From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1525356959; cv=none; d=google.com; s=arc-20160816; b=UKaCftdvxfqWmC7ac7fGHuz4CMRvM0nrFE7v8WUb/oiVAzCyRg6UD9WYEMf4WMNrnd JJs1IYmPh6uD2wfRl459gNsKxUnnHGbGrc4fMI/SVrD0D58gWKGEQ2p0rwOcyptp/mNS ilWwLJNYXlaAEat+QLc32i48KqzYgFaO6tAEXxvDCq3fXadf4nAdT6zjMR3OG34GdJHF zo6a8WkVdIhINAHqSPOZeDpKpBp6Tp7CtUlDbA6poPngGTVwpI3FupyFNFqP7uypYTtE 3et0ZNFcQnTERvkh3FmlVGNiE1xtFTrCj8MFUnnhY+LCU59d0AKo8HPWoDdkosp3gztd qbmQ== 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=UK5wc6DlUcroqlO7Swx8mX58fL3XtYOgQeE0FdL7+yM=; b=bdwP28d0gAai1XPCmA2oBWC4kwiIO7saP+eBeIfAG91sr+LpnRiWsYGHctZ5vmWSny s0ogjCYiDNuj+KfdH4lLXCt5L/ywQd3u77ZOQbtiQNjjqRWvnVILlmKmkm4wrO/hFWsd fVXvi70KpBzxJk0ivJ6Vunom4DmvH9JMgzYgpjx2kZE8+76aT0QMK5xj0CtAdwAtFBgl 6x+1LGbVpe1p3zCNVT5M/mOAMrIX4YZSU/2usTbgR9dPl6VH2XeI9blFWG9Go5+8oCVO /MFTonHvFz2QfcAt5sRpyjVwBhHGM60AMhxg+bj+QqyQO6uIkvsvKEb3QWkmKo4HNVrX YIfA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=SCYKEXLS; 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=SCYKEXLS; 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: AB8JxZp3MQmZZ6oNm3X5fe1bQ1T4o6Ql+t77Nx3UuR1G4D5mj7PNDW0sv4E6Oua5EgFMYH61+7XlKQ== 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 , Chintan Pandya Subject: [PATCH v2 6/6] arm64: update Documentation/arm64/tagged-pointers.txt Date: Thu, 3 May 2018 16:15:44 +0200 Message-Id: <1a708210a8056aa356407e72973e00970523e7e2.1525356769.git.andreyknvl@google.com> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog In-Reply-To: References: In-Reply-To: References: X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599452699569642930?= X-GMAIL-MSGID: =?utf-8?q?1599452699569642930?= 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 -- 2.17.0.441.gb46fe60e1d-goog