From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: [PATCH v5 19/30] arm64/sve: Preserve SVE registers around kernel-mode NEON use Date: Tue, 31 Oct 2017 15:51:11 +0000 Message-ID: <1509465082-30427-20-git-send-email-Dave.Martin@arm.com> References: <1509465082-30427-1-git-send-email-Dave.Martin@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Received: from foss.arm.com ([217.140.101.70]:37780 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753616AbdJaPwI (ORCPT ); Tue, 31 Oct 2017 11:52:08 -0400 In-Reply-To: <1509465082-30427-1-git-send-email-Dave.Martin@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-arm-kernel@lists.infradead.org Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Szabolcs Nagy , Okamoto Takayuki , kvmarm@lists.cs.columbia.edu, libc-alpha@sourceware.org, linux-arch@vger.kernel.org Kernel-mode NEON will corrupt the SVE vector registers, due to the way they alias the FPSIMD vector registers in the hardware. This patch ensures that any live SVE register content for the task is saved by kernel_neon_begin(). The data will be restored in the usual way on return to userspace. Signed-off-by: Dave Martin Reviewed-by: Ard Biesheuvel Reviewed-by: Alex BennĂ©e Reviewed-by: Catalin Marinas --- arch/arm64/kernel/fpsimd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index c112972..ae10ddb 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -885,8 +885,10 @@ void kernel_neon_begin(void) __this_cpu_write(kernel_neon_busy, true); /* Save unsaved task fpsimd state, if any: */ - if (current->mm && !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE)) - fpsimd_save_state(¤t->thread.fpsimd_state); + if (current->mm) { + task_fpsimd_save(); + set_thread_flag(TIF_FOREIGN_FPSTATE); + } /* Invalidate any task state remaining in the fpsimd regs: */ __this_cpu_write(fpsimd_last_state, NULL); -- 2.1.4