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Mon, 19 Jul 2021 06:51:09 -0700 (PDT) To: Akira Tsukamoto , Palmer Dabbelt , Geert Uytterhoeven , Qiu Wenbo , Paul Walmsley , Albert Ou , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org References: <5e1b5d90-5a1e-5e9f-7b92-6c53b8589c2a@gmail.com> From: Guenter Roeck Subject: Re: [PATCH v4 1/1] riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall Message-ID: Date: Mon, 19 Jul 2021 06:51:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <5e1b5d90-5a1e-5e9f-7b92-6c53b8589c2a@gmail.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210719_065111_693299_BB4662C6 X-CRM114-Status: GOOD ( 15.97 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org SGksCgpPbiA3LzE5LzIxIDU6NTMgQU0sIEFraXJhIFRzdWthbW90byB3cm90ZToKPiAKPiBUaGlz IHBhdGNoIHdpbGwgcmVkdWNlIGNwdSB1c2FnZSBkcmFtYXRpY2FsbHkgaW4ga2VybmVsIHNwYWNl IGVzcGVjaWFsbHkKPiBmb3IgYXBwbGljYXRpb24gd2hpY2ggdXNlIHN5cy1jYWxsIHdpdGggbGFy Z2UgYnVmZmVyIHNpemUsIHN1Y2ggYXMKPiBuZXR3b3JrIGFwcGxpY2F0aW9ucy4gVGhlIG1haW4g cmVhc29uIGJlaGluZCB0aGlzIGlzIHRoYXQgZXZlcnkKPiB1bmFsaWduZWQgbWVtb3J5IGFjY2Vz cyB3aWxsIHJhaXNlIGV4Y2VwdGlvbnMgYW5kIHN3aXRjaCBiZXR3ZWVuIHMtbW9kZQo+IGFuZCBt LW1vZGUgY2F1c2luZyBsYXJnZSBvdmVyaGVhZC4KPiAKCkkgaGFkIHRvIHJldmVydCB0aGUgb3Jp Z2luYWwgcGF0Y2ggZnJvbSB0aGUgbWFpbmxpbmUga2VybmVsIHByaW9yIHRvIGFwcGx5aW5nCnRo aXMgcGF0Y2guIE9idmlvdXNseSB0aGF0IG1lYW5zIHRoYXQgdGhlcmUgbWF5IGJlIG90aGVyIGNo YW5nZXMgYWZmZWN0aW5nIHRoZQpvdXRjb21lLgoKcmlzY3Y2NCBpbWFnZXMgd29yaywgYnV0IHJp c2N2MzIgaW1hZ2VzIHN0aWxsIGZhaWwgd2l0aCB0aGlzIHBhdGNoIGFwcGxpZWQuClRoZSBlcnJv ciBpcyBhIGJpdCBkaWZmZXJlbnQgdGhhbiBiZWZvcmUsIHRob3VnaC4KCi4uLgpbICAgMTEuODk5 OTc5XSBSdW4gL3NiaW4vaW5pdCBhcyBpbml0IHByb2Nlc3MKWyAgIDEyLjE1MjY2Nl0gcmFuZG9t OiBmYXN0IGluaXQgZG9uZQptb3VuOiBhcHBsZXQgbm90IGZvdW5kCiLvv73vv73vv73vv73vv71W 77+9dDogYXBwbGV0IG5vdCBmb3VuZAovYmnvv73vv73vv73vv73vv71W77+9Ri06IGFwcGxldCBu b3QgZm91bmQKbW91bjogYXBwbGV0IG5vdCBmb3VuZApzd2FvbjogYXBwbGV0IG5vdCBmb3VuZApo b3N0bmFtZS1GOiBhcHBsZXQgbm90IGZvdW5kCgpBZnRlciB0aGlzLCB0aGUgaW1hZ2UgaGFuZ3Mu CgpGb3IgY29tcGFyaXNvbiwgdGhlIG1haW5saW5lIGtlcm5lbCAodjUuMTQtcmMyKSBmYWlscyBh cyBmb2xsb3dzLgoKWyAgIDEwLjc4ODEwNV0gUnVuIC9zYmluL2luaXQgYXMgaW5pdCBwcm9jZXNz ClN0YXJ0aW5nIHN5c2xvZ2Q6IE9LClN0YXJ0aW5nIGtsb2dkOiBPSwovZXRjL2luaXQuZC9TMDJz eXNjdGw6IGxpbmUgNjg6IHN5bnRheCBlcnJvcjogRU9GIGluIGJhY2txdW90ZSBzdWJzdGl0dXRp b24KL2V0Yy9pbml0LmQvUzIwdXJhbmRvbTogbGluZSAxOiBzeW50YXggZXJyb3I6IHVudGVybWlu YXRlZCBxdW90ZWQgc3RyaW5nClN0YXJ0aW5nIG5ldHdvcms6IC9iaW4vc2g6IHN5bnRheCBlcnJv cjogdW50ZXJtaW5hdGVkIHF1b3RlZCBzdHJpbmcKc2VkOiB1bm1hdGNoZWQgJy8nCi9iaW4vc2g6 IHN5bnRheCBlcnJvcjogdW50ZXJtaW5hdGVkIHF1b3RlZCBzdHJpbmcKRkFJTAovZXRjL2luaXQu ZC9TNTVydW50ZXN0OiBsaW5lIDQ4OiBzeW50YXggZXJyb3I6IEVPRiBpbiBiYWNrcXVvdGUgc3Vi c3RpdHV0aW9uCgpJJ2xsIGJlIGhhcHB5IHRvIHByb3ZpZGUgaW5mb3JtYXRpb24gb24gaG93IHRv IHJlcHJvZHVjZSB0aGUgcHJvYmxlbQppZiBuZWVkZWQuIFBsZWFzZSBsZXQgbWUga25vdy4KClRo YW5rcywKR3VlbnRlcgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KbGludXgtcmlzY3YgbWFpbGluZyBsaXN0CmxpbnV4LXJpc2N2QGxpc3RzLmluZnJhZGVh ZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51eC1y aXNjdgo=