From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Tue, 10 Oct 2017 19:38:34 +0100 Subject: [PATCH v3 17/28] arm64/sve: Preserve SVE registers around kernel-mode NEON use In-Reply-To: <1507660725-7986-1-git-send-email-Dave.Martin@arm.com> References: <1507660725-7986-1-git-send-email-Dave.Martin@arm.com> Message-ID: <1507660725-7986-18-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.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 Benn?e --- 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 5673f50..b1d383a 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -909,8 +909,10 @@ 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