: objtool: relocate_kernel+0x69: unsupported stack regist= er modification /* setup a new stack at the end of the physical control page */ lea PAGE_SIZE(%rsi), %rsp 79: 48 8d a6 00 10 00 00 lea 0x1000(%rsi),%rsp Maybe the answer is to put the UNWIND_HINT_FUNC into #ifdef CONFIG_CFI_CLANG but that seems wrong. I'll have another look at putting it in the data section, and see if I can remember why I didn't want to do that before (and if that's still relevant now). --=-s61U3xegMYCIifdpMjrd Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et GfZI+LGqSv0YtNa54T9D1AWJy08ZKkWvfGGIXN9UFAPMJ6OLLH/UUEgFa+7KlrEvMUupDFGnnR06 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