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bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG

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Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.

After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).

This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].

 [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
 [2] https://reviews.llvm.org/D111588
 [3] https://reviews.llvm.org/D111199

Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
This commit is contained in:
Yonghong Song
2021-10-12 09:48:38 -07:00
committed by Andrii Nakryiko
parent ebf17ac628
commit 0f3ba10651
7 changed files with 46 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
include/uapi/linux/btf.h
View File

@@ -43,7 +43,7 @@ struct btf_type {
* "size" tells the size of the type it is describing.
*
* "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
* FUNC, FUNC_PROTO, VAR and TAG.
* FUNC, FUNC_PROTO, VAR and DECL_TAG.
* "type" is a type_id referring to another type.
*/
union {
@@ -74,7 +74,7 @@ enum {
BTF_KIND_VAR = 14, /* Variable */
BTF_KIND_DATASEC = 15, /* Section */
BTF_KIND_FLOAT = 16, /* Floating point */
BTF_KIND_TAG = 17, /* Tag */
BTF_KIND_DECL_TAG = 17, /* Decl Tag */
NR_BTF_KINDS,
BTF_KIND_MAX = NR_BTF_KINDS - 1,
@@ -174,14 +174,14 @@ struct btf_var_secinfo {
__u32 size;
};
/* BTF_KIND_TAG is followed by a single "struct btf_tag" to describe
/* BTF_KIND_DECL_TAG is followed by a single "struct btf_decl_tag" to describe
* additional information related to the tag applied location.
* If component_idx == -1, the tag is applied to a struct, union,
* variable or function. Otherwise, it is applied to a struct/union
* member or a func argument, and component_idx indicates which member
* or argument (0 ... vlen-1).
*/
struct btf_tag {
struct btf_decl_tag {
__s32 component_idx;
};

36
src/btf.c
View File

@@ -309,8 +309,8 @@ static int btf_type_size(const struct btf_type *t)
return base_size + sizeof(struct btf_var);
case BTF_KIND_DATASEC:
return base_size + vlen * sizeof(struct btf_var_secinfo);
case BTF_KIND_TAG:
return base_size + sizeof(struct btf_tag);
case BTF_KIND_DECL_TAG:
return base_size + sizeof(struct btf_decl_tag);
default:
pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
return -EINVAL;
@@ -383,8 +383,8 @@ static int btf_bswap_type_rest(struct btf_type *t)
v->size = bswap_32(v->size);
}
return 0;
case BTF_KIND_TAG:
btf_tag(t)->component_idx = bswap_32(btf_tag(t)->component_idx);
case BTF_KIND_DECL_TAG:
btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
return 0;
default:
pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
@@ -596,7 +596,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_VAR:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
type_id = t->type;
break;
case BTF_KIND_ARRAY:
@@ -2569,7 +2569,7 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
}
/*
* Append new BTF_KIND_TAG type with:
* Append new BTF_KIND_DECL_TAG type with:
* - *value* - non-empty/non-NULL string;
* - *ref_type_id* - referenced type ID, it might not exist yet;
* - *component_idx* - -1 for tagging reference type, otherwise struct/union
@@ -2578,7 +2578,7 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
* - >0, type ID of newly added BTF type;
* - <0, on error.
*/
int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
int component_idx)
{
struct btf_type *t;
@@ -2593,7 +2593,7 @@ int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
if (btf_ensure_modifiable(btf))
return libbpf_err(-ENOMEM);
sz = sizeof(struct btf_type) + sizeof(struct btf_tag);
sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
t = btf_add_type_mem(btf, sz);
if (!t)
return libbpf_err(-ENOMEM);
@@ -2603,9 +2603,9 @@ int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
return value_off;
t->name_off = value_off;
t->info = btf_type_info(BTF_KIND_TAG, 0, false);
t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
t->type = ref_type_id;
btf_tag(t)->component_idx = component_idx;
btf_decl_tag(t)->component_idx = component_idx;
return btf_commit_type(btf, sz);
}
@@ -3427,7 +3427,7 @@ static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
}
/* Calculate type signature hash of INT or TAG. */
static long btf_hash_int_tag(struct btf_type *t)
static long btf_hash_int_decl_tag(struct btf_type *t)
{
__u32 info = *(__u32 *)(t + 1);
long h;
@@ -3705,8 +3705,8 @@ static int btf_dedup_prep(struct btf_dedup *d)
h = btf_hash_common(t);
break;
case BTF_KIND_INT:
case BTF_KIND_TAG:
h = btf_hash_int_tag(t);
case BTF_KIND_DECL_TAG:
h = btf_hash_int_decl_tag(t);
break;
case BTF_KIND_ENUM:
h = btf_hash_enum(t);
@@ -3761,11 +3761,11 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
case BTF_KIND_FUNC_PROTO:
case BTF_KIND_VAR:
case BTF_KIND_DATASEC:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
return 0;
case BTF_KIND_INT:
h = btf_hash_int_tag(t);
h = btf_hash_int_decl_tag(t);
for_each_dedup_cand(d, hash_entry, h) {
cand_id = (__u32)(long)hash_entry->value;
cand = btf_type_by_id(d->btf, cand_id);
@@ -4382,13 +4382,13 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
}
break;
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
ref_type_id = btf_dedup_ref_type(d, t->type);
if (ref_type_id < 0)
return ref_type_id;
t->type = ref_type_id;
h = btf_hash_int_tag(t);
h = btf_hash_int_decl_tag(t);
for_each_dedup_cand(d, hash_entry, h) {
cand_id = (__u32)(long)hash_entry->value;
cand = btf_type_by_id(d->btf, cand_id);
@@ -4671,7 +4671,7 @@ int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ct
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
return visit(&t->type, ctx);
case BTF_KIND_ARRAY: {

12
src/btf.h
View File

@@ -236,7 +236,7 @@ LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id,
__u32 offset, __u32 byte_sz);
/* tag construction API */
LIBBPF_API int btf__add_tag(struct btf *btf, const char *value, int ref_type_id,
LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
int component_idx);
struct btf_dedup_opts {
@@ -426,9 +426,9 @@ static inline bool btf_is_float(const struct btf_type *t)
return btf_kind(t) == BTF_KIND_FLOAT;
}
static inline bool btf_is_tag(const struct btf_type *t)
static inline bool btf_is_decl_tag(const struct btf_type *t)
{
return btf_kind(t) == BTF_KIND_TAG;
return btf_kind(t) == BTF_KIND_DECL_TAG;
}
static inline __u8 btf_int_encoding(const struct btf_type *t)
@@ -499,10 +499,10 @@ btf_var_secinfos(const struct btf_type *t)
return (struct btf_var_secinfo *)(t + 1);
}
struct btf_tag;
static inline struct btf_tag *btf_tag(const struct btf_type *t)
struct btf_decl_tag;
static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
{
return (struct btf_tag *)(t + 1);
return (struct btf_decl_tag *)(t + 1);
}
#ifdef __cplusplus

6
src/btf_dump.c
View File

@@ -316,7 +316,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d)
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
d->type_states[t->type].referenced = 1;
break;
@@ -584,7 +584,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_DATASEC:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
d->type_states[id].order_state = ORDERED;
return 0;
@@ -2217,7 +2217,7 @@ static int btf_dump_dump_type_data(struct btf_dump *d,
case BTF_KIND_FWD:
case BTF_KIND_FUNC:
case BTF_KIND_FUNC_PROTO:
case BTF_KIND_TAG:
case BTF_KIND_DECL_TAG:
err = btf_dump_unsupported_data(d, t, id);
break;
case BTF_KIND_INT:

24
src/libbpf.c
View File

@@ -195,8 +195,8 @@ enum kern_feature_id {
FEAT_BTF_FLOAT,
/* BPF perf link support */
FEAT_PERF_LINK,
/* BTF_KIND_TAG support */
FEAT_BTF_TAG,
/* BTF_KIND_DECL_TAG support */
FEAT_BTF_DECL_TAG,
__FEAT_CNT,
};
@@ -2024,7 +2024,7 @@ static const char *__btf_kind_str(__u16 kind)
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
case BTF_KIND_FLOAT: return "float";
case BTF_KIND_TAG: return "tag";
case BTF_KIND_DECL_TAG: return "decl_tag";
default: return "unknown";
}
}
@@ -2524,9 +2524,9 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
return !has_func || !has_datasec || !has_func_global || !has_float || !has_tag;
return !has_func || !has_datasec || !has_func_global || !has_float || !has_decl_tag;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2535,15 +2535,15 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_tag = kernel_supports(obj, FEAT_BTF_TAG);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
struct btf_type *t;
int i, j, vlen;
for (i = 1; i <= btf__get_nr_types(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
if ((!has_datasec && btf_is_var(t)) || (!has_tag && btf_is_tag(t))) {
/* replace VAR/TAG with INT */
if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
/* replace VAR/DECL_TAG with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
@@ -4248,7 +4248,7 @@ static int probe_kern_btf_float(void)
strs, sizeof(strs)));
}
static int probe_kern_btf_tag(void)
static int probe_kern_btf_decl_tag(void)
{
static const char strs[] = "\0tag";
__u32 types[] = {
@@ -4258,7 +4258,7 @@ static int probe_kern_btf_tag(void)
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* attr */
BTF_TYPE_TAG_ENC(1, 2, -1),
BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
@@ -4481,8 +4481,8 @@ static struct kern_feature_desc {
[FEAT_PERF_LINK] = {
"BPF perf link support", probe_perf_link,
},
[FEAT_BTF_TAG] = {
"BTF_KIND_TAG support", probe_kern_btf_tag,
[FEAT_BTF_DECL_TAG] = {
"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
},
};

2
src/libbpf.map
View File

@@ -394,5 +394,5 @@ LIBBPF_0.6.0 {
bpf_object__prev_map;
bpf_object__prev_program;
btf__add_btf;
btf__add_tag;
btf__add_decl_tag;
} LIBBPF_0.5.0;

4
src/libbpf_internal.h
View File

@@ -69,8 +69,8 @@
#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
#define BTF_TYPE_FLOAT_ENC(name, sz) \
BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
#define BTF_TYPE_TAG_ENC(value, type, component_idx) \
BTF_TYPE_ENC(value, BTF_INFO_ENC(BTF_KIND_TAG, 0, 0), type), (component_idx)
#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)
#ifndef likely
#define likely(x) __builtin_expect(!!(x), 1)