From mboxrd@z Thu Jan 1 00:00:00 1970 From: yang.shi@linaro.org (Shi, Yang) Date: Thu, 12 Nov 2015 11:33:15 -0800 Subject: [PATCH 1/2] arm64: bpf: add 'store immediate' instruction In-Reply-To: <20151111123955.GK9562@arm.com> References: <1447195301-16757-1-git-send-email-yang.shi@linaro.org> <1447195301-16757-2-git-send-email-yang.shi@linaro.org> <20151111121256.GI9562@arm.com> <20151111123955.GK9562@arm.com> Message-ID: <5644E97B.6050203@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/11/2015 4:39 AM, Will Deacon wrote: > On Wed, Nov 11, 2015 at 12:12:56PM +0000, Will Deacon wrote: >> On Tue, Nov 10, 2015 at 06:45:39PM -0800, Z Lim wrote: >>> On Tue, Nov 10, 2015 at 2:41 PM, Yang Shi wrote: >>>> aarch64 doesn't have native store immediate instruction, such operation >>> >>> Actually, aarch64 does have "STR (immediate)". For arm64 JIT, we can >>> consider using it as an optimization. >> >> Yes, I'd definitely like to see that in preference to moving via a >> temporary register. > > Wait a second, we're both talking rubbish here :) The STR (immediate) > form is referring to the addressing mode, whereas this patch wants to > store an immediate value to memory, which does need moving to a register > first. Yes, the immediate means immediate offset for addressing index. Doesn't mean to store immediate to memory. I don't think any load-store architecture has store immediate instruction. Thanks, Yang > > So the original patch is fine. > > Will >