Add the following functions to libbpf API:
* btf__add_type_attr()
* btf__add_decl_attr()
These functions allow to add to BTF the type tags and decl tags with
info->kflag set to 1. The kflag indicates that the tag directly
encodes an __attribute__ and not a normal tag.
See Documentation/bpf/btf.rst changes in the subsequent patch for
details on the semantics.
Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxxxxxx>
Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/lib/bpf/btf.c | 86 +++++++++++++++++++++++++++++-----------
tools/lib/bpf/btf.h | 3 ++
tools/lib/bpf/libbpf.map | 2 +
3 files changed, 68 insertions(+), 23 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 48c66f3a9200..f21862bab755 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2090,7 +2090,7 @@ static int validate_type_id(int id)
}
/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
-static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
+static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id, int kflag)
{
struct btf_type *t;
int sz, name_off = 0;
@@ -2113,7 +2113,7 @@ static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref
}
t->name_off = name_off;
- t->info = btf_type_info(kind, 0, 0);
+ t->info = btf_type_info(kind, 0, kflag);
t->type = ref_type_id;
return btf_commit_type(btf, sz);
@@ -2128,7 +2128,7 @@ static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref
*/
int btf__add_ptr(struct btf *btf, int ref_type_id)
{
- return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
+ return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id, 0);
}
/*
@@ -2506,7 +2506,7 @@ int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
struct btf_type *t;
int id;
- id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
+ id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0, 0);
if (id <= 0)
return id;
t = btf_type_by_id(btf, id);
@@ -2536,7 +2536,7 @@ int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
if (!name || !name[0])
return libbpf_err(-EINVAL);
- return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
+ return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id, 0);
}
/*
@@ -2548,7 +2548,7 @@ int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
*/
int btf__add_volatile(struct btf *btf, int ref_type_id)
{
- return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
+ return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id, 0);
}
/*
@@ -2560,7 +2560,7 @@ int btf__add_volatile(struct btf *btf, int ref_type_id)
*/
int btf__add_const(struct btf *btf, int ref_type_id)
{
- return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
+ return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id, 0);
}
/*
@@ -2572,7 +2572,7 @@ int btf__add_const(struct btf *btf, int ref_type_id)
*/
int btf__add_restrict(struct btf *btf, int ref_type_id)
{
- return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
+ return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id, 0);
}
/*
@@ -2588,7 +2588,24 @@ 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);
+ return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id, 0);
+}
+
+/*
+ * 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;
+ * Set info->kflag to 1, indicating this tag is an __attribute__
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_type_attr(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, 1);
}
/*
@@ -2610,7 +2627,7 @@ int btf__add_func(struct btf *btf, const char *name,
linkage != BTF_FUNC_EXTERN)
return libbpf_err(-EINVAL);
- id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
+ id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id, 0);
if (id > 0) {
struct btf_type *t = btf_type_by_id(btf, id);
@@ -2845,18 +2862,8 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
return 0;
}
-/*
- * 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
- * member or function argument index;
- * Returns:
- * - >0, type ID of newly added BTF type;
- * - <0, on error.
- */
-int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
- int component_idx)
+static int btf_add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
+ int component_idx, int kflag)
{
struct btf_type *t;
int sz, value_off;
@@ -2880,13 +2887,46 @@ int btf__add_decl_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_DECL_TAG, 0, false);
+ t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, kflag);
t->type = ref_type_id;
btf_decl_tag(t)->component_idx = component_idx;
return btf_commit_type(btf, sz);
}
+/*
+ * 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
+ * member or function argument index;
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
+ int component_idx)
+{
+ return btf_add_decl_tag(btf, value, ref_type_id, component_idx, 0);
+}
+
+/*
+ * 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
+ * member or function argument index;
+ * Set info->kflag to 1, indicating this tag is an __attribute__
+ * Returns:
+ * - >0, type ID of newly added BTF type;
+ * - <0, on error.
+ */
+int btf__add_decl_attr(struct btf *btf, const char *value, int ref_type_id,
+ int component_idx)
+{
+ return btf_add_decl_tag(btf, value, ref_type_id, component_idx, 1);
+}
+
struct btf_ext_sec_info_param {
__u32 off;
__u32 len;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 47ee8f6ac489..4392451d634b 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -227,6 +227,7 @@ 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);
+LIBBPF_API int btf__add_type_attr(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,
@@ -243,6 +244,8 @@ LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id,
/* tag construction API */
LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
int component_idx);
+LIBBPF_API int btf__add_decl_attr(struct btf *btf, const char *value, int ref_type_id,
+ int component_idx);
struct btf_dedup_opts {
size_t sz;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index a8b2936a1646..8616e10b3c1b 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -436,4 +436,6 @@ LIBBPF_1.6.0 {
bpf_linker__add_buf;
bpf_linker__add_fd;
bpf_linker__new_fd;
+ btf__add_decl_attr;
+ btf__add_type_attr;
} LIBBPF_1.5.0;
--
2.48.1
