From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x224jwFtVh8TGXVwGKHygC+PmEjMyB361Ci/LGKUuwtBcbeCJtL06Of+1TiyjIWU6JiooLQhN ARC-Seal: i=1; a=rsa-sha256; t=1517393269; cv=none; d=google.com; s=arc-20160816; b=bzcNYSFHv1nQhRtGYLCg76k2bx2UIYMZAkHpzca7f2WJf/UM1iP2zEgjYi/jOBGmg0 qXrJu5ETl3kSshsj3tfVLitqrOerOVJ7afUBmDiAkV9G73BjuH3TDF9rvKHWYMN8a12h zAdAucRxzHrLmuqyl99JWNGYef4+DBiDcGE06H3p82XF94Zm18k6B/s3IPfj0DrAAY/u BAde1cFXe8UrtOCmHXE7YunmOrRhyyJ6S+LuZvQvtUXTjuyxUIXcChZwgUPhCqOyh/BJ XsGzlH/CyeJ+a9dGajWmxQOUl3mwBPhglMektUaeML1rUK7851ccsHzK7leK13CX7Hs9 NuIQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:date:face:references:in-reply-to:cc:to:from:subject :message-id:dkim-signature:arc-authentication-results; bh=o9jYOa7WYpRlbqNeiXVwwH+Atit3aIccuhUu+k/4LPw=; b=XqR7JwzISSmYxImVSgvGXNs5eFTAUPBeCYrnIJQjwO+gSYoUpT2xPKrV2qRWiwHcQg 8/b0sopnvZZnCAyNYw6J9pRV6MkYxjoREdBONN26hk2u12E9eqkVov53yZBjXC1DDBws R2M9DKyUC12mHLKmDWIrpa7Ajksh9r5Yn0Fgs2aQzprWZ03jyyuBRUhilMF2OVzao+DB o+P3UcKTUdEuzXEBA5mh3Wgw9KTmwjcE76xfDClNtEQ+RmYBnmTpQ3bsPYBMK/Rs8fWN NRX65i/yG5Ks0aey08lR9xDdvDB/jMsBjMr4WzxRIyYSf8/eIE36pBAXRjvn7Fow7Mtm IQ3g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=twosheds.20170209 header.b=mL5Fp8MK; spf=pass (google.com: best guess record for domain of batv+ceef2fc3471354218b5e+5274+infradead.org+dwmw2@twosheds.srs.infradead.org designates 90.155.92.209 as permitted sender) smtp.mailfrom=BATV+ceef2fc3471354218b5e+5274+infradead.org+dwmw2@twosheds.srs.infradead.org Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=twosheds.20170209 header.b=mL5Fp8MK; spf=pass (google.com: best guess record for domain of batv+ceef2fc3471354218b5e+5274+infradead.org+dwmw2@twosheds.srs.infradead.org designates 90.155.92.209 as permitted sender) smtp.mailfrom=BATV+ceef2fc3471354218b5e+5274+infradead.org+dwmw2@twosheds.srs.infradead.org Message-ID: <1517393226.18619.156.camel@infradead.org> Subject: Re: [PATCH 20/24] objtool: Another static block fail From: David Woodhouse To: Peter Zijlstra , Josh Poimboeuf Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, Dave Hansen , Ashok Raj , Tim Chen , Andy Lutomirski , Linus Torvalds , Greg KH , Andrea Arcangeli , Andi Kleen , Arjan Van De Ven , Dan Williams , Paolo Bonzini , Jun Nakajima , Asit Mallick , Jason Baron In-Reply-To: <20180131100119.GJ2269@hirez.programming.kicks-ass.net> References: <20180123152539.374360046@infradead.org> <20180123152639.170696914@infradead.org> <20180129225252.bi2etgk3eqprcv3x@treble> <20180130095653.GZ2269@hirez.programming.kicks-ass.net> <20180131031221.7k2igskvrpsphc2u@treble> <20180131100119.GJ2269@hirez.programming.kicks-ass.net> Face: 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 Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-8ptDD52cLPMYx4ZhCSgE" Date: Wed, 31 Jan 2018 10:07:06 +0000 Mime-Version: 1.0 X-Mailer: Evolution 3.18.5.2-0ubuntu3.2 X-SRS-Rewrite: SMTP reverse-path rewritten from by twosheds.infradead.org. See http://www.infradead.org/rpr.html X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590397857832042088?= X-GMAIL-MSGID: =?utf-8?q?1591102164700965546?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --=-8ptDD52cLPMYx4ZhCSgE Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2018-01-31 at 11:01 +0100, Peter Zijlstra wrote: > On Tue, Jan 30, 2018 at 09:12:21PM -0600, Josh Poimboeuf wrote: > >=C2=A0 > > Or, maybe we should just forget the whole thing and just stick with the > > dynamic IBRS checks with lfence.=C2=A0 Yes, it's less ideal for the ker= nel, > > but adding these acrobatics to objtool also has a cost. >=20 > For now, IBRS seems off the table entirely. But no, I really don't want > to have to unconditionally eat the LFENCE cost in all those sites. There's also alternatives. And without the IBRS-on-kernel-entry bits there aren't that many call sites that really need this anyway and don't have *other* conditionals that really are runtime-only (like dumpable etc.). --=-8ptDD52cLPMYx4ZhCSgE 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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