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[209.85.220.65]) by mx.google.com with SMTPS id l7sor11990207pff.50.2019.05.06.06.53.13 for (Google Transport Security); Mon, 06 May 2019 06:53:13 -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=kv7aGbZw; 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=DfsikH3ADmgNVGOW8dVHffAJXBPBy/1Drd0IdtpjjJ8=; b=kv7aGbZwowOP86IiNXKGTzv02HGdI2dS555U/AmH12LgQOZnKLK39c4sVdRuufn96A qthFKSfdn7G60uj86be1sn6Yz08bEym7ZdQPS1mHAwXca2PX4G4xwzBsumjfQSNalrzf yL5bwTZ9P03pKULjLPyCJCemso/1RN2dFNxsJkh8Db8dDQ4uyTu4XB2OtIwgRdUtOIbE AyYkrbplUjKWiH4tJjgIH/K5mFuPdBD8NVSdZa64NURA8ieEyhpOBhaJlBUr1GIoMIGp v2ptbSyS2qLsf62uamUc0COAt9buSU1YrXxFbkm18U+53rgjezb09axtZoHwZgv8hVgU L1Yg== X-Google-Smtp-Source: APXvYqz1fgwxD3Q1L0PJp0GBoiDCnAmVuD+UduBO6dKustad4HqnmYC98uMKFLNp2x7D5yl19BVMVIT9EGy2Pg34Ktk= X-Received: by 2002:aa7:9116:: with SMTP id 22mr33262822pfh.165.1557150792655; Mon, 06 May 2019 06:53:12 -0700 (PDT) MIME-Version: 1.0 References: <8e20df035de677029b3f970744ba2d35e2df1db3.1556630205.git.andreyknvl@google.com> <20190503165113.GJ55449@arrakis.emea.arm.com> In-Reply-To: <20190503165113.GJ55449@arrakis.emea.arm.com> From: Andrey Konovalov Date: Mon, 6 May 2019 15:53:01 +0200 Message-ID: Subject: Re: [PATCH v14 08/17] mm, arm64: untag user pointers in get_vaddr_frames To: Catalin Marinas Cc: Linux ARM , Linux Memory Management List , LKML , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Kuehling@google.com, Felix , Deucher@google.com, Alexander , Koenig@google.com, Christian , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Chintan Pandya , 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, May 3, 2019 at 6:51 PM Catalin Marinas wrote: > > On Tue, Apr 30, 2019 at 03:25:04PM +0200, 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. > > > > get_vaddr_frames uses provided user pointers for vma lookups, which can > > only by done with untagged pointers. Instead of locating and changing > > all callers of this function, perform untagging in it. > > > > Signed-off-by: Andrey Konovalov > > --- > > mm/frame_vector.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > > index c64dca6e27c2..c431ca81dad5 100644 > > --- a/mm/frame_vector.c > > +++ b/mm/frame_vector.c > > @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > > if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) > > nr_frames = vec->nr_allocated; > > > > + start = untagged_addr(start); > > + > > down_read(&mm->mmap_sem); > > locked = 1; > > vma = find_vma_intersection(mm, start, start + 1); > > Is this some buffer that the user may have malloc'ed? I got lost when > trying to track down the provenience of this buffer. The caller that I found when I was looking at this: drivers/gpu/drm/exynos/exynos_drm_g2d.c:482 exynos_g2d_set_cmdlist_ioctl()->g2d_map_cmdlist_gem()->g2d_userptr_get_dma_addr()->get_vaddr_frames() > > -- > Catalin