From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522169877; cv=none; d=google.com; s=arc-20160816; b=IoZpU2svHUvil6pRXiTc0nPI8jPMahp6VcJlzG/Ykf5/9NrISCXty7Dwf7vqYKM/8O ROBwQdW+g8ZGWWatPc8Sqf0a+ZWpyz3PwDUi2shxzwcPQIw6ckZLJX3PXIs4GSdjlTGe WxLV8oWEVV3U1B34xDAWrtstZ6dkMkJsE0lR/6aYpr2WBjRftVqwSGC7OM7GMLuALT3w Ax9TANBIBCaJnLycEdI489CqE2/MtokU3ywfyptUbG7gSvEHV0jCDzJBrmm+pOBhbxnV EXcMNqqddi5kwDgW0poWWf+K+ELnY6m7e4fZZamtAjBObbVI+mTNq4F4cmmiR7M3+aGj 4Kcw== 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=TrPsSA82+Wc4vKs2A+va2uJYYyXutDQZXj+lR7R4i7Y=; b=SLnQuJaiOaO0Kb/FOt+Fko9auh+jhgxEH4OuSfyj6gLQHpdO8iWGTSPygXHrq5dBat HsZrvu+uaurqd3ZMi8UyCga5NVcKQa1uDF+PWbUnPDehUWomvHSe1WKxOenQc6NDdGWk +/2EuFOXOnsx8f4tUH6oZWcHaSsY961MqKJqGfbjTjtQPe7IRWHZ87XWk37QXJG/194y 2VjbHDCGQa+0JdL6L/+gGWzuQEVYivevlnhMsMbwCdcsh+W2UZVHLz9zp5L0UrcFbLzJ beVp51X0yl/8orwxPAhuvYzIGY9xiaNoxceupPNUCJ5dqT/TF5su3TQgasTELmp2Ho4e El1A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=hGaHk3rT; 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=hGaHk3rT; 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: AIpwx48mmB0IcT064n10LjGGUrdOaAg2hz0T4aQdm7Lr/dGWIh29GAk/0bOK3XWMNVpO7eivSW7BnQ== 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: [RFC PATCH v2 6/6] arm64: update Documentation/arm64/tagged-pointers.txt Date: Tue, 27 Mar 2018 18:57:42 +0200 Message-Id: <080040fac18377cb6b9cd418668a10e1113b3c2a.1522169685.git.andreyknvl@google.com> X-Mailer: git-send-email 2.17.0.rc0.231.g781580f067-goog In-Reply-To: References: In-Reply-To: References: X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596110800969348216?= X-GMAIL-MSGID: =?utf-8?q?1596110800969348216?= 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.rc0.231.g781580f067-goog