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Tue, 23 Jun 2020 17:40:36 +0000 From: Song Liu To: Alexei Starovoitov CC: bpf , Network Development , Alexei Starovoitov , Daniel Borkmann , Kernel Team , John Fastabend , KP Singh Subject: Re: [PATCH bpf-next 1/3] bpf: introduce helper bpf_get_task_stack_trace() Thread-Topic: [PATCH bpf-next 1/3] bpf: introduce helper bpf_get_task_stack_trace() Thread-Index: AQHWSS0VOUl6AqeRSEG9pyL6IiSf06jmUOoAgAAcCQCAAAuAAA== Date: Tue, 23 Jun 2020 17:40:36 +0000 Message-ID: References: <20200623070802.2310018-1-songliubraving@fb.com> <20200623070802.2310018-2-songliubraving@fb.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.80.23.2.2) authentication-results: gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=none action=none header.from=fb.com; x-originating-ip: [2620:10d:c090:400::5:d062] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 42ead549-039a-46d5-e6ba-08d8179c89d7 x-ms-traffictypediagnostic: BYAPR15MB3253: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:6108; 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charset="us-ascii" Content-ID: <283A8D3DB651054FB9DDA8049EE3901F@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 42ead549-039a-46d5-e6ba-08d8179c89d7 X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Jun 2020 17:40:36.7120 (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: MSJxjwHRTwrVY9wuvdvuZMUuVp7xUEl2SmhM9p57s90VcMxqDaIQt4ezCjn7OMwnHQ48kEoglmXYXrva9OBgsA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3253 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-23_11:2020-06-23,2020-06-23 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 clxscore=1015 impostorscore=0 suspectscore=0 phishscore=0 mlxlogscore=999 priorityscore=1501 mlxscore=0 lowpriorityscore=0 adultscore=0 spamscore=0 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006120000 definitions=main-2006230124 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > On Jun 23, 2020, at 9:59 AM, Song Liu wrote: >=20 >=20 >=20 >> On Jun 23, 2020, at 8:19 AM, Alexei Starovoitov wrote: >>=20 >> On Tue, Jun 23, 2020 at 12:08 AM Song Liu wrote: >>>=20 >=20 > [...] >=20 >>>=20 >>> +BPF_CALL_3(bpf_get_task_stack_trace, struct task_struct *, task, >>> + void *, entries, u32, size) >>> +{ >>> + return stack_trace_save_tsk(task, (unsigned long *)entries, siz= e, 0); >>> +} >>> + >>> +static int bpf_get_task_stack_trace_btf_ids[5]; >>> +static const struct bpf_func_proto bpf_get_task_stack_trace_proto =3D = { >>> + .func =3D bpf_get_task_stack_trace, >>> + .gpl_only =3D true, >>=20 >> why? >=20 > Actually, I am not sure when we should use gpl_only =3D true.=20 >=20 >>=20 >>> + .ret_type =3D RET_INTEGER, >>> + .arg1_type =3D ARG_PTR_TO_BTF_ID, >>> + .arg2_type =3D ARG_PTR_TO_MEM, >>> + .arg3_type =3D ARG_CONST_SIZE_OR_ZERO, >>=20 >> OR_ZERO ? why? >=20 > Will fix.=20 >=20 >>=20 >>> + .btf_id =3D bpf_get_task_stack_trace_btf_ids, >>> +}; >>> + >>> static const struct bpf_func_proto * >>> raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog = *prog) >>> { >>> @@ -1521,6 +1538,10 @@ tracing_prog_func_proto(enum bpf_func_id func_id= , const struct bpf_prog *prog) >>> return prog->expected_attach_type =3D=3D BPF_TRACE_ITER ? >>> &bpf_seq_write_proto : >>> NULL; >>> + case BPF_FUNC_get_task_stack_trace: >>> + return prog->expected_attach_type =3D=3D BPF_TRACE_ITER= ? >>> + &bpf_get_task_stack_trace_proto : >>=20 >> why limit to iter only? >=20 > I guess it is also useful for other types. Maybe move to bpf_tracing_func= _proto()? >=20 >>=20 >>> + * >>> + * int bpf_get_task_stack_trace(struct task_struct *task, void *entrie= s, u32 size) >>> + * Description >>> + * Save a task stack trace into array *entries*. This is a= wrapper >>> + * over stack_trace_save_tsk(). >>=20 >> size is not documented and looks wrong. >> the verifier checks it in bytes, but it's consumed as number of u32s. >=20 > I am not 100% sure, but verifier seems check it correctly. And I think it= is consumed > as u64s? I was wrong. Verifier checks as bytes. Will fix.=20 Song=