From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: [PATCH v3 11/12] arm64: BTI: Reset BTYPE when skipping emulated instructions Date: Fri, 18 Oct 2019 18:25:44 +0100 Message-ID: <1571419545-20401-12-git-send-email-Dave.Martin@arm.com> References: <1571419545-20401-1-git-send-email-Dave.Martin@arm.com> Return-path: In-Reply-To: <1571419545-20401-1-git-send-email-Dave.Martin@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Andrew Jones , Arnd Bergmann , Catalin Marinas , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Kees Cook , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Marc Zyngier , Mark Brown , Paul Elliott , Peter Zijlstra , Richard Henderson , Sudakshina Das , Szabolcs Nagy , Thomas Gleixner , Will Deacon , Yu-cheng Yu , Amit Kachhap , V List-Id: linux-arch.vger.kernel.org Since normal execution of any non-branch instruction resets the PSTATE BTYPE field to 0, so do the same thing when emulating a trapped instruction. Branches don't trap directly, so we should never need to assign a non-zero value to BTYPE here. Signed-off-by: Dave Martin --- Changes since v2: * Drop (u64) case when masking out PSR_BTYPE_MASK in arm64_skip_faulting_instruction(). PSTATE may grow, but we should address this more generally rather than with point hacks in this series. --- arch/arm64/kernel/traps.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 3af2768..5c46a7b 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -331,6 +331,8 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) if (regs->pstate & PSR_MODE32_BIT) advance_itstate(regs); + else + regs->pstate &= ~PSR_BTYPE_MASK; } static LIST_HEAD(undef_hook); -- 2.1.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from [217.140.110.172] ([217.140.110.172]:47188 "EHLO foss.arm.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S2505494AbfJRR1c (ORCPT ); Fri, 18 Oct 2019 13:27:32 -0400 From: Dave Martin Subject: [PATCH v3 11/12] arm64: BTI: Reset BTYPE when skipping emulated instructions Date: Fri, 18 Oct 2019 18:25:44 +0100 Message-ID: <1571419545-20401-12-git-send-email-Dave.Martin@arm.com> In-Reply-To: <1571419545-20401-1-git-send-email-Dave.Martin@arm.com> References: <1571419545-20401-1-git-send-email-Dave.Martin@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: Andrew Jones , Arnd Bergmann , Catalin Marinas , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Kees Cook , =?UTF-8?q?Kristina=20Mart=C5=A1enko?= , Marc Zyngier , Mark Brown , Paul Elliott , Peter Zijlstra , Richard Henderson , Sudakshina Das , Szabolcs Nagy , Thomas Gleixner , Will Deacon , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org Message-ID: <20191018172544.1niO2ETIOXlzTjALE0-cHXCa7JSRQhRSONoRt3-EKx4@z> Since normal execution of any non-branch instruction resets the PSTATE BTYPE field to 0, so do the same thing when emulating a trapped instruction. Branches don't trap directly, so we should never need to assign a non-zero value to BTYPE here. Signed-off-by: Dave Martin --- Changes since v2: * Drop (u64) case when masking out PSR_BTYPE_MASK in arm64_skip_faulting_instruction(). PSTATE may grow, but we should address this more generally rather than with point hacks in this series. --- arch/arm64/kernel/traps.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 3af2768..5c46a7b 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -331,6 +331,8 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) if (regs->pstate & PSR_MODE32_BIT) advance_itstate(regs); + else + regs->pstate &= ~PSR_BTYPE_MASK; } static LIST_HEAD(undef_hook); -- 2.1.4