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 DA0E6EADA for ; Thu, 13 Mar 2025 19:58:21 +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=1741895905; cv=none; b=uVhAtcCWBBEWuNShDpBeijcHBKrKOZYaDT3PBxgP31tgI+bEb5m3wHLstJyG0L8CFxCCVWJXZeVaspS990sHbvV/4f5Jk3tQpfkA4rcWaMlTPYOqLK/bBTcLOz3VxN/TbtttAuNtmKdczCOL+1dV32jliAjzhE8u9ln6iLoo7F4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741895905; c=relaxed/simple; bh=BPFdX0ni1gzC8Ah9GU+XEZMutChUkCnYlskvXYhef8A=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Hgo2OM3l3HSHtC+6EmbQYs6AzywKw4/4slep/WYoEjbYXC8AKpleboIn9hAsfPzpepcQw3iqlTKlJVR/uWOM0N8Wu5bPBDxxPH7kKvJOiS1mtcJLSz+//ZFccTmrXNXP/+/A30vET0jHVKjYs5eSEhvfJVn7DMf7ELYXZLRrlcM= 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=S+MlHair; 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="S+MlHair" 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=Jve+Xyq94Yg6ueZY2tids1pGB6JCzbQ6LlcNUKf7Ipw=; b=S+MlHairJZ1+CVveB6WZ+NAS+P 6aTcrCVJ5JW9X3ROVFkVM5pEhdIugBTSOT8MtGx8/Stc8VfZ7npC/e11s9ijZunhSP9/HBDTRn4WJ G/AM3ZWIZtRfvnjikwtrUAzFyjwp2K4uleMgMd5myvC06iwU8Ea1xQobz1+GqrP3qwKSFyHEzKSe/ qHvmhp5lPKd3tSCuPZg6yeRPDPn5RVpYGqrT18Xu5cAoY8XZhOsDKcRvxEMjz5EExLr3kZ8cW6/sj pyUJhC9MvCckwlh5wGceccJ7HZX6gdRJz4fV6ALZ2RMqvBEs7mfQNxocWVtETXI/B5YvDlP0oXu8F 6VB9XNRQ==; 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 1tsoh0-00000002n15-2X8u; Thu, 13 Mar 2025 19:58:10 +0000 Message-ID: <7f36d90ada07281dd0efa4339c991cb2ecec4da2.camel@infradead.org> Subject: Re: [PATCH v7 0/8] x86/kexec: Add exception handling for relocate_kernel From: David Woodhouse To: Ingo Molnar 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 , jpoimboe@kernel.org, bsz@amazon.de Date: Thu, 13 Mar 2025 19:58:10 +0000 In-Reply-To: References: <20250312144257.2348250-1-dwmw2@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-oH+uD1IlVSVLINYYXlcp" 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 --=-oH+uD1IlVSVLINYYXlcp Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2025-03-13 at 11:54 +0100, Ingo Molnar wrote: >=20 > * Ingo Molnar wrote: >=20 > > I applied the first 3 patches to tip:x86/boot for=20 > > phased-risk-reduction reasons, and because I had some questions and > > suggestions starting at patch #4. >=20 > So there's a new objtool build warning from the new exc_handler code: >=20 > =C2=A0vmlinux.o: warning: objtool: exc_handler+0xe: early indirect call >=20 > That's with a x86-64 defconfig + KVM enablement. Reproduced that by going back to x86-64 defconfig.=20 vmlinux.o: warning: objtool: exc_handler+0xe: early indirect call SYM_CODE_START_LOCAL_NOALIGN(exc_handler) pushq %rax 2b6: 50 push %rax pushq %rbx 2b7: 53 push %rbx pushq %rcx 2b8: 51 push %rcx pushq %rdx 2b9: 52 push %rdx pushq %rsi 2ba: 56 push %rsi /* Set up %rdx/%rsi for debug output */ pr_setup 2bb: 48 8d 35 6e ff ff ff lea -0x92(%rip),%rsi # 230 /* rip and exception info */ print_reg 'E', 'x', 'c', ':', 0x28(%rsp) 2c2: b0 45 mov $0x45,%al 2c4: ff d6 call *%rsi So it's the 'call *$rsi' instruction at 0x2c4, but that's annotated with ANNOTATE_RETPOLINE_SAFE: .macro print_reg a, b, c, d, r movb $\a, %al ANNOTATE_RETPOLINE_SAFE call *%rsi So what's wrong with that? What *more* do I have to tell objtool to make it shut up and go away? Am I missing some documentation which would tell me what it's actually unhappy about? Because "early indirect call" doesn't enlighten me very much, and reading tools/objtool/check.c doesn't either. --=-oH+uD1IlVSVLINYYXlcp 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 aDJAwtycb8yXtILj+TvfhLFhafxroXrflspavejQkEiHjNjtHnwbZ+o43g0/yxjwnarGI3kgcak7 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