From: Will Deacon <will.deacon@arm.com>
To: Z Lim <zlim.lnx@gmail.com>
Cc: Yang Shi <yang.shi@linaro.org>,
Alexei Starovoitov <ast@kernel.org>,
daniel@iogearbox.net, Catalin Marinas <catalin.marinas@arm.com>,
Xi Wang <xi.wang@gmail.com>, LKML <linux-kernel@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
linaro-kernel@lists.linaro.org
Subject: Re: [PATCH 1/2] arm64: bpf: add 'store immediate' instruction
Date: Wed, 11 Nov 2015 12:39:56 +0000 [thread overview]
Message-ID: <20151111123955.GK9562@arm.com> (raw)
In-Reply-To: <20151111121256.GI9562@arm.com>
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 <yang.shi@linaro.org> 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.
So the original patch is fine.
Will
next prev parent reply other threads:[~2015-11-11 12:39 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-10 22:41 [PATCH 0/2] arm64: bpf: add BPF_ST and BPF_XADD instructions support Yang Shi
2015-11-10 22:41 ` [PATCH 1/2] arm64: bpf: add 'store immediate' instruction Yang Shi
2015-11-11 2:45 ` Z Lim
2015-11-11 12:12 ` Will Deacon
2015-11-11 12:39 ` Will Deacon [this message]
2015-11-12 19:33 ` Shi, Yang
2015-11-13 3:45 ` Z Lim
2015-11-23 19:34 ` Shi, Yang
2015-11-10 22:41 ` [PATCH 2/2] arm64: bpf: add BPF XADD instruction Yang Shi
2015-11-11 0:08 ` Eric Dumazet
2015-11-11 0:26 ` Shi, Yang
2015-11-11 0:42 ` Alexei Starovoitov
2015-11-11 2:52 ` Z Lim
2015-11-11 8:49 ` Arnd Bergmann
2015-11-11 10:24 ` Will Deacon
2015-11-11 10:42 ` Daniel Borkmann
2015-11-11 11:58 ` Will Deacon
2015-11-11 12:21 ` Daniel Borkmann
2015-11-11 12:38 ` Will Deacon
2015-11-11 12:58 ` Peter Zijlstra
2015-11-11 15:52 ` Daniel Borkmann
2015-11-11 16:23 ` Will Deacon
2015-11-11 17:27 ` Alexei Starovoitov
2015-11-11 17:35 ` David Miller
2015-11-11 17:44 ` Will Deacon
2015-11-11 19:01 ` David Miller
2015-11-11 17:57 ` Peter Zijlstra
2015-11-11 18:11 ` Alexei Starovoitov
2015-11-11 18:31 ` Peter Zijlstra
2015-11-11 18:41 ` Peter Zijlstra
2015-11-11 18:44 ` Peter Zijlstra
2015-11-11 18:54 ` Peter Zijlstra
2015-11-11 19:55 ` Alexei Starovoitov
2015-11-11 22:21 ` Peter Zijlstra
2015-11-11 23:40 ` Alexei Starovoitov
2015-11-12 8:57 ` Peter Zijlstra
2015-11-11 18:50 ` Daniel Borkmann
2015-11-11 19:04 ` David Miller
2015-11-11 19:23 ` Peter Zijlstra
2015-11-11 19:41 ` Daniel Borkmann
2015-11-11 18:46 ` Will Deacon
2015-11-11 19:01 ` David Miller
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