From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1524077609; cv=none; d=google.com; s=arc-20160816; b=0fbvA/tV4dNHUaH/Wls2VWEfs47Sw7FTQ+EZ5s70tlAswnRethONbF7Usky+oY16Sj C+mhFSlhKfMgnLJ56zCzyKdsQXhhJVYYcw3LS/kO7uecZYzGsE+ISUCQKDwX0JLi6U0r yQMpF9tzK5Ek7FUmnE3BGGhXlyK9sHUDrFSJ8jaB8OYsLasa1PGf2VR11L+3j3uk46Oa JpnisjmXErIISB367IygU1yBu8zebT7JNDEQM72RbEKe41aVI1YtUXpb3xfGniYYyoR4 SUd0gd5MQC58k9kr3mNRYGhDecECN9xtCWz0I5F5T/NHth+nQGSc2Ru2P6lo0sfhCIef nIgA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=EZGWuFfiHqjCbpQnzR64TWy+WxEaujGKaSajXvCUFAc=; b=f+cyOtB3SKktAuGKL87rbvTTmmO036a7x5o95GOY4p5pBmigezus40TLCWv8Ptnv7b asvrESvbApt4hu1hVSnjTVlm7w8eT+e2oruehreDh5sVnLWFl1snwmk/sCZ/BG0WS+4f MEsoyyCtUI64sZhMqgzy/76ixBDF4HZZoEyf6J2aibWhsTY2qPq9kMo+vUrhQUYiIH95 aHxwAoG3PSKbMZsUzXPPW0biO+eXKhwa4auhSPkWQBYgecA6Ez/Jq0W6Xd71DCpGUSMu UELvjA4qLImUMS9LF0Ide5idlOx0JSmO9WnmzVsro317v164Sx0/f3g2HHWI8wSu9s8J 1ITQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=XoOfHGDK; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=XoOfHGDK; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com X-Google-Smtp-Source: AIpwx4+jqENAWip/MUW3PGvlX0PAg25j/IaqTVI58MpVYsnVtxnKfu+qYLlIBk/+1UQ8zcYiy7iy7A== From: Andrey Konovalov To: Catalin Marinas , Will Deacon , Jonathan Corbet , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , James Morse , Kees Cook , Bart Van Assche , Kate Stewart , Greg Kroah-Hartman , Thomas Gleixner , Philippe Ombredanne , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Dan Williams , "Aneesh Kumar K . V" , Zi Yan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan Subject: [PATCH 6/6] arm64: update Documentation/arm64/tagged-pointers.txt Date: Wed, 18 Apr 2018 20:53:15 +0200 Message-Id: <0fdb6332cc5bf333f80212d0b17edadd2bdc9fcf.1524077494.git.andreyknvl@google.com> X-Mailer: git-send-email 2.17.0.484.g0c8726318c-goog In-Reply-To: References: In-Reply-To: References: X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1598111203386194872?= X-GMAIL-MSGID: =?utf-8?q?1598111203386194872?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Add a note that work on passing tagged user pointers to the kernel via syscalls has started, but might not be complete yet. Signed-off-by: Andrey Konovalov --- Documentation/arm64/tagged-pointers.txt | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Documentation/arm64/tagged-pointers.txt b/Documentation/arm64/tagged-pointers.txt index a25a99e82bb1..361481283f00 100644 --- a/Documentation/arm64/tagged-pointers.txt +++ b/Documentation/arm64/tagged-pointers.txt @@ -35,8 +35,9 @@ Using non-zero address tags in any of these locations may result in an error code being returned, a (fatal) signal being raised, or other modes of failure. -For these reasons, passing non-zero address tags to the kernel via -system calls is forbidden, and using a non-zero address tag for sp is +Some initial work for supporting non-zero address tags passed to the +kernel via system calls has been done, but the kernel doesn't provide +any guarantees at this point. Using a non-zero address tag for sp is strongly discouraged. Programs maintaining a frame pointer and frame records that use non-zero -- 2.17.0.484.g0c8726318c-goog