From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01CE2C433F5 for ; Sat, 19 Feb 2022 01:22:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240870AbiBSBWZ (ORCPT ); Fri, 18 Feb 2022 20:22:25 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236726AbiBSBWW (ORCPT ); Fri, 18 Feb 2022 20:22:22 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 145643B285 for ; Fri, 18 Feb 2022 17:22:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645233721; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=NKNuU6T0+CgHInxcOtBxN9jDk/rXumbRGkWZ7rGGpH8=; b=CGb7ljFFJ6pZ7r/ECLxYtuGa5/l5lH2i4PYS2PMQZGFq9fpiemIGFl8u5KrZ41HltkZGwC mDHQdW+fstPwbsNKnPxi3NyplHA2omy+sKFzptqikcQ7hSgUTr/ODS7WuJ1PBR8kjIQptM mugSTlvgZSyk7oQ89h+NE6n0rIdKZwc= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-615-RUHg1i0POLu3wraNJzZa8w-1; Fri, 18 Feb 2022 20:22:00 -0500 X-MC-Unique: RUHg1i0POLu3wraNJzZa8w-1 Received: by mail-qv1-f70.google.com with SMTP id o6-20020a0562140e4600b0042cf952661bso10652993qvc.10 for ; Fri, 18 Feb 2022 17:21:59 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=NKNuU6T0+CgHInxcOtBxN9jDk/rXumbRGkWZ7rGGpH8=; b=6kZahylozOhagbo4ueiaAmrmhN2BBHTzd55C5xR3H8KGkK681+M0Sz9mhz7wpsMCmS 5kMxxi5EImgcVMvpwEomQCWaRXCiBJheKJONTbYtgID+7J3Uzc7YK4Y4K21QF+1llXvC lfbqhdpCTerUdecib1uSPqHBl6tjy+P1lFsCkwK/5z0wAQvENRURpI7dJ/kiG7+rYvAz KSjEu3TUPVRCPwayjabDQMqyfpBG0zOMVuggNaMSSmM61Chf9ATKiJH6O/JUewthXaCk oJ4lP0+EdW2gO/V+o3yktRvaogAvU+4834eds4mv2u028LmQBdU3obw52JIRUFBIiGHS 9QZg== X-Gm-Message-State: AOAM531xVUKcJPciWSYQpjPHn9wdrxPq1VsSg357WGbDtCItcTc9uwJe S/9RrLbjYpaTcDXK5hzoaD9nofD6MGan/SDpG1RTAsKCV8EfU7lneqYL6gF/+E7/Qx624K3qHd+ iOlhrfveTNExWD/pliAcs/MO9 X-Received: by 2002:ac8:5c4e:0:b0:2cb:9724:8b21 with SMTP id j14-20020ac85c4e000000b002cb97248b21mr9242196qtj.544.1645233719566; Fri, 18 Feb 2022 17:21:59 -0800 (PST) X-Google-Smtp-Source: ABdhPJzRni3V2rINh2mu0p+1lIHNNRGvbQyoiDfj6ZyQYSg7zwdZjdUFXldPTpjwYIVPc1enbzm1kQ== X-Received: by 2002:ac8:5c4e:0:b0:2cb:9724:8b21 with SMTP id j14-20020ac85c4e000000b002cb97248b21mr9242189qtj.544.1645233719327; Fri, 18 Feb 2022 17:21:59 -0800 (PST) Received: from treble ([2600:1700:6e32:6c00::35]) by smtp.gmail.com with ESMTPSA id x17sm2584234qtr.69.2022.02.18.17.21.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Feb 2022 17:21:58 -0800 (PST) Date: Fri, 18 Feb 2022 17:21:55 -0800 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, keescook@chromium.org, samitolvanen@google.com, mark.rutland@arm.com, alyssa.milburn@intel.com Subject: Re: [PATCH 14/29] x86/ibt: Add IBT feature, MSR and #CP handling Message-ID: <20220219012155.z24prt3yj25ytacs@treble> References: <20220218164902.008644515@infradead.org> <20220218171409.395399333@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220218171409.395399333@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 18, 2022 at 05:49:16PM +0100, Peter Zijlstra wrote: > +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection) > +{ > + if (!cpu_feature_enabled(X86_FEATURE_IBT)) { > + pr_err("Whaaa?!?!\n"); > + return; > + } Might want to upgrade that to a proper warning :-) > +bool ibt_selftest(void) > +{ > + ibt_selftest_ok = false; > + > + asm (ANNOTATE_NOENDBR > + "1: lea 2f(%%rip), %%rax\n\t" > + ANNOTATE_RETPOLINE_SAFE > + " jmp *%%rax\n\t" > + "2: nop\n\t" > + > + /* unsigned ibt_selftest_ip = 2b */ > + ".pushsection .data,\"aw\"\n\t" > + ".align 8\n\t" > + ".type ibt_selftest_ip, @object\n\t" > + ".size ibt_selftest_ip, 8\n\t" > + "ibt_selftest_ip:\n\t" > + ".quad 2b\n\t" > + ".popsection\n\t" > + > + : : : "rax", "memory"); Can 'ibt_selftest_ip' just be defined in C (with __ro_after_init) and passed as an output to the asm doing 'mov $2b, %[ibt_selftest_ip]'? -- Josh