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X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 0cYDLbIsDpGQkmmDXpeGnSAXIwV/FPaygchzE87Q+I8t89fom9tlyjeJ2TSZdIvhALyuOmDt6xWKaJbn4AIXPGpHwFLMovCiwKdVzUwtfEM= X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR10MB6802 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-25_05,2025-07-24_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxlogscore=999 bulkscore=0 phishscore=0 adultscore=0 suspectscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2505160000 definitions=main-2507250163 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzI1MDE2MyBTYWx0ZWRfX0vJLQt3AJiRY 52lKvzPvOgJVjqAXmHEZM9kLq/yBmU/THZTblMVEgepuAHqMlpo+zbMrbNNfxHOeCDGA7Jg0RG4 tOhTnGS3kTmOXCPLsh2yaqfPosCHUBGmntyL1nBzXUeL8R5wSEZ4kqGsQDXSCZoOuqPOH4iJowu 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data not having been loaded for the module that contains the symbol. > > Oops! > > > Signed-off-by: Kris Van Hees > > This seems not to do what it says on the tin (though what it does > doesn't look bad). > > It's not guarding against a module not being loaded: it's doing all > lookups in vmlinux rather than the shared repo if the module isn't > found. I guess this is desirable (it does increase the set of available > types), but it might be worth mentioning that we're doing this > somewhere, given that at no point does what is actually implemented > guard against BTF not having been loaded for the module that contains > the symbol :) maybe "push the code that decides which BTF to use down > next to the code that loads it" or something? Yes, it does, in the sense that it forces the the data to be loaded if it is not loaded yet. > There are a few rather odd hunks in here, notably: > > > - /* > > - * Ensure the shared BTF is loaded, and if no BTF is given, use the > > - * shared one. > > - */ > > - if (!dtp->dt_shared_btf) { > > - dt_btf_load_module(dtp, dtp->dt_exec); > > + /* Ensure the shared BTF is loaded. */ > > + if (!dtp->dt_shared_btf) > > + dt_btf_load_module(dtp, dtp->dt_exec); > > > If we don't have the dt_shared_btf... load the dt_exec? I mean yes this > will probably load dt_shared_btf as a side-effect, but why not check > dtp->dt_exec? (Hell, why not check both?) dt_exec is the dt_module_t representing vmlinux, and thus its dm_btf *is* shared_btf. And if you look at the load code, this *will* initialize the shared_btf (not *will probably*). > > + /* If the module does not have BTF data yet, try to load it. */ > > + if (!btf) { > > + btf = dt_btf_load_module(dtp, dmp); > > That looks good though. > > > + /* If no BTF momdule data was found, use the shared BTF. */ > > + if (!btf) > > + btf = dtp->dt_shared_btf; > > s/momdule/module/ Thanks. > > if (base > 0) > > - return dt_btf_lookup_name_kind(dtp, dtp->dt_shared_btf, > > - name, kind); > > + return dt_btf_lookup_name_kind(dtp, dtp->dt_exec, name, kind); > > This definitely looks wrong. The intent here is seemingly to climb to > the parent (the shared BTF) if a lookup in the child fails, since you > don't have anything like libctf here to do that for you. Replacing it > with a lookup of dt_exec isn't going to do the same thing at all! dt_exec == vmlinux, so this will trigger a lookup in shared_btf (which is the BTF of vmlinux aka dt_exec).