From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41yjSz2WMYzDqgZ for ; Sun, 26 Aug 2018 14:58:10 +1000 (AEST) Subject: Re: [PATCH] treewide: remove current_text_addr From: "H. Peter Anvin" To: Helge Deller , Nick Desaulniers , torvalds@linux-foundation.org, akpm@linux-foundation.org Cc: ebiederm@xmission.com, tglx@linutronix.de, mingo@redhat.com, horms@verge.net.au, natechancellor@gmail.com, pombredanne@nexb.com, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Mark Salter , Aurelien Jacquiot , Yoshinori Sato , Richard Kuo , Tony Luck , Fenghua Yu , Geert Uytterhoeven , Michal Simek , Ralf Baechle , Paul Burton , James Hogan , Greentime Hu , Vincent Chen , Ley Foon Tan , Jonas Bonn , Stefan Kristiansson , Stafford Horne , "James E.J. Bottomley" , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Palmer Dabbelt , Albert Ou , Martin Schwidefsky , Heiko Carstens , Rich Felker , "David S. Miller" , Guan Xuetao , x86@kernel.org, Jeff Dike , Richard Weinberger , Chris Zankel , Max Filippov , Tobias Klauser , Noam Camus , Mickael GUENE , Nicolas Pitre , Kees Cook , Dave Martin , Marc Zyngier , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Laura Abbott , Yury Norov , Mark Rutland , Huacai Chen , "Maciej W. Rozycki" , Arnd Bergmann , David Howells , Sukadev Bhattiprolu , Nicholas Piggin , "Aneesh Kumar K.V" , Philippe Bergheaud , Ram Pai , Christophe Leroy , Cornelia Huck , Vasily Gorbik , Nick Alcock , Shannon Nelson , Nagarathnam Muthusamy , Andy Lutomirski , Borislav Petkov , Dave Hansen , Vitaly Kuznetsov , Jiri Kosina , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-c6x-dev@linux-c6x.org, uclinux-h8-devel@lists.sourceforge.jp, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@vger.kernel.org, linux-mips@linux-mips.org, nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org References: <20180821202900.208417-1-ndesaulniers@google.com> <207784db-4fcc-85e7-a0b2-fec26b7dab81@gmx.de> <81141365-8168-799b-f34f-da5f92efaaf9@zytor.com> Message-ID: <7f49eeab-a5cc-867f-58fb-abd266f9c2c9@zytor.com> Date: Sat, 25 Aug 2018 21:56:11 -0700 MIME-Version: 1.0 In-Reply-To: <81141365-8168-799b-f34f-da5f92efaaf9@zytor.com> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 08/25/18 20:16, H. Peter Anvin wrote: > On 08/25/18 19:38, H. Peter Anvin wrote: >> >> If it was worthwhile it would make more sense to at least force this >> into the rodata section with the string, something like the attached >> file for an example; however, I have a hunch it doesn't matter. >> > > An even nuttier version which avoids the extra pointer indirection. > Read it and fear. > > -hpa > OK, so one more thing, I guess: it is necessary to suppress the tailcall optimization for _RET_IP_ to make any sense, but that should be pretty simple: static inline void notailcall(void) { asm volatile(""); } -hpa