Received: by 2002:a25:4158:0:0:0:0:0 with SMTP id o85csp7654956yba; Thu, 2 May 2019 13:49:46 -0700 (PDT) X-Google-Smtp-Source: APXvYqz+FrzqnAsBy2dNENyfdj3IkVeowo/IqG+sdyyemUFD/puKsrA9uRm9To3BYGqucbBOwPYf X-Received: by 2002:a17:902:864b:: with SMTP id y11mr5617270plt.1.1556830185864; Thu, 02 May 2019 13:49:45 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556830185; cv=none; d=google.com; s=arc-20160816; b=lxpbP4mo4/LPzPgfFLICLTwXbW9acmAq+Wnvx4QIXF0SIumGjyvthr33hYCQYX/0cE QwHpd79Ir5UnpR7nGw+mUNmeyBA37Dquy9Ok86bWeXr7TCuRMS1GoPrisJBTOWgLi6oV efKUjVuLtaJvW9sVyX6tKqI2tZ5oiaY91KPLh4lQKkx3UJkRqs3Hd/NkpBPY4q4CA4rB AmRstPch2nc6phpxkWTVVF1GuuRVpHBrxEOJ0t56wLgGtoL0EUoRnvkEt+EMSLde3+H0 1H5cTms0cJQNMRNlnJ8hrtXxPAKCVcBXognToBIlbUlLNm51gTSLBX3hywTn6GH8TPlI qfbw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:subject:cc:to:from:date; bh=2qqKWpflCqe6bBekEeTxoGCJzWtl0xaHCrHE3INUGYA=; b=N2YxOBNTM4WnOIVFQPX3vfVP5W+Ny1qz3boJuIqT+ldj7qwDtv9tiO8unrbqPSfWcl dWXciTDm3klp9uVJ4krK25IXnkXxcWCebYrjVt5mCey7KIUgoAOoYMW4SsE1TZxt/jSw 8Ak1BHzncZKvejMtvWHwk6W5bDDg9pVoJwUJWyUKWcofgbquAIrNqOm9grune1OxJEzy OEa7Io4myAYLU7TniHb1jq5HwEH8mb3CwUH8lM0l8jMXNlZYs5wsaL3ohezt7OIlO3DN IPrK2TsK6xQbK1oIpgKahxuLFbbtZY/umQWCx5UY5nswEAXmZj9FlmF7nFHraHZdZmGb kiJw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 1si212461plo.217.2019.05.02.13.49.30; Thu, 02 May 2019 13:49:45 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726326AbfEBUsZ (ORCPT + 99 others); Thu, 2 May 2019 16:48:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:55244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbfEBUsZ (ORCPT ); Thu, 2 May 2019 16:48:25 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E395B2081C; Thu, 2 May 2019 20:48:21 +0000 (UTC) Date: Thu, 2 May 2019 16:48:19 -0400 From: Steven Rostedt To: Linus Torvalds Cc: Peter Zijlstra , Linux List Kernel Mailing , Ingo Molnar , Andrew Morton , Andy Lutomirski , Nicolai Stange , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "the arch/x86 maintainers" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Konrad Rzeszutek Wilk , Tim Chen , Sebastian Andrzej Siewior , Mimi Zohar , Juergen Gross , Nick Desaulniers , Nayna Jain , Masahiro Yamada , Joerg Roedel , "open list:KERNEL SELFTEST FRAMEWORK" , stable Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions Message-ID: <20190502164819.24a818a1@gandalf.local.home> In-Reply-To: References: <20190501202830.347656894@goodmis.org> <20190501203152.397154664@goodmis.org> <20190501232412.1196ef18@oasis.local.home> <20190502162133.GX2623@hirez.programming.kicks-ass.net> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2 May 2019 11:02:40 -0700 Linus Torvalds wrote: > Indeed, the 32-bit case for same-RPL exceptions/iret is entirely > different, and I'd forgotten about that. > > And honestly, this makes the 32-bit case much worse. Now the entry > stack modifications of int3 suddenly affect not just the entry, but > every exit too. > > This is _exactly_ the kind of subtle kernel entry/exit code I wanted > us to avoid. I just want to point out that I never got the trampoline version working on i386. I didn't have the time to debug why it would crash when stressed. -- Steve