Some projects, for example xdp-tools [0], prefer to check in a minimized vmlinux.h rather than the complete file which can get rather large. However, when you try to add a minimized version of a complex struct (eg struct xfrm_state), things can get quite complex if you're trying to manually untangle and deduplicate the dependencies. This commit teaches bpftool to do a minimized dump of a single type by providing an optional root_id argument. Example usage: $ ./bpftool btf dump file ~/dev/linux/vmlinux | rg "STRUCT 'xfrm_state'" [12643] STRUCT 'xfrm_state' size=912 vlen=58 $ ./bpftool btf dump file ~/dev/linux/vmlinux root_id 12643 format c #ifndef __VMLINUX_H__ #define __VMLINUX_H__ [..] struct xfrm_type_offload; struct xfrm_sec_ctx; struct xfrm_state { possible_net_t xs_net; union { struct hlist_node gclist; struct hlist_node bydst; }; union { struct hlist_node dev_gclist; struct hlist_node bysrc; }; struct hlist_node byspi; [..] [0]: https://github.com/xdp-project/xdp-tools/blob/master/headers/bpf/vmlinux.h Signed-off-by: Daniel Xu <dxu@xxxxxxxxx> --- .../bpf/bpftool/Documentation/bpftool-btf.rst | 7 +++++-- tools/bpf/bpftool/btf.c | 21 ++++++++++++++++++- 2 files changed, 25 insertions(+), 3 deletions(-) diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst index 245569f43035..4899b2c10777 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst @@ -24,7 +24,7 @@ BTF COMMANDS ============= | **bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*] -| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*] +| **bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*] [**root_id** *ROOT_ID*] | **bpftool** **btf help** | | *BTF_SRC* := { **id** *BTF_ID* | **prog** *PROG* | **map** *MAP* [{**key** | **value** | **kv** | **all**}] | **file** *FILE* } @@ -43,7 +43,7 @@ bpftool btf { show | list } [id *BTF_ID*] that hold open file descriptors (FDs) against BTF objects. On such kernels bpftool will automatically emit this information as well. -bpftool btf dump *BTF_SRC* [format *FORMAT*] +bpftool btf dump *BTF_SRC* [format *FORMAT*] [root_id *ROOT_ID*] Dump BTF entries from a given *BTF_SRC*. When **id** is specified, BTF object with that ID will be loaded and all @@ -67,6 +67,9 @@ bpftool btf dump *BTF_SRC* [format *FORMAT*] formatting, the output is sorted by default. Use the **unsorted** option to avoid sorting the output. + **root_id** option can be used to filter a dump to a single type and all + its dependent types. It cannot be used with any other types of filtering. + bpftool btf help Print short help message. diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 3e995faf9efa..18b037a1414b 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -993,6 +993,25 @@ static int do_dump(int argc, char **argv) goto done; } NEXT_ARG(); + } else if (is_prefix(*argv, "root_id")) { + __u32 root_id; + char *end; + + if (root_type_cnt) { + p_err("cannot use root_id with other type filtering"); + err = -EINVAL; + goto done; + } + + NEXT_ARG(); + root_id = strtoul(*argv, &end, 0); + if (*end) { + err = -1; + p_err("can't parse %s as root ID", *argv); + goto done; + } + root_type_ids[root_type_cnt++] = root_id; + NEXT_ARG(); } else if (is_prefix(*argv, "unsorted")) { sort_dump_c = false; NEXT_ARG(); @@ -1403,7 +1422,7 @@ static int do_help(int argc, char **argv) fprintf(stderr, "Usage: %1$s %2$s { show | list } [id BTF_ID]\n" - " %1$s %2$s dump BTF_SRC [format FORMAT]\n" + " %1$s %2$s dump BTF_SRC [format FORMAT] [root_id ROOT_ID]\n" " %1$s %2$s help\n" "\n" " BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n" -- 2.46.0