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Merge branch 'bpf: add support for BTF_KIND_DECL_TAG typedef'

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Yonghong Song says:

====================

Latest upstream llvm-project added support for btf_decl_tag attributes
for typedef declarations ([1], [2]). Similar to other btf_decl_tag cases,
func/func_param/global_var/struct/union/field, btf_decl_tag with typedef
declaration can carry information from kernel source to clang compiler
and then to dwarf/BTF, for bpf verification or other use cases.

This patch set added kernel support for BTF_KIND_DECL_TAG to typedef
declaration (Patch 1). Additional selftests are added to cover
unit testing, dedup, or bpf program usage of btf_decl_tag with typedef.
(Patches 2, 3 and 4). The btf documentation is updated to include
BTF_KIND_DECL_TAG typedef (Patch 5).

  [1] https://reviews.llvm.org/D110127
  [2] https://reviews.llvm.org/D112259
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2021-10-22 17:04:44 -07:00
commit 1c50884370
4 changed files with 89 additions and 13 deletions
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6
Documentation/bpf/btf.rst
View File

@ -474,7 +474,7 @@ No additional type data follow ``btf_type``.
* ``info.kind_flag``: 0
* ``info.kind``: BTF_KIND_DECL_TAG
* ``info.vlen``: 0
* ``type``: ``struct``, ``union``, ``func`` or ``var``
* ``type``: ``struct``, ``union``, ``func``, ``var`` or ``typedef``
``btf_type`` is followed by ``struct btf_decl_tag``.::
@ -483,8 +483,8 @@ No additional type data follow ``btf_type``.
};
The ``name_off`` encodes btf_decl_tag attribute string.
The ``type`` should be ``struct``, ``union``, ``func`` or ``var``.
For ``var`` type, ``btf_decl_tag.component_idx`` must be ``-1``.
The ``type`` should be ``struct``, ``union``, ``func``, ``var`` or ``typedef``.
For ``var`` or ``typedef`` type, ``btf_decl_tag.component_idx`` must be ``-1``.
For the other three types, if the btf_decl_tag attribute is
applied to the ``struct``, ``union`` or ``func`` itself,
``btf_decl_tag.component_idx`` must be ``-1``. Otherwise,

4
kernel/bpf/btf.c
View File

@ -468,7 +468,7 @@ static bool btf_type_is_decl_tag(const struct btf_type *t)
static bool btf_type_is_decl_tag_target(const struct btf_type *t)
{
return btf_type_is_func(t) || btf_type_is_struct(t) ||
btf_type_is_var(t);
btf_type_is_var(t) || btf_type_is_typedef(t);
}
u32 btf_nr_types(const struct btf *btf)
@ -3885,7 +3885,7 @@ static int btf_decl_tag_resolve(struct btf_verifier_env *env,
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx != -1) {
if (btf_type_is_var(next_type)) {
if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid component_idx");
return -EINVAL;
}

83
tools/testing/selftests/bpf/prog_tests/btf.c
View File

@ -3903,6 +3903,42 @@ static struct btf_raw_test raw_tests[] = {
.btf_load_err = true,
.err_str = "Invalid component_idx",
},
{
.descr = "decl_tag test #13, typedef, well-formed",
.raw_types = {
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
BTF_TYPEDEF_ENC(NAME_TBD, 1), /* [2] */
BTF_DECL_TAG_ENC(NAME_TBD, 2, -1),
BTF_END_RAW,
},
BTF_STR_SEC("\0t\0tag"),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "tag_type_check_btf",
.key_size = sizeof(int),
.value_size = 4,
.key_type_id = 1,
.value_type_id = 1,
.max_entries = 1,
},
{
.descr = "decl_tag test #14, typedef, invalid component_idx",
.raw_types = {
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
BTF_TYPEDEF_ENC(NAME_TBD, 1), /* [2] */
BTF_DECL_TAG_ENC(NAME_TBD, 2, 0),
BTF_END_RAW,
},
BTF_STR_SEC("\0local\0tag"),
.map_type = BPF_MAP_TYPE_ARRAY,
.map_name = "tag_type_check_btf",
.key_size = sizeof(int),
.value_size = 4,
.key_type_id = 1,
.value_type_id = 1,
.max_entries = 1,
.btf_load_err = true,
.err_str = "Invalid component_idx",
},
}; /* struct btf_raw_test raw_tests[] */
@ -6841,11 +6877,12 @@ const struct btf_dedup_test dedup_tests[] = {
BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),
BTF_FUNC_ENC(NAME_TBD, 12), /* [13] func */
BTF_TYPE_FLOAT_ENC(NAME_TBD, 2), /* [14] float */
BTF_DECL_TAG_ENC(NAME_TBD, 13, -1), /* [15] tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, 1), /* [16] tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, -1), /* [15] decl_tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, 1), /* [16] decl_tag */
BTF_DECL_TAG_ENC(NAME_TBD, 7, -1), /* [17] decl_tag */
BTF_END_RAW,
},
BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P"),
BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P\0Q"),
},
.expect = {
.raw_types = {
@ -6869,11 +6906,12 @@ const struct btf_dedup_test dedup_tests[] = {
BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),
BTF_FUNC_ENC(NAME_TBD, 12), /* [13] func */
BTF_TYPE_FLOAT_ENC(NAME_TBD, 2), /* [14] float */
BTF_DECL_TAG_ENC(NAME_TBD, 13, -1), /* [15] tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, 1), /* [16] tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, -1), /* [15] decl_tag */
BTF_DECL_TAG_ENC(NAME_TBD, 13, 1), /* [16] decl_tag */
BTF_DECL_TAG_ENC(NAME_TBD, 7, -1), /* [17] decl_tag */
BTF_END_RAW,
},
BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P"),
BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P\0Q"),
},
.opts = {
.dont_resolve_fwds = false,
@ -7168,6 +7206,39 @@ const struct btf_dedup_test dedup_tests[] = {
.dont_resolve_fwds = false,
},
},
{
.descr = "dedup: typedef tags",
.input = {
.raw_types = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
BTF_TYPEDEF_ENC(NAME_NTH(1), 1), /* [2] */
BTF_TYPEDEF_ENC(NAME_NTH(1), 1), /* [3] */
/* tag -> t: tag1, tag2 */
BTF_DECL_TAG_ENC(NAME_NTH(2), 2, -1), /* [4] */
BTF_DECL_TAG_ENC(NAME_NTH(3), 2, -1), /* [5] */
/* tag -> t: tag1, tag3 */
BTF_DECL_TAG_ENC(NAME_NTH(2), 3, -1), /* [6] */
BTF_DECL_TAG_ENC(NAME_NTH(4), 3, -1), /* [7] */
BTF_END_RAW,
},
BTF_STR_SEC("\0t\0tag1\0tag2\0tag3"),
},
.expect = {
.raw_types = {
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
BTF_TYPEDEF_ENC(NAME_NTH(1), 1), /* [2] */
BTF_DECL_TAG_ENC(NAME_NTH(2), 2, -1), /* [3] */
BTF_DECL_TAG_ENC(NAME_NTH(3), 2, -1), /* [4] */
BTF_DECL_TAG_ENC(NAME_NTH(4), 2, -1), /* [5] */
BTF_END_RAW,
},
BTF_STR_SEC("\0t\0tag1\0tag2\0tag3"),
},
.opts = {
.dont_resolve_fwds = false,
},
},
};

9
tools/testing/selftests/bpf/progs/tag.c
View File

@ -24,18 +24,23 @@ struct key_t {
int c;
} __tag1 __tag2;
typedef struct {
int a;
int b;
} value_t __tag1 __tag2;
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 3);
__type(key, struct key_t);
__type(value, __u64);
__type(value, value_t);
} hashmap1 SEC(".maps");
static __noinline int foo(int x __tag1 __tag2) __tag1 __tag2
{
struct key_t key;
__u64 val = 1;
value_t val = {};
key.a = key.b = key.c = x;
bpf_map_update_elem(&hashmap1, &key, &val, 0);