| Message ID | 20201106055111.3972047-6-andrii@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | Integrate kernel module BTF support | expand |
On Thu, 5 Nov 2020, Andrii Nakryiko wrote: > Display vmlinux BTF name and kernel module names when listing available BTFs > on the system. > > In human-readable output mode, module BTFs are reported with "name > [module-name]", while vmlinux BTF will be reported as "name [vmlinux]". > Square brackets are added by bpftool and follow kernel convention when > displaying modules in human-readable text outputs. > I had a go at testing this and all looks good, but I was curious if "bpftool btf dump" is expected to work with module BTF? I see the various modules in /sys/kernel/btf, but if I run: # bpftool btf dump file /sys/kernel/btf/ixgbe Error: failed to load BTF from /sys/kernel/btf/ixgbe: Invalid argument ...while it still works for vmlinux: # bpftool btf dump file /sys/kernel/btf/vmlinux [1] INT '(anon)' size=4 bits_offset=0 nr_bits=32 encoding=(none) [2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 encoding=(none) ... "bpftool btf show" works for ixgbe: # bpftool btf show|grep ixgbe 19: name [ixgbe] size 182074B Is this perhaps not expected to work yet? (I updated pahole to the latest changes etc and BTF generation seemed to work fine for modules during kernel build). For the "bpftool btf show" functionality, feel free to add Tested-by: Alan Maguire <alan.maguire@oracle.com> Thanks! Alan
On Mon, Nov 9, 2020 at 8:43 AM Alan Maguire <alan.maguire@oracle.com> wrote: > > On Thu, 5 Nov 2020, Andrii Nakryiko wrote: > > > Display vmlinux BTF name and kernel module names when listing available BTFs > > on the system. > > > > In human-readable output mode, module BTFs are reported with "name > > [module-name]", while vmlinux BTF will be reported as "name [vmlinux]". > > Square brackets are added by bpftool and follow kernel convention when > > displaying modules in human-readable text outputs. > > > > I had a go at testing this and all looks good, but I was curious > if "bpftool btf dump" is expected to work with module BTF? I see > the various modules in /sys/kernel/btf, but if I run: > > # bpftool btf dump file /sys/kernel/btf/ixgbe You need to specify vmlinux as a base BTF. There is a -B flag for that, added in [0]. So just add -B /sys/kernel/btf/vmlinux. I think we might want to teach bpftool to do this automatically if we see that file points at module BTF in /sys/kernel/btf, as a convenience feature. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20201105043402.2530976-12-andrii@kernel.org/ > Error: failed to load BTF from /sys/kernel/btf/ixgbe: Invalid argument > > ...while it still works for vmlinux: > > # bpftool btf dump file /sys/kernel/btf/vmlinux > [1] INT '(anon)' size=4 bits_offset=0 nr_bits=32 encoding=(none) > [2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 > encoding=(none) > ... > > "bpftool btf show" works for ixgbe: > > # bpftool btf show|grep ixgbe > 19: name [ixgbe] size 182074B > > Is this perhaps not expected to work yet? (I updated pahole > to the latest changes etc and BTF generation seemed to work > fine for modules during kernel build). > > For the "bpftool btf show" functionality, feel free to add > > Tested-by: Alan Maguire <alan.maguire@oracle.com> Ok, thanks. > > Thanks! > > Alan
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index c96b56e8e3a4..ed5e97157241 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -742,9 +742,14 @@ show_btf_plain(struct bpf_btf_info *info, int fd, struct btf_attach_table *btf_map_table) { struct btf_attach_point *obj; + const char *name = u64_to_ptr(info->name); int n; printf("%u: ", info->id); + if (info->kernel_btf) + printf("name [%s] ", name); + else if (name && name[0]) + printf("name %s ", name); printf("size %uB", info->btf_size); n = 0; @@ -771,6 +776,7 @@ show_btf_json(struct bpf_btf_info *info, int fd, struct btf_attach_table *btf_map_table) { struct btf_attach_point *obj; + const char *name = u64_to_ptr(info->name); jsonw_start_object(json_wtr); /* btf object */ jsonw_uint_field(json_wtr, "id", info->id); @@ -796,6 +802,11 @@ show_btf_json(struct bpf_btf_info *info, int fd, emit_obj_refs_json(&refs_table, info->id, json_wtr); /* pids */ + jsonw_bool_field(json_wtr, "kernel", info->kernel_btf); + + if (name && name[0]) + jsonw_string_field(json_wtr, "name", name); + jsonw_end_object(json_wtr); /* btf object */ } @@ -803,15 +814,30 @@ static int show_btf(int fd, struct btf_attach_table *btf_prog_table, struct btf_attach_table *btf_map_table) { - struct bpf_btf_info info = {}; + struct bpf_btf_info info; __u32 len = sizeof(info); + char name[64]; int err; + memset(&info, 0, sizeof(info)); err = bpf_obj_get_info_by_fd(fd, &info, &len); if (err) { p_err("can't get BTF object info: %s", strerror(errno)); return -1; } + /* if kernel support emitting BTF object name, pass name pointer */ + if (info.name_len) { + memset(&info, 0, sizeof(info)); + info.name_len = sizeof(name); + info.name = ptr_to_u64(name); + len = sizeof(info); + + err = bpf_obj_get_info_by_fd(fd, &info, &len); + if (err) { + p_err("can't get BTF object info: %s", strerror(errno)); + return -1; + } + } if (json_output) show_btf_json(&info, fd, btf_prog_table, btf_map_table);
Display vmlinux BTF name and kernel module names when listing available BTFs on the system. In human-readable output mode, module BTFs are reported with "name [module-name]", while vmlinux BTF will be reported as "name [vmlinux]". Square brackets are added by bpftool and follow kernel convention when displaying modules in human-readable text outputs. [vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s 1: name [vmlinux] size 4082281B 6: size 2365B prog_ids 8,6 map_ids 3 7: name [button] size 46895B 8: name [pcspkr] size 42328B 9: name [serio_raw] size 39375B 10: name [floppy] size 57185B 11: name [i2c_core] size 76186B 12: name [crc32c_intel] size 16036B 13: name [i2c_piix4] size 50497B 14: name [irqbypass] size 14124B 15: name [kvm] size 197985B 16: name [kvm_intel] size 123564B 17: name [cryptd] size 42466B 18: name [crypto_simd] size 17187B 19: name [glue_helper] size 39205B 20: name [aesni_intel] size 41034B 25: size 36150B pids bpftool(2519) In JSON mode, two fields (boolean "kernel" and string "name") are reported for each BTF object. vmlinux BTF is reported with name "vmlinux" (kernel itself returns and empty name for vmlinux BTF). [vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s -jp [{ "id": 1, "size": 4082281, "prog_ids": [], "map_ids": [], "kernel": true, "name": "vmlinux" },{ "id": 6, "size": 2365, "prog_ids": [8,6 ], "map_ids": [3 ], "kernel": false },{ "id": 7, "size": 46895, "prog_ids": [], "map_ids": [], "kernel": true, "name": "button" },{ ... Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- tools/bpf/bpftool/btf.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-)