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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=eLRTvF39CVqCAmddGFaUsqwSoY4prNIEuh/o+NUz9p0=; b=NZV0CMz1WumvESn1ojVcKzqLiezS53ZCX8QyPEcOrME//7MUDUilPE4noeI34bRqVg rvogNYJx1O2uLnBKfpziUtoZRddkT04vnkPNaNTMpqK8pMVCCPqbwGMjdlfpvJ9lU4jh FRYbJiQah7fl9gtGvaNyuLntn9HCDk9egRg/tixDLELwus52+jtA/kETzd1gJD5Tjb+8 t3wxnAQQWzrzAu5VKsGqqVON0WgV6wXvsyMuk35uy4OSZC/itcjZi20JukD/dJj8gflg bwdw0hxWFfMiOOhLHp1eZLJp3jAUfuBy52oWN/ZZnRPXGA/9Ipj0II53ohm8HZ9+RzKl idyA== X-Gm-Message-State: APjAAAUUZA8Yc82IOjc/cKWe3g/9Ox1uKwTfateW8mpRdms+0XrLaGEv XwJhMpKNdKvqUN+VBw6+OOdfRGaF5Nm6XSnePfIUZQ== X-Google-Smtp-Source: APXvYqzB/CyaeixcYXmheo+/rDDZ8UwTzUWhRNGhABApN6r+1HSU0y6CYCp+GyizuEe28jQkvtHrxlkE/Z+LErTCmf0= X-Received: by 2002:ab0:6387:: with SMTP id y7mr2789274uao.110.1572039622492; Fri, 25 Oct 2019 14:40:22 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191024225132.13410-1-samitolvanen@google.com> <20191024225132.13410-3-samitolvanen@google.com> <20191025094137.GB40270@lakrids.cambridge.arm.com> In-Reply-To: <20191025094137.GB40270@lakrids.cambridge.arm.com> From: Sami Tolvanen Date: Fri, 25 Oct 2019 14:40:11 -0700 Message-ID: Subject: Re: [PATCH v2 02/17] arm64/lib: copy_page: avoid x18 register in assembler code To: Mark Rutland X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191025_144024_294216_1A729223 X-CRM114-Status: GOOD ( 10.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , LKML , Steven Rostedt , Miguel Ojeda , Masami Hiramatsu , clang-built-linux , Kernel Hardening , Laura Abbott , Will Deacon , Dave Martin , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 25, 2019 at 2:41 AM Mark Rutland wrote: > > diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S > > index bbb8562396af..8b562264c165 100644 > > --- a/arch/arm64/lib/copy_page.S > > +++ b/arch/arm64/lib/copy_page.S > > @@ -34,45 +34,45 @@ alternative_else_nop_endif > > ldp x14, x15, [x1, #96] > > ldp x16, x17, [x1, #112] > > > > - mov x18, #(PAGE_SIZE - 128) > > + add x0, x0, #256 > > add x1, x1, #128 > > 1: > > - subs x18, x18, #128 > > + tst x0, #(PAGE_SIZE - 1) > > > > alternative_if ARM64_HAS_NO_HW_PREFETCH > > prfm pldl1strm, [x1, #384] > > alternative_else_nop_endif > > > > - stnp x2, x3, [x0] > > + stnp x2, x3, [x0, #-256] > > ldp x2, x3, [x1] > > - stnp x4, x5, [x0, #16] > > + stnp x4, x5, [x0, #-240] > > ldp x4, x5, [x1, #16] > > For legibility, could we make the offset and bias explicit in the STNPs > so that these line up? e.g. > > stnp x4, x5, [x0, #16 - 256] > ldp x4, x5, [x1, #16] > > ... that'd make it much easier to see by eye that this is sound, much as > I trust my mental arithmetic. ;) Sure, that makes sense. I'll change this in v3. Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel