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charset="us-ascii" Content-ID: <1852585075682D4AADDEA23E3847E2EE@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 1be2e03e-b623-4775-ce88-08d764756c45 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Nov 2019 17:59:38.5370 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: m3YZAQsq1/g6AxHdLfHr0DQYkHBEiriGci/jSkWYLL8nWlri1CN4d3uwQBNU6I5iu4QctToMnyK26P2BwVWIXQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1855 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-08_06:2019-11-08,2019-11-08 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 adultscore=0 priorityscore=1501 phishscore=0 clxscore=1015 mlxscore=0 lowpriorityscore=0 mlxlogscore=607 malwarescore=0 impostorscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911080176 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org > On Nov 8, 2019, at 9:57 AM, Alexei Starovoitov wrote: >=20 > On 11/8/19 9:32 AM, Song Liu wrote: >>=20 >>=20 >>> On Nov 8, 2019, at 9:28 AM, Song Liu wrote: >>>=20 >>>=20 >>>=20 >>>> On Nov 7, 2019, at 10:40 PM, Alexei Starovoitov wrote= : >>>>=20 >>>> Make the verifier check that BTF types of function arguments match act= ual types >>>> passed into top-level BPF program and into BPF-to-BPF calls. If types = match >>>> such BPF programs and sub-programs will have full support of BPF tramp= oline. If >>>> types mismatch the trampoline has to be conservative. It has to save/r= estore >>>> all 5 program arguments and assume 64-bit scalars. If FENTRY/FEXIT pro= gram is >>>> attached to this program in the future such FENTRY/FEXIT program will = be able >>>> to follow pointers only via bpf_probe_read_kernel(). >>>>=20 >>>> Signed-off-by: Alexei Starovoitov >>>=20 >>> Acked-by: Song Liu >>=20 >> One nit though: maybe use "reliable" instead of "unreliable" >>=20 >> +struct bpf_func_info_aux { >> + bool reliable; >> +}; >> + >>=20 >> + bool func_proto_reliable; >>=20 >> So the default value 0, is not reliable. >=20 > I don't see how this can work. > Once particular func proto was found unreliable the verifier won't keep=20 > checking. If we start with 'bool reliable =3D false' > how do you see the whole mechanism working ? > Say the first time the verifier analyzed the subroutine and everything > matches. Can it do reliable =3D true ? No. It has to check all other > callsites. Then it would need another variable and extra pass ? I see. I missed the multiple call sites part.=20 Thanks for the explanation.=20 Song