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Lu" Date: Fri, 17 Jun 2022 07:22:57 -0700 Message-ID: Subject: Re: [PATCHv3 5/8] x86/uaccess: Provide untagged_addr() and remove tags before address check To: Peter Zijlstra Cc: "Kirill A. Shutemov" , "Edgecombe, Rick P" , "Lutomirski, Andy" , "dave.hansen@linux.intel.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "kcc@google.com" , "andreyknvl@gmail.com" , "ak@linux.intel.com" , "dvyukov@google.com" , "x86@kernel.org" , "ryabinin.a.a@gmail.com" , "glider@google.com" Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655475814; a=rsa-sha256; cv=none; b=NOuRRRglhdcoFwqS8j47Y/xeox4ZI7MXq3ksl7nFt5UE28DCGsRDSFQNcF6grccT74rpg8 ovU5qd9s48/QZYX0H9Vxa43L+2JvK0a1xcCV3eYVomhQYKe0EU27HJgswnV8smWtJmH5zL kd9ne5+tvuYcUV5z1tcckcMguCVDojg= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=PDlfWJH2; spf=pass (imf17.hostedemail.com: domain of hjl.tools@gmail.com designates 209.85.210.172 as permitted sender) smtp.mailfrom=hjl.tools@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655475814; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=s48+XZroV3EtTjiSKpn6ew2kCrik7JfCW2Vjzd0vaYU=; b=fa+h5HcjM/uK0rkJnv7KRnqsQNnH6GnOphGxzP9iJ3HQubK+GaSCItE8EeyVhnWLU70lsY 2lVW2jajnyvbtN9JjT28X0k2YuONLeCS8rohkGvsMeR7RM9DPB2+S+Ug1jBfvklp79eREs gaI0PPDWByVXiEkUyuIB1YseDZ2sMPM= X-Stat-Signature: 8f9kzw7g7sam13zwyhf7sg3woxjwtf9c X-Rspamd-Queue-Id: 13B504009A Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=PDlfWJH2; spf=pass (imf17.hostedemail.com: domain of hjl.tools@gmail.com designates 209.85.210.172 as permitted sender) smtp.mailfrom=hjl.tools@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1655475813-375862 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jun 17, 2022 at 4:36 AM Peter Zijlstra wrote: > > On Thu, Jun 16, 2022 at 07:44:40PM +0300, Kirill A. Shutemov wrote: > > Any objection against this variant (was posted in the thread): > > > > #define untagged_addr(mm, addr) ({ \ > > u64 __addr = (__force u64)(addr); \ > > s64 sign = (s64)__addr >> 63; \ > > __addr &= (mm)->context.untag_mask | sign; \ > > (__force __typeof__(addr))__addr; \ > > }) > > > > ? > > Yeah, I suppose that should work fine. Won't the sign bit be put at the wrong place? -- H.J.