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libbpf: Support BTF_KIND_TYPE_TAG 

Add libbpf support for BTF_KIND_TYPE_TAG.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012614.1505315-1-yhs@fb.com
This commit is contained in:
Yonghong Song 2021-11-11 17:26:14 -08:00 committed by Alexei Starovoitov
parent 8c42d2fa4e
commit 2dc1e488e5
6 changed files with 73 additions and 2 deletions
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23
tools/lib/bpf/btf.c
View File

@ -299,6 +299,7 @@ static int btf_type_size(const struct btf_type *t)
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_FLOAT:
case BTF_KIND_TYPE_TAG:
return base_size;
case BTF_KIND_INT:
return base_size + sizeof(__u32);
@ -349,6 +350,7 @@ static int btf_bswap_type_rest(struct btf_type *t)
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_FLOAT:
case BTF_KIND_TYPE_TAG:
return 0;
case BTF_KIND_INT:
*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
@ -649,6 +651,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
return btf__align_of(btf, t->type);
case BTF_KIND_ARRAY:
return btf__align_of(btf, btf_array(t)->type);
@ -2235,6 +2238,22 @@ int btf__add_restrict(struct btf *btf, int ref_type_id)
return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
}
/*
* Append new BTF_KIND_TYPE_TAG type with:
* - *value*, non-empty/non-NULL tag value;
* - *ref_type_id* - referenced type ID, it might not exist yet;
* Returns:
* - >0, type ID of newly added BTF type;
* - <0, on error.
*/
int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
{
if (!value|| !value[0])
return libbpf_err(-EINVAL);
return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
}
/*
* Append new BTF_KIND_FUNC type with:
* - *name*, non-empty/non-NULL name;
@ -3639,6 +3658,7 @@ static int btf_dedup_prep(struct btf_dedup *d)
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_FLOAT:
case BTF_KIND_TYPE_TAG:
h = btf_hash_common(t);
break;
case BTF_KIND_INT:
@ -3699,6 +3719,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_VAR:
case BTF_KIND_DATASEC:
case BTF_KIND_DECL_TAG:
case BTF_KIND_TYPE_TAG:
return 0;
case BTF_KIND_INT:
@ -4297,6 +4318,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_TYPE_TAG:
ref_type_id = btf_dedup_ref_type(d, t->type);
if (ref_type_id < 0)
return ref_type_id;
@ -4603,6 +4625,7 @@ int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ct
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_DECL_TAG:
case BTF_KIND_TYPE_TAG:
return visit(&t->type, ctx);
case BTF_KIND_ARRAY: {

9
tools/lib/bpf/btf.h
View File

@ -227,6 +227,7 @@ LIBBPF_API int btf__add_typedef(struct btf *btf, const char *name, int ref_type_
LIBBPF_API int btf__add_volatile(struct btf *btf, int ref_type_id);
LIBBPF_API int btf__add_const(struct btf *btf, int ref_type_id);
LIBBPF_API int btf__add_restrict(struct btf *btf, int ref_type_id);
LIBBPF_API int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id);
/* func and func_proto construction APIs */
LIBBPF_API int btf__add_func(struct btf *btf, const char *name,
@ -458,7 +459,8 @@ static inline bool btf_is_mod(const struct btf_type *t)
return kind == BTF_KIND_VOLATILE ||
kind == BTF_KIND_CONST ||
kind == BTF_KIND_RESTRICT;
kind == BTF_KIND_RESTRICT ||
kind == BTF_KIND_TYPE_TAG;
}
static inline bool btf_is_func(const struct btf_type *t)
@ -491,6 +493,11 @@ static inline bool btf_is_decl_tag(const struct btf_type *t)
return btf_kind(t) == BTF_KIND_DECL_TAG;
}
static inline bool btf_is_type_tag(const struct btf_type *t)
{
return btf_kind(t) == BTF_KIND_TYPE_TAG;
}
static inline __u8 btf_int_encoding(const struct btf_type *t)
{
return BTF_INT_ENCODING(*(__u32 *)(t + 1));

9
tools/lib/bpf/btf_dump.c
View File

@ -330,6 +330,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d)
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_DECL_TAG:
case BTF_KIND_TYPE_TAG:
d->type_states[t->type].referenced = 1;
break;
@ -573,6 +574,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
return btf_dump_order_type(d, t->type, through_ptr);
case BTF_KIND_FUNC_PROTO: {
@ -747,6 +749,7 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
btf_dump_emit_type(d, t->type, cont_id);
break;
case BTF_KIND_ARRAY:
@ -1167,6 +1170,7 @@ skip_mod:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_FUNC_PROTO:
case BTF_KIND_TYPE_TAG:
id = t->type;
break;
case BTF_KIND_ARRAY:
@ -1335,6 +1339,11 @@ static void btf_dump_emit_type_chain(struct btf_dump *d,
case BTF_KIND_RESTRICT:
btf_dump_printf(d, " restrict");
break;
case BTF_KIND_TYPE_TAG:
btf_dump_emit_mods(d, decls);
name = btf_name_of(d, t->name_off);
btf_dump_printf(d, " __attribute__((btf_type_tag(\"%s\")))", name);
break;
case BTF_KIND_ARRAY: {
const struct btf_array *a = btf_array(t);
const struct btf_type *next_t;

31
tools/lib/bpf/libbpf.c
View File

@ -197,6 +197,8 @@ enum kern_feature_id {
FEAT_PERF_LINK,
/* BTF_KIND_DECL_TAG support */
FEAT_BTF_DECL_TAG,
/* BTF_KIND_TYPE_TAG support */
FEAT_BTF_TYPE_TAG,
__FEAT_CNT,
};
@ -2076,6 +2078,7 @@ static const char *__btf_kind_str(__u16 kind)
case BTF_KIND_DATASEC: return "datasec";
case BTF_KIND_FLOAT: return "float";
case BTF_KIND_DECL_TAG: return "decl_tag";
case BTF_KIND_TYPE_TAG: return "type_tag";
default: return "unknown";
}
}
@ -2588,8 +2591,10 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
return !has_func || !has_datasec || !has_func_global || !has_float || !has_decl_tag;
return !has_func || !has_datasec || !has_func_global || !has_float ||
!has_decl_tag || !has_type_tag;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@ -2599,6 +2604,7 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
struct btf_type *t;
int i, j, vlen;
@ -2657,6 +2663,10 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
*/
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
} else if (!has_type_tag && btf_is_type_tag(t)) {
/* replace TYPE_TAG with a CONST */
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
}
}
}
@ -4460,6 +4470,22 @@ static int probe_kern_btf_decl_tag(void)
strs, sizeof(strs)));
}
static int probe_kern_btf_type_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* attr */
BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */
/* ptr */
BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs)));
}
static int probe_kern_array_mmap(void)
{
struct bpf_create_map_attr attr = {
@ -4657,6 +4683,9 @@ static struct kern_feature_desc {
[FEAT_BTF_DECL_TAG] = {
"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
},
[FEAT_BTF_TYPE_TAG] = {
"BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
},
};
static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)

1
tools/lib/bpf/libbpf.map
View File

@ -403,6 +403,7 @@ LIBBPF_0.6.0 {
bpf_program__set_extra_flags;
btf__add_btf;
btf__add_decl_tag;
btf__add_type_tag;
btf__dedup;
btf__dedup_deprecated;
btf__raw_data;

2
tools/lib/bpf/libbpf_internal.h
View File

@ -73,6 +73,8 @@
BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
#define BTF_TYPE_DECL_TAG_ENC(value, type, component_idx) \
BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_DECL_TAG, 0, 0), type), (component_idx)
#define BTF_TYPE_TYPE_TAG_ENC(value, type) \
BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TYPE_TAG, 0, 0), type)
#ifndef likely
#define likely(x) __builtin_expect(!!(x), 1)