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bpf: bpftool support for dumping data/bss/rodata sections

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Add the ability to bpftool to handle BTF Var and DataSec kinds
in order to dump them out of btf_dumper_type(). The value has a
single object with the section name, which itself holds an array
of variables it dumps. A single variable is an object by itself
printed along with its name. From there further type information
is dumped along with corresponding value information.

Example output from .rodata:

  # ./bpftool m d i 150
  [{
          "value": {
              ".rodata": [{
                      "load_static_data.bar": 18446744073709551615
                  },{
                      "num2": 24
                  },{
                      "num5": 43947
                  },{
                      "num6": 171
                  },{
                      "str0": [97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,0,0,0,0,0,0
                      ]
                  },{
                      "struct0": {
                          "a": 42,
                          "b": 4278120431,
                          "c": 1229782938247303441
                      }
                  },{
                      "struct2": {
                          "a": 0,
                          "b": 0,
                          "c": 0
                      }
                  }
              ]
          }
      }
  ]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2019-04-09 23:20:15 +02:00 committed by Alexei Starovoitov
parent 1713d68b3b
commit 817998afa0
2 changed files with 65 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
tools/bpf/bpftool/btf_dumper.c
View File

@ -309,6 +309,48 @@ static int btf_dumper_struct(const struct btf_dumper *d, __u32 type_id,
return ret;
}
static int btf_dumper_var(const struct btf_dumper *d, __u32 type_id,
__u8 bit_offset, const void *data)
{
const struct btf_type *t = btf__type_by_id(d->btf, type_id);
int ret;
jsonw_start_object(d->jw);
jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
ret = btf_dumper_do_type(d, t->type, bit_offset, data);
jsonw_end_object(d->jw);
return ret;
}
static int btf_dumper_datasec(const struct btf_dumper *d, __u32 type_id,
const void *data)
{
struct btf_var_secinfo *vsi;
const struct btf_type *t;
int ret = 0, i, vlen;
t = btf__type_by_id(d->btf, type_id);
if (!t)
return -EINVAL;
vlen = BTF_INFO_VLEN(t->info);
vsi = (struct btf_var_secinfo *)(t + 1);
jsonw_start_object(d->jw);
jsonw_name(d->jw, btf__name_by_offset(d->btf, t->name_off));
jsonw_start_array(d->jw);
for (i = 0; i < vlen; i++) {
ret = btf_dumper_do_type(d, vsi[i].type, 0, data + vsi[i].offset);
if (ret)
break;
}
jsonw_end_array(d->jw);
jsonw_end_object(d->jw);
return ret;
}
static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
__u8 bit_offset, const void *data)
{
@ -341,6 +383,10 @@ static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id,
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
return btf_dumper_modifier(d, type_id, bit_offset, data);
case BTF_KIND_VAR:
return btf_dumper_var(d, type_id, bit_offset, data);
case BTF_KIND_DATASEC:
return btf_dumper_datasec(d, type_id, data);
default:
jsonw_printf(d->jw, "(unsupported-kind");
return -EINVAL;
@ -377,6 +423,7 @@ static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
{
const struct btf_type *proto_type;
const struct btf_array *array;
const struct btf_var *var;
const struct btf_type *t;
if (!type_id) {
@ -440,6 +487,18 @@ static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
if (pos == -1)
return -1;
break;
case BTF_KIND_VAR:
var = (struct btf_var *)(t + 1);
if (var->linkage == BTF_VAR_STATIC)
BTF_PRINT_ARG("static ");
BTF_PRINT_TYPE(t->type);
BTF_PRINT_ARG(" %s",
btf__name_by_offset(btf, t->name_off));
break;
case BTF_KIND_DATASEC:
BTF_PRINT_ARG("section (\"%s\") ",
btf__name_by_offset(btf, t->name_off));
break;
case BTF_KIND_UNKN:
default:
return -1;

10
tools/bpf/bpftool/map.c
View File

@ -153,11 +153,13 @@ static int do_dump_btf(const struct btf_dumper *d,
/* start of key-value pair */
jsonw_start_object(d->jw);
jsonw_name(d->jw, "key");
if (map_info->btf_key_type_id) {
jsonw_name(d->jw, "key");
ret = btf_dumper_type(d, map_info->btf_key_type_id, key);
if (ret)
goto err_end_obj;
ret = btf_dumper_type(d, map_info->btf_key_type_id, key);
if (ret)
goto err_end_obj;
}
if (!map_is_per_cpu(map_info->type)) {
jsonw_name(d->jw, "value");