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([2001:b07:6468:f312:7ffb:1107:73ba:dbcf]) by smtp.gmail.com with ESMTPSA id u15sm21457907wml.21.2020.10.11.23.59.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 11 Oct 2020 23:59:40 -0700 (PDT) Subject: Re: [PATCH v3 05/16] fuzz: Declare DMA Read callback function To: Alexander Bulekov References: <20200921022506.873303-1-alxndr@bu.edu> <20200921022506.873303-6-alxndr@bu.edu> <6ed304a0-38ee-1013-7d85-7b0ae0e7c4d2@redhat.com> <20201011154524.wvq2vsff7eig27c4@mozz.bu.edu> From: Paolo Bonzini Message-ID: <2bc8a9b9-49c1-58cb-4696-fd83f7e3257f@redhat.com> Date: Mon, 12 Oct 2020 08:59:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20201011154524.wvq2vsff7eig27c4@mozz.bu.edu> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/11 23:52:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: darren.kenny@oracle.com, bsd@redhat.com, philmd@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/10/20 17:45, Alexander Bulekov wrote: > On 201008 0939, Paolo Bonzini wrote: >> On 21/09/20 04:24, Alexander Bulekov wrote: >>> This patch declares the fuzz_dma_read_cb function and uses the >>> preprocessor and linker(weak symbols) to handle these cases: >>> >>> When we build softmmu/all with --enable-fuzzing, there should be no >>> strong symbol defined for fuzz_dma_read_cb, and we link against a weak >>> stub function. >>> >>> When we build softmmu/fuzz with --enable-fuzzing, we link against the >>> strong symbol in general_fuzz.c >>> >>> When we build softmmu/all without --enable-fuzzing, fuzz_dma_read_cb is >>> an empty, inlined function. As long as we don't call any other functions >>> when building the arguments, there should be no overhead. >> >> Can you move the weak function somewhere in tests/qtest/fuzz instead? >> Then you don't need an #ifdef because you can add it to specific_fuzz_ss. > > If I understand correctly, specific_fuzz_ss is only used to build > qemu-fuzz targets. The goal here was to support building qemu-system > with --enable-fuzzing (ie CONFIG_FUZZ=y), where specific_fuzz isn't > used. If its too ugly, we could make a stub file under tests/qtest/fuzz > and add it to specific_ss when: 'CONFIG_FUZZ'. You're right. Paolo