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charset="us-ascii" Content-ID: <46809490EE79F54DB017D6E367B762B8@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 5e3575e1-4164-4a5d-ea1a-08d763a8024d X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Nov 2019 17:29:14.2709 (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: qZct8zYiYq0c8yNJ1Dz8KTR4I+SAOpN/5D+1wspBU7FRW+HINntKiF1b1gIwEo8M X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR15MB2991 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-11-07_05:2019-11-07,2019-11-07 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 mlxlogscore=999 impostorscore=0 adultscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 spamscore=0 mlxscore=0 phishscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1911070163 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Nov 06, 2019 at 06:50:02PM -0800, Andrii Nakryiko wrote: > On Wed, Nov 6, 2019 at 5:47 PM Martin KaFai Lau wrote: > > > > Access the skb->cb[] in the kfree_skb test. > > > > Signed-off-by: Martin KaFai Lau > > --- >=20 > Acked-by: Andrii Nakryiko >=20 > > .../selftests/bpf/prog_tests/kfree_skb.c | 54 +++++++++++++++---- > > tools/testing/selftests/bpf/progs/kfree_skb.c | 25 +++++++-- > > 2 files changed, 63 insertions(+), 16 deletions(-) > > >=20 > [...] >=20 > > > > + meta.ifindex =3D _(dev->ifindex); I hit this when I put "meta.ifindex =3D dev->ifindex;" inside __builtin_preserve_access_index: libbpf: prog 'tp_btf/kfree_skb': relo #0: no matching targets found for [13= ] meta + 0:0 libbpf: prog 'tp_btf/kfree_skb': relo #0: failed to relocate: -3 libbpf: failed to perform CO-RE relocations: -3 My blind guess was it thought meta has to be relocated too. Hence, I moved= it out such that I can put __builtin_preserve_access_index only to "dev->ifind= ex". > > + meta.cb8_0 =3D cb8[8]; > > + meta.cb32_0 =3D cb32[2]; These two do not need relo. >=20 > Have you tried doing it inside __builtin_preserve_access_index region? > Does it fail because of extra allocations against meta? >=20 > > + > > bpf_probe_read_kernel(&pkt_type, sizeof(pkt_type), _(&skb->__pk= t_type_offset)); > > pkt_type &=3D 7; > > >=20 > [...]