From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: Re: [RFC PATCH 5/5] selftest/x86: Add CET quick test Date: Fri, 22 May 2020 08:10:14 -0700 Message-ID: References: <20200521211720.20236-1-yu-cheng.yu@intel.com> <20200521211720.20236-6-yu-cheng.yu@intel.com> <20200522092848.GJ325280@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga12.intel.com ([192.55.52.136]:38059 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729931AbgEVPKK (ORCPT ); Fri, 22 May 2020 11:10:10 -0400 In-Reply-To: <20200522092848.GJ325280@hirez.programming.kicks-ass.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit On Fri, 2020-05-22 at 11:28 +0200, Peter Zijlstra wrote: > On Thu, May 21, 2020 at 02:17:20PM -0700, Yu-cheng Yu wrote: > > > +#pragma GCC push_options > > +#pragma GCC optimize ("O0") > > +void ibt_violation(void) > > +{ > > +#ifdef __i386__ > > + asm volatile("lea 1f, %eax"); > > + asm volatile("jmp *%eax"); > > +#else > > + asm volatile("lea 1f, %rax"); > > + asm volatile("jmp *%rax"); > > +#endif > > + asm volatile("1:"); > > + result[test_id] = -1; > > + test_id++; > > + setcontext(&ucp); > > +} > > + > > +void shstk_violation(void) > > +{ > > +#ifdef __i386__ > > + unsigned long x = 0; > > + > > + ((unsigned long *)&x)[2] = (unsigned long)stack_hacked; > > +#else > > + unsigned long long x = 0; > > + > > + ((unsigned long long *)&x)[2] = (unsigned long)stack_hacked; > > +#endif > > +} > > +#pragma GCC pop_options > > This is absolutely atrocious. > > The #pragma like Kees already said just need to go. Also, there's > absolutely no clue what so ever what it attempts to achieve. > > The __i386__ ifdeffery is horrible crap. Splitting an asm with #ifdef > like that is also horrible crap. > > This is not how you write code. > > Get asm/asm.h into userspace and then write something like: > > > void ibt_violation(void) > { > asm volatile("lea 1f, %" _ASM_AX "\n\t" > "jmp *%" _ASM_AX "\n\t" > "1:\n\t" ::: "a"); > > WRITE_ONCE(result[test_id], -1); > WRITE_ONCE(test_id, test_id+1); > > setcontext(&ucp); > } > > void shstk_violation(void) > { > unsigned long x = 0; > > WRITE_ONCE(x[2], stack_hacked); > } Thanks! I will change it. Yu-cheng From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga12.intel.com ([192.55.52.136]:38059 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729931AbgEVPKK (ORCPT ); Fri, 22 May 2020 11:10:10 -0400 Message-ID: Subject: Re: [RFC PATCH 5/5] selftest/x86: Add CET quick test From: Yu-cheng Yu Date: Fri, 22 May 2020 08:10:14 -0700 In-Reply-To: <20200522092848.GJ325280@hirez.programming.kicks-ass.net> References: <20200521211720.20236-1-yu-cheng.yu@intel.com> <20200521211720.20236-6-yu-cheng.yu@intel.com> <20200522092848.GJ325280@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang Message-ID: <20200522151014.Ui1JMAzlx5dMK2bNPIOpVEBJK3w5rlRD-imYpWSm3E8@z> On Fri, 2020-05-22 at 11:28 +0200, Peter Zijlstra wrote: > On Thu, May 21, 2020 at 02:17:20PM -0700, Yu-cheng Yu wrote: > > > +#pragma GCC push_options > > +#pragma GCC optimize ("O0") > > +void ibt_violation(void) > > +{ > > +#ifdef __i386__ > > + asm volatile("lea 1f, %eax"); > > + asm volatile("jmp *%eax"); > > +#else > > + asm volatile("lea 1f, %rax"); > > + asm volatile("jmp *%rax"); > > +#endif > > + asm volatile("1:"); > > + result[test_id] = -1; > > + test_id++; > > + setcontext(&ucp); > > +} > > + > > +void shstk_violation(void) > > +{ > > +#ifdef __i386__ > > + unsigned long x = 0; > > + > > + ((unsigned long *)&x)[2] = (unsigned long)stack_hacked; > > +#else > > + unsigned long long x = 0; > > + > > + ((unsigned long long *)&x)[2] = (unsigned long)stack_hacked; > > +#endif > > +} > > +#pragma GCC pop_options > > This is absolutely atrocious. > > The #pragma like Kees already said just need to go. Also, there's > absolutely no clue what so ever what it attempts to achieve. > > The __i386__ ifdeffery is horrible crap. Splitting an asm with #ifdef > like that is also horrible crap. > > This is not how you write code. > > Get asm/asm.h into userspace and then write something like: > > > void ibt_violation(void) > { > asm volatile("lea 1f, %" _ASM_AX "\n\t" > "jmp *%" _ASM_AX "\n\t" > "1:\n\t" ::: "a"); > > WRITE_ONCE(result[test_id], -1); > WRITE_ONCE(test_id, test_id+1); > > setcontext(&ucp); > } > > void shstk_violation(void) > { > unsigned long x = 0; > > WRITE_ONCE(x[2], stack_hacked); > } Thanks! I will change it. Yu-cheng