[PATCH v2 bpf-next 02/17] bpftool: dump more info about DATASEC members
From: Andrii Nakryiko <andrii@kernel.org>
Date: 2021-04-16 20:24:13
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [tooling] (bpftool), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Quentin Monnet, Linus Torvalds
Dump succinct information for each member of DATASEC: its kinds and name. This
is extremely helpful to see at a quick glance what is inside each DATASEC of
a given BTF. Without this, one has to jump around BTF data to just find out
the name of a VAR or FUNC. DATASEC's var_secinfo member is special in that
regard because it doesn't itself contain the name of the member, delegating
that to the referenced VAR and FUNC kinds. Other kinds, like
STRUCT/UNION/FUNC/ENUM, encode member names directly and thus are clearly
identifiable in BTF dump.
The new output looks like this:
[35] DATASEC '.bss' size=0 vlen=6
type_id=8 offset=0 size=4 (VAR 'input_bss1')
type_id=13 offset=0 size=4 (VAR 'input_bss_weak')
type_id=16 offset=0 size=4 (VAR 'output_bss1')
type_id=17 offset=0 size=4 (VAR 'output_data1')
type_id=18 offset=0 size=4 (VAR 'output_rodata1')
type_id=20 offset=0 size=8 (VAR 'output_sink1')
[36] DATASEC '.data' size=0 vlen=2
type_id=9 offset=0 size=4 (VAR 'input_data1')
type_id=14 offset=0 size=4 (VAR 'input_data_weak')
[37] DATASEC '.kconfig' size=0 vlen=2
type_id=25 offset=0 size=4 (VAR 'LINUX_KERNEL_VERSION')
type_id=28 offset=0 size=1 (VAR 'CONFIG_BPF_SYSCALL')
[38] DATASEC '.ksyms' size=0 vlen=1
type_id=30 offset=0 size=1 (VAR 'bpf_link_fops')
[39] DATASEC '.rodata' size=0 vlen=2
type_id=12 offset=0 size=4 (VAR 'input_rodata1')
type_id=15 offset=0 size=4 (VAR 'input_rodata_weak')
[40] DATASEC 'license' size=0 vlen=1
type_id=24 offset=0 size=4 (VAR 'LICENSE')
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/bpf/bpftool/btf.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 001749a34899..385d5c955cf3 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c@@ -100,26 +100,28 @@ static const char *btf_str(const struct btf *btf, __u32 off) return btf__name_by_offset(btf, off) ? : "(invalid)"; } +static int btf_kind_safe(int kind) +{ + return kind <= BTF_KIND_MAX ? kind : BTF_KIND_UNKN; +} + static int dump_btf_type(const struct btf *btf, __u32 id, const struct btf_type *t) { json_writer_t *w = json_wtr; - int kind, safe_kind; - - kind = BTF_INFO_KIND(t->info); - safe_kind = kind <= BTF_KIND_MAX ? kind : BTF_KIND_UNKN; + int kind = btf_kind(t); if (json_output) { jsonw_start_object(w); jsonw_uint_field(w, "id", id); - jsonw_string_field(w, "kind", btf_kind_str[safe_kind]); + jsonw_string_field(w, "kind", btf_kind_str[btf_kind_safe(kind)]); jsonw_string_field(w, "name", btf_str(btf, t->name_off)); } else { - printf("[%u] %s '%s'", id, btf_kind_str[safe_kind], + printf("[%u] %s '%s'", id, btf_kind_str[btf_kind_safe(kind)], btf_str(btf, t->name_off)); } - switch (BTF_INFO_KIND(t->info)) { + switch (kind) { case BTF_KIND_INT: { __u32 v = *(__u32 *)(t + 1); const char *enc;
@@ -302,7 +304,8 @@ static int dump_btf_type(const struct btf *btf, __u32 id, break; } case BTF_KIND_DATASEC: { - const struct btf_var_secinfo *v = (const void *)(t+1); + const struct btf_var_secinfo *v = (const void *)(t + 1); + const struct btf_type *vt; __u16 vlen = BTF_INFO_VLEN(t->info); int i;
@@ -324,6 +327,13 @@ static int dump_btf_type(const struct btf *btf, __u32 id, } else { printf("\n\ttype_id=%u offset=%u size=%u", v->type, v->offset, v->size); + + if (v->type <= btf__get_nr_types(btf)) { + vt = btf__type_by_id(btf, v->type); + printf(" (%s '%s')", + btf_kind_str[btf_kind_safe(btf_kind(vt))], + btf_str(btf, vt->name_off)); + } } } if (json_output)
--
2.30.2