Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752658AbeAFK6U (ORCPT + 1 other); Sat, 6 Jan 2018 05:58:20 -0500 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:28100 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751330AbeAFK6S (ORCPT ); Sat, 6 Jan 2018 05:58:18 -0500 X-Amazon-filename: smime.p7s X-IronPort-AV: E=Sophos;i="5.46,321,1511827200"; d="p7s'?scan'208";a="702096537" Message-ID: <1515236016.29312.223.camel@amazon.co.uk> Subject: Re: [PATCH v3 01/13] x86/retpoline: Add initial retpoline support To: Linus Torvalds CC: "linux-kernel@vger.kernel.org" , "peterz@infradead.org" , "tim.c.chen@linux.intel.com" , "bp@suse.de" , "tglx@linutronix.de" , "ak@linux.intel.com" , "riel@redhat.com" , "keescook@google.com" , "gnomes@lxorguk.ukuu.org.uk" , "pjt@google.com" , "dave.hansen@intel.com" , "luto@amacapital.net" , "jikos@kernel.org" , "gregkh@linux-foundation.org" In-Reply-To: References: <1515058213.12987.89.camel@amazon.co.uk> <20180104143710.8961-1-dwmw@amazon.co.uk> <1515160619.29312.126.camel@amazon.co.uk> <1515170506.29312.149.camel@amazon.co.uk> <20180105164505.xpw5pefxsyu3z56e@pd.tnic> <1515172353.29312.161.camel@amazon.co.uk> <1515189618.29312.197.camel@amazon.co.uk> Face: 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 Organization: Amazon Content-Type: multipart/signed; micalg=sha-256; protocol="application/x-pkcs7-signature"; boundary="=-l3lYVtsPqwrzawVpVe4e" Date: Sat, 6 Jan 2018 10:53:36 +0000 X-Mailer: Evolution 3.18.5.2-0ubuntu3.2 MIME-Version: 1.0 From: "Woodhouse, David" X-Evolution-Source: 1481217574.17989.4@uc8d3ff76b9bc5848a9cc Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: --=-l3lYVtsPqwrzawVpVe4e Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2018-01-05 at 15:50 -0800, Linus Torvalds wrote: >=20 > > + > > +.macro RETPOLINE_CALL reg:req > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 jmp=C2=A0=C2=A0=C2=A0=C2=A0 1113f > > +1110:=C2=A0 RETPOLINE_JMP \reg > > +1113:=C2=A0 call=C2=A0=C2=A0=C2=A0 1110b > > +.endm (Note that RETPOLINE_CALL is purely internal to nospec-branch.h, used only from the NOSPEC_CALL macro to make the ALTERNATIVE_2 invocation les s ugly than it would have been. But the same applies to NOSPEC_CALL which is the one that gets used in our .S files including retpoline.S) > Why do these still force a register name? >=20 > Is it because this is the only user? By "register name" are you asking why it's invoked as "NOSPEC_CALL rbx" instead of "NOSPEC_CALL %rbx" with the percent sign? I think I can probably clean that up now, and turn a lot of %\reg occurrences into just \reg. The only remaining %\reg would be left in retpoline.S inside the THUNK macro used from .irp. --=-l3lYVtsPqwrzawVpVe4e Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEE4w ggUuMIIEFqADAgECAhEApEtL31g6H7ROXdOiQnA9RjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTcxMjIxMDAwMDAwWhcNMTgxMjIxMjM1 OTU5WjAiMSAwHgYJKoZIhvcNAQkBFhFkd213QGFtYXpvbi5jby51azCCASIwDQYJKoZIhvcNAQEB BQADggEPADCCAQoCggEBAKdGKgXuwKMg2r+i/4BZZC0ddRxNq3xIKTakie/VCSzoO7P17A36ZzUc VMEYPfqDt/65xoc6Tdih+qkY2pNDppZ1DZ8mVrAX6O2O60ZhmXB60wMoDvXPZInvkMOW4drqnje/ 7/NOypn/XQAY+ln4KT+3tHG3TfryyJFMedqC/r29KJlCeeCxIzdtq2j5mN42tvPVv4+p+Kr77uui 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