Merge branch 'libbpf-support-bpf-to-bpf-calls'

Andrii Nakryiko says:

====================
Currently, libbpf supports a limited form of BPF-to-BPF subprogram calls. The
restriction is that entry-point BPF program should use *all* of defined
sub-programs in BPF .o file. If any of the subprograms is not used, such
entry-point BPF program will be rejected by verifier as containing unreachable
dead code. This is not a big limitation for cases with single entry-point BPF
programs, but is quite a heavy restriction for multi-programs that use only
partially overlapping set of subprograms.

This patch set removes all such restrictions and adds complete support for
using BPF sub-program calls on BPF side. This is achieved through libbpf
tracking subprograms individually and detecting which subprograms are used by
any given entry-point BPF program, and subsequently only appending and
relocating code for just those used subprograms.

In addition, libbpf now also supports multiple entry-point BPF programs within
the same ELF section. This allows to structure code so that there are few
variants of BPF programs of the same type and attaching to the same target
(e.g., for tracepoints and kprobes) without the need to worry about ELF
section name clashes.

This patch set opens way for more wider adoption of BPF subprogram calls,
especially for real-world production use-cases with complicated net of
subprograms. This will allow to further scale BPF verification process through
good use of global functions, which can be verified independently. This is
also important prerequisite for static linking which allows static BPF
libraries to not worry about naming clashes for section names, as well as use
static non-inlined functions (subprograms) without worries of verifier
rejecting program due to dead code.

Patch set is structured as follows:
- patched 1-6 contain all the libbpf changes necessary to support multi-prog
  sections and bpf2bpf subcalls;
- patch 7 adds dedicated selftests validating all combinations of possible
  sub-calls (within and across sections, static vs global functions);
- patch 8 deprecated bpf_program__title() in favor of
  bpf_program__section_name(). The intent was to also deprecate
  bpf_object__find_program_by_title() as it's now non-sensical with multiple
  programs per section. But there were too many selftests uses of this and
  I didn't want to delay this patches further and make it even bigger, so left
  it for a follow up cleanup;
- patches 9-10 remove uses for title-related APIs from bpftool and
  bpf_program__title() use from selftests;
- patch 11 is converting fexit_bpf2bpf to have explicit subtest (it does
  contain 4 subtests, which are not handled as sub-tests);
- patches 12-14 convert few complicated BPF selftests to use __noinline
  functions to further validate correctness of libbpf's bpf2bpf processing
  logic.

v2->v3:
  - explained subprog relocation algorithm in more details (Alexei);
  - pyperf, strobelight and cls_redirect got new subprog variants, leaving
    other modes intact (Alexei);
v1->v2:
  - rename DEPRECATED to LIBBPF_DEPRECATED to avoid name clashes;
  - fix test_subprogs build;
  - convert a bunch of complicated selftests to __noinline (Alexei).
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/prog.c

@@ -1304,7 +1304,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		enum bpf_prog_type prog_type = common_prog_type;
 
 		if (prog_type == BPF_PROG_TYPE_UNSPEC) {
-			const char *sec_name = bpf_program__title(pos, false);
+			const char *sec_name = bpf_program__section_name(pos);
 
 			err = get_prog_type_by_name(sec_name, &prog_type,
 						    &expected_attach_type);
@@ -1398,7 +1398,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 		err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
 		if (err) {
 			p_err("failed to pin program %s",
-			      bpf_program__title(prog, false));
+			      bpf_program__section_name(prog));
 			goto err_close_obj;
 		}
 	} else {

tools/lib/bpf/btf.h

@@ -57,14 +57,16 @@ LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
 LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
 LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
 					     __u32 *size);
-LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
-					const struct btf_ext *btf_ext,
-					const char *sec_name, __u32 insns_cnt,
-					void **func_info, __u32 *cnt);
-LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
-					const struct btf_ext *btf_ext,
-					const char *sec_name, __u32 insns_cnt,
-					void **line_info, __u32 *cnt);
+LIBBPF_API LIBBPF_DEPRECATED("btf_ext__reloc_func_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
+int btf_ext__reloc_func_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **func_info, __u32 *cnt);
+LIBBPF_API LIBBPF_DEPRECATED("btf_ext__reloc_line_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
+int btf_ext__reloc_line_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **line_info, __u32 *cnt);
 LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
 LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
 

tools/lib/bpf/libbpf.c

@@ -73,8 +73,6 @@
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
-static struct bpf_program *bpf_object__find_prog_by_idx(struct bpf_object *obj,
-							int idx);
 static const struct btf_type *
 skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
 
@@ -193,6 +191,7 @@ struct reloc_desc {
 	int insn_idx;
 	int map_idx;
 	int sym_off;
+	bool processed;
 };
 
 struct bpf_sec_def;
@@ -217,20 +216,45 @@ struct bpf_sec_def {
  * linux/filter.h.
  */
 struct bpf_program {
-	/* Index in elf obj file, for relocation use. */
-	int idx;
-	char *name;
-	int prog_ifindex;
-	char *section_name;
 	const struct bpf_sec_def *sec_def;
-	/* section_name with / replaced by _; makes recursive pinning
+	char *sec_name;
+	size_t sec_idx;
+	/* this program's instruction offset (in number of instructions)
+	 * within its containing ELF section
+	 */
+	size_t sec_insn_off;
+	/* number of original instructions in ELF section belonging to this
+	 * program, not taking into account subprogram instructions possible
+	 * appended later during relocation
+	 */
+	size_t sec_insn_cnt;
+	/* Offset (in number of instructions) of the start of instruction
+	 * belonging to this BPF program  within its containing main BPF
+	 * program. For the entry-point (main) BPF program, this is always
+	 * zero. For a sub-program, this gets reset before each of main BPF
+	 * programs are processed and relocated and is used to determined
+	 * whether sub-program was already appended to the main program, and
+	 * if yes, at which instruction offset.
+	 */
+	size_t sub_insn_off;
+
+	char *name;
+	/* sec_name with / replaced by _; makes recursive pinning
 	 * in bpf_object__pin_programs easier
 	 */
 	char *pin_name;
+
+	/* instructions that belong to BPF program; insns[0] is located at
+	 * sec_insn_off instruction within its ELF section in ELF file, so
+	 * when mapping ELF file instruction index to the local instruction,
+	 * one needs to subtract sec_insn_off; and vice versa.
+	 */
 	struct bpf_insn *insns;
-	size_t insns_cnt, main_prog_cnt;
-	enum bpf_prog_type type;
-	bool load;
+	/* actual number of instruction in this BPF program's image; for
+	 * entry-point BPF programs this includes the size of main program
+	 * itself plus all the used sub-programs, appended at the end
+	 */
+	size_t insns_cnt;
 
 	struct reloc_desc *reloc_desc;
 	int nr_reloc;
@@ -246,7 +270,10 @@ struct bpf_program {
 	void *priv;
 	bpf_program_clear_priv_t clear_priv;
 
+	bool load;
+	enum bpf_prog_type type;
 	enum bpf_attach_type expected_attach_type;
+	int prog_ifindex;
 	__u32 attach_btf_id;
 	__u32 attach_prog_fd;
 	void *func_info;
@@ -384,7 +411,7 @@ struct bpf_object {
 	int kconfig_map_idx;
 
 	bool loaded;
-	bool has_pseudo_calls;
+	bool has_subcalls;
 
 	/*
 	 * Information when doing elf related work. Only valid if fd
@@ -446,6 +473,8 @@ static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
 static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr);
 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
 static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
+static int elf_sym_by_sec_off(const struct bpf_object *obj, size_t sec_idx,
+			      size_t off, __u32 sym_type, GElf_Sym *sym);
 
 void bpf_program__unload(struct bpf_program *prog)
 {
@@ -486,152 +515,160 @@ static void bpf_program__exit(struct bpf_program *prog)
 
 	bpf_program__unload(prog);
 	zfree(&prog->name);
-	zfree(&prog->section_name);
+	zfree(&prog->sec_name);
 	zfree(&prog->pin_name);
 	zfree(&prog->insns);
 	zfree(&prog->reloc_desc);
 
 	prog->nr_reloc = 0;
 	prog->insns_cnt = 0;
-	prog->idx = -1;
+	prog->sec_idx = -1;
 }
 
 static char *__bpf_program__pin_name(struct bpf_program *prog)
 {
 	char *name, *p;
 
-	name = p = strdup(prog->section_name);
+	name = p = strdup(prog->sec_name);
 	while ((p = strchr(p, '/')))
 		*p = '_';
 
 	return name;
 }
 
+static bool insn_is_subprog_call(const struct bpf_insn *insn)
+{
+	return BPF_CLASS(insn->code) == BPF_JMP &&
+	       BPF_OP(insn->code) == BPF_CALL &&
+	       BPF_SRC(insn->code) == BPF_K &&
+	       insn->src_reg == BPF_PSEUDO_CALL &&
+	       insn->dst_reg == 0 &&
+	       insn->off == 0;
+}
+
 static int
-bpf_program__init(void *data, size_t size, const char *section_name, int idx,
-		  struct bpf_program *prog)
+bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
+		      const char *name, size_t sec_idx, const char *sec_name,
+		      size_t sec_off, void *insn_data, size_t insn_data_sz)
 {
-	const size_t bpf_insn_sz = sizeof(struct bpf_insn);
+	int i;
 
-	if (size == 0 || size % bpf_insn_sz) {
-		pr_warn("corrupted section '%s', size: %zu\n",
-			section_name, size);
+	if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
+		pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
+			sec_name, name, sec_off, insn_data_sz);
 		return -EINVAL;
 	}
 
 	memset(prog, 0, sizeof(*prog));
+	prog->obj = obj;
+
+	prog->sec_idx = sec_idx;
+	prog->sec_insn_off = sec_off / BPF_INSN_SZ;
+	prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
+	/* insns_cnt can later be increased by appending used subprograms */
+	prog->insns_cnt = prog->sec_insn_cnt;
 
-	prog->section_name = strdup(section_name);
-	if (!prog->section_name) {
-		pr_warn("failed to alloc name for prog under section(%d) %s\n",
-			idx, section_name);
+	prog->type = BPF_PROG_TYPE_UNSPEC;
+	prog->load = true;
+
+	prog->instances.fds = NULL;
+	prog->instances.nr = -1;
+
+	prog->sec_name = strdup(sec_name);
+	if (!prog->sec_name)
+		goto errout;
+
+	prog->name = strdup(name);
+	if (!prog->name)
 		goto errout;
-	}
 
 	prog->pin_name = __bpf_program__pin_name(prog);
-	if (!prog->pin_name) {
-		pr_warn("failed to alloc pin name for prog under section(%d) %s\n",
-			idx, section_name);
+	if (!prog->pin_name)
 		goto errout;
-	}
 
-	prog->insns = malloc(size);
-	if (!prog->insns) {
-		pr_warn("failed to alloc insns for prog under section %s\n",
-			section_name);
+	prog->insns = malloc(insn_data_sz);
+	if (!prog->insns)
 		goto errout;
+	memcpy(prog->insns, insn_data, insn_data_sz);
+
+	for (i = 0; i < prog->insns_cnt; i++) {
+		if (insn_is_subprog_call(&prog->insns[i])) {
+			obj->has_subcalls = true;
+			break;
+		}
 	}
-	prog->insns_cnt = size / bpf_insn_sz;
-	memcpy(prog->insns, data, size);
-	prog->idx = idx;
-	prog->instances.fds = NULL;
-	prog->instances.nr = -1;
-	prog->type = BPF_PROG_TYPE_UNSPEC;
-	prog->load = true;
 
 	return 0;
 errout:
+	pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
 	bpf_program__exit(prog);
 	return -ENOMEM;
 }
 
 static int
-bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
-			const char *section_name, int idx)
+bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
+			 const char *sec_name, int sec_idx)
 {
-	struct bpf_program prog, *progs;
+	struct bpf_program *prog, *progs;
+	void *data = sec_data->d_buf;
+	size_t sec_sz = sec_data->d_size, sec_off, prog_sz;
 	int nr_progs, err;
-
-	err = bpf_program__init(data, size, section_name, idx, &prog);
-	if (err)
-		return err;
+	const char *name;
+	GElf_Sym sym;
 
 	progs = obj->programs;
 	nr_progs = obj->nr_programs;
+	sec_off = 0;
 
-	progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
-	if (!progs) {
-		/*
-		 * In this case the original obj->programs
-		 * is still valid, so don't need special treat for
-		 * bpf_close_object().
-		 */
-		pr_warn("failed to alloc a new program under section '%s'\n",
-			section_name);
-		bpf_program__exit(&prog);
-		return -ENOMEM;
-	}
-
-	pr_debug("elf: found program '%s'\n", prog.section_name);
-	obj->programs = progs;
-	obj->nr_programs = nr_progs + 1;
-	prog.obj = obj;
-	progs[nr_progs] = prog;
-	return 0;
-}
-
-static int
-bpf_object__init_prog_names(struct bpf_object *obj)
-{
-	Elf_Data *symbols = obj->efile.symbols;
-	struct bpf_program *prog;
-	size_t pi, si;
+	while (sec_off < sec_sz) {
+		if (elf_sym_by_sec_off(obj, sec_idx, sec_off, STT_FUNC, &sym)) {
+			pr_warn("sec '%s': failed to find program symbol at offset %zu\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
 
-	for (pi = 0; pi < obj->nr_programs; pi++) {
-		const char *name = NULL;
+		prog_sz = sym.st_size;
 
-		prog = &obj->programs[pi];
+		name = elf_sym_str(obj, sym.st_name);
+		if (!name) {
+			pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
 
-		for (si = 0; si < symbols->d_size / sizeof(GElf_Sym) && !name; si++) {
-			GElf_Sym sym;
+		if (sec_off + prog_sz > sec_sz) {
+			pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
+				sec_name, sec_off);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
 
-			if (!gelf_getsym(symbols, si, &sym))
-				continue;
-			if (sym.st_shndx != prog->idx)
-				continue;
-			if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
-				continue;
+		pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
+			 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
 
-			name = elf_sym_str(obj, sym.st_name);
-			if (!name) {
-				pr_warn("prog '%s': failed to get symbol name\n",
-					prog->section_name);
-				return -LIBBPF_ERRNO__LIBELF;
-			}
+		progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
+		if (!progs) {
+			/*
+			 * In this case the original obj->programs
+			 * is still valid, so don't need special treat for
+			 * bpf_close_object().
+			 */
+			pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
+				sec_name, name);
+			return -ENOMEM;
 		}
+		obj->programs = progs;
 
-		if (!name && prog->idx == obj->efile.text_shndx)
-			name = ".text";
+		prog = &progs[nr_progs];
 
-		if (!name) {
-			pr_warn("prog '%s': failed to find program symbol\n",
-				prog->section_name);
-			return -EINVAL;
-		}
+		err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
+					    sec_off, data + sec_off, prog_sz);
+		if (err)
+			return err;
 
-		prog->name = strdup(name);
-		if (!prog->name)
-			return -ENOMEM;
+		nr_progs++;
+		obj->nr_programs = nr_progs;
+
+		sec_off += prog_sz;
 	}
 
 	return 0;
@@ -2675,6 +2712,26 @@ static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
 	return data;
 }
 
+static int elf_sym_by_sec_off(const struct bpf_object *obj, size_t sec_idx,
+			      size_t off, __u32 sym_type, GElf_Sym *sym)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	size_t n = symbols->d_size / sizeof(GElf_Sym);
+	int i;
+
+	for (i = 0; i < n; i++) {
+		if (!gelf_getsym(symbols, i, sym))
+			continue;
+		if (sym->st_shndx != sec_idx || sym->st_value != off)
+			continue;
+		if (GELF_ST_TYPE(sym->st_info) != sym_type)
+			continue;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
 static bool is_sec_name_dwarf(const char *name)
 {
 	/* approximation, but the actual list is too long */
@@ -2715,19 +2772,55 @@ static bool ignore_elf_section(GElf_Shdr *hdr, const char *name)
 	return false;
 }
 
+static int cmp_progs(const void *_a, const void *_b)
+{
+	const struct bpf_program *a = _a;
+	const struct bpf_program *b = _b;
+
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx < b->sec_idx ? -1 : 1;
+
+	/* sec_insn_off can't be the same within the section */
+	return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
+}
+
 static int bpf_object__elf_collect(struct bpf_object *obj)
 {
 	Elf *elf = obj->efile.elf;
 	Elf_Data *btf_ext_data = NULL;
 	Elf_Data *btf_data = NULL;
-	Elf_Scn *scn = NULL;
 	int idx = 0, err = 0;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+	GElf_Shdr sh;
 
+	/* a bunch of ELF parsing functionality depends on processing symbols,
+	 * so do the first pass and find the symbol table
+	 */
+	scn = NULL;
 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
-		const char *name;
-		GElf_Shdr sh;
-		Elf_Data *data;
+		if (elf_sec_hdr(obj, scn, &sh))
+			return -LIBBPF_ERRNO__FORMAT;
+
+		if (sh.sh_type == SHT_SYMTAB) {
+			if (obj->efile.symbols) {
+				pr_warn("elf: multiple symbol tables in %s\n", obj->path);
+				return -LIBBPF_ERRNO__FORMAT;
+			}
 
+			data = elf_sec_data(obj, scn);
+			if (!data)
+				return -LIBBPF_ERRNO__FORMAT;
+
+			obj->efile.symbols = data;
+			obj->efile.symbols_shndx = elf_ndxscn(scn);
+			obj->efile.strtabidx = sh.sh_link;
+		}
+	}
+
+	scn = NULL;
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
 		idx++;
 
 		if (elf_sec_hdr(obj, scn, &sh))
@@ -2766,20 +2859,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
 			btf_ext_data = data;
 		} else if (sh.sh_type == SHT_SYMTAB) {
-			if (obj->efile.symbols) {
-				pr_warn("elf: multiple symbol tables in %s\n", obj->path);
-				return -LIBBPF_ERRNO__FORMAT;
-			}
-			obj->efile.symbols = data;
-			obj->efile.symbols_shndx = idx;
-			obj->efile.strtabidx = sh.sh_link;
+			/* already processed during the first pass above */
 		} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
 			if (sh.sh_flags & SHF_EXECINSTR) {
 				if (strcmp(name, ".text") == 0)
 					obj->efile.text_shndx = idx;
-				err = bpf_object__add_program(obj, data->d_buf,
-							      data->d_size,
-							      name, idx);
+				err = bpf_object__add_programs(obj, data, name, idx);
 				if (err)
 					return err;
 			} else if (strcmp(name, DATA_SEC) == 0) {
@@ -2833,6 +2918,11 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 		pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
 		return -LIBBPF_ERRNO__FORMAT;
 	}
+
+	/* sort BPF programs by section name and in-section instruction offset
+	 * for faster search */
+	qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
+
 	return bpf_object__init_btf(obj, btf_data, btf_ext_data);
 }
 
@@ -3157,20 +3247,6 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
 	return 0;
 }
 
-static struct bpf_program *
-bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
-{
-	struct bpf_program *prog;
-	size_t i;
-
-	for (i = 0; i < obj->nr_programs; i++) {
-		prog = &obj->programs[i];
-		if (prog->idx == idx)
-			return prog;
-	}
-	return NULL;
-}
-
 struct bpf_program *
 bpf_object__find_program_by_title(const struct bpf_object *obj,
 				  const char *title)
@@ -3178,12 +3254,18 @@ bpf_object__find_program_by_title(const struct bpf_object *obj,
 	struct bpf_program *pos;
 
 	bpf_object__for_each_program(pos, obj) {
-		if (pos->section_name && !strcmp(pos->section_name, title))
+		if (pos->sec_name && !strcmp(pos->sec_name, title))
 			return pos;
 	}
 	return NULL;
 }
 
+static bool prog_is_subprog(const struct bpf_object *obj,
+			    const struct bpf_program *prog)
+{
+	return prog->sec_idx == obj->efile.text_shndx && obj->has_subcalls;
+}
+
 struct bpf_program *
 bpf_object__find_program_by_name(const struct bpf_object *obj,
 				 const char *name)
@@ -3191,6 +3273,8 @@ bpf_object__find_program_by_name(const struct bpf_object *obj,
 	struct bpf_program *prog;
 
 	bpf_object__for_each_program(prog, obj) {
+		if (prog_is_subprog(obj, prog))
+			continue;
 		if (!strcmp(prog->name, name))
 			return prog;
 	}
@@ -3240,6 +3324,8 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 	const char *sym_sec_name;
 	struct bpf_map *map;
 
+	reloc_desc->processed = false;
+
 	/* sub-program call relocation */
 	if (insn->code == (BPF_JMP | BPF_CALL)) {
 		if (insn->src_reg != BPF_PSEUDO_CALL) {
@@ -3261,7 +3347,6 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 		reloc_desc->type = RELO_CALL;
 		reloc_desc->insn_idx = insn_idx;
 		reloc_desc->sym_off = sym->st_value;
-		obj->has_pseudo_calls = true;
 		return 0;
 	}
 
@@ -3361,14 +3446,50 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 	return 0;
 }
 
+static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
+{
+	return insn_idx >= prog->sec_insn_off &&
+	       insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
+}
+
+static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
+						 size_t sec_idx, size_t insn_idx)
+{
+	int l = 0, r = obj->nr_programs - 1, m;
+	struct bpf_program *prog;
+
+	while (l < r) {
+		m = l + (r - l + 1) / 2;
+		prog = &obj->programs[m];
+
+		if (prog->sec_idx < sec_idx ||
+		    (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
+			l = m;
+		else
+			r = m - 1;
+	}
+	/* matching program could be at index l, but it still might be the
+	 * wrong one, so we need to double check conditions for the last time
+	 */
+	prog = &obj->programs[l];
+	if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
+		return prog;
+	return NULL;
+}
+
 static int
-bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
-			   Elf_Data *data, struct bpf_object *obj)
+bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data)
 {
 	Elf_Data *symbols = obj->efile.symbols;
 	const char *relo_sec_name, *sec_name;
 	size_t sec_idx = shdr->sh_info;
+	struct bpf_program *prog;
+	struct reloc_desc *relos;
 	int err, i, nrels;
+	const char *sym_name;
+	__u32 insn_idx;
+	GElf_Sym sym;
+	GElf_Rel rel;
 
 	relo_sec_name = elf_sec_str(obj, shdr->sh_name);
 	sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
@@ -3379,19 +3500,7 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 		 relo_sec_name, sec_idx, sec_name);
 	nrels = shdr->sh_size / shdr->sh_entsize;
 
-	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
-	if (!prog->reloc_desc) {
-		pr_warn("failed to alloc memory in relocation\n");
-		return -ENOMEM;
-	}
-	prog->nr_reloc = nrels;
-
 	for (i = 0; i < nrels; i++) {
-		const char *sym_name;
-		__u32 insn_idx;
-		GElf_Sym sym;
-		GElf_Rel rel;
-
 		if (!gelf_getrel(data, i, &rel)) {
 			pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
 			return -LIBBPF_ERRNO__FORMAT;
@@ -3408,15 +3517,42 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 		}
 
 		insn_idx = rel.r_offset / BPF_INSN_SZ;
-		sym_name = elf_sym_str(obj, sym.st_name) ?: "<?>";
+		/* relocations against static functions are recorded as
+		 * relocations against the section that contains a function;
+		 * in such case, symbol will be STT_SECTION and sym.st_name
+		 * will point to empty string (0), so fetch section name
+		 * instead
+		 */
+		if (GELF_ST_TYPE(sym.st_info) == STT_SECTION && sym.st_name == 0)
+			sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym.st_shndx));
+		else
+			sym_name = elf_sym_str(obj, sym.st_name);
+		sym_name = sym_name ?: "<?";
 
 		pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
 			 relo_sec_name, i, insn_idx, sym_name);
 
-		err = bpf_program__record_reloc(prog, &prog->reloc_desc[i],
+		prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+		if (!prog) {
+			pr_warn("sec '%s': relo #%d: program not found in section '%s' for insn #%u\n",
+				relo_sec_name, i, sec_name, insn_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		relos = libbpf_reallocarray(prog->reloc_desc,
+					    prog->nr_reloc + 1, sizeof(*relos));
+		if (!relos)
+			return -ENOMEM;
+		prog->reloc_desc = relos;
+
+		/* adjust insn_idx to local BPF program frame of reference */
+		insn_idx -= prog->sec_insn_off;
+		err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
 						insn_idx, sym_name, &sym, &rel);
 		if (err)
 			return err;
+
+		prog->nr_reloc++;
 	}
 	return 0;
 }
@@ -4089,75 +4225,6 @@ bpf_object__create_maps(struct bpf_object *obj)
 	return err;
 }
 
-static int
-check_btf_ext_reloc_err(struct bpf_program *prog, int err,
-			void *btf_prog_info, const char *info_name)
-{
-	if (err != -ENOENT) {
-		pr_warn("Error in loading %s for sec %s.\n",
-			info_name, prog->section_name);
-		return err;
-	}
-
-	/* err == -ENOENT (i.e. prog->section_name not found in btf_ext) */
-
-	if (btf_prog_info) {
-		/*
-		 * Some info has already been found but has problem
-		 * in the last btf_ext reloc. Must have to error out.
-		 */
-		pr_warn("Error in relocating %s for sec %s.\n",
-			info_name, prog->section_name);
-		return err;
-	}
-
-	/* Have problem loading the very first info. Ignore the rest. */
-	pr_warn("Cannot find %s for main program sec %s. Ignore all %s.\n",
-		info_name, prog->section_name, info_name);
-	return 0;
-}
-
-static int
-bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
-			  const char *section_name,  __u32 insn_offset)
-{
-	int err;
-
-	if (!insn_offset || prog->func_info) {
-		/*
-		 * !insn_offset => main program
-		 *
-		 * For sub prog, the main program's func_info has to
-		 * be loaded first (i.e. prog->func_info != NULL)
-		 */
-		err = btf_ext__reloc_func_info(obj->btf, obj->btf_ext,
-					       section_name, insn_offset,
-					       &prog->func_info,
-					       &prog->func_info_cnt);
-		if (err)
-			return check_btf_ext_reloc_err(prog, err,
-						       prog->func_info,
-						       "bpf_func_info");
-
-		prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
-	}
-
-	if (!insn_offset || prog->line_info) {
-		err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
-					       section_name, insn_offset,
-					       &prog->line_info,
-					       &prog->line_info_cnt);
-		if (err)
-			return check_btf_ext_reloc_err(prog, err,
-						       prog->line_info,
-						       "bpf_line_info");
-
-		prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
-	}
-
-	return 0;
-}
-
 #define BPF_CORE_SPEC_MAX_LEN 64
 
 /* represents BPF CO-RE field or array element accessor */
@@ -4927,8 +4994,7 @@ static int bpf_core_calc_field_relo(const struct bpf_program *prog,
 			*val = sz;
 		} else {
 			pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n",
-				bpf_program__title(prog, false),
-				relo->kind, relo->insn_off / 8);
+				prog->name, relo->kind, relo->insn_off / 8);
 			return -EINVAL;
 		}
 		if (validate)
@@ -4950,8 +5016,7 @@ static int bpf_core_calc_field_relo(const struct bpf_program *prog,
 			if (byte_sz >= 8) {
 				/* bitfield can't be read with 64-bit read */
 				pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n",
-					bpf_program__title(prog, false),
-					relo->kind, relo->insn_off / 8);
+					prog->name, relo->kind, relo->insn_off / 8);
 				return -E2BIG;
 			}
 			byte_sz *= 2;
@@ -5116,8 +5181,8 @@ static int bpf_core_calc_relo(const struct bpf_program *prog,
 	} else if (err == -EOPNOTSUPP) {
 		/* EOPNOTSUPP means unknown/unsupported relocation */
 		pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%d) at insn #%d\n",
-			bpf_program__title(prog, false), relo_idx,
-			core_relo_kind_str(relo->kind), relo->kind, relo->insn_off / 8);
+			prog->name, relo_idx, core_relo_kind_str(relo->kind),
+			relo->kind, relo->insn_off / 8);
 	}
 
 	return err;
@@ -5131,7 +5196,7 @@ static void bpf_core_poison_insn(struct bpf_program *prog, int relo_idx,
 				 int insn_idx, struct bpf_insn *insn)
 {
 	pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n",
-		 bpf_program__title(prog, false), relo_idx, insn_idx);
+		 prog->name, relo_idx, insn_idx);
 	insn->code = BPF_JMP | BPF_CALL;
 	insn->dst_reg = 0;
 	insn->src_reg = 0;
@@ -5175,6 +5240,11 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
 	if (relo->insn_off % BPF_INSN_SZ)
 		return -EINVAL;
 	insn_idx = relo->insn_off / BPF_INSN_SZ;
+	/* adjust insn_idx from section frame of reference to the local
+	 * program's frame of reference; (sub-)program code is not yet
+	 * relocated, so it's enough to just subtract in-section offset
+	 */
+	insn_idx = insn_idx - prog->sec_insn_off;
 	insn = &prog->insns[insn_idx];
 	class = BPF_CLASS(insn->code);
 
@@ -5198,14 +5268,14 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
 			return -EINVAL;
 		if (res->validate && insn->imm != orig_val) {
 			pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %u -> %u\n",
-				bpf_program__title(prog, false), relo_idx,
+				prog->name, relo_idx,
 				insn_idx, insn->imm, orig_val, new_val);
 			return -EINVAL;
 		}
 		orig_val = insn->imm;
 		insn->imm = new_val;
 		pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %u -> %u\n",
-			 bpf_program__title(prog, false), relo_idx, insn_idx,
+			 prog->name, relo_idx, insn_idx,
 			 orig_val, new_val);
 		break;
 	case BPF_LDX:
@@ -5213,21 +5283,18 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
 	case BPF_STX:
 		if (res->validate && insn->off != orig_val) {
 			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %u -> %u\n",
-				bpf_program__title(prog, false), relo_idx,
-				insn_idx, insn->off, orig_val, new_val);
+				prog->name, relo_idx, insn_idx, insn->off, orig_val, new_val);
 			return -EINVAL;
 		}
 		if (new_val > SHRT_MAX) {
 			pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %u\n",
-				bpf_program__title(prog, false), relo_idx,
-				insn_idx, new_val);
+				prog->name, relo_idx, insn_idx, new_val);
 			return -ERANGE;
 		}
 		orig_val = insn->off;
 		insn->off = new_val;
 		pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %u -> %u\n",
-			 bpf_program__title(prog, false), relo_idx, insn_idx,
-			 orig_val, new_val);
+			 prog->name, relo_idx, insn_idx, orig_val, new_val);
 		break;
 	case BPF_LD: {
 		__u64 imm;
@@ -5238,14 +5305,14 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
 		    insn[1].code != 0 || insn[1].dst_reg != 0 ||
 		    insn[1].src_reg != 0 || insn[1].off != 0) {
 			pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
-				bpf_program__title(prog, false), relo_idx, insn_idx);
+				prog->name, relo_idx, insn_idx);
 			return -EINVAL;
 		}
 
 		imm = insn[0].imm + ((__u64)insn[1].imm << 32);
 		if (res->validate && imm != orig_val) {
 			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n",
-				bpf_program__title(prog, false), relo_idx,
+				prog->name, relo_idx,
 				insn_idx, (unsigned long long)imm,
 				orig_val, new_val);
 			return -EINVAL;
@@ -5254,15 +5321,14 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
 		insn[0].imm = new_val;
 		insn[1].imm = 0; /* currently only 32-bit values are supported */
 		pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n",
-			 bpf_program__title(prog, false), relo_idx, insn_idx,
+			 prog->name, relo_idx, insn_idx,
 			 (unsigned long long)imm, new_val);
 		break;
 	}
 	default:
 		pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n",
-			bpf_program__title(prog, false), relo_idx,
-			insn_idx, insn->code, insn->src_reg, insn->dst_reg,
-			insn->off, insn->imm);
+			prog->name, relo_idx, insn_idx, insn->code,
+			insn->src_reg, insn->dst_reg, insn->off, insn->imm);
 		return -EINVAL;
 	}
 
@@ -5392,7 +5458,6 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 			       const struct btf *targ_btf,
 			       struct hashmap *cand_cache)
 {
-	const char *prog_name = bpf_program__title(prog, false);
 	struct bpf_core_spec local_spec, cand_spec, targ_spec = {};
 	const void *type_key = u32_as_hash_key(relo->type_id);
 	struct bpf_core_relo_res cand_res, targ_res;
@@ -5419,13 +5484,13 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 	err = bpf_core_parse_spec(local_btf, local_id, spec_str, relo->kind, &local_spec);
 	if (err) {
 		pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
-			prog_name, relo_idx, local_id, btf_kind_str(local_type),
+			prog->name, relo_idx, local_id, btf_kind_str(local_type),
 			str_is_empty(local_name) ? "<anon>" : local_name,
 			spec_str, err);
 		return -EINVAL;
 	}
 
-	pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog_name,
+	pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog->name,
 		 relo_idx, core_relo_kind_str(relo->kind), relo->kind);
 	bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec);
 	libbpf_print(LIBBPF_DEBUG, "\n");
@@ -5442,7 +5507,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 	/* libbpf doesn't support candidate search for anonymous types */
 	if (str_is_empty(spec_str)) {
 		pr_warn("prog '%s': relo #%d: <%s> (%d) relocation doesn't support anonymous types\n",
-			prog_name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
+			prog->name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
 		return -EOPNOTSUPP;
 	}
 
@@ -5450,7 +5515,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 		cand_ids = bpf_core_find_cands(local_btf, local_id, targ_btf);
 		if (IS_ERR(cand_ids)) {
 			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld",
-				prog_name, relo_idx, local_id, btf_kind_str(local_type),
+				prog->name, relo_idx, local_id, btf_kind_str(local_type),
 				local_name, PTR_ERR(cand_ids));
 			return PTR_ERR(cand_ids);
 		}
@@ -5466,13 +5531,13 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 		err = bpf_core_spec_match(&local_spec, targ_btf, cand_id, &cand_spec);
 		if (err < 0) {
 			pr_warn("prog '%s': relo #%d: error matching candidate #%d ",
-				prog_name, relo_idx, i);
+				prog->name, relo_idx, i);
 			bpf_core_dump_spec(LIBBPF_WARN, &cand_spec);
 			libbpf_print(LIBBPF_WARN, ": %d\n", err);
 			return err;
 		}
 
-		pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog_name,
+		pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog->name,
 			 relo_idx, err == 0 ? "non-matching" : "matching", i);
 		bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
 		libbpf_print(LIBBPF_DEBUG, "\n");
@@ -5492,7 +5557,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 			 * should all resolve to the same bit offset
 			 */
 			pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
-				prog_name, relo_idx, cand_spec.bit_offset,
+				prog->name, relo_idx, cand_spec.bit_offset,
 				targ_spec.bit_offset);
 			return -EINVAL;
 		} else if (cand_res.poison != targ_res.poison || cand_res.new_val != targ_res.new_val) {
@@ -5501,7 +5566,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 			 * proceed due to ambiguity
 			 */
 			pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %u != %s %u\n",
-				prog_name, relo_idx,
+				prog->name, relo_idx,
 				cand_res.poison ? "failure" : "success", cand_res.new_val,
 				targ_res.poison ? "failure" : "success", targ_res.new_val);
 			return -EINVAL;
@@ -5534,7 +5599,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 	 */
 	if (j == 0) {
 		pr_debug("prog '%s': relo #%d: no matching targets found\n",
-			 prog_name, relo_idx);
+			 prog->name, relo_idx);
 
 		/* calculate single target relo result explicitly */
 		err = bpf_core_calc_relo(prog, relo, relo_idx, &local_spec, NULL, &targ_res);
@@ -5547,7 +5612,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 	err = bpf_core_patch_insn(prog, relo, relo_idx, &targ_res);
 	if (err) {
 		pr_warn("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
-			prog_name, relo_idx, relo->insn_off, err);
+			prog->name, relo_idx, relo->insn_off, err);
 		return -EINVAL;
 	}
 
@@ -5565,7 +5630,7 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 	struct bpf_program *prog;
 	struct btf *targ_btf;
 	const char *sec_name;
-	int i, err = 0;
+	int i, err = 0, insn_idx, sec_idx;
 
 	if (obj->btf_ext->core_relo_info.len == 0)
 		return 0;
@@ -5592,24 +5657,37 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 			err = -EINVAL;
 			goto out;
 		}
+		/* bpf_object's ELF is gone by now so it's not easy to find
+		 * section index by section name, but we can find *any*
+		 * bpf_program within desired section name and use it's
+		 * prog->sec_idx to do a proper search by section index and
+		 * instruction offset
+		 */
 		prog = NULL;
 		for (i = 0; i < obj->nr_programs; i++) {
-			if (!strcmp(obj->programs[i].section_name, sec_name)) {
-				prog = &obj->programs[i];
+			prog = &obj->programs[i];
+			if (strcmp(prog->sec_name, sec_name) == 0)
 				break;
-			}
 		}
 		if (!prog) {
-			pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
-				sec_name);
-			err = -EINVAL;
-			goto out;
+			pr_warn("sec '%s': failed to find a BPF program\n", sec_name);
+			return -ENOENT;
 		}
+		sec_idx = prog->sec_idx;
 
 		pr_debug("sec '%s': found %d CO-RE relocations\n",
 			 sec_name, sec->num_info);
 
 		for_each_btf_ext_rec(seg, sec, i, rec) {
+			insn_idx = rec->insn_off / BPF_INSN_SZ;
+			prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
+			if (!prog) {
+				pr_warn("sec '%s': failed to find program at insn #%d for CO-RE offset relocation #%d\n",
+					sec_name, insn_idx, i);
+				err = -EINVAL;
+				goto out;
+			}
+
 			err = bpf_core_apply_relo(prog, rec, i, obj->btf,
 						  targ_btf, cand_cache);
 			if (err) {
@@ -5633,89 +5711,32 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
 	return err;
 }
 
+/* Relocate data references within program code:
+ *  - map references;
+ *  - global variable references;
+ *  - extern references.
+ */
 static int
-bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
-			struct reloc_desc *relo)
-{
-	struct bpf_insn *insn, *new_insn;
-	struct bpf_program *text;
-	size_t new_cnt;
-	int err;
-
-	if (prog->idx != obj->efile.text_shndx && prog->main_prog_cnt == 0) {
-		text = bpf_object__find_prog_by_idx(obj, obj->efile.text_shndx);
-		if (!text) {
-			pr_warn("no .text section found yet relo into text exist\n");
-			return -LIBBPF_ERRNO__RELOC;
-		}
-		new_cnt = prog->insns_cnt + text->insns_cnt;
-		new_insn = libbpf_reallocarray(prog->insns, new_cnt, sizeof(*insn));
-		if (!new_insn) {
-			pr_warn("oom in prog realloc\n");
-			return -ENOMEM;
-		}
-		prog->insns = new_insn;
-
-		if (obj->btf_ext) {
-			err = bpf_program_reloc_btf_ext(prog, obj,
-							text->section_name,
-							prog->insns_cnt);
-			if (err)
-				return err;
-		}
-
-		memcpy(new_insn + prog->insns_cnt, text->insns,
-		       text->insns_cnt * sizeof(*insn));
-		prog->main_prog_cnt = prog->insns_cnt;
-		prog->insns_cnt = new_cnt;
-		pr_debug("added %zd insn from %s to prog %s\n",
-			 text->insns_cnt, text->section_name,
-			 prog->section_name);
-	}
-
-	insn = &prog->insns[relo->insn_idx];
-	insn->imm += relo->sym_off / 8 + prog->main_prog_cnt - relo->insn_idx;
-	return 0;
-}
-
-static int
-bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
+bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
 {
-	int i, err;
-
-	if (!prog)
-		return 0;
-
-	if (obj->btf_ext) {
-		err = bpf_program_reloc_btf_ext(prog, obj,
-						prog->section_name, 0);
-		if (err)
-			return err;
-	}
-
-	if (!prog->reloc_desc)
-		return 0;
+	int i;
 
 	for (i = 0; i < prog->nr_reloc; i++) {
 		struct reloc_desc *relo = &prog->reloc_desc[i];
 		struct bpf_insn *insn = &prog->insns[relo->insn_idx];
 		struct extern_desc *ext;
 
-		if (relo->insn_idx + 1 >= (int)prog->insns_cnt) {
-			pr_warn("relocation out of range: '%s'\n",
-				prog->section_name);
-			return -LIBBPF_ERRNO__RELOC;
-		}
-
 		switch (relo->type) {
 		case RELO_LD64:
 			insn[0].src_reg = BPF_PSEUDO_MAP_FD;
 			insn[0].imm = obj->maps[relo->map_idx].fd;
+			relo->processed = true;
 			break;
 		case RELO_DATA:
 			insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
 			insn[1].imm = insn[0].imm + relo->sym_off;
 			insn[0].imm = obj->maps[relo->map_idx].fd;
+			relo->processed = true;
 			break;
 		case RELO_EXTERN:
 			ext = &obj->externs[relo->sym_off];
@@ -5727,11 +5748,10 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 				insn[0].imm = (__u32)ext->ksym.addr;
 				insn[1].imm = ext->ksym.addr >> 32;
 			}
+			relo->processed = true;
 			break;
 		case RELO_CALL:
-			err = bpf_program__reloc_text(prog, obj, relo);
-			if (err)
-				return err;
+			/* will be handled as a follow up pass */
 			break;
 		default:
 			pr_warn("prog '%s': relo #%d: bad relo type %d\n",
@@ -5740,8 +5760,378 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 		}
 	}
 
-	zfree(&prog->reloc_desc);
-	prog->nr_reloc = 0;
+	return 0;
+}
+
+static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
+				    const struct bpf_program *prog,
+				    const struct btf_ext_info *ext_info,
+				    void **prog_info, __u32 *prog_rec_cnt,
+				    __u32 *prog_rec_sz)
+{
+	void *copy_start = NULL, *copy_end = NULL;
+	void *rec, *rec_end, *new_prog_info;
+	const struct btf_ext_info_sec *sec;
+	size_t old_sz, new_sz;
+	const char *sec_name;
+	int i, off_adj;
+
+	for_each_btf_ext_sec(ext_info, sec) {
+		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+		if (!sec_name)
+			return -EINVAL;
+		if (strcmp(sec_name, prog->sec_name) != 0)
+			continue;
+
+		for_each_btf_ext_rec(ext_info, sec, i, rec) {
+			__u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
+
+			if (insn_off < prog->sec_insn_off)
+				continue;
+			if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
+				break;
+
+			if (!copy_start)
+				copy_start = rec;
+			copy_end = rec + ext_info->rec_size;
+		}
+
+		if (!copy_start)
+			return -ENOENT;
+
+		/* append func/line info of a given (sub-)program to the main
+		 * program func/line info
+		 */
+		old_sz = (*prog_rec_cnt) * ext_info->rec_size;
+		new_sz = old_sz + (copy_end - copy_start);
+		new_prog_info = realloc(*prog_info, new_sz);
+		if (!new_prog_info)
+			return -ENOMEM;
+		*prog_info = new_prog_info;
+		*prog_rec_cnt = new_sz / ext_info->rec_size;
+		memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
+
+		/* Kernel instruction offsets are in units of 8-byte
+		 * instructions, while .BTF.ext instruction offsets generated
+		 * by Clang are in units of bytes. So convert Clang offsets
+		 * into kernel offsets and adjust offset according to program
+		 * relocated position.
+		 */
+		off_adj = prog->sub_insn_off - prog->sec_insn_off;
+		rec = new_prog_info + old_sz;
+		rec_end = new_prog_info + new_sz;
+		for (; rec < rec_end; rec += ext_info->rec_size) {
+			__u32 *insn_off = rec;
+
+			*insn_off = *insn_off / BPF_INSN_SZ + off_adj;
+		}
+		*prog_rec_sz = ext_info->rec_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static int
+reloc_prog_func_and_line_info(const struct bpf_object *obj,
+			      struct bpf_program *main_prog,
+			      const struct bpf_program *prog)
+{
+	int err;
+
+	/* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
+	 * supprot func/line info
+	 */
+	if (!obj->btf_ext || !kernel_supports(FEAT_BTF_FUNC))
+		return 0;
+
+	/* only attempt func info relocation if main program's func_info
+	 * relocation was successful
+	 */
+	if (main_prog != prog && !main_prog->func_info)
+		goto line_info;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
+				       &main_prog->func_info,
+				       &main_prog->func_info_cnt,
+				       &main_prog->func_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->func_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
+			prog->name);
+	}
+
+line_info:
+	/* don't relocate line info if main program's relocation failed */
+	if (main_prog != prog && !main_prog->line_info)
+		return 0;
+
+	err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
+				       &main_prog->line_info,
+				       &main_prog->line_info_cnt,
+				       &main_prog->line_info_rec_size);
+	if (err) {
+		if (err != -ENOENT) {
+			pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n",
+				prog->name, err);
+			return err;
+		}
+		if (main_prog->line_info) {
+			/*
+			 * Some info has already been found but has problem
+			 * in the last btf_ext reloc. Must have to error out.
+			 */
+			pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
+			return err;
+		}
+		/* Have problem loading the very first info. Ignore the rest. */
+		pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
+			prog->name);
+	}
+	return 0;
+}
+
+static int cmp_relo_by_insn_idx(const void *key, const void *elem)
+{
+	size_t insn_idx = *(const size_t *)key;
+	const struct reloc_desc *relo = elem;
+
+	if (insn_idx == relo->insn_idx)
+		return 0;
+	return insn_idx < relo->insn_idx ? -1 : 1;
+}
+
+static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
+{
+	return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
+		       sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
+}
+
+static int
+bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
+		       struct bpf_program *prog)
+{
+	size_t sub_insn_idx, insn_idx, new_cnt;
+	struct bpf_program *subprog;
+	struct bpf_insn *insns, *insn;
+	struct reloc_desc *relo;
+	int err;
+
+	err = reloc_prog_func_and_line_info(obj, main_prog, prog);
+	if (err)
+		return err;
+
+	for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		if (!insn_is_subprog_call(insn))
+			continue;
+
+		relo = find_prog_insn_relo(prog, insn_idx);
+		if (relo && relo->type != RELO_CALL) {
+			pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
+				prog->name, insn_idx, relo->type);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (relo) {
+			/* sub-program instruction index is a combination of
+			 * an offset of a symbol pointed to by relocation and
+			 * call instruction's imm field; for global functions,
+			 * call always has imm = -1, but for static functions
+			 * relocation is against STT_SECTION and insn->imm
+			 * points to a start of a static function
+			 */
+			sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
+		} else {
+			/* if subprogram call is to a static function within
+			 * the same ELF section, there won't be any relocation
+			 * emitted, but it also means there is no additional
+			 * offset necessary, insns->imm is relative to
+			 * instruction's original position within the section
+			 */
+			sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
+		}
+
+		/* we enforce that sub-programs should be in .text section */
+		subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
+		if (!subprog) {
+			pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
+				prog->name);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		/* if it's the first call instruction calling into this
+		 * subprogram (meaning this subprog hasn't been processed
+		 * yet) within the context of current main program:
+		 *   - append it at the end of main program's instructions blog;
+		 *   - process is recursively, while current program is put on hold;
+		 *   - if that subprogram calls some other not yet processes
+		 *   subprogram, same thing will happen recursively until
+		 *   there are no more unprocesses subprograms left to append
+		 *   and relocate.
+		 */
+		if (subprog->sub_insn_off == 0) {
+			subprog->sub_insn_off = main_prog->insns_cnt;
+
+			new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
+			insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
+			if (!insns) {
+				pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
+				return -ENOMEM;
+			}
+			main_prog->insns = insns;
+			main_prog->insns_cnt = new_cnt;
+
+			memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
+			       subprog->insns_cnt * sizeof(*insns));
+
+			pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
+				 main_prog->name, subprog->insns_cnt, subprog->name);
+
+			err = bpf_object__reloc_code(obj, main_prog, subprog);
+			if (err)
+				return err;
+		}
+
+		/* main_prog->insns memory could have been re-allocated, so
+		 * calculate pointer again
+		 */
+		insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
+		/* calculate correct instruction position within current main
+		 * prog; each main prog can have a different set of
+		 * subprograms appended (potentially in different order as
+		 * well), so position of any subprog can be different for
+		 * different main programs */
+		insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
+
+		if (relo)
+			relo->processed = true;
+
+		pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
+			 prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
+	}
+
+	return 0;
+}
+
+/*
+ * Relocate sub-program calls.
+ *
+ * Algorithm operates as follows. Each entry-point BPF program (referred to as
+ * main prog) is processed separately. For each subprog (non-entry functions,
+ * that can be called from either entry progs or other subprogs) gets their
+ * sub_insn_off reset to zero. This serves as indicator that this subprogram
+ * hasn't been yet appended and relocated within current main prog. Once its
+ * relocated, sub_insn_off will point at the position within current main prog
+ * where given subprog was appended. This will further be used to relocate all
+ * the call instructions jumping into this subprog.
+ *
+ * We start with main program and process all call instructions. If the call
+ * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
+ * is zero), subprog instructions are appended at the end of main program's
+ * instruction array. Then main program is "put on hold" while we recursively
+ * process newly appended subprogram. If that subprogram calls into another
+ * subprogram that hasn't been appended, new subprogram is appended again to
+ * the *main* prog's instructions (subprog's instructions are always left
+ * untouched, as they need to be in unmodified state for subsequent main progs
+ * and subprog instructions are always sent only as part of a main prog) and
+ * the process continues recursively. Once all the subprogs called from a main
+ * prog or any of its subprogs are appended (and relocated), all their
+ * positions within finalized instructions array are known, so it's easy to
+ * rewrite call instructions with correct relative offsets, corresponding to
+ * desired target subprog.
+ *
+ * Its important to realize that some subprogs might not be called from some
+ * main prog and any of its called/used subprogs. Those will keep their
+ * subprog->sub_insn_off as zero at all times and won't be appended to current
+ * main prog and won't be relocated within the context of current main prog.
+ * They might still be used from other main progs later.
+ *
+ * Visually this process can be shown as below. Suppose we have two main
+ * programs mainA and mainB and BPF object contains three subprogs: subA,
+ * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
+ * subC both call subB:
+ *
+ *        +--------+ +-------+
+ *        |        v v       |
+ *     +--+---+ +--+-+-+ +---+--+
+ *     | subA | | subB | | subC |
+ *     +--+---+ +------+ +---+--+
+ *        ^                  ^
+ *        |                  |
+ *    +---+-------+   +------+----+
+ *    |   mainA   |   |   mainB   |
+ *    +-----------+   +-----------+
+ *
+ * We'll start relocating mainA, will find subA, append it and start
+ * processing sub A recursively:
+ *
+ *    +-----------+------+
+ *    |   mainA   | subA |
+ *    +-----------+------+
+ *
+ * At this point we notice that subB is used from subA, so we append it and
+ * relocate (there are no further subcalls from subB):
+ *
+ *    +-----------+------+------+
+ *    |   mainA   | subA | subB |
+ *    +-----------+------+------+
+ *
+ * At this point, we relocate subA calls, then go one level up and finish with
+ * relocatin mainA calls. mainA is done.
+ *
+ * For mainB process is similar but results in different order. We start with
+ * mainB and skip subA and subB, as mainB never calls them (at least
+ * directly), but we see subC is needed, so we append and start processing it:
+ *
+ *    +-----------+------+
+ *    |   mainB   | subC |
+ *    +-----------+------+
+ * Now we see subC needs subB, so we go back to it, append and relocate it:
+ *
+ *    +-----------+------+------+
+ *    |   mainB   | subC | subB |
+ *    +-----------+------+------+
+ *
+ * At this point we unwind recursion, relocate calls in subC, then in mainB.
+ */
+static int
+bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
+{
+	struct bpf_program *subprog;
+	int i, j, err;
+
+	/* mark all subprogs as not relocated (yet) within the context of
+	 * current main program
+	 */
+	for (i = 0; i < obj->nr_programs; i++) {
+		subprog = &obj->programs[i];
+		if (!prog_is_subprog(obj, subprog))
+			continue;
+
+		subprog->sub_insn_off = 0;
+		for (j = 0; j < subprog->nr_reloc; j++)
+			if (subprog->reloc_desc[j].type == RELO_CALL)
+				subprog->reloc_desc[j].processed = false;
+	}
+
+	err = bpf_object__reloc_code(obj, prog, prog);
+	if (err)
+		return err;
+
+
 	return 0;
 }
 
@@ -5760,37 +6150,45 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
 			return err;
 		}
 	}
-	/* ensure .text is relocated first, as it's going to be copied as-is
-	 * later for sub-program calls
+	/* relocate data references first for all programs and sub-programs,
+	 * as they don't change relative to code locations, so subsequent
+	 * subprogram processing won't need to re-calculate any of them
 	 */
 	for (i = 0; i < obj->nr_programs; i++) {
 		prog = &obj->programs[i];
-		if (prog->idx != obj->efile.text_shndx)
-			continue;
-
-		err = bpf_program__relocate(prog, obj);
+		err = bpf_object__relocate_data(obj, prog);
 		if (err) {
 			pr_warn("prog '%s': failed to relocate data references: %d\n",
 				prog->name, err);
 			return err;
 		}
-		break;
 	}
-	/* now relocate everything but .text, which by now is relocated
-	 * properly, so we can copy raw sub-program instructions as is safely
+	/* now relocate subprogram calls and append used subprograms to main
+	 * programs; each copy of subprogram code needs to be relocated
+	 * differently for each main program, because its code location might
+	 * have changed
 	 */
 	for (i = 0; i < obj->nr_programs; i++) {
 		prog = &obj->programs[i];
-		if (prog->idx == obj->efile.text_shndx)
+		/* sub-program's sub-calls are relocated within the context of
+		 * its main program only
+		 */
+		if (prog_is_subprog(obj, prog))
 			continue;
 
-		err = bpf_program__relocate(prog, obj);
+		err = bpf_object__relocate_calls(obj, prog);
 		if (err) {
 			pr_warn("prog '%s': failed to relocate calls: %d\n",
 				prog->name, err);
 			return err;
 		}
 	}
+	/* free up relocation descriptors */
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		zfree(&prog->reloc_desc);
+		prog->nr_reloc = 0;
+	}
 	return 0;
 }
 
@@ -5910,41 +6308,53 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 	return 0;
 }
 
-static int bpf_object__collect_reloc(struct bpf_object *obj)
+static int cmp_relocs(const void *_a, const void *_b)
 {
-	int i, err;
+	const struct reloc_desc *a = _a;
+	const struct reloc_desc *b = _b;
 
-	if (!obj_elf_valid(obj)) {
-		pr_warn("Internal error: elf object is closed\n");
-		return -LIBBPF_ERRNO__INTERNAL;
-	}
+	if (a->insn_idx != b->insn_idx)
+		return a->insn_idx < b->insn_idx ? -1 : 1;
+
+	/* no two relocations should have the same insn_idx, but ... */
+	if (a->type != b->type)
+		return a->type < b->type ? -1 : 1;
+
+	return 0;
+}
+
+static int bpf_object__collect_relos(struct bpf_object *obj)
+{
+	int i, err;
 
 	for (i = 0; i < obj->efile.nr_reloc_sects; i++) {
 		GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr;
 		Elf_Data *data = obj->efile.reloc_sects[i].data;
 		int idx = shdr->sh_info;
-		struct bpf_program *prog;
 
 		if (shdr->sh_type != SHT_REL) {
 			pr_warn("internal error at %d\n", __LINE__);
 			return -LIBBPF_ERRNO__INTERNAL;
 		}
 
-		if (idx == obj->efile.st_ops_shndx) {
+		if (idx == obj->efile.st_ops_shndx)
 			err = bpf_object__collect_st_ops_relos(obj, shdr, data);
-		} else if (idx == obj->efile.btf_maps_shndx) {
+		else if (idx == obj->efile.btf_maps_shndx)
 			err = bpf_object__collect_map_relos(obj, shdr, data);
-		} else {
-			prog = bpf_object__find_prog_by_idx(obj, idx);
-			if (!prog) {
-				pr_warn("relocation failed: no prog in section(%d)\n", idx);
-				return -LIBBPF_ERRNO__RELOC;
-			}
-			err = bpf_program__collect_reloc(prog, shdr, data, obj);
-		}
+		else
+			err = bpf_object__collect_prog_relos(obj, shdr, data);
 		if (err)
 			return err;
 	}
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		struct bpf_program *p = &obj->programs[i];
+		
+		if (!p->nr_reloc)
+			continue;
+
+		qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
+	}
 	return 0;
 }
 
@@ -6110,8 +6520,7 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 	int err = 0, fd, i, btf_id;
 
 	if (prog->obj->loaded) {
-		pr_warn("prog '%s'('%s'): can't load after object was loaded\n",
-			prog->name, prog->section_name);
+		pr_warn("prog '%s': can't load after object was loaded\n", prog->name);
 		return -EINVAL;
 	}
 
@@ -6127,7 +6536,7 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 	if (prog->instances.nr < 0 || !prog->instances.fds) {
 		if (prog->preprocessor) {
 			pr_warn("Internal error: can't load program '%s'\n",
-				prog->section_name);
+				prog->name);
 			return -LIBBPF_ERRNO__INTERNAL;
 		}
 
@@ -6142,8 +6551,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 
 	if (!prog->preprocessor) {
 		if (prog->instances.nr != 1) {
-			pr_warn("Program '%s' is inconsistent: nr(%d) != 1\n",
-				prog->section_name, prog->instances.nr);
+			pr_warn("prog '%s': inconsistent nr(%d) != 1\n",
+				prog->name, prog->instances.nr);
 		}
 		err = load_program(prog, prog->insns, prog->insns_cnt,
 				   license, kern_ver, &fd);
@@ -6161,13 +6570,13 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 				   prog->insns_cnt, &result);
 		if (err) {
 			pr_warn("Preprocessing the %dth instance of program '%s' failed\n",
-				i, prog->section_name);
+				i, prog->name);
 			goto out;
 		}
 
 		if (!result.new_insn_ptr || !result.new_insn_cnt) {
 			pr_debug("Skip loading the %dth instance of program '%s'\n",
-				 i, prog->section_name);
+				 i, prog->name);
 			prog->instances.fds[i] = -1;
 			if (result.pfd)
 				*result.pfd = -1;
@@ -6178,7 +6587,7 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 				   result.new_insn_cnt, license, kern_ver, &fd);
 		if (err) {
 			pr_warn("Loading the %dth instance of program '%s' failed\n",
-				i, prog->section_name);
+				i, prog->name);
 			goto out;
 		}
 
@@ -6188,18 +6597,12 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
 	}
 out:
 	if (err)
-		pr_warn("failed to load program '%s'\n", prog->section_name);
+		pr_warn("failed to load program '%s'\n", prog->name);
 	zfree(&prog->insns);
 	prog->insns_cnt = 0;
 	return err;
 }
 
-static bool bpf_program__is_function_storage(const struct bpf_program *prog,
-					     const struct bpf_object *obj)
-{
-	return prog->idx == obj->efile.text_shndx && obj->has_pseudo_calls;
-}
-
 static int
 bpf_object__load_progs(struct bpf_object *obj, int log_level)
 {
@@ -6216,7 +6619,7 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
 
 	for (i = 0; i < obj->nr_programs; i++) {
 		prog = &obj->programs[i];
-		if (bpf_program__is_function_storage(prog, obj))
+		if (prog_is_subprog(obj, prog))
 			continue;
 		if (!prog->load) {
 			pr_debug("prog '%s': skipped loading\n", prog->name);
@@ -6280,14 +6683,13 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
 	err = err ? : bpf_object__collect_externs(obj);
 	err = err ? : bpf_object__finalize_btf(obj);
 	err = err ? : bpf_object__init_maps(obj, opts);
-	err = err ? : bpf_object__init_prog_names(obj);
-	err = err ? : bpf_object__collect_reloc(obj);
+	err = err ? : bpf_object__collect_relos(obj);
 	if (err)
 		goto out;
 	bpf_object__elf_finish(obj);
 
 	bpf_object__for_each_program(prog, obj) {
-		prog->sec_def = find_sec_def(prog->section_name);
+		prog->sec_def = find_sec_def(prog->sec_name);
 		if (!prog->sec_def)
 			/* couldn't guess, but user might manually specify */
 			continue;
@@ -6668,7 +7070,7 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
 
 	if (instance < 0 || instance >= prog->instances.nr) {
 		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
-			instance, prog->section_name, prog->instances.nr);
+			instance, prog->name, prog->instances.nr);
 		return -EINVAL;
 	}
 
@@ -6699,7 +7101,7 @@ int bpf_program__unpin_instance(struct bpf_program *prog, const char *path,
 
 	if (instance < 0 || instance >= prog->instances.nr) {
 		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
-			instance, prog->section_name, prog->instances.nr);
+			instance, prog->name, prog->instances.nr);
 		return -EINVAL;
 	}
 
@@ -6729,8 +7131,7 @@ int bpf_program__pin(struct bpf_program *prog, const char *path)
 	}
 
 	if (prog->instances.nr <= 0) {
-		pr_warn("no instances of prog %s to pin\n",
-			   prog->section_name);
+		pr_warn("no instances of prog %s to pin\n", prog->name);
 		return -EINVAL;
 	}
 
@@ -6792,8 +7193,7 @@ int bpf_program__unpin(struct bpf_program *prog, const char *path)
 	}
 
 	if (prog->instances.nr <= 0) {
-		pr_warn("no instances of prog %s to pin\n",
-			   prog->section_name);
+		pr_warn("no instances of prog %s to pin\n", prog->name);
 		return -EINVAL;
 	}
 
@@ -7285,7 +7685,7 @@ bpf_program__next(struct bpf_program *prev, const struct bpf_object *obj)
 
 	do {
 		prog = __bpf_program__iter(prog, obj, true);
-	} while (prog && bpf_program__is_function_storage(prog, obj));
+	} while (prog && prog_is_subprog(obj, prog));
 
 	return prog;
 }
@@ -7297,7 +7697,7 @@ bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj)
 
 	do {
 		prog = __bpf_program__iter(prog, obj, false);
-	} while (prog && bpf_program__is_function_storage(prog, obj));
+	} while (prog && prog_is_subprog(obj, prog));
 
 	return prog;
 }
@@ -7328,11 +7728,16 @@ const char *bpf_program__name(const struct bpf_program *prog)
 	return prog->name;
 }
 
+const char *bpf_program__section_name(const struct bpf_program *prog)
+{
+	return prog->sec_name;
+}
+
 const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
 {
 	const char *title;
 
-	title = prog->section_name;
+	title = prog->sec_name;
 	if (needs_copy) {
 		title = strdup(title);
 		if (!title) {
@@ -7405,14 +7810,14 @@ int bpf_program__nth_fd(const struct bpf_program *prog, int n)
 
 	if (n >= prog->instances.nr || n < 0) {
 		pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
-			n, prog->section_name, prog->instances.nr);
+			n, prog->name, prog->instances.nr);
 		return -EINVAL;
 	}
 
 	fd = prog->instances.fds[n];
 	if (fd < 0) {
 		pr_warn("%dth instance of program '%s' is invalid\n",
-			n, prog->section_name);
+			n, prog->name);
 		return -ENOENT;
 	}
 
@@ -7772,7 +8177,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 	const struct btf *btf;
 	struct bpf_map *map;
 	Elf_Data *symbols;
-	unsigned int moff;
+	unsigned int moff, insn_idx;
 	const char *name;
 	__u32 member_idx;
 	GElf_Sym sym;
@@ -7817,6 +8222,12 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 				map->name, (size_t)rel.r_offset, shdr_idx);
 			return -LIBBPF_ERRNO__RELOC;
 		}
+		if (sym.st_value % BPF_INSN_SZ) {
+			pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
+				map->name, (__u64)sym.st_value);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		insn_idx = sym.st_value / BPF_INSN_SZ;
 
 		member = find_member_by_offset(st_ops->type, moff * 8);
 		if (!member) {
@@ -7833,7 +8244,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 			return -EINVAL;
 		}
 
-		prog = bpf_object__find_prog_by_idx(obj, shdr_idx);
+		prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
 		if (!prog) {
 			pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
 				map->name, shdr_idx, name);
@@ -7843,7 +8254,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 		if (prog->type == BPF_PROG_TYPE_UNSPEC) {
 			const struct bpf_sec_def *sec_def;
 
-			sec_def = find_sec_def(prog->section_name);
+			sec_def = find_sec_def(prog->sec_name);
 			if (sec_def &&
 			    sec_def->prog_type != BPF_PROG_TYPE_STRUCT_OPS) {
 				/* for pr_warn */
@@ -7866,7 +8277,7 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 
 invalid_prog:
 	pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
-		map->name, prog->name, prog->section_name, prog->type,
+		map->name, prog->name, prog->sec_name, prog->type,
 		prog->attach_btf_id, prog->expected_attach_type, name);
 	return -EINVAL;
 }
@@ -7970,7 +8381,7 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog)
 {
 	enum bpf_attach_type attach_type = prog->expected_attach_type;
 	__u32 attach_prog_fd = prog->attach_prog_fd;
-	const char *name = prog->section_name;
+	const char *name = prog->sec_name;
 	int i, err;
 
 	if (!name)
@@ -8497,14 +8908,14 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
 	int prog_fd, err;
 
 	if (pfd < 0) {
-		pr_warn("program '%s': invalid perf event FD %d\n",
-			bpf_program__title(prog, false), pfd);
+		pr_warn("prog '%s': invalid perf event FD %d\n",
+			prog->name, pfd);
 		return ERR_PTR(-EINVAL);
 	}
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warn("program '%s': can't attach BPF program w/o FD (did you load it?)\n",
-			bpf_program__title(prog, false));
+		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			prog->name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -8517,20 +8928,18 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
 	if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
 		err = -errno;
 		free(link);
-		pr_warn("program '%s': failed to attach to pfd %d: %s\n",
-			bpf_program__title(prog, false), pfd,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("prog '%s': failed to attach to pfd %d: %s\n",
+			prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		if (err == -EPROTO)
-			pr_warn("program '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
-				bpf_program__title(prog, false), pfd);
+			pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
+				prog->name, pfd);
 		return ERR_PTR(err);
 	}
 	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
 		err = -errno;
 		free(link);
-		pr_warn("program '%s': failed to enable pfd %d: %s\n",
-			bpf_program__title(prog, false), pfd,
-			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		pr_warn("prog '%s': failed to enable pfd %d: %s\n",
+			prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return ERR_PTR(err);
 	}
 	return link;
@@ -8652,9 +9061,8 @@ struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
 	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
 				    0 /* offset */, -1 /* pid */);
 	if (pfd < 0) {
-		pr_warn("program '%s': failed to create %s '%s' perf event: %s\n",
-			bpf_program__title(prog, false),
-			retprobe ? "kretprobe" : "kprobe", func_name,
+		pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
@@ -8662,9 +9070,8 @@ struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warn("program '%s': failed to attach to %s '%s': %s\n",
-			bpf_program__title(prog, false),
-			retprobe ? "kretprobe" : "kprobe", func_name,
+		pr_warn("prog '%s': failed to attach to %s '%s': %s\n",
+			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
 	}
@@ -8677,7 +9084,7 @@ static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
 	const char *func_name;
 	bool retprobe;
 
-	func_name = bpf_program__title(prog, false) + sec->len;
+	func_name = prog->sec_name + sec->len;
 	retprobe = strcmp(sec->sec, "kretprobe/") == 0;
 
 	return bpf_program__attach_kprobe(prog, retprobe, func_name);
@@ -8695,9 +9102,8 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
 	pfd = perf_event_open_probe(true /* uprobe */, retprobe,
 				    binary_path, func_offset, pid);
 	if (pfd < 0) {
-		pr_warn("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
-			bpf_program__title(prog, false),
-			retprobe ? "uretprobe" : "uprobe",
+		pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
 			binary_path, func_offset,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
@@ -8706,9 +9112,8 @@ struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warn("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
-			bpf_program__title(prog, false),
-			retprobe ? "uretprobe" : "uprobe",
+		pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			prog->name, retprobe ? "uretprobe" : "uprobe",
 			binary_path, func_offset,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
@@ -8776,9 +9181,8 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
 
 	pfd = perf_event_open_tracepoint(tp_category, tp_name);
 	if (pfd < 0) {
-		pr_warn("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
-			bpf_program__title(prog, false),
-			tp_category, tp_name,
+		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			prog->name, tp_category, tp_name,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
@@ -8786,9 +9190,8 @@ struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
 	if (IS_ERR(link)) {
 		close(pfd);
 		err = PTR_ERR(link);
-		pr_warn("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
-			bpf_program__title(prog, false),
-			tp_category, tp_name,
+		pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			prog->name, tp_category, tp_name,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return link;
 	}
@@ -8801,7 +9204,7 @@ static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
 	char *sec_name, *tp_cat, *tp_name;
 	struct bpf_link *link;
 
-	sec_name = strdup(bpf_program__title(prog, false));
+	sec_name = strdup(prog->sec_name);
 	if (!sec_name)
 		return ERR_PTR(-ENOMEM);
 
@@ -8830,8 +9233,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warn("program '%s': can't attach before loaded\n",
-			bpf_program__title(prog, false));
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -8844,9 +9246,8 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 	if (pfd < 0) {
 		pfd = -errno;
 		free(link);
-		pr_warn("program '%s': failed to attach to raw tracepoint '%s': %s\n",
-			bpf_program__title(prog, false), tp_name,
-			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
+			prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link->fd = pfd;
@@ -8856,7 +9257,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
 static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
 				      struct bpf_program *prog)
 {
-	const char *tp_name = bpf_program__title(prog, false) + sec->len;
+	const char *tp_name = prog->sec_name + sec->len;
 
 	return bpf_program__attach_raw_tracepoint(prog, tp_name);
 }
@@ -8870,8 +9271,7 @@ static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog)
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warn("program '%s': can't attach before loaded\n",
-			bpf_program__title(prog, false));
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -8884,9 +9284,8 @@ static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog)
 	if (pfd < 0) {
 		pfd = -errno;
 		free(link);
-		pr_warn("program '%s': failed to attach: %s\n",
-			bpf_program__title(prog, false),
-			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		pr_warn("prog '%s': failed to attach: %s\n",
+			prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(pfd);
 	}
 	link->fd = pfd;
@@ -8932,8 +9331,7 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd,
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warn("program '%s': can't attach before loaded\n",
-			bpf_program__title(prog, false));
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -8947,8 +9345,8 @@ bpf_program__attach_fd(struct bpf_program *prog, int target_fd,
 	if (link_fd < 0) {
 		link_fd = -errno;
 		free(link);
-		pr_warn("program '%s': failed to attach to %s: %s\n",
-			bpf_program__title(prog, false), target_name,
+		pr_warn("prog '%s': failed to attach to %s: %s\n",
+			prog->name, target_name,
 			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(link_fd);
 	}
@@ -8992,8 +9390,7 @@ bpf_program__attach_iter(struct bpf_program *prog,
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
-		pr_warn("program '%s': can't attach before loaded\n",
-			bpf_program__title(prog, false));
+		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
 		return ERR_PTR(-EINVAL);
 	}
 
@@ -9007,9 +9404,8 @@ bpf_program__attach_iter(struct bpf_program *prog,
 	if (link_fd < 0) {
 		link_fd = -errno;
 		free(link);
-		pr_warn("program '%s': failed to attach to iterator: %s\n",
-			bpf_program__title(prog, false),
-			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
+		pr_warn("prog '%s': failed to attach to iterator: %s\n",
+			prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
 		return ERR_PTR(link_fd);
 	}
 	link->fd = link_fd;
@@ -9020,7 +9416,7 @@ struct bpf_link *bpf_program__attach(struct bpf_program *prog)
 {
 	const struct bpf_sec_def *sec_def;
 
-	sec_def = find_sec_def(bpf_program__title(prog, false));
+	sec_def = find_sec_def(prog->sec_name);
 	if (!sec_def || !sec_def->attach_fn)
 		return ERR_PTR(-ESRCH);
 
@@ -10090,12 +10486,11 @@ int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
 		struct bpf_program *prog = *s->progs[i].prog;
 		struct bpf_link **link = s->progs[i].link;
 		const struct bpf_sec_def *sec_def;
-		const char *sec_name = bpf_program__title(prog, false);
 
 		if (!prog->load)
 			continue;
 
-		sec_def = find_sec_def(sec_name);
+		sec_def = find_sec_def(prog->sec_name);
 		if (!sec_def || !sec_def->attach_fn)
 			continue;
 

tools/lib/bpf/libbpf.h

@@ -198,8 +198,9 @@ LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
 					 __u32 ifindex);
 
 LIBBPF_API const char *bpf_program__name(const struct bpf_program *prog);
-LIBBPF_API const char *bpf_program__title(const struct bpf_program *prog,
-					  bool needs_copy);
+LIBBPF_API const char *bpf_program__section_name(const struct bpf_program *prog);
+LIBBPF_API LIBBPF_DEPRECATED("BPF program title is confusing term; please use bpf_program__section_name() instead")
+const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy);
 LIBBPF_API bool bpf_program__autoload(const struct bpf_program *prog);
 LIBBPF_API int bpf_program__set_autoload(struct bpf_program *prog, bool autoload);
 

tools/lib/bpf/libbpf.map

@@ -302,6 +302,7 @@ LIBBPF_0.1.0 {
 
 LIBBPF_0.2.0 {
 	global:
+		bpf_program__section_name;
 		perf_buffer__buffer_cnt;
 		perf_buffer__buffer_fd;
 		perf_buffer__epoll_fd;

tools/lib/bpf/libbpf_common.h

@@ -15,6 +15,8 @@
 #define LIBBPF_API __attribute__((visibility("default")))
 #endif
 
+#define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
+
 /* Helper macro to declare and initialize libbpf options struct
  *
  * This dance with uninitialized declaration, followed by memset to zero,

tools/testing/selftests/bpf/flow_dissector_load.h

@@ -23,7 +23,13 @@ static inline int bpf_flow_load(struct bpf_object **obj,
 	if (ret)
 		return ret;
 
-	main_prog = bpf_object__find_program_by_title(*obj, section_name);
+	main_prog = NULL;
+	bpf_object__for_each_program(prog, *obj) {
+		if (strcmp(section_name, bpf_program__section_name(prog)) == 0) {
+			main_prog = prog;
+			break;
+		}
+	}
 	if (!main_prog)
 		return -1;
 

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

@@ -49,6 +49,7 @@ void test_bpf_verif_scale(void)
 		{ "test_verif_scale3.o", BPF_PROG_TYPE_SCHED_CLS },
 
 		{ "pyperf_global.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
+		{ "pyperf_subprogs.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 
 		/* full unroll by llvm */
 		{ "pyperf50.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
@@ -86,6 +87,9 @@ void test_bpf_verif_scale(void)
 		{ "strobemeta_nounroll1.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 		{ "strobemeta_nounroll2.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 
+		/* non-inlined subprogs */
+		{ "strobemeta_subprogs.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
+
 		{ "test_sysctl_loop1.o", BPF_PROG_TYPE_CGROUP_SYSCTL },
 		{ "test_sysctl_loop2.o", BPF_PROG_TYPE_CGROUP_SYSCTL },
 

tools/testing/selftests/bpf/prog_tests/cls_redirect.c

@@ -12,10 +12,13 @@
 
 #include "progs/test_cls_redirect.h"
 #include "test_cls_redirect.skel.h"
+#include "test_cls_redirect_subprogs.skel.h"
 
 #define ENCAP_IP INADDR_LOOPBACK
 #define ENCAP_PORT (1234)
 
+static int duration = 0;
+
 struct addr_port {
 	in_port_t port;
 	union {
@@ -361,30 +364,18 @@ static void close_fds(int *fds, int n)
 			close(fds[i]);
 }
 
-void test_cls_redirect(void)
+static void test_cls_redirect_common(struct bpf_program *prog)
 {
-	struct test_cls_redirect *skel = NULL;
 	struct bpf_prog_test_run_attr tattr = {};
 	int families[] = { AF_INET, AF_INET6 };
 	struct sockaddr_storage ss;
 	struct sockaddr *addr;
 	socklen_t slen;
 	int i, j, err;
-
 	int servers[__NR_KIND][ARRAY_SIZE(families)] = {};
 	int conns[__NR_KIND][ARRAY_SIZE(families)] = {};
 	struct tuple tuples[__NR_KIND][ARRAY_SIZE(families)];
 
-	skel = test_cls_redirect__open();
-	if (CHECK_FAIL(!skel))
-		return;
-
-	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
-	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
-
-	if (CHECK_FAIL(test_cls_redirect__load(skel)))
-		goto cleanup;
-
 	addr = (struct sockaddr *)&ss;
 	for (i = 0; i < ARRAY_SIZE(families); i++) {
 		slen = prepare_addr(&ss, families[i]);
@@ -402,7 +393,7 @@ void test_cls_redirect(void)
 			goto cleanup;
 	}
 
-	tattr.prog_fd = bpf_program__fd(skel->progs.cls_redirect);
+	tattr.prog_fd = bpf_program__fd(prog);
 	for (i = 0; i < ARRAY_SIZE(tests); i++) {
 		struct test_cfg *test = &tests[i];
 
@@ -450,7 +441,58 @@ void test_cls_redirect(void)
 	}
 
 cleanup:
-	test_cls_redirect__destroy(skel);
 	close_fds((int *)servers, sizeof(servers) / sizeof(servers[0][0]));
 	close_fds((int *)conns, sizeof(conns) / sizeof(conns[0][0]));
 }
+
+static void test_cls_redirect_inlined(void)
+{
+	struct test_cls_redirect *skel;
+	int err;
+
+	skel = test_cls_redirect__open();
+	if (CHECK(!skel, "skel_open", "failed\n"))
+		return;
+
+	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
+	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
+
+	err = test_cls_redirect__load(skel);
+	if (CHECK(err, "skel_load", "failed: %d\n", err))
+		goto cleanup;
+
+	test_cls_redirect_common(skel->progs.cls_redirect);
+
+cleanup:
+	test_cls_redirect__destroy(skel);
+}
+
+static void test_cls_redirect_subprogs(void)
+{
+	struct test_cls_redirect_subprogs *skel;
+	int err;
+
+	skel = test_cls_redirect_subprogs__open();
+	if (CHECK(!skel, "skel_open", "failed\n"))
+		return;
+
+	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
+	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
+
+	err = test_cls_redirect_subprogs__load(skel);
+	if (CHECK(err, "skel_load", "failed: %d\n", err))
+		goto cleanup;
+
+	test_cls_redirect_common(skel->progs.cls_redirect);
+
+cleanup:
+	test_cls_redirect_subprogs__destroy(skel);
+}
+
+void test_cls_redirect(void)
+{
+	if (test__start_subtest("cls_redirect_inlined"))
+		test_cls_redirect_inlined();
+	if (test__start_subtest("cls_redirect_subprogs"))
+		test_cls_redirect_subprogs();
+}

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

@@ -208,11 +208,18 @@ static void test_func_map_prog_compatibility(void)
 
 void test_fexit_bpf2bpf(void)
 {
-	test_target_no_callees();
-	test_target_yes_callees();
-	test_func_replace();
-	test_func_replace_verify();
-	test_func_sockmap_update();
-	test_func_replace_return_code();
-	test_func_map_prog_compatibility();
+	if (test__start_subtest("target_no_callees"))
+		test_target_no_callees();
+	if (test__start_subtest("target_yes_callees"))
+		test_target_yes_callees();
+	if (test__start_subtest("func_replace"))
+		test_func_replace();
+	if (test__start_subtest("func_replace_verify"))
+		test_func_replace_verify();
+	if (test__start_subtest("func_sockmap_update"))
+		test_func_sockmap_update();
+	if (test__start_subtest("func_replace_return_code"))
+		test_func_replace_return_code();
+	if (test__start_subtest("func_map_prog_compatibility"))
+		test_func_map_prog_compatibility();
 }

tools/testing/selftests/bpf/prog_tests/l4lb_all.c

@@ -80,9 +80,8 @@ static void test_l4lb(const char *file)
 
 void test_l4lb_all(void)
 {
-	const char *file1 = "./test_l4lb.o";
-	const char *file2 = "./test_l4lb_noinline.o";
-
-	test_l4lb(file1);
-	test_l4lb(file2);
+	if (test__start_subtest("l4lb_inline"))
+		test_l4lb("test_l4lb.o");
+	if (test__start_subtest("l4lb_noinline"))
+		test_l4lb("test_l4lb_noinline.o");
 }

tools/testing/selftests/bpf/prog_tests/reference_tracking.c

@@ -27,7 +27,7 @@ void test_reference_tracking(void)
 		const char *title;
 
 		/* Ignore .text sections */
-		title = bpf_program__title(prog, false);
+		title = bpf_program__section_name(prog);
 		if (strstr(title, ".text") != NULL)
 			continue;
 

tools/testing/selftests/bpf/prog_tests/subprogs.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+#include <time.h>
+#include "test_subprogs.skel.h"
+
+static int duration;
+
+void test_subprogs(void)
+{
+	struct test_subprogs *skel;
+	int err;
+
+	skel = test_subprogs__open_and_load();
+	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+		return;
+
+	err = test_subprogs__attach(skel);
+	if (CHECK(err, "skel_attach", "failed to attach skeleton: %d\n", err))
+		goto cleanup;
+
+	usleep(1);
+
+	CHECK(skel->bss->res1 != 12, "res1", "got %d, exp %d\n", skel->bss->res1, 12);
+	CHECK(skel->bss->res2 != 17, "res2", "got %d, exp %d\n", skel->bss->res2, 17);
+	CHECK(skel->bss->res3 != 19, "res3", "got %d, exp %d\n", skel->bss->res3, 19);
+	CHECK(skel->bss->res4 != 36, "res4", "got %d, exp %d\n", skel->bss->res4, 36);
+
+cleanup:
+	test_subprogs__destroy(skel);
+}

tools/testing/selftests/bpf/prog_tests/xdp_noinline.c

 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 #include <network_helpers.h>
+#include "test_xdp_noinline.skel.h"
 
 void test_xdp_noinline(void)
 {
-	const char *file = "./test_xdp_noinline.o";
 	unsigned int nr_cpus = bpf_num_possible_cpus();
+	struct test_xdp_noinline *skel;
 	struct vip key = {.protocol = 6};
 	struct vip_meta {
 		__u32 flags;
@@ -25,58 +26,42 @@ void test_xdp_noinline(void)
 	} real_def = {.dst = MAGIC_VAL};
 	__u32 ch_key = 11, real_num = 3;
 	__u32 duration, retval, size;
-	int err, i, prog_fd, map_fd;
+	int err, i;
 	__u64 bytes = 0, pkts = 0;
-	struct bpf_object *obj;
 	char buf[128];
 	u32 *magic = (u32 *)buf;
 
-	err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
-	if (CHECK_FAIL(err))
+	skel = test_xdp_noinline__open_and_load();
+	if (CHECK(!skel, "skel_open_and_load", "failed\n"))
 		return;
 
-	map_fd = bpf_find_map(__func__, obj, "vip_map");
-	if (map_fd < 0)
-		goto out;
-	bpf_map_update_elem(map_fd, &key, &value, 0);
+	bpf_map_update_elem(bpf_map__fd(skel->maps.vip_map), &key, &value, 0);
+	bpf_map_update_elem(bpf_map__fd(skel->maps.ch_rings), &ch_key, &real_num, 0);
+	bpf_map_update_elem(bpf_map__fd(skel->maps.reals), &real_num, &real_def, 0);
 
-	map_fd = bpf_find_map(__func__, obj, "ch_rings");
-	if (map_fd < 0)
-		goto out;
-	bpf_map_update_elem(map_fd, &ch_key, &real_num, 0);
-
-	map_fd = bpf_find_map(__func__, obj, "reals");
-	if (map_fd < 0)
-		goto out;
-	bpf_map_update_elem(map_fd, &real_num, &real_def, 0);
-
-	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v4, sizeof(pkt_v4),
+	err = bpf_prog_test_run(bpf_program__fd(skel->progs.balancer_ingress_v4),
+				NUM_ITER, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
 	CHECK(err || retval != 1 || size != 54 ||
 	      *magic != MAGIC_VAL, "ipv4",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
 
-	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v6, sizeof(pkt_v6),
+	err = bpf_prog_test_run(bpf_program__fd(skel->progs.balancer_ingress_v6),
+				NUM_ITER, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
 	CHECK(err || retval != 1 || size != 74 ||
 	      *magic != MAGIC_VAL, "ipv6",
 	      "err %d errno %d retval %d size %d magic %x\n",
 	      err, errno, retval, size, *magic);
 
-	map_fd = bpf_find_map(__func__, obj, "stats");
-	if (map_fd < 0)
-		goto out;
-	bpf_map_lookup_elem(map_fd, &stats_key, stats);
+	bpf_map_lookup_elem(bpf_map__fd(skel->maps.stats), &stats_key, stats);
 	for (i = 0; i < nr_cpus; i++) {
 		bytes += stats[i].bytes;
 		pkts += stats[i].pkts;
 	}
-	if (CHECK_FAIL(bytes != MAGIC_BYTES * NUM_ITER * 2 ||
-		       pkts != NUM_ITER * 2)) {
-		printf("test_xdp_noinline:FAIL:stats %lld %lld\n",
-		       bytes, pkts);
-	}
-out:
-	bpf_object__close(obj);
+	CHECK(bytes != MAGIC_BYTES * NUM_ITER * 2 || pkts != NUM_ITER * 2,
+	      "stats", "bytes %lld pkts %lld\n",
+	      (unsigned long long)bytes, (unsigned long long)pkts);
+	test_xdp_noinline__destroy(skel);
 }

tools/testing/selftests/bpf/progs/pyperf.h

@@ -67,7 +67,12 @@ typedef struct {
 	void* co_name; // PyCodeObject.co_name
 } FrameData;
 
-static __always_inline void *get_thread_state(void *tls_base, PidData *pidData)
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void *get_thread_state(void *tls_base, PidData *pidData)
 {
 	void* thread_state;
 	int key;
@@ -155,7 +160,9 @@ struct {
 } stackmap SEC(".maps");
 
 #ifdef GLOBAL_FUNC
-__attribute__((noinline))
+__noinline
+#elif defined(SUBPROGS)
+static __noinline
 #else
 static __always_inline
 #endif

tools/testing/selftests/bpf/progs/pyperf_subprogs.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#define STACK_MAX_LEN 50
+#define SUBPROGS
+#include "pyperf.h"

tools/testing/selftests/bpf/progs/strobemeta.h

@@ -266,8 +266,12 @@ struct tls_index {
 	uint64_t offset;
 };
 
-static __always_inline void *calc_location(struct strobe_value_loc *loc,
-					   void *tls_base)
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void *calc_location(struct strobe_value_loc *loc, void *tls_base)
 {
 	/*
 	 * tls_mode value is:
@@ -327,10 +331,15 @@ static __always_inline void *calc_location(struct strobe_value_loc *loc,
 		: NULL;
 }
 
-static __always_inline void read_int_var(struct strobemeta_cfg *cfg,
-					 size_t idx, void *tls_base,
-					 struct strobe_value_generic *value,
-					 struct strobemeta_payload *data)
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void read_int_var(struct strobemeta_cfg *cfg,
+			 size_t idx, void *tls_base,
+			 struct strobe_value_generic *value,
+			 struct strobemeta_payload *data)
 {
 	void *location = calc_location(&cfg->int_locs[idx], tls_base);
 	if (!location)
@@ -440,8 +449,13 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg,
  * read_strobe_meta returns NULL, if no metadata was read; otherwise returns
  * pointer to *right after* payload ends
  */
-static __always_inline void *read_strobe_meta(struct task_struct *task,
-					      struct strobemeta_payload *data)
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void *read_strobe_meta(struct task_struct *task,
+			      struct strobemeta_payload *data)
 {
 	pid_t pid = bpf_get_current_pid_tgid() >> 32;
 	struct strobe_value_generic value = {0};

tools/testing/selftests/bpf/progs/strobemeta_subprogs.c

+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+// Copyright (c) 2019 Facebook
+
+#define STROBE_MAX_INTS 2
+#define STROBE_MAX_STRS 25
+#define STROBE_MAX_MAPS 13
+#define STROBE_MAX_MAP_ENTRIES 20
+#define NO_UNROLL
+#define SUBPROGS
+#include "strobemeta.h"

tools/testing/selftests/bpf/progs/test_cls_redirect.c

@@ -22,6 +22,12 @@
 
 #include "test_cls_redirect.h"
 
+#ifdef SUBPROGS
+#define INLINING __noinline
+#else
+#define INLINING __always_inline
+#endif
+
 #define offsetofend(TYPE, MEMBER) \
 	(offsetof(TYPE, MEMBER) + sizeof((((TYPE *)0)->MEMBER)))
 
@@ -125,7 +131,7 @@ typedef struct buf {
 	uint8_t *const tail;
 } buf_t;
 
-static size_t buf_off(const buf_t *buf)
+static __always_inline size_t buf_off(const buf_t *buf)
 {
 	/* Clang seems to optimize constructs like
 	 *    a - b + c
@@ -145,7 +151,7 @@ static size_t buf_off(const buf_t *buf)
 	return off;
 }
 
-static bool buf_copy(buf_t *buf, void *dst, size_t len)
+static __always_inline bool buf_copy(buf_t *buf, void *dst, size_t len)
 {
 	if (bpf_skb_load_bytes(buf->skb, buf_off(buf), dst, len)) {
 		return false;
@@ -155,7 +161,7 @@ static bool buf_copy(buf_t *buf, void *dst, size_t len)
 	return true;
 }
 
-static bool buf_skip(buf_t *buf, const size_t len)
+static __always_inline bool buf_skip(buf_t *buf, const size_t len)
 {
 	/* Check whether off + len is valid in the non-linear part. */
 	if (buf_off(buf) + len > buf->skb->len) {
@@ -173,7 +179,7 @@ static bool buf_skip(buf_t *buf, const size_t len)
  * If scratch is not NULL, the function will attempt to load non-linear
  * data via bpf_skb_load_bytes. On success, scratch is returned.
  */
-static void *buf_assign(buf_t *buf, const size_t len, void *scratch)
+static __always_inline void *buf_assign(buf_t *buf, const size_t len, void *scratch)
 {
 	if (buf->head + len > buf->tail) {
 		if (scratch == NULL) {
@@ -188,7 +194,7 @@ static void *buf_assign(buf_t *buf, const size_t len, void *scratch)
 	return ptr;
 }
 
-static bool pkt_skip_ipv4_options(buf_t *buf, const struct iphdr *ipv4)
+static INLINING bool pkt_skip_ipv4_options(buf_t *buf, const struct iphdr *ipv4)
 {
 	if (ipv4->ihl <= 5) {
 		return true;
@@ -197,13 +203,13 @@ static bool pkt_skip_ipv4_options(buf_t *buf, const struct iphdr *ipv4)
 	return buf_skip(buf, (ipv4->ihl - 5) * 4);
 }
 
-static bool ipv4_is_fragment(const struct iphdr *ip)
+static INLINING bool ipv4_is_fragment(const struct iphdr *ip)
 {
 	uint16_t frag_off = ip->frag_off & bpf_htons(IP_OFFSET_MASK);
 	return (ip->frag_off & bpf_htons(IP_MF)) != 0 || frag_off > 0;
 }
 
-static struct iphdr *pkt_parse_ipv4(buf_t *pkt, struct iphdr *scratch)
+static __always_inline struct iphdr *pkt_parse_ipv4(buf_t *pkt, struct iphdr *scratch)
 {
 	struct iphdr *ipv4 = buf_assign(pkt, sizeof(*ipv4), scratch);
 	if (ipv4 == NULL) {
@@ -222,7 +228,7 @@ static struct iphdr *pkt_parse_ipv4(buf_t *pkt, struct iphdr *scratch)
 }
 
 /* Parse the L4 ports from a packet, assuming a layout like TCP or UDP. */
-static bool pkt_parse_icmp_l4_ports(buf_t *pkt, flow_ports_t *ports)
+static INLINING bool pkt_parse_icmp_l4_ports(buf_t *pkt, flow_ports_t *ports)
 {
 	if (!buf_copy(pkt, ports, sizeof(*ports))) {
 		return false;
@@ -237,7 +243,7 @@ static bool pkt_parse_icmp_l4_ports(buf_t *pkt, flow_ports_t *ports)
 	return true;
 }
 
-static uint16_t pkt_checksum_fold(uint32_t csum)
+static INLINING uint16_t pkt_checksum_fold(uint32_t csum)
 {
 	/* The highest reasonable value for an IPv4 header
 	 * checksum requires two folds, so we just do that always.
@@ -247,7 +253,7 @@ static uint16_t pkt_checksum_fold(uint32_t csum)
 	return (uint16_t)~csum;
 }
 
-static void pkt_ipv4_checksum(struct iphdr *iph)
+static INLINING void pkt_ipv4_checksum(struct iphdr *iph)
 {
 	iph->check = 0;
 
@@ -268,10 +274,11 @@ static void pkt_ipv4_checksum(struct iphdr *iph)
 	iph->check = pkt_checksum_fold(acc);
 }
 
-static bool pkt_skip_ipv6_extension_headers(buf_t *pkt,
-					    const struct ipv6hdr *ipv6,
-					    uint8_t *upper_proto,
-					    bool *is_fragment)
+static INLINING
+bool pkt_skip_ipv6_extension_headers(buf_t *pkt,
+				     const struct ipv6hdr *ipv6,
+				     uint8_t *upper_proto,
+				     bool *is_fragment)
 {
 	/* We understand five extension headers.
 	 * https://tools.ietf.org/html/rfc8200#section-4.1 states that all
@@ -336,7 +343,7 @@ static bool pkt_skip_ipv6_extension_headers(buf_t *pkt,
  * scratch is allocated on the stack. However, this usage should be safe since
  * it's the callers stack after all.
  */
-static inline __attribute__((__always_inline__)) struct ipv6hdr *
+static __always_inline struct ipv6hdr *
 pkt_parse_ipv6(buf_t *pkt, struct ipv6hdr *scratch, uint8_t *proto,
 	       bool *is_fragment)
 {
@@ -354,20 +361,20 @@ pkt_parse_ipv6(buf_t *pkt, struct ipv6hdr *scratch, uint8_t *proto,
 
 /* Global metrics, per CPU
  */
-struct bpf_map_def metrics_map SEC("maps") = {
-	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
-	.key_size = sizeof(unsigned int),
-	.value_size = sizeof(metrics_t),
-	.max_entries = 1,
-};
-
-static metrics_t *get_global_metrics(void)
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, unsigned int);
+	__type(value, metrics_t);
+} metrics_map SEC(".maps");
+
+static INLINING metrics_t *get_global_metrics(void)
 {
 	uint64_t key = 0;
 	return bpf_map_lookup_elem(&metrics_map, &key);
 }
 
-static ret_t accept_locally(struct __sk_buff *skb, encap_headers_t *encap)
+static INLINING ret_t accept_locally(struct __sk_buff *skb, encap_headers_t *encap)
 {
 	const int payload_off =
 		sizeof(*encap) +
@@ -388,8 +395,8 @@ static ret_t accept_locally(struct __sk_buff *skb, encap_headers_t *encap)
 	return bpf_redirect(skb->ifindex, BPF_F_INGRESS);
 }
 
-static ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *encap,
-			      struct in_addr *next_hop, metrics_t *metrics)
+static INLINING ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *encap,
+				       struct in_addr *next_hop, metrics_t *metrics)
 {
 	metrics->forwarded_packets_total_gre++;
 
@@ -509,8 +516,8 @@ static ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *encap,
 	return bpf_redirect(skb->ifindex, 0);
 }
 
-static ret_t forward_to_next_hop(struct __sk_buff *skb, encap_headers_t *encap,
-				 struct in_addr *next_hop, metrics_t *metrics)
+static INLINING ret_t forward_to_next_hop(struct __sk_buff *skb, encap_headers_t *encap,
+					  struct in_addr *next_hop, metrics_t *metrics)
 {
 	/* swap L2 addresses */
 	/* This assumes that packets are received from a router.
@@ -546,7 +553,7 @@ static ret_t forward_to_next_hop(struct __sk_buff *skb, encap_headers_t *encap,
 	return bpf_redirect(skb->ifindex, 0);
 }
 
-static ret_t skip_next_hops(buf_t *pkt, int n)
+static INLINING ret_t skip_next_hops(buf_t *pkt, int n)
 {
 	switch (n) {
 	case 1:
@@ -566,8 +573,8 @@ static ret_t skip_next_hops(buf_t *pkt, int n)
  * pkt is positioned just after the variable length GLB header
  * iff the call is successful.
  */
-static ret_t get_next_hop(buf_t *pkt, encap_headers_t *encap,
-			  struct in_addr *next_hop)
+static INLINING ret_t get_next_hop(buf_t *pkt, encap_headers_t *encap,
+				   struct in_addr *next_hop)
 {
 	if (encap->unigue.next_hop > encap->unigue.hop_count) {
 		return TC_ACT_SHOT;
@@ -601,8 +608,8 @@ static ret_t get_next_hop(buf_t *pkt, encap_headers_t *encap,
  * return value, and calling code works while still being "generic" to
  * IPv4 and IPv6.
  */
-static uint64_t fill_tuple(struct bpf_sock_tuple *tuple, void *iph,
-			   uint64_t iphlen, uint16_t sport, uint16_t dport)
+static INLINING uint64_t fill_tuple(struct bpf_sock_tuple *tuple, void *iph,
+				    uint64_t iphlen, uint16_t sport, uint16_t dport)
 {
 	switch (iphlen) {
 	case sizeof(struct iphdr): {
@@ -630,9 +637,9 @@ static uint64_t fill_tuple(struct bpf_sock_tuple *tuple, void *iph,
 	}
 }
 
-static verdict_t classify_tcp(struct __sk_buff *skb,
-			      struct bpf_sock_tuple *tuple, uint64_t tuplen,
-			      void *iph, struct tcphdr *tcp)
+static INLINING verdict_t classify_tcp(struct __sk_buff *skb,
+				       struct bpf_sock_tuple *tuple, uint64_t tuplen,
+				       void *iph, struct tcphdr *tcp)
 {
 	struct bpf_sock *sk =
 		bpf_skc_lookup_tcp(skb, tuple, tuplen, BPF_F_CURRENT_NETNS, 0);
@@ -663,8 +670,8 @@ static verdict_t classify_tcp(struct __sk_buff *skb,
 	return UNKNOWN;
 }
 
-static verdict_t classify_udp(struct __sk_buff *skb,
-			      struct bpf_sock_tuple *tuple, uint64_t tuplen)
+static INLINING verdict_t classify_udp(struct __sk_buff *skb,
+				       struct bpf_sock_tuple *tuple, uint64_t tuplen)
 {
 	struct bpf_sock *sk =
 		bpf_sk_lookup_udp(skb, tuple, tuplen, BPF_F_CURRENT_NETNS, 0);
@@ -681,9 +688,9 @@ static verdict_t classify_udp(struct __sk_buff *skb,
 	return UNKNOWN;
 }
 
-static verdict_t classify_icmp(struct __sk_buff *skb, uint8_t proto,
-			       struct bpf_sock_tuple *tuple, uint64_t tuplen,
-			       metrics_t *metrics)
+static INLINING verdict_t classify_icmp(struct __sk_buff *skb, uint8_t proto,
+					struct bpf_sock_tuple *tuple, uint64_t tuplen,
+					metrics_t *metrics)
 {
 	switch (proto) {
 	case IPPROTO_TCP:
@@ -698,7 +705,7 @@ static verdict_t classify_icmp(struct __sk_buff *skb, uint8_t proto,
 	}
 }
 
-static verdict_t process_icmpv4(buf_t *pkt, metrics_t *metrics)
+static INLINING verdict_t process_icmpv4(buf_t *pkt, metrics_t *metrics)
 {
 	struct icmphdr icmp;
 	if (!buf_copy(pkt, &icmp, sizeof(icmp))) {
@@ -745,7 +752,7 @@ static verdict_t process_icmpv4(buf_t *pkt, metrics_t *metrics)
 			     sizeof(tuple.ipv4), metrics);
 }
 
-static verdict_t process_icmpv6(buf_t *pkt, metrics_t *metrics)
+static INLINING verdict_t process_icmpv6(buf_t *pkt, metrics_t *metrics)
 {
 	struct icmp6hdr icmp6;
 	if (!buf_copy(pkt, &icmp6, sizeof(icmp6))) {
@@ -797,8 +804,8 @@ static verdict_t process_icmpv6(buf_t *pkt, metrics_t *metrics)
 			     metrics);
 }
 
-static verdict_t process_tcp(buf_t *pkt, void *iph, uint64_t iphlen,
-			     metrics_t *metrics)
+static INLINING verdict_t process_tcp(buf_t *pkt, void *iph, uint64_t iphlen,
+				      metrics_t *metrics)
 {
 	metrics->l4_protocol_packets_total_tcp++;
 
@@ -819,8 +826,8 @@ static verdict_t process_tcp(buf_t *pkt, void *iph, uint64_t iphlen,
 	return classify_tcp(pkt->skb, &tuple, tuplen, iph, tcp);
 }
 
-static verdict_t process_udp(buf_t *pkt, void *iph, uint64_t iphlen,
-			     metrics_t *metrics)
+static INLINING verdict_t process_udp(buf_t *pkt, void *iph, uint64_t iphlen,
+				      metrics_t *metrics)
 {
 	metrics->l4_protocol_packets_total_udp++;
 
@@ -837,7 +844,7 @@ static verdict_t process_udp(buf_t *pkt, void *iph, uint64_t iphlen,
 	return classify_udp(pkt->skb, &tuple, tuplen);
 }
 
-static verdict_t process_ipv4(buf_t *pkt, metrics_t *metrics)
+static INLINING verdict_t process_ipv4(buf_t *pkt, metrics_t *metrics)
 {
 	metrics->l3_protocol_packets_total_ipv4++;
 
@@ -874,7 +881,7 @@ static verdict_t process_ipv4(buf_t *pkt, metrics_t *metrics)
 	}
 }
 
-static verdict_t process_ipv6(buf_t *pkt, metrics_t *metrics)
+static INLINING verdict_t process_ipv6(buf_t *pkt, metrics_t *metrics)
 {
 	metrics->l3_protocol_packets_total_ipv6++;
 

tools/testing/selftests/bpf/progs/test_cls_redirect_subprogs.c

+#define SUBPROGS
+#include "test_cls_redirect.c"

tools/testing/selftests/bpf/progs/test_l4lb_noinline.c

@@ -17,9 +17,7 @@
 #include "test_iptunnel_common.h"
 #include <bpf/bpf_endian.h>
 
-int _version SEC("version") = 1;
-
-static __u32 rol32(__u32 word, unsigned int shift)
+static __always_inline __u32 rol32(__u32 word, unsigned int shift)
 {
 	return (word << shift) | (word >> ((-shift) & 31));
 }
@@ -52,7 +50,7 @@ static __u32 rol32(__u32 word, unsigned int shift)
 
 typedef unsigned int u32;
 
-static u32 jhash(const void *key, u32 length, u32 initval)
+static __noinline u32 jhash(const void *key, u32 length, u32 initval)
 {
 	u32 a, b, c;
 	const unsigned char *k = key;
@@ -88,7 +86,7 @@ static u32 jhash(const void *key, u32 length, u32 initval)
 	return c;
 }
 
-static u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
+static __noinline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 {
 	a += initval;
 	b += initval;
@@ -97,7 +95,7 @@ static u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 	return c;
 }
 
-static u32 jhash_2words(u32 a, u32 b, u32 initval)
+static __noinline u32 jhash_2words(u32 a, u32 b, u32 initval)
 {
 	return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
 }
@@ -200,8 +198,7 @@ struct {
 	__type(value, struct ctl_value);
 } ctl_array SEC(".maps");
 
-static __u32 get_packet_hash(struct packet_description *pckt,
-			     bool ipv6)
+static __noinline __u32 get_packet_hash(struct packet_description *pckt, bool ipv6)
 {
 	if (ipv6)
 		return jhash_2words(jhash(pckt->srcv6, 16, MAX_VIPS),
@@ -210,10 +207,10 @@ static __u32 get_packet_hash(struct packet_description *pckt,
 		return jhash_2words(pckt->src, pckt->ports, CH_RINGS_SIZE);
 }
 
-static bool get_packet_dst(struct real_definition **real,
-			   struct packet_description *pckt,
-			   struct vip_meta *vip_info,
-			   bool is_ipv6)
+static __noinline bool get_packet_dst(struct real_definition **real,
+				      struct packet_description *pckt,
+				      struct vip_meta *vip_info,
+				      bool is_ipv6)
 {
 	__u32 hash = get_packet_hash(pckt, is_ipv6);
 	__u32 key = RING_SIZE * vip_info->vip_num + hash % RING_SIZE;
@@ -233,8 +230,8 @@ static bool get_packet_dst(struct real_definition **real,
 	return true;
 }
 
-static int parse_icmpv6(void *data, void *data_end, __u64 off,
-			struct packet_description *pckt)
+static __noinline int parse_icmpv6(void *data, void *data_end, __u64 off,
+				   struct packet_description *pckt)
 {
 	struct icmp6hdr *icmp_hdr;
 	struct ipv6hdr *ip6h;
@@ -255,8 +252,8 @@ static int parse_icmpv6(void *data, void *data_end, __u64 off,
 	return TC_ACT_UNSPEC;
 }
 
-static int parse_icmp(void *data, void *data_end, __u64 off,
-		      struct packet_description *pckt)
+static __noinline int parse_icmp(void *data, void *data_end, __u64 off,
+				 struct packet_description *pckt)
 {
 	struct icmphdr *icmp_hdr;
 	struct iphdr *iph;
@@ -280,8 +277,8 @@ static int parse_icmp(void *data, void *data_end, __u64 off,
 	return TC_ACT_UNSPEC;
 }
 
-static bool parse_udp(void *data, __u64 off, void *data_end,
-		      struct packet_description *pckt)
+static __noinline bool parse_udp(void *data, __u64 off, void *data_end,
+				 struct packet_description *pckt)
 {
 	struct udphdr *udp;
 	udp = data + off;
@@ -299,8 +296,8 @@ static bool parse_udp(void *data, __u64 off, void *data_end,
 	return true;
 }
 
-static bool parse_tcp(void *data, __u64 off, void *data_end,
-		      struct packet_description *pckt)
+static __noinline bool parse_tcp(void *data, __u64 off, void *data_end,
+				 struct packet_description *pckt)
 {
 	struct tcphdr *tcp;
 
@@ -321,8 +318,8 @@ static bool parse_tcp(void *data, __u64 off, void *data_end,
 	return true;
 }
 
-static int process_packet(void *data, __u64 off, void *data_end,
-			  bool is_ipv6, struct __sk_buff *skb)
+static __noinline int process_packet(void *data, __u64 off, void *data_end,
+				     bool is_ipv6, struct __sk_buff *skb)
 {
 	void *pkt_start = (void *)(long)skb->data;
 	struct packet_description pckt = {};

tools/testing/selftests/bpf/progs/test_subprogs.c

+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+const char LICENSE[] SEC("license") = "GPL";
+
+__noinline int sub1(int x)
+{
+	return x + 1;
+}
+
+static __noinline int sub5(int v);
+
+__noinline int sub2(int y)
+{
+	return sub5(y + 2);
+}
+
+static __noinline int sub3(int z)
+{
+	return z + 3 + sub1(4);
+}
+
+static __noinline int sub4(int w)
+{
+	return w + sub3(5) + sub1(6);
+}
+
+/* sub5() is an identitify function, just to test weirder functions layout and
+ * call patterns
+ */
+static __noinline int sub5(int v)
+{
+	return sub1(v) - 1; /* compensates sub1()'s + 1 */
+}
+
+/* unfortunately verifier rejects `struct task_struct *t` as an unkown pointer
+ * type, so we need to accept pointer as integer and then cast it inside the
+ * function
+ */
+__noinline int get_task_tgid(uintptr_t t)
+{
+	/* this ensures that CO-RE relocs work in multi-subprogs .text */
+	return BPF_CORE_READ((struct task_struct *)(void *)t, tgid);
+}
+
+int res1 = 0;
+int res2 = 0;
+int res3 = 0;
+int res4 = 0;
+
+SEC("raw_tp/sys_enter")
+int prog1(void *ctx)
+{
+	/* perform some CO-RE relocations to ensure they work with multi-prog
+	 * sections correctly
+	 */
+	struct task_struct *t = (void *)bpf_get_current_task();
+
+	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
+		return 1;
+
+	res1 = sub1(1) + sub3(2); /* (1 + 1) + (2 + 3 + (4 + 1)) = 12 */
+	return 0;
+}
+
+SEC("raw_tp/sys_exit")
+int prog2(void *ctx)
+{
+	struct task_struct *t = (void *)bpf_get_current_task();
+
+	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
+		return 1;
+
+	res2 = sub2(3) + sub3(4); /* (3 + 2) + (4 + 3 + (4 + 1)) = 17 */
+	return 0;
+}
+
+/* prog3 has the same section name as prog1 */
+SEC("raw_tp/sys_enter")
+int prog3(void *ctx)
+{
+	struct task_struct *t = (void *)bpf_get_current_task();
+
+	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
+		return 1;
+
+	res3 = sub3(5) + 6; /* (5 + 3 + (4 + 1)) + 6 = 19 */
+	return 0;
+}
+
+/* prog4 has the same section name as prog2 */
+SEC("raw_tp/sys_exit")
+int prog4(void *ctx)
+{
+	struct task_struct *t = (void *)bpf_get_current_task();
+
+	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
+		return 1;
+
+	res4 = sub4(7) + sub1(8); /* (7 + (5 + 3 + (4 + 1)) + (6 + 1)) + (8 + 1) = 36 */
+	return 0;
+}

tools/testing/selftests/bpf/progs/test_xdp_noinline.c

@@ -16,7 +16,7 @@
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_endian.h>
 
-static __u32 rol32(__u32 word, unsigned int shift)
+static __always_inline __u32 rol32(__u32 word, unsigned int shift)
 {
 	return (word << shift) | (word >> ((-shift) & 31));
 }
@@ -49,7 +49,7 @@ static __u32 rol32(__u32 word, unsigned int shift)
 
 typedef unsigned int u32;
 
-static __attribute__ ((noinline))
+static __noinline
 u32 jhash(const void *key, u32 length, u32 initval)
 {
 	u32 a, b, c;
@@ -86,7 +86,7 @@ u32 jhash(const void *key, u32 length, u32 initval)
 	return c;
 }
 
-__attribute__ ((noinline))
+__noinline
 u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 {
 	a += initval;
@@ -96,7 +96,7 @@ u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 	return c;
 }
 
-__attribute__ ((noinline))
+__noinline
 u32 jhash_2words(u32 a, u32 b, u32 initval)
 {
 	return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
@@ -213,7 +213,7 @@ struct eth_hdr {
 	unsigned short eth_proto;
 };
 
-static inline __u64 calc_offset(bool is_ipv6, bool is_icmp)
+static __noinline __u64 calc_offset(bool is_ipv6, bool is_icmp)
 {
 	__u64 off = sizeof(struct eth_hdr);
 	if (is_ipv6) {
@@ -797,8 +797,8 @@ static int process_packet(void *data, __u64 off, void *data_end,
 	return XDP_DROP;
 }
 
-__attribute__ ((section("xdp-test"), used))
-int balancer_ingress(struct xdp_md *ctx)
+SEC("xdp-test-v4")
+int balancer_ingress_v4(struct xdp_md *ctx)
 {
 	void *data = (void *)(long)ctx->data;
 	void *data_end = (void *)(long)ctx->data_end;
@@ -812,11 +812,27 @@ int balancer_ingress(struct xdp_md *ctx)
 	eth_proto = bpf_ntohs(eth->eth_proto);
 	if (eth_proto == ETH_P_IP)
 		return process_packet(data, nh_off, data_end, 0, ctx);
-	else if (eth_proto == ETH_P_IPV6)
+	else
+		return XDP_DROP;
+}
+
+SEC("xdp-test-v6")
+int balancer_ingress_v6(struct xdp_md *ctx)
+{
+	void *data = (void *)(long)ctx->data;
+	void *data_end = (void *)(long)ctx->data_end;
+	struct eth_hdr *eth = data;
+	__u32 eth_proto;
+	__u32 nh_off;
+
+	nh_off = sizeof(struct eth_hdr);
+	if (data + nh_off > data_end)
+		return XDP_DROP;
+	eth_proto = bpf_ntohs(eth->eth_proto);
+	if (eth_proto == ETH_P_IPV6)
 		return process_packet(data, nh_off, data_end, 1, ctx);
 	else
 		return XDP_DROP;
 }
 
-char _license[] __attribute__ ((section("license"), used)) = "GPL";
-int _version __attribute__ ((section("version"), used)) = 1;
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/test_socket_cookie.c

@@ -151,7 +151,7 @@ static int run_test(int cgfd)
 	}
 
 	bpf_object__for_each_program(prog, pobj) {
-		prog_name = bpf_program__title(prog, /*needs_copy*/ false);
+		prog_name = bpf_program__section_name(prog);
 
 		if (libbpf_attach_type_by_name(prog_name, &attach_type))
 			goto err;