From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 41908155725; Tue, 9 Jul 2024 10:04:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720519448; cv=none; b=djcUnJFeTNFp/yo5mVFywwNVTm5OTOJ9G7HkHx9w3L5z9bTmW5aFyZd8BEJCKpVH7A8zg8DhpD6Xh0chLXS7x6h1yt+qBFeAlAtuHOOOePercsb2DXQaWQJE262Hp90eDHQ+5A2sXE8iXM+itApIAyLScN+U3cvnBDvbLRptG5k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720519448; c=relaxed/simple; bh=UG06XE/wrNje1GxMLozW0TRTmIefwRDVuD1S9dkvSOE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eL08WRT0taaONlTRUNsxthLBYGCsrq2uSjp2BkCOrMlq9GbSLUMtlQPp/OCTi2yoCEfC0rmL0gXpJEiwI1kCS+OZMhU9KY8tfAKI0JK7wN+URV7p7L6vbuVcdXbwqvl/iUT2VFt4UWy1U9CZDmweaVBfgqDOZYCEQYIFuooZ6LY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A1B1412FC; Tue, 9 Jul 2024 03:04:30 -0700 (PDT) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D76AD3F762; Tue, 9 Jul 2024 03:04:03 -0700 (PDT) Date: Tue, 9 Jul 2024 11:04:00 +0100 From: Mark Rutland To: Linus Torvalds Cc: Christian Brauner , Al Viro , linux-fsdevel , the arch/x86 maintainers , Linux ARM , Linux Kernel Mailing List Subject: Re: FYI: path walking optimizations pending for 6.11 Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Linus, On Wed, Jun 19, 2024 at 01:25:02PM -0700, Linus Torvalds wrote: > I've pushed out four branches based on 6.10-rc4, because I think it's > pretty ready. But I'll rebase them if people have commentary that > needs addressing, so don't treat them as some kind of stable base yet. > My plan is to merge them during the next merge window unless somebody > screams. > > The branches are: > > arm64-uaccess: > arm64: access_ok() optimization > arm64: start using 'asm goto' for put_user() > arm64: start using 'asm goto' for get_user() when available > runtime-constants: > arm64: add 'runtime constant' support > runtime constants: add x86 architecture support > runtime constants: add default dummy infrastructure > vfs: dcache: move hashlen_hash() from callers into d_hash() Apologies, the arm64 branches/patches have been on my TODO list for review/test/benchmark for the last couple of weeks, but I haven't had both the time and machine availability to do so. Looking at the arm64 runtime constants patch, I see there's a redundant store in __runtime_fixup_16(), which I think is just a leftover from applying the last roudn or feedback: +/* 16-bit immediate for wide move (movz and movk) in bits 5..20 */ +static inline void __runtime_fixup_16(__le32 *p, unsigned int val) +{ + u32 insn = le32_to_cpu(*p); + insn &= 0xffe0001f; + insn |= (val & 0xffff) << 5; + *p = insn; + *p = cpu_to_le32(insn); +} ... i.e. the first assignment to '*p' should go; the compiler should be smart enough to elide it entirely, but it shouldn't be there. For the sake of review, would you be happy to post the uaccess and runtime-constants patches to the list again? I think there might be some remaining issues with (real) PAN and we might need to do a bit more preparatory work there. Mark.