From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753800AbdLFIsP (ORCPT ); Wed, 6 Dec 2017 03:48:15 -0500 Received: from mail-qt0-f194.google.com ([209.85.216.194]:43181 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750989AbdLFIsN (ORCPT ); Wed, 6 Dec 2017 03:48:13 -0500 X-Google-Smtp-Source: AGs4zMZRy3OZom3H/6GqFSTx5YTSfefimv+wLcrQx7B1O4RTMikr2iXPjBjVXPY2PMivUr2LLyw2xNS5TkaUSdVFXAs= MIME-Version: 1.0 In-Reply-To: References: <1511921105-3647-1-git-send-email-me@tobin.cc> <1511921105-3647-4-git-send-email-me@tobin.cc> <20171205204402.GD11064@eros> From: Geert Uytterhoeven Date: Wed, 6 Dec 2017 09:48:12 +0100 X-Google-Sender-Auth: wxY5-fIs_05D4LA4sOVwrT0cE9g Message-ID: Subject: Re: [PATCH V11 3/5] printk: hash addresses printed with %p To: Linus Torvalds Cc: "Tobin C. Harding" , "kernel-hardening@lists.openwall.com" , "Jason A. Donenfeld" , "Theodore Ts'o" , Kees Cook , Paolo Bonzini , Tycho Andersen , "Roberts, William C" , Tejun Heo , Jordan Glover , Greg KH , Petr Mladek , Joe Perches , Ian Campbell , Sergey Senozhatsky , Catalin Marinas , Will Deacon , Steven Rostedt , Chris Fries , Dave Weinstein , Daniel Micay , Djalal Harouni , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , "linux-kernel@vger.kernel.org" , Network Development , David Miller , Stephen Rothwell , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Sergei Shtylyov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Linus, On Wed, Dec 6, 2017 at 12:33 AM, Linus Torvalds wrote: > On Tue, Dec 5, 2017 at 2:57 PM, Geert Uytterhoeven wrote: >> Lowest 3 is good enough for all natural types, up to long long. >> We may still receive complaints from people who care about seeing if >> a pointer is cacheline-aligned or not. Fixing that may need up to 7 bits, I'm >> afraid, which is a bit too much to give up. > > I really think even the lowest three is a bit too much. > > Who really cares? If it's something that is particularly _about_ > alignment (ie an alignment trap), maybe just print out those bits > separately. If I'm not mistaken, some architectures don't generate alignment traps, but just zero the LSBs. > And for everything else? It's purely about getting used to it. Yes, we will get used to it. I agree that for debugging during development, we will just use %px and be fine. Storm in a glass of water, everybody will have forgotten by the time v4.16 is released. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH V11 3/5] printk: hash addresses printed with %p Date: Wed, 6 Dec 2017 09:48:12 +0100 Message-ID: References: <1511921105-3647-1-git-send-email-me@tobin.cc> <1511921105-3647-4-git-send-email-me@tobin.cc> <20171205204402.GD11064@eros> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: "Tobin C. Harding" , "kernel-hardening@lists.openwall.com" , "Jason A. Donenfeld" , "Theodore Ts'o" , Kees Cook , Paolo Bonzini , Tycho Andersen , "Roberts, William C" , Tejun Heo , Jordan Glover , Greg KH , Petr Mladek , Joe Perches , Ian Campbell , Sergey Senozhatsky , Catalin Marinas , Will Deacon , Steven Rostedt , Chris Fries , To: Linus Torvalds Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Linus, On Wed, Dec 6, 2017 at 12:33 AM, Linus Torvalds wrote: > On Tue, Dec 5, 2017 at 2:57 PM, Geert Uytterhoeven wrote: >> Lowest 3 is good enough for all natural types, up to long long. >> We may still receive complaints from people who care about seeing if >> a pointer is cacheline-aligned or not. Fixing that may need up to 7 bits, I'm >> afraid, which is a bit too much to give up. > > I really think even the lowest three is a bit too much. > > Who really cares? If it's something that is particularly _about_ > alignment (ie an alignment trap), maybe just print out those bits > separately. If I'm not mistaken, some architectures don't generate alignment traps, but just zero the LSBs. > And for everything else? It's purely about getting used to it. Yes, we will get used to it. I agree that for debugging during development, we will just use %px and be fine. Storm in a glass of water, everybody will have forgotten by the time v4.16 is released. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 Sender: geert.uytterhoeven@gmail.com In-Reply-To: References: <1511921105-3647-1-git-send-email-me@tobin.cc> <1511921105-3647-4-git-send-email-me@tobin.cc> <20171205204402.GD11064@eros> From: Geert Uytterhoeven Date: Wed, 6 Dec 2017 09:48:12 +0100 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: [kernel-hardening] Re: [PATCH V11 3/5] printk: hash addresses printed with %p To: Linus Torvalds Cc: "Tobin C. Harding" , "kernel-hardening@lists.openwall.com" , "Jason A. Donenfeld" , Theodore Ts'o , Kees Cook , Paolo Bonzini , Tycho Andersen , "Roberts, William C" , Tejun Heo , Jordan Glover , Greg KH , Petr Mladek , Joe Perches , Ian Campbell , Sergey Senozhatsky , Catalin Marinas , Will Deacon , Steven Rostedt , Chris Fries , Dave Weinstein , Daniel Micay , Djalal Harouni , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , "linux-kernel@vger.kernel.org" , Network Development , David Miller , Stephen Rothwell , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Sergei Shtylyov List-ID: Hi Linus, On Wed, Dec 6, 2017 at 12:33 AM, Linus Torvalds wrote: > On Tue, Dec 5, 2017 at 2:57 PM, Geert Uytterhoeven wrote: >> Lowest 3 is good enough for all natural types, up to long long. >> We may still receive complaints from people who care about seeing if >> a pointer is cacheline-aligned or not. Fixing that may need up to 7 bits, I'm >> afraid, which is a bit too much to give up. > > I really think even the lowest three is a bit too much. > > Who really cares? If it's something that is particularly _about_ > alignment (ie an alignment trap), maybe just print out those bits > separately. If I'm not mistaken, some architectures don't generate alignment traps, but just zero the LSBs. > And for everything else? It's purely about getting used to it. Yes, we will get used to it. I agree that for debugging during development, we will just use %px and be fine. Storm in a glass of water, everybody will have forgotten by the time v4.16 is released. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds