Support BTF_KIND_TYPE_TAG for btf_type_tag attributes

.github/workflows/test.yml

@@ -0,0 +1,34 @@
+name: bpf-ci
+
+on:
+  pull_request:
+
+concurrency: 
+  group: ci-test-${{ github.head_ref }}
+  cancel-in-progress: true
+
+jobs:
+  VM_Test:
+    timeout-minutes: 100
+    runs-on: ubuntu-latest
+    env:
+      PROJECT_NAME: 'libbpf'
+      AUTHOR_EMAIL: "$(git log -1 --pretty=\"%aE\")"
+      KERNEL: LATEST
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: install
+        run: sudo apt-get update && sudo apt-get install aptitude qemu-kvm zstd binutils-dev elfutils libcap-dev libelf-dev libdw-dev python3-docutils
+      - name: Get bpf-next source
+        if: ${{ github.repository == 'kernel-patches/vmtest' }}
+        uses: actions/checkout@v2
+        with:
+          repository: kernel-patches/bpf
+          ref: 'bpf-next'
+          path: 'linux'
+      - name: Move linux source in place
+        if: ${{ github.repository == 'kernel-patches/vmtest' }}
+        run: rsync --exclude .git -av linux/. . && rm -rf linux
+      - name: Kernel LATEST + selftests
+        run: export REPO_ROOT=$GITHUB_WORKSPACE; export CI_ROOT=$REPO_ROOT/travis-ci; export VMTEST_ROOT=$CI_ROOT/vmtest; ${CI_ROOT}/vmtest/run_vmtest.sh || exit 1

Documentation/bpf/btf.rst

@@ -86,6 +86,7 @@ sequentially and type id is assigned to each recognized type starting from id
     #define BTF_KIND_DATASEC        15      /* Section      */
     #define BTF_KIND_FLOAT          16      /* Floating point       */
     #define BTF_KIND_DECL_TAG       17      /* Decl Tag     */
+    #define BTF_KIND_TYPE_TAG       18      /* Type Tag     */
 
 Note that the type section encodes debug info, not just pure types.
 ``BTF_KIND_FUNC`` is not a type, and it represents a defined subprogram.
@@ -107,7 +108,7 @@ Each type contains the following common data::
          * "size" tells the size of the type it is describing.
          *
          * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
-         * FUNC, FUNC_PROTO and DECL_TAG.
+         * FUNC, FUNC_PROTO, DECL_TAG and TYPE_TAG.
          * "type" is a type_id referring to another type.
          */
         union {
@@ -492,6 +493,16 @@ the attribute is applied to a ``struct``/``union`` member or
 a ``func`` argument, and ``btf_decl_tag.component_idx`` should be a
 valid index (starting from 0) pointing to a member or an argument.
 
+2.2.17 BTF_KIND_TYPE_TAG
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+``struct btf_type`` encoding requirement:
+ * ``name_off``: offset to a non-empty string
+ * ``info.kind_flag``: 0
+ * ``info.kind``: BTF_KIND_TYPE_TAG
+ * ``info.vlen``: 0
+ * ``type``: the type with ``btf_type_tag`` attribute
+
 3. BTF Kernel API
 *****************
 

README

@@ -1,18 +0,0 @@
-Linux kernel
-============
-
-There are several guides for kernel developers and users. These guides can
-be rendered in a number of formats, like HTML and PDF. Please read
-Documentation/admin-guide/README.rst first.
-
-In order to build the documentation, use ``make htmldocs`` or
-``make pdfdocs``.  The formatted documentation can also be read online at:
-
-    https://www.kernel.org/doc/html/latest/
-
-There are various text files in the Documentation/ subdirectory,
-several of them using the Restructured Text markup notation.
-
-Please read the Documentation/process/changes.rst file, as it contains the
-requirements for building and running the kernel, and information about
-the problems which may result by upgrading your kernel.

include/uapi/linux/btf.h

@@ -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 DECL_TAG.
+	 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG.
 	 * "type" is a type_id referring to another type.
 	 */
 	union {
@@ -75,6 +75,7 @@ enum {
 	BTF_KIND_DATASEC	= 15,	/* Section	*/
 	BTF_KIND_FLOAT		= 16,	/* Floating point	*/
 	BTF_KIND_DECL_TAG	= 17,	/* Decl Tag */
+	BTF_KIND_TYPE_TAG	= 18,	/* Type Tag */
 
 	NR_BTF_KINDS,
 	BTF_KIND_MAX		= NR_BTF_KINDS - 1,

kernel/bpf/btf.c

@@ -282,6 +282,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
 	[BTF_KIND_DATASEC]	= "DATASEC",
 	[BTF_KIND_FLOAT]	= "FLOAT",
 	[BTF_KIND_DECL_TAG]	= "DECL_TAG",
+	[BTF_KIND_TYPE_TAG]	= "TYPE_TAG",
 };
 
 const char *btf_type_str(const struct btf_type *t)
@@ -418,6 +419,7 @@ static bool btf_type_is_modifier(const struct btf_type *t)
 	case BTF_KIND_VOLATILE:
 	case BTF_KIND_CONST:
 	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPE_TAG:
 		return true;
 	}
 
@@ -1737,6 +1739,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type,
 		case BTF_KIND_VOLATILE:
 		case BTF_KIND_CONST:
 		case BTF_KIND_RESTRICT:
+		case BTF_KIND_TYPE_TAG:
 			id = type->type;
 			type = btf_type_by_id(btf, type->type);
 			break;
@@ -2345,6 +2348,8 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env,
 				   const struct btf_type *t,
 				   u32 meta_left)
 {
+	const char *value;
+
 	if (btf_type_vlen(t)) {
 		btf_verifier_log_type(env, t, "vlen != 0");
 		return -EINVAL;
@@ -2360,7 +2365,7 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env,
 		return -EINVAL;
 	}
 
-	/* typedef type must have a valid name, and other ref types,
+	/* typedef/type_tag type must have a valid name, and other ref types,
 	 * volatile, const, restrict, should have a null name.
 	 */
 	if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
@@ -2369,6 +2374,12 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env,
 			btf_verifier_log_type(env, t, "Invalid name");
 			return -EINVAL;
 		}
+	} else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
+		value = btf_name_by_offset(env->btf, t->name_off);
+		if (!value || !value[0]) {
+			btf_verifier_log_type(env, t, "Invalid name");
+			return -EINVAL;
+		}
 	} else {
 		if (t->name_off) {
 			btf_verifier_log_type(env, t, "Invalid name");
@@ -4059,6 +4070,7 @@ static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
 	[BTF_KIND_DATASEC] = &datasec_ops,
 	[BTF_KIND_FLOAT] = &float_ops,
 	[BTF_KIND_DECL_TAG] = &decl_tag_ops,
+	[BTF_KIND_TYPE_TAG] = &modifier_ops,
 };
 
 static s32 btf_check_meta(struct btf_verifier_env *env,

tools/bpf/bpftool/btf.c

@@ -39,6 +39,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
 	[BTF_KIND_DATASEC]	= "DATASEC",
 	[BTF_KIND_FLOAT]	= "FLOAT",
 	[BTF_KIND_DECL_TAG]	= "DECL_TAG",
+	[BTF_KIND_TYPE_TAG]	= "TYPE_TAG",
 };
 
 struct btf_attach_point {
@@ -142,6 +143,7 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	case BTF_KIND_VOLATILE:
 	case BTF_KIND_RESTRICT:
 	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_TYPE_TAG:
 		if (json_output)
 			jsonw_uint_field(w, "type_id", t->type);
 		else

tools/include/uapi/linux/btf.h

@@ -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 DECL_TAG.
+	 * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG.
 	 * "type" is a type_id referring to another type.
 	 */
 	union {
@@ -75,6 +75,7 @@ enum {
 	BTF_KIND_DATASEC	= 15,	/* Section	*/
 	BTF_KIND_FLOAT		= 16,	/* Floating point	*/
 	BTF_KIND_DECL_TAG	= 17,	/* Decl Tag */
+	BTF_KIND_TYPE_TAG	= 18,	/* Type Tag */
 
 	NR_BTF_KINDS,
 	BTF_KIND_MAX		= NR_BTF_KINDS - 1,

tools/lib/bpf/btf.c

@@ -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: {

tools/lib/bpf/btf.h

@@ -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));

tools/lib/bpf/btf_dump.c

@@ -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 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
 		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;