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author | Yonghong Song <yhs@fb.com> | 2018-11-28 09:38:23 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-13 08:52:10 +0100 |
commit | 29e704b7a7b119291511a9f18bd2c46da50cf4f7 (patch) | |
tree | 48065b98bf4fbe94fd802e88bfa586b5da188d52 /tools/bpf | |
parent | 12c49ac4cfa935ba76cde8f717c49d422e05e7bb (diff) | |
download | linux-stable-29e704b7a7b119291511a9f18bd2c46da50cf4f7.tar.gz linux-stable-29e704b7a7b119291511a9f18bd2c46da50cf4f7.tar.bz2 linux-stable-29e704b7a7b119291511a9f18bd2c46da50cf4f7.zip |
tools: bpftool: fix a bitfield pretty print issue
[ Upstream commit 528bff0cdb6649f97f2c4802e4ac7a4b50645f2f ]
Commit b12d6ec09730 ("bpf: btf: add btf print functionality")
added btf pretty print functionality to bpftool.
There is a problem though in printing a bitfield whose type
has modifiers.
For example, for a type like
typedef int ___int;
struct tmp_t {
int a:3;
___int b:3;
};
Suppose we have a map
struct bpf_map_def SEC("maps") tmpmap = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(__u32),
.value_size = sizeof(struct tmp_t),
.max_entries = 1,
};
and the hash table is populated with one element with
key 0 and value (.a = 1 and .b = 2).
In BTF, the struct member "b" will have a type "typedef" which
points to an int type. The current implementation does not
pass the bit offset during transition from typedef to int type,
hence incorrectly print the value as
$ bpftool m d id 79
[{
"key": 0,
"value": {
"a": 0x1,
"b": 0x1
}
}
]
This patch fixed the issue by carrying bit_offset along the type
chain during bit_field print. The correct result can be printed as
$ bpftool m d id 76
[{
"key": 0,
"value": {
"a": 0x1,
"b": 0x2
}
}
]
The kernel pretty print is implemented correctly and does not
have this issue.
Fixes: b12d6ec09730 ("bpf: btf: add btf print functionality")
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'tools/bpf')
-rw-r--r-- | tools/bpf/bpftool/btf_dumper.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c index 55bc512a1831..e4e6e2b3fd84 100644 --- a/tools/bpf/bpftool/btf_dumper.c +++ b/tools/bpf/bpftool/btf_dumper.c @@ -32,7 +32,7 @@ static void btf_dumper_ptr(const void *data, json_writer_t *jw, } static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id, - const void *data) + __u8 bit_offset, const void *data) { int actual_type_id; @@ -40,7 +40,7 @@ static int btf_dumper_modifier(const struct btf_dumper *d, __u32 type_id, if (actual_type_id < 0) return actual_type_id; - return btf_dumper_do_type(d, actual_type_id, 0, data); + return btf_dumper_do_type(d, actual_type_id, bit_offset, data); } static void btf_dumper_enum(const void *data, json_writer_t *jw) @@ -237,7 +237,7 @@ static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id, case BTF_KIND_VOLATILE: case BTF_KIND_CONST: case BTF_KIND_RESTRICT: - return btf_dumper_modifier(d, type_id, data); + return btf_dumper_modifier(d, type_id, bit_offset, data); default: jsonw_printf(d->jw, "(unsupported-kind"); return -EINVAL; |