From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [RFC PATCH 3/5] selftest/x86: Fix sigreturn_64 test. Date: Thu, 21 May 2020 14:17:18 -0700 Message-ID: <20200521211720.20236-4-yu-cheng.yu@intel.com> References: <20200521211720.20236-1-yu-cheng.yu@intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200521211720.20236-1-yu-cheng.yu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.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 Cc: Yu-cheng Yu List-Id: linux-arch.vger.kernel.org When shadow stack is enabled, selftests/x86/sigreturn_64 triggers a fault when doing sigreturn to 32-bit context but the task's shadow stack pointer is above 32-bit address range. Fix it by: - Allocate a small shadow stack below 32-bit address, - Switch to the new shadow stack, - Run tests, - Switch back to the original 64-bit shadow stack. Signed-off-by: Yu-cheng Yu --- tools/testing/selftests/x86/sigreturn.c | 28 +++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c index 57c4f67f16ef..5bcd74d416ff 100644 --- a/tools/testing/selftests/x86/sigreturn.c +++ b/tools/testing/selftests/x86/sigreturn.c @@ -45,6 +45,14 @@ #include #include #include +#include +#include +#include + +#ifdef __x86_64__ +int arch_prctl(int code, unsigned long *addr); +#define ARCH_CET_ALLOC_SHSTK 0x3004 +#endif /* Pull in AR_xyz defines. */ typedef unsigned int u32; @@ -766,6 +774,20 @@ int main() int total_nerrs = 0; unsigned short my_cs, my_ss; +#ifdef __x86_64__ + /* Alloc a shadow stack within 32-bit address range */ + unsigned long arg, ssp_64, ssp_32; + ssp_64 = _get_ssp(); + + if (ssp_64 != 0) { + arg = 0x1001; + arch_prctl(ARCH_CET_ALLOC_SHSTK, &arg); + ssp_32 = arg + 0x1000 - 8; + asm volatile("RSTORSSP (%0)\n":: "r" (ssp_32)); + asm volatile("SAVEPREVSSP"); + } +#endif + asm volatile ("mov %%cs,%0" : "=r" (my_cs)); asm volatile ("mov %%ss,%0" : "=r" (my_ss)); setup_ldt(); @@ -870,6 +892,12 @@ int main() #ifdef __x86_64__ total_nerrs += test_nonstrict_ss(); + + if (ssp_64 != 0) { + ssp_64 -= 8; + asm volatile("RSTORSSP (%0)\n":: "r" (ssp_64)); + asm volatile("SAVEPREVSSP"); + } #endif return total_nerrs ? 1 : 0; -- 2.21.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com ([134.134.136.20]:63542 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730662AbgEUVRk (ORCPT ); Thu, 21 May 2020 17:17:40 -0400 From: Yu-cheng Yu Subject: [RFC PATCH 3/5] selftest/x86: Fix sigreturn_64 test. Date: Thu, 21 May 2020 14:17:18 -0700 Message-ID: <20200521211720.20236-4-yu-cheng.yu@intel.com> In-Reply-To: <20200521211720.20236-1-yu-cheng.yu@intel.com> References: <20200521211720.20236-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: 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 , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang Cc: Yu-cheng Yu Message-ID: <20200521211718.GBDakspQRB2UYTF1EIYMZVJ4wH-rfp7NqbHozF_mgHY@z> When shadow stack is enabled, selftests/x86/sigreturn_64 triggers a fault when doing sigreturn to 32-bit context but the task's shadow stack pointer is above 32-bit address range. Fix it by: - Allocate a small shadow stack below 32-bit address, - Switch to the new shadow stack, - Run tests, - Switch back to the original 64-bit shadow stack. Signed-off-by: Yu-cheng Yu --- tools/testing/selftests/x86/sigreturn.c | 28 +++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c index 57c4f67f16ef..5bcd74d416ff 100644 --- a/tools/testing/selftests/x86/sigreturn.c +++ b/tools/testing/selftests/x86/sigreturn.c @@ -45,6 +45,14 @@ #include #include #include +#include +#include +#include + +#ifdef __x86_64__ +int arch_prctl(int code, unsigned long *addr); +#define ARCH_CET_ALLOC_SHSTK 0x3004 +#endif /* Pull in AR_xyz defines. */ typedef unsigned int u32; @@ -766,6 +774,20 @@ int main() int total_nerrs = 0; unsigned short my_cs, my_ss; +#ifdef __x86_64__ + /* Alloc a shadow stack within 32-bit address range */ + unsigned long arg, ssp_64, ssp_32; + ssp_64 = _get_ssp(); + + if (ssp_64 != 0) { + arg = 0x1001; + arch_prctl(ARCH_CET_ALLOC_SHSTK, &arg); + ssp_32 = arg + 0x1000 - 8; + asm volatile("RSTORSSP (%0)\n":: "r" (ssp_32)); + asm volatile("SAVEPREVSSP"); + } +#endif + asm volatile ("mov %%cs,%0" : "=r" (my_cs)); asm volatile ("mov %%ss,%0" : "=r" (my_ss)); setup_ldt(); @@ -870,6 +892,12 @@ int main() #ifdef __x86_64__ total_nerrs += test_nonstrict_ss(); + + if (ssp_64 != 0) { + ssp_64 -= 8; + asm volatile("RSTORSSP (%0)\n":: "r" (ssp_64)); + asm volatile("SAVEPREVSSP"); + } #endif return total_nerrs ? 1 : 0; -- 2.21.0