From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Mon, 1 Sep 2014 10:34:28 +0100 Subject: [PATCH v2] arm64: fix bug for reloading FPSIMD state after cpu power off In-Reply-To: <1409540991-7573-1-git-send-email-leoy@marvell.com> References: <1409540991-7573-1-git-send-email-leoy@marvell.com> Message-ID: <20140901093427.GC608@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Sep 01, 2014 at 04:09:51AM +0100, Leo Yan wrote: > Now arm64 defers reloading FPSIMD state, but this optimization also > introduces the bug after cpu resume back from low power mode. > > The reason is after the cpu has been powered off, s/w need set the > cpu's fpsimd_last_state to NULL so that it will force to reload > FPSIMD state for the thread, otherwise there has the chance to meet > the condition for both the task's fpsimd_state.cpu field contains the > id of the current cpu, and the cpu's fpsimd_last_state per-cpu variable > points to the task's fpsimd_state, so finally kernel will skip to reload > the context during it return back to userland. > > Signed-off-by: Leo Yan Reviewed-by: Catalin Marinas (and cc'ing Will to pick it up since he's handling the 3.17 release) Thanks.