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 DB75AC433F5 for ; Wed, 9 Mar 2022 20:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234672AbiCIUw3 (ORCPT ); Wed, 9 Mar 2022 15:52:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238252AbiCIUw1 (ORCPT ); Wed, 9 Mar 2022 15:52:27 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 920FBAD101; Wed, 9 Mar 2022 12:51:23 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 41A93B823D5; Wed, 9 Mar 2022 20:51:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F7F2C340E8; Wed, 9 Mar 2022 20:51:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646859081; bh=ZUQl8VjoXzxjjlXQpxYp7jLs7LQAHPOAzRTYa+vp71A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OA2O0miFItD1GHJrCIsLcNp/1NSkFzqK3+DHFFnITaEAz3K16E084xNgS+fnzfxuR 1xOUjrDjKC2W01GEFNLrd6UtCBwcoNQx1x/59BO748C3St6B1LWOfWPH+PBzYjYJ+o hR+sXMcR/E3SuBL+qrjH1Jazsze+eG+u2vbZXxx/LWMq9jOdMGKaaazjUyW/qJDj8q kMjfK+iooKeaxEKd+EyX0Km6mYoUHNJythjG8Xx42lsl3z6WN68Kvz2wIbcAgsFIwn 1EmLs2bbIFKYhVabtERmpj1z2B/wBcq9OQW+fXlWmHDN2PvaDyvH5szu2020JEA9E4 lXKI2AZ9GqVWg== Date: Wed, 9 Mar 2022 13:51:13 -0700 From: Nathan Chancellor To: Kees Cook Cc: Thomas Bogendoerfer , Marc Zyngier , Guenter Roeck , Yanteng Si , linux-mips@vger.kernel.org, Nick Desaulniers , Mark Rutland , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org Subject: Re: [PATCH] MIPS: Only use current_stack_pointer on GCC Message-ID: References: <20220309204537.390428-1-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220309204537.390428-1-keescook@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Nit: I think the subject needs to be updated (I assume this was written before Nick's fix?). On Wed, Mar 09, 2022 at 12:45:37PM -0800, Kees Cook wrote: > Unfortunately, Clang did not have support for "sp" as a global register > definition, and was crashing after the addition of current_stack_pointer. > This has been fixed in Clang 15, but earlier Clang versions need to > avoid this code, so add a versioned test and revert back to the > open-coded asm instances. Fixes Clang build error: > > fatal error: error in backend: Invalid register name global variable > > Fixes: 200ed341b864 ("mips: Implement "current_stack_pointer"") > Reported-by: Nathan Chancellor > Cc: Thomas Bogendoerfer > Cc: Marc Zyngier > Cc: Guenter Roeck > Cc: Yanteng Si > Cc: linux-mips@vger.kernel.org > Signed-off-by: Kees Cook Thanks for sending this! Reviewed-by: Nathan Chancellor > --- > arch/mips/Kconfig | 2 +- > arch/mips/include/asm/thread_info.h | 2 ++ > arch/mips/kernel/irq.c | 3 ++- > arch/mips/lib/uncached.c | 4 +++- > 4 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index 3f58b45fc953..15769013f46e 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -4,7 +4,7 @@ config MIPS > default y > select ARCH_32BIT_OFF_T if !64BIT > select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT > - select ARCH_HAS_CURRENT_STACK_POINTER > + select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 150000 Nit: This can be 140000, as release/14.x has received the fix: https://github.com/llvm/llvm-project/commit/0826716786cd4a8c7cbcb8c01e4d9fac46b7a17a > select ARCH_HAS_DEBUG_VIRTUAL if !64BIT > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_KCOV > diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h > index 4463348d2372..ecae7470faa4 100644 > --- a/arch/mips/include/asm/thread_info.h > +++ b/arch/mips/include/asm/thread_info.h > @@ -69,7 +69,9 @@ static inline struct thread_info *current_thread_info(void) > return __current_thread_info; > } > > +#ifdef CONFIG_ARCH_HAS_CURRENT_STACK_POINTER > register unsigned long current_stack_pointer __asm__("sp"); > +#endif > > #endif /* !__ASSEMBLY__ */ > > diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c > index fc313c49a417..5e11582fe308 100644 > --- a/arch/mips/kernel/irq.c > +++ b/arch/mips/kernel/irq.c > @@ -75,8 +75,9 @@ void __init init_IRQ(void) > #ifdef CONFIG_DEBUG_STACKOVERFLOW > static inline void check_stack_overflow(void) > { > - unsigned long sp = current_stack_pointer; > + unsigned long sp; > > + __asm__ __volatile__("move %0, $sp" : "=r" (sp)); > sp &= THREAD_MASK; > > /* > diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c > index f8d4ca046c3e..f80a67c092b6 100644 > --- a/arch/mips/lib/uncached.c > +++ b/arch/mips/lib/uncached.c > @@ -40,7 +40,9 @@ unsigned long run_uncached(void *func) > register long ret __asm__("$2"); > long lfunc = (long)func, ufunc; > long usp; > - long sp = current_stack_pointer; > + long sp; > + > + __asm__("move %0, $sp" : "=r" (sp)); > > if (sp >= (long)CKSEG0 && sp < (long)CKSEG2) > usp = CKSEG1ADDR(sp); > -- > 2.32.0 >