From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752448AbaKKHwz (ORCPT ); Tue, 11 Nov 2014 02:52:55 -0500 Received: from mail.emea.novell.com ([130.57.118.101]:43695 "EHLO mail.emea.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751934AbaKKHwy convert rfc822-to-8bit (ORCPT ); Tue, 11 Nov 2014 02:52:54 -0500 Message-Id: <5461CE6302000078000464C5@mail.emea.novell.com> X-Mailer: Novell GroupWise Internet Agent 14.0.1 Date: Tue, 11 Nov 2014 07:52:51 +0000 From: "Jan Beulich" To: "Linus Torvalds" Cc: "Ingo Molnar" , "Ingo Molnar" , "Thomas Gleixner" , "Tony Jones" , "Linux Kernel Mailing List" , "Peter Anvin" Subject: Re: [PATCH, RFC] x86: also CFI-annotate certain inline asm()s References: <5458A9600200007800044AE5@mail.emea.novell.com> <20141110100117.GA15841@gmail.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 10.11.14 at 19:10, wrote: > Btw, the sane thing to do is to make your infrastructure just say "If > my frame walker hits a push/pop without CFI information, I'll just add > it myself". > > Yes, that involved having to actuall ylook at the instruction. Tough > shit. Just do it right. There aren't that many push/pop patterns. Did you think this through? Inspecting instructions while unwinding the stack would involve significant amounts of architecture specific code, whereas the unwinder is largely architecture independent. Apart from code to obtain machine state, only the annotations are (necessarily) connected to the architecture since they accompany machine instructions. Did you ever write a disassembler capable of correctly dealing with everything a compiler may generate (i.e. including data literals in the middle of code)? Anyway - I'm sure I won't convince you now or ever, this is too religious a topic for you afaict, and hence an objective and fair discussion is impossible. Jan