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[217.140.101.70]) by mx.google.com with ESMTP id w44si2331943edd.126.2019.03.25.07.02.22 for ; Mon, 25 Mar 2019 07:02:23 -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 95C1780D; Mon, 25 Mar 2019 07:02:21 -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 128E53F59C; Mon, 25 Mar 2019 07:02:12 -0700 (PDT) Subject: Re: [PATCH v13 14/20] drm/amdgpu, arm64: untag user pointers in amdgpu_ttm_tt_get_user_pages 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: <017804b2198a906463d634f84777b6087c9b4a40.1553093421.git.andreyknvl@google.com> <20190322155955.GT13384@arrakis.emea.arm.com> From: Kevin Brodsky Message-ID: Date: Mon, 25 Mar 2019 14:02:11 +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: <20190322155955.GT13384@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 15:59, Catalin Marinas wrote: > On Wed, Mar 20, 2019 at 03:51:28PM +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. >> >> amdgpu_ttm_tt_get_user_pages() 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 >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> index 73e71e61dc99..891b027fa33b 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c >> @@ -751,10 +751,11 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages) >> * check that we only use anonymous memory to prevent problems >> * with writeback >> */ >> - unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE; >> + unsigned long userptr = untagged_addr(gtt->userptr); >> + unsigned long end = userptr + ttm->num_pages * PAGE_SIZE; >> struct vm_area_struct *vma; >> >> - vma = find_vma(mm, gtt->userptr); >> + vma = find_vma(mm, userptr); >> if (!vma || vma->vm_file || vma->vm_end < end) { >> up_read(&mm->mmap_sem); >> return -EPERM; > I tried to track this down but I failed to see whether user could > provide an tagged pointer here (under the restrictions as per Vincenzo's > ABI document). ->userptr is set by radeon_ttm_tt_set_userptr(), itself called from radeon_gem_userptr_ioctl(). Any page-aligned value is allowed. Kevin