From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1518005275.3677.112.camel@infradead.org> Subject: Re: [PATCH 6/6] s390: introduce execute-trampolines for branches From: David Woodhouse In-Reply-To: <20180207100726.GB31392@amd> References: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com> <1517986811-27819-7-git-send-email-schwidefsky@de.ibm.com> <20180207100726.GB31392@amd> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-AvY0hL8pbp8MTb1b9ofj" Date: Wed, 07 Feb 2018 12:07:55 +0000 Mime-Version: 1.0 List-Archive: List-Post: To: Pavel Machek , Martin Schwidefsky Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Christian Borntraeger , Cornelia Huck , David Hildenbrand , Greg Kroah-Hartman , Jon Masters , Marcus Meissner , Jiri Kosina , Dominik Brodowski , Alan Cox List-ID: --=-AvY0hL8pbp8MTb1b9ofj Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2018-02-07 at 11:07 +0100, Pavel Machek wrote: > This is really unfortunate naming of kernel option. >=20 > spectre_v2=3Doff sounds like we are turning the "bug" off, but i somehow > suspect you are turning the bug _workaround_ off. That's consistent with what we have on x86. > > +ifdef CONFIG_EXPOLINE > > +=C2=A0=C2=A0ifeq ($(call cc-option-yn,$(CC_FLAGS_MARCH) -mindirect-bra= nch=3Dthunk),y) > > +=C2=A0=C2=A0=C2=A0=C2=A0CC_FLAGS_EXPOLINE :=3D -mindirect-branch=3Dthu= nk > > +=C2=A0=C2=A0=C2=A0=C2=A0CC_FLAGS_EXPOLINE +=3D -mfunction-return=3Dthu= nk > > +=C2=A0=C2=A0=C2=A0=C2=A0CC_FLAGS_EXPOLINE +=3D -mindirect-branch-table > > +=C2=A0=C2=A0=C2=A0=C2=A0export CC_FLAGS_EXPOLINE > > +=C2=A0=C2=A0=C2=A0=C2=A0cflags-y +=3D $(CC_FLAGS_EXPOLINE) > > +=C2=A0=C2=A0else > > +=C2=A0=C2=A0=C2=A0=C2=A0$(warning "Your gcc lacks the -mindirect-branc= h=3D option") > > +=C2=A0=C2=A0endif > > +endif That isn't, though. Linus asked us to drop the $(warning) part. ... and then spent a week building with a non-retpoline compiler and not noticing, so he might have changed his mind ;) --=-AvY0hL8pbp8MTb1b9ofj Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEFQw ggUxMIIEGaADAgECAhBNRhEyk/HZ7naOeTHWrzuAMA0GCSqGSIb3DQEBCwUAMIGXMQswCQYDVQQG EwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYD VQQKExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RPIFJTQSBDbGllbnQgQXV0aGVu dGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTAeFw0xNzEyMjEwMDAwMDBaFw0xODEyMjEyMzU5 NTlaMCQxIjAgBgkqhkiG9w0BCQEWE2R3bXcyQGluZnJhZGVhZC5vcmcwggEiMA0GCSqGSIb3DQEB AQUAA4IBDwAwggEKAoIBAQDgzLNWa18DNpGUj/ZeH0Sgz53ESIbzdPw3OJeuNP6jZhxZojbyfxbM hETscxI/Hj6UZ4a7sHm5BkVjlsB1Af2Za/PXUt8MmLAcPMHkMPGunvkUibEvblDvpqMkQZlaZM+t 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