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[209.85.220.65]) by mx.google.com with SMTPS id a15sor13898275pgw.83.2019.04.02.05.47.46 for (Google Transport Security); Tue, 02 Apr 2019 05:47:46 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=RvtPBpLv; 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 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=u3PSOHs4we7+LgIG6ZQZir4Fy57VqCCMcbhzYXQWknQ=; b=RvtPBpLvPglDtwnPF4yXUeK5oDlzVoAw9Ac/QiLLKSGbikn9e6229p73Q0tOoviq2D BavSCer7Dzqe0/C31mrVK/886gbUDYWuPnxHOlht2sOu/e62noERB05hR+v+Bbj+JICn Lb7g/8TOjfYKi5cKqi9tDj/4Gjl0w7oFGi+cz1GXwEAzmc5l0cphMO74o+wu5S8JjZik 7AqeS2RJ0S+0J5+xNSxMiTjPOKYRkB2DaefRCT/WCl4ZMTNyy1aYXf9qwji/GQQh7uA6 a4SkVWVDmZ28lLA5h47JmaNF3G6jNLy7QP3Ylvcw6DiwtS/xNNeagblhaZ/cgn7jvFfX OA/w== X-Google-Smtp-Source: APXvYqwSO12tw5fRix4o6PstoDzeaM5ZQf6IJ2XlmsbVCqK/ZDPoD7HrCoDXID/J7Vmm+PM48eFxdwxASU4WIrz1GI4= X-Received: by 2002:a65:6496:: with SMTP id e22mr52163844pgv.249.1554209265963; Tue, 02 Apr 2019 05:47:45 -0700 (PDT) MIME-Version: 1.0 References: <44ad2d0c55dbad449edac23ae46d151a04102a1d.1553093421.git.andreyknvl@google.com> <20190322114357.GC13384@arrakis.emea.arm.com> <20190328141934.38960af0@gandalf.local.home> <20190329103039.GA44339@arrakis.emea.arm.com> In-Reply-To: <20190329103039.GA44339@arrakis.emea.arm.com> From: Andrey Konovalov Date: Tue, 2 Apr 2019 14:47:34 +0200 Message-ID: Subject: Re: [PATCH v13 04/20] mm, arm64: untag user pointers passed to memory syscalls To: Catalin Marinas Cc: Steven Rostedt , Will Deacon , Mark Rutland , Kees Cook , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Vincenzo Frascino , Eric Dumazet , "David S. Miller" , Alexei Starovoitov , Daniel Borkmann , Peter Zijlstra , Arnaldo Carvalho de Melo , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Linux ARM , Linux Memory Management List , linux-arch , LKML , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Ruben Ayrapetyan , Luc Van Oostenryck , Dave Martin , Kevin Brodsky , Szabolcs Nagy Content-Type: text/plain; charset="UTF-8" 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, Mar 29, 2019 at 11:30 AM Catalin Marinas wrote: > > (I trimmed down the cc list a bit since it's always bouncing) > > On Thu, Mar 28, 2019 at 02:19:34PM -0400, Steven Rostedt wrote: > > On Thu, 28 Mar 2019 19:10:07 +0100 > > Andrey Konovalov wrote: > > > > > > > Signed-off-by: Andrey Konovalov > > > > > --- > > > > > ipc/shm.c | 2 ++ > > > > > mm/madvise.c | 2 ++ > > > > > mm/mempolicy.c | 5 +++++ > > > > > mm/migrate.c | 1 + > > > > > mm/mincore.c | 2 ++ > > > > > mm/mlock.c | 5 +++++ > > > > > mm/mmap.c | 7 +++++++ > > > > > mm/mprotect.c | 1 + > > > > > mm/mremap.c | 2 ++ > > > > > mm/msync.c | 2 ++ > > > > > 10 files changed, 29 insertions(+) > > > > > > > > I wonder whether it's better to keep these as wrappers in the arm64 > > > > code. > > > > > > I don't think I understand what you propose, could you elaborate? > > > > I believe Catalin is saying that instead of placing things like: > > > > @@ -1593,6 +1593,7 @@ SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg) > > unsigned long ret; > > long err; > > > > + shmaddr = untagged_addr(shmaddr); > > > > To instead have the shmaddr set to the untagged_addr() before calling > > the system call, and passing the untagged addr to the system call, as > > that goes through the arm64 architecture specific code first. > > Indeed. For example, we already have a SYSCALL_DEFINE6(mmap, ...) in > arch/arm64/kernel/sys.c, just add the untagging there. We could do > something similar for the other syscalls. I don't mind doing this in the > generic code but if it's only needed for arm64, I'd rather keep the > generic changes to a minimum. Do I understand correctly, that I'll need to add ksys_ wrappers for each of the memory syscalls, and then redefine them in arch/arm64/kernel/sys.c with arm64_ prefix, like it is done for the personality syscall right now? This will require generic changes as well. > > (I had a hack overriding __SC_CAST to do this automatically for pointer > arguments but this wouldn't work on mmap() and friends as the argument > is unsigned long) > > -- > Catalin