| Message ID | 20241218024422.23423-5-alibuda@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | net/smc: Introduce smc_ops | expand |
On 12/17/24 6:44 PM, D. Wythe wrote: > When a struct_ops named xxx_ops was registered by a module, and > it will be used in both built-in modules and the module itself, > so that the btf_type of xxx_ops will be present in btf_vmlinux > instead of in btf_mod, which means that the btf_type of > bpf_struct_ops_xxx_ops and xxx_ops will not be in the same btf. > > Here are four possible case: > > +--------+-------------+-------------+---------------------------------+ > | | st_opx_xxx | xxx | | > +--------+-------------+-------------+---------------------------------+ > | case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux | > +--------+-------------+-------------+---------------------------------+ > | case 1 | btf_vmlinux | bpf_mod | INVALID | > +--------+-------------+-------------+---------------------------------+ > | case 2 | btf_mod | btf_vmlinux | reg in mod but be used both in | > | | | | vmlinux and mod. | > +--------+-------------+-------------+---------------------------------+ > | case 3 | btf_mod | btf_mod | be used and reg only in mod | > +--------+-------------+-------------+---------------------------------+ > > At present, cases 0, 1, and 3 can be correctly identified, because > st_ops_xxx is searched from the same btf with xxx. In order to > handle case 2 correctly without affecting other cases, we cannot simply > change the search method for st_ops_xxx from find_btf_by_prefix_kind() > to find_ksym_btf_id(), because in this way, case 1 will not be > recognized anymore. > > To address this issue, if st_ops_xxx cannot be found in the btf with xxx > and mod_btf does not exist, do find_ksym_btf_id() again to > avoid such issue. > > Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") > Signed-off-by: D. Wythe <alibuda@linux.alibaba.com> > --- > tools/lib/bpf/libbpf.c | 25 +++++++++++++++++-------- > 1 file changed, 17 insertions(+), 8 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 66173ddb5a2d..56bf74894110 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -1005,7 +1005,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, > const struct btf_member *kern_data_member; > struct btf *btf = NULL; > __s32 kern_vtype_id, kern_type_id; > - char tname[256]; > + char tname[256], stname[256]; > + int ret; > __u32 i; > > snprintf(tname, sizeof(tname), "%.*s", > @@ -1020,17 +1021,25 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, > } > kern_type = btf__type_by_id(btf, kern_type_id); > > + ret = snprintf(stname, sizeof(stname), "%s%s", STRUCT_OPS_VALUE_PREFIX, tname); How about always look for "struct bpf_struct_ops_smc_ops" first, figure out the btf, and then look for "struct smc_ops", would it work? If CONFIG_SMC=y instead of =m, this change cannot be tested? > + if (ret < 0 || ret >= sizeof(stname)) > + return -ENAMETOOLONG; > + > /* Find the corresponding "map_value" type that will be used > * in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example, > * find "struct bpf_struct_ops_tcp_congestion_ops" from the > * btf_vmlinux. > */ > - kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX, > - tname, BTF_KIND_STRUCT); > + kern_vtype_id = btf__find_by_name_kind(btf, stname, BTF_KIND_STRUCT); > if (kern_vtype_id < 0) { > - pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", > - STRUCT_OPS_VALUE_PREFIX, tname); > - return kern_vtype_id; > + if (kern_vtype_id == -ENOENT && !*mod_btf) > + kern_vtype_id = find_ksym_btf_id(obj, stname, BTF_KIND_STRUCT, > + &btf, mod_btf); > + if (kern_vtype_id < 0) { > + pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n", > + stname); > + return kern_vtype_id; > + } > } > kern_vtype = btf__type_by_id(btf, kern_vtype_id); > > @@ -1046,8 +1055,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, > break; > } > if (i == btf_vlen(kern_vtype)) { > - pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n", > - tname, STRUCT_OPS_VALUE_PREFIX, tname); > + pr_warn("struct_ops init_kern: struct %s data is not found in struct %s\n", > + tname, stname); > return -EINVAL; > } >
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 66173ddb5a2d..56bf74894110 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1005,7 +1005,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, const struct btf_member *kern_data_member; struct btf *btf = NULL; __s32 kern_vtype_id, kern_type_id; - char tname[256]; + char tname[256], stname[256]; + int ret; __u32 i; snprintf(tname, sizeof(tname), "%.*s", @@ -1020,17 +1021,25 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, } kern_type = btf__type_by_id(btf, kern_type_id); + ret = snprintf(stname, sizeof(stname), "%s%s", STRUCT_OPS_VALUE_PREFIX, tname); + if (ret < 0 || ret >= sizeof(stname)) + return -ENAMETOOLONG; + /* Find the corresponding "map_value" type that will be used * in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example, * find "struct bpf_struct_ops_tcp_congestion_ops" from the * btf_vmlinux. */ - kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX, - tname, BTF_KIND_STRUCT); + kern_vtype_id = btf__find_by_name_kind(btf, stname, BTF_KIND_STRUCT); if (kern_vtype_id < 0) { - pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n", - STRUCT_OPS_VALUE_PREFIX, tname); - return kern_vtype_id; + if (kern_vtype_id == -ENOENT && !*mod_btf) + kern_vtype_id = find_ksym_btf_id(obj, stname, BTF_KIND_STRUCT, + &btf, mod_btf); + if (kern_vtype_id < 0) { + pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n", + stname); + return kern_vtype_id; + } } kern_vtype = btf__type_by_id(btf, kern_vtype_id); @@ -1046,8 +1055,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw, break; } if (i == btf_vlen(kern_vtype)) { - pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n", - tname, STRUCT_OPS_VALUE_PREFIX, tname); + pr_warn("struct_ops init_kern: struct %s data is not found in struct %s\n", + tname, stname); return -EINVAL; }
When a struct_ops named xxx_ops was registered by a module, and it will be used in both built-in modules and the module itself, so that the btf_type of xxx_ops will be present in btf_vmlinux instead of in btf_mod, which means that the btf_type of bpf_struct_ops_xxx_ops and xxx_ops will not be in the same btf. Here are four possible case: +--------+-------------+-------------+---------------------------------+ | | st_opx_xxx | xxx | | +--------+-------------+-------------+---------------------------------+ | case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux | +--------+-------------+-------------+---------------------------------+ | case 1 | btf_vmlinux | bpf_mod | INVALID | +--------+-------------+-------------+---------------------------------+ | case 2 | btf_mod | btf_vmlinux | reg in mod but be used both in | | | | | vmlinux and mod. | +--------+-------------+-------------+---------------------------------+ | case 3 | btf_mod | btf_mod | be used and reg only in mod | +--------+-------------+-------------+---------------------------------+ At present, cases 0, 1, and 3 can be correctly identified, because st_ops_xxx is searched from the same btf with xxx. In order to handle case 2 correctly without affecting other cases, we cannot simply change the search method for st_ops_xxx from find_btf_by_prefix_kind() to find_ksym_btf_id(), because in this way, case 1 will not be recognized anymore. To address this issue, if st_ops_xxx cannot be found in the btf with xxx and mod_btf does not exist, do find_ksym_btf_id() again to avoid such issue. Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: D. Wythe <alibuda@linux.alibaba.com> --- tools/lib/bpf/libbpf.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)