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[217.140.101.70]) by mx.google.com with ESMTP id d56si483463eda.12.2019.03.25.06.54.57 for ; Mon, 25 Mar 2019 06:54:57 -0700 (PDT) Received-SPF: pass (google.com: domain of kevin.brodsky@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of kevin.brodsky@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3014F80D; Mon, 25 Mar 2019 06:54:56 -0700 (PDT) Received: from [10.1.199.35] (e107154-lin.cambridge.arm.com [10.1.199.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6EDE93F59C; Mon, 25 Mar 2019 06:54:48 -0700 (PDT) Subject: Re: [PATCH v13 09/20] net, arm64: untag user pointers in tcp_zerocopy_receive To: Catalin Marinas , Andrey Konovalov Cc: Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Arnaldo Carvalho de Melo , Alex Deucher , =?UTF-8?Q?Christian_K=c3=b6nig?= , "David (ChunMing) Zhou" , Yishai Hadas , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya , Luc Van Oostenryck , Dave Martin , Szabolcs Nagy References: <2280b62096ce1fa5c9e9429d18f08f82f4be1b0b.1553093421.git.andreyknvl@google.com> <20190322120434.GD13384@arrakis.emea.arm.com> From: Kevin Brodsky Message-ID: Date: Mon, 25 Mar 2019 13:54:46 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: <20190322120434.GD13384@arrakis.emea.arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB 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 22/03/2019 12:04, Catalin Marinas wrote: > On Wed, Mar 20, 2019 at 03:51:23PM +0100, Andrey Konovalov wrote: >> This patch is a part of a series that extends arm64 kernel ABI to allow to >> pass tagged user pointers (with the top byte set to something else other >> than 0x00) as syscall arguments. >> >> tcp_zerocopy_receive() uses provided user pointers for vma lookups, which >> can only by done with untagged pointers. >> >> Untag user pointers in this function. >> >> Signed-off-by: Andrey Konovalov >> --- >> net/ipv4/tcp.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c >> index 6baa6dc1b13b..855a1f68c1ea 100644 >> --- a/net/ipv4/tcp.c >> +++ b/net/ipv4/tcp.c >> @@ -1761,6 +1761,8 @@ static int tcp_zerocopy_receive(struct sock *sk, >> if (address & (PAGE_SIZE - 1) || address != zc->address) >> return -EINVAL; >> >> + address = untagged_addr(address); >> + >> if (sk->sk_state == TCP_LISTEN) >> return -ENOTCONN; > I don't think we need this patch if we stick to Vincenzo's ABI > restrictions. Can zc->address be an anonymous mmap()? My understanding > of TCP_ZEROCOPY_RECEIVE is that this is an mmap() on a socket, so user > should not tag such pointer. Good point, I hadn't looked into the interface properly. The `vma->vm_ops != &tcp_vm_ops` check just below makes sure that the mapping is specifically tied to a TCP socket, so definitely not included in the ABI relaxation. > We want to allow tagged pointers to work transparently only for heap and > stack, hence the restriction to anonymous mmap() and those addresses > below sbrk(0). That's not quite true: in the ABI relaxation v2, all private mappings that are either anonymous or backed by a regular file are included. The scope is quite a bit larger than heap and stack, even though this is what we're primarily interested in for now. Kevin