[PATCH v2 bpf-next 00/10] libbpf: support custom .rodata.*/.data.* sections

[PATCH v2 bpf-next 00/10] libbpf: support custom .rodata.*/.data.* sections

[Andrii Nakryiko]

This patch set refactors internals of libbpf to enable support for multiple
custom .rodata.* and .data.* sections. Each such section is backed by its own
BPF_MAP_TYPE_ARRAY, memory-mappable just like .rodata/.data. This is not
extended to .bss because .bss is not a great name, it is generated by compiler
with name that reflects completely irrelevant historical implementation
details. Given that users have to annotate their variables with
SEC(".data.my_sec") explicitly, standardizing on .rodata. and .data. prefixes
makes more sense and keeps things simpler.

Additionally, this patch set makes it simpler to work with those special
internal maps by allowing to look them up by their full ELF section name.

Patch #1 is a preparatory patch that deprecates one libbpf API and moves
custom logic into libbpf.c, where it's used. This code is later refactored
with the rest of libbpf.c logic to support multiple data section maps.

See individual patches for all the details.

For new custom "dot maps", their full ELF section names are used as the names
that are sent into the kernel. Object name isn't prepended like for
.data/.rodata/.bss. The reason is that with longer custom names, there isn't
much space left for object name anyways. Also, if BTF is supported,
btf_value_type_id points to DATASEC BTF type, which contains full original ELF
name of the section, so tools like bpftool could use that to recover full
name. This patch set doesn't add this logic yet, this is left for follow up
patches.

One interesting possibility that is now open by these changes is that it's
possible to do:

    bpf_trace_printk("My fmt %s", sizeof("My fmt %s"), "blah");
    
and it will work as expected. I haven't updated libbpf-provided helpers in
bpf_helpers.h for snprintf, seq_printf, and printk, because using
`static const char ___fmt[] = fmt;` trick is still efficient and doesn't fill
out the buffer at runtime (no copying). But we might consider updating them in
the future, especially with the array check that Kumar proposed (see [0]).

  [0] https://lore.kernel.org/bpf/20211012041524.udytbr2xs5wid6x2@apollo.localdomain/

v1->v2:
  - don't prepend object name for new dot maps;
  - add __read_mostly example in selftests (Daniel).

Andrii Nakryiko (10):
  libbpf: deprecate btf__finalize_data() and move it into libbpf.c
  libbpf: extract ELF processing state into separate struct
  libbpf: use Elf64-specific types explicitly for dealing with ELF
  libbpf: remove assumptions about uniqueness of .rodata/.data/.bss maps
  bpftool: support multiple .rodata/.data internal maps in skeleton
  bpftool: improve skeleton generation for data maps without DATASEC
    type
  libbpf: support multiple .rodata.* and .data.* BPF maps
  selftests/bpf: demonstrate use of custom .rodata/.data sections
  libbpf: simplify look up by name of internal maps
  selftests/bpf: switch to ".bss"/".rodata"/".data" lookups for internal
    maps

 tools/bpf/bpftool/gen.c                       | 158 ++--
 tools/lib/bpf/btf.c                           |  93 --
 tools/lib/bpf/btf.h                           |   1 +
 tools/lib/bpf/libbpf.c                        | 893 +++++++++++-------
 tools/lib/bpf/libbpf_internal.h               |   8 +-
 tools/lib/bpf/linker.c                        |   1 -
 .../selftests/bpf/prog_tests/core_autosize.c  |   2 +-
 .../selftests/bpf/prog_tests/core_reloc.c     |   2 +-
 .../selftests/bpf/prog_tests/global_data.c    |  11 +-
 .../bpf/prog_tests/global_data_init.c         |   2 +-
 .../selftests/bpf/prog_tests/kfree_skb.c      |   2 +-
 .../selftests/bpf/prog_tests/rdonly_maps.c    |   2 +-
 .../selftests/bpf/prog_tests/skeleton.c       |  29 +
 .../selftests/bpf/progs/test_skeleton.c       |  18 +
 14 files changed, 731 insertions(+), 491 deletions(-)

-- 
2.30.2

[PATCH v2 bpf-next 01/10] libbpf: deprecate btf__finalize_data() and move it into libbpf.c

[Andrii Nakryiko]

There isn't a good use case where anyone but libbpf itself needs to call
btf__finalize_data(). It was implemented for internal use and it's not
clear why it was made into public API in the first place. To function, it
requires active ELF data, which is stored inside bpf_object for the
duration of opening phase only. But the only BTF that needs bpf_object's
ELF is that bpf_object's BTF itself, which libbpf fixes up automatically
during bpf_object__open() operation anyways. There is no need for any
additional fix up and no reasonable scenario where it's useful and
appropriate.

Thus, btf__finalize_data() is just an API atavism and is better removed.
So this patch marks it as deprecated immediately (v0.6+) and moves the
code from btf.c into libbpf.c where it's used in the context of
bpf_object opening phase. Such code co-location allows to make code
structure more straightforward and remove bpf_object__section_size() and
bpf_object__variable_offset() internal helpers from libbpf_internal.h,
making them static. Their naming is also adjusted to not create
a wrong illusion that they are some sort of method of bpf_object. They
are internal helpers and are called appropriately.

This is part of libbpf 1.0 effort ([0]).

  [0] Closes: https://github.com/libbpf/libbpf/issues/276

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/btf.c             |  93 ----------------------------
 tools/lib/bpf/btf.h             |   1 +
 tools/lib/bpf/libbpf.c          | 106 ++++++++++++++++++++++++++++++--
 tools/lib/bpf/libbpf_internal.h |   4 --
 4 files changed, 102 insertions(+), 102 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1f6dea11f600..3a01c4b7f36a 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1107,99 +1107,6 @@ struct btf *btf__parse_split(const char *path, struct btf *base_btf)
 	return libbpf_ptr(btf_parse(path, base_btf, NULL));
 }
 
-static int compare_vsi_off(const void *_a, const void *_b)
-{
-	const struct btf_var_secinfo *a = _a;
-	const struct btf_var_secinfo *b = _b;
-
-	return a->offset - b->offset;
-}
-
-static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
-			     struct btf_type *t)
-{
-	__u32 size = 0, off = 0, i, vars = btf_vlen(t);
-	const char *name = btf__name_by_offset(btf, t->name_off);
-	const struct btf_type *t_var;
-	struct btf_var_secinfo *vsi;
-	const struct btf_var *var;
-	int ret;
-
-	if (!name) {
-		pr_debug("No name found in string section for DATASEC kind.\n");
-		return -ENOENT;
-	}
-
-	/* .extern datasec size and var offsets were set correctly during
-	 * extern collection step, so just skip straight to sorting variables
-	 */
-	if (t->size)
-		goto sort_vars;
-
-	ret = bpf_object__section_size(obj, name, &size);
-	if (ret || !size || (t->size && t->size != size)) {
-		pr_debug("Invalid size for section %s: %u bytes\n", name, size);
-		return -ENOENT;
-	}
-
-	t->size = size;
-
-	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
-		t_var = btf__type_by_id(btf, vsi->type);
-		var = btf_var(t_var);
-
-		if (!btf_is_var(t_var)) {
-			pr_debug("Non-VAR type seen in section %s\n", name);
-			return -EINVAL;
-		}
-
-		if (var->linkage == BTF_VAR_STATIC)
-			continue;
-
-		name = btf__name_by_offset(btf, t_var->name_off);
-		if (!name) {
-			pr_debug("No name found in string section for VAR kind\n");
-			return -ENOENT;
-		}
-
-		ret = bpf_object__variable_offset(obj, name, &off);
-		if (ret) {
-			pr_debug("No offset found in symbol table for VAR %s\n",
-				 name);
-			return -ENOENT;
-		}
-
-		vsi->offset = off;
-	}
-
-sort_vars:
-	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
-	return 0;
-}
-
-int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
-{
-	int err = 0;
-	__u32 i;
-
-	for (i = 1; i <= btf->nr_types; i++) {
-		struct btf_type *t = btf_type_by_id(btf, i);
-
-		/* Loader needs to fix up some of the things compiler
-		 * couldn't get its hands on while emitting BTF. This
-		 * is section size and global variable offset. We use
-		 * the info from the ELF itself for this purpose.
-		 */
-		if (btf_is_datasec(t)) {
-			err = btf_fixup_datasec(obj, btf, t);
-			if (err)
-				break;
-		}
-	}
-
-	return libbpf_err(err);
-}
-
 static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
 
 int btf__load_into_kernel(struct btf *btf)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 4011e206e6f7..c9364be42035 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -123,6 +123,7 @@ LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *b
 LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_from_kernel_by_id instead")
 LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
 
+LIBBPF_DEPRECATED_SINCE(0, 6, "intended for internal libbpf use only")
 LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
 LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_into_kernel instead")
 LIBBPF_API int btf__load(struct btf *btf);
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 760c7e346603..fdc25a112150 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1324,8 +1324,7 @@ static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
 	return false;
 }
 
-int bpf_object__section_size(const struct bpf_object *obj, const char *name,
-			     __u32 *size)
+static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
 {
 	int ret = -ENOENT;
 
@@ -1357,8 +1356,7 @@ int bpf_object__section_size(const struct bpf_object *obj, const char *name,
 	return *size ? 0 : ret;
 }
 
-int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
-				__u32 *off)
+static int find_elf_var_offset(const struct bpf_object *obj, const char *name, __u32 *off)
 {
 	Elf_Data *symbols = obj->efile.symbols;
 	const char *sname;
@@ -2650,6 +2648,104 @@ static int bpf_object__init_btf(struct bpf_object *obj,
 	return 0;
 }
 
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+	const struct btf_var_secinfo *a = _a;
+	const struct btf_var_secinfo *b = _b;
+
+	return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+			     struct btf_type *t)
+{
+	__u32 size = 0, off = 0, i, vars = btf_vlen(t);
+	const char *name = btf__name_by_offset(btf, t->name_off);
+	const struct btf_type *t_var;
+	struct btf_var_secinfo *vsi;
+	const struct btf_var *var;
+	int ret;
+
+	if (!name) {
+		pr_debug("No name found in string section for DATASEC kind.\n");
+		return -ENOENT;
+	}
+
+	/* .extern datasec size and var offsets were set correctly during
+	 * extern collection step, so just skip straight to sorting variables
+	 */
+	if (t->size)
+		goto sort_vars;
+
+	ret = find_elf_sec_sz(obj, name, &size);
+	if (ret || !size || (t->size && t->size != size)) {
+		pr_debug("Invalid size for section %s: %u bytes\n", name, size);
+		return -ENOENT;
+	}
+
+	t->size = size;
+
+	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
+		t_var = btf__type_by_id(btf, vsi->type);
+		var = btf_var(t_var);
+
+		if (!btf_is_var(t_var)) {
+			pr_debug("Non-VAR type seen in section %s\n", name);
+			return -EINVAL;
+		}
+
+		if (var->linkage == BTF_VAR_STATIC)
+			continue;
+
+		name = btf__name_by_offset(btf, t_var->name_off);
+		if (!name) {
+			pr_debug("No name found in string section for VAR kind\n");
+			return -ENOENT;
+		}
+
+		ret = find_elf_var_offset(obj, name, &off);
+		if (ret) {
+			pr_debug("No offset found in symbol table for VAR %s\n",
+				 name);
+			return -ENOENT;
+		}
+
+		vsi->offset = off;
+	}
+
+sort_vars:
+	qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
+	return 0;
+}
+
+static int btf_finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+	int err = 0;
+	__u32 i, n = btf__get_nr_types(btf);
+
+	for (i = 1; i <= n; i++) {
+		struct btf_type *t = btf_type_by_id(btf, i);
+
+		/* Loader needs to fix up some of the things compiler
+		 * couldn't get its hands on while emitting BTF. This
+		 * is section size and global variable offset. We use
+		 * the info from the ELF itself for this purpose.
+		 */
+		if (btf_is_datasec(t)) {
+			err = btf_fixup_datasec(obj, btf, t);
+			if (err)
+				break;
+		}
+	}
+
+	return libbpf_err(err);
+}
+
+int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+	return btf_finalize_data(obj, btf);
+}
+
 static int bpf_object__finalize_btf(struct bpf_object *obj)
 {
 	int err;
@@ -2657,7 +2753,7 @@ static int bpf_object__finalize_btf(struct bpf_object *obj)
 	if (!obj->btf)
 		return 0;
 
-	err = btf__finalize_data(obj, obj->btf);
+	err = btf_finalize_data(obj, obj->btf);
 	if (err) {
 		pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
 		return err;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f6a5748dd318..4bbd327a4ce9 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -303,10 +303,6 @@ struct bpf_prog_load_params {
 
 int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr);
 
-int bpf_object__section_size(const struct bpf_object *obj, const char *name,
-			     __u32 *size);
-int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
-				__u32 *off);
 struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
 void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
 				const char **prefix, int *kind);
-- 
2.30.2

[PATCH v2 bpf-next 02/10] libbpf: extract ELF processing state into separate struct

[Andrii Nakryiko]

Name currently anonymous internal struct that keeps ELF-related state
for bpf_object. Just a bit of clean up, no functional changes.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 70 ++++++++++++++++++++----------------------
 1 file changed, 34 insertions(+), 36 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index fdc25a112150..84a0683d214b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -462,6 +462,35 @@ struct module_btf {
 	int fd_array_idx;
 };
 
+struct elf_state {
+	int fd;
+	const void *obj_buf;
+	size_t obj_buf_sz;
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	Elf_Data *symbols;
+	Elf_Data *data;
+	Elf_Data *rodata;
+	Elf_Data *bss;
+	Elf_Data *st_ops_data;
+	size_t shstrndx; /* section index for section name strings */
+	size_t strtabidx;
+	struct {
+		GElf_Shdr shdr;
+		Elf_Data *data;
+	} *reloc_sects;
+	int nr_reloc_sects;
+	int maps_shndx;
+	int btf_maps_shndx;
+	__u32 btf_maps_sec_btf_id;
+	int text_shndx;
+	int symbols_shndx;
+	int data_shndx;
+	int rodata_shndx;
+	int bss_shndx;
+	int st_ops_shndx;
+};
+
 struct bpf_object {
 	char name[BPF_OBJ_NAME_LEN];
 	char license[64];
@@ -484,40 +513,10 @@ struct bpf_object {
 
 	struct bpf_gen *gen_loader;
 
+	/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
+	struct elf_state efile;
 	/*
-	 * Information when doing elf related work. Only valid if fd
-	 * is valid.
-	 */
-	struct {
-		int fd;
-		const void *obj_buf;
-		size_t obj_buf_sz;
-		Elf *elf;
-		GElf_Ehdr ehdr;
-		Elf_Data *symbols;
-		Elf_Data *data;
-		Elf_Data *rodata;
-		Elf_Data *bss;
-		Elf_Data *st_ops_data;
-		size_t shstrndx; /* section index for section name strings */
-		size_t strtabidx;
-		struct {
-			GElf_Shdr shdr;
-			Elf_Data *data;
-		} *reloc_sects;
-		int nr_reloc_sects;
-		int maps_shndx;
-		int btf_maps_shndx;
-		__u32 btf_maps_sec_btf_id;
-		int text_shndx;
-		int symbols_shndx;
-		int data_shndx;
-		int rodata_shndx;
-		int bss_shndx;
-		int st_ops_shndx;
-	} efile;
-	/*
-	 * All loaded bpf_object is linked in a list, which is
+	 * All loaded bpf_object are linked in a list, which is
 	 * hidden to caller. bpf_objects__<func> handlers deal with
 	 * all objects.
 	 */
@@ -551,7 +550,6 @@ struct bpf_object {
 
 	char path[];
 };
-#define obj_elf_valid(o)	((o)->efile.elf)
 
 static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
 static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
@@ -1185,7 +1183,7 @@ static struct bpf_object *bpf_object__new(const char *path,
 
 static void bpf_object__elf_finish(struct bpf_object *obj)
 {
-	if (!obj_elf_valid(obj))
+	if (!obj->efile.elf)
 		return;
 
 	if (obj->efile.elf) {
@@ -1210,7 +1208,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	int err = 0;
 	GElf_Ehdr *ep;
 
-	if (obj_elf_valid(obj)) {
+	if (obj->efile.elf) {
 		pr_warn("elf: init internal error\n");
 		return -LIBBPF_ERRNO__LIBELF;
 	}
-- 
2.30.2

[PATCH v2 bpf-next 03/10] libbpf: use Elf64-specific types explicitly for dealing with ELF

[Andrii Nakryiko]

Minimize the usage of class-agnostic gelf_xxx() APIs from libelf. These
APIs require copying ELF data structures into local GElf_xxx structs and
have a more cumbersome API. BPF ELF file is defined to be always 64-bit
ELF object, even when intended to be run on 32-bit host architectures,
so there is no need to do class-agnostic conversions everywhere. BPF
static linker implementation within libbpf has been using Elf64-specific
types since initial implementation.

Add two simple helpers, elf_sym_by_idx() and elf_rel_by_idx(), for more
succinct direct access to ELF symbol and relocation records within ELF
data itself and switch all the GElf_xxx usage into Elf64_xxx
equivalents. The only remaining place within libbpf.c that's still using
gelf API is gelf_getclass(), as there doesn't seem to be a direct way to
get underlying ELF bitness.

No functional changes intended.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c          | 353 ++++++++++++++++++--------------
 tools/lib/bpf/libbpf_internal.h |   4 +-
 tools/lib/bpf/linker.c          |   1 -
 3 files changed, 196 insertions(+), 162 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 84a0683d214b..74f7d9252d13 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -467,7 +467,7 @@ struct elf_state {
 	const void *obj_buf;
 	size_t obj_buf_sz;
 	Elf *elf;
-	GElf_Ehdr ehdr;
+	Elf64_Ehdr *ehdr;
 	Elf_Data *symbols;
 	Elf_Data *data;
 	Elf_Data *rodata;
@@ -476,7 +476,7 @@ struct elf_state {
 	size_t shstrndx; /* section index for section name strings */
 	size_t strtabidx;
 	struct {
-		GElf_Shdr shdr;
+		Elf64_Shdr *shdr;
 		Elf_Data *data;
 	} *reloc_sects;
 	int nr_reloc_sects;
@@ -555,9 +555,11 @@ static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
 static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
 static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
 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 Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
 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 Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
 
 void bpf_program__unload(struct bpf_program *prog)
 {
@@ -699,25 +701,25 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
 	size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
 	int nr_progs, err, i;
 	const char *name;
-	GElf_Sym sym;
+	Elf64_Sym *sym;
 
 	progs = obj->programs;
 	nr_progs = obj->nr_programs;
-	nr_syms = symbols->d_size / sizeof(GElf_Sym);
+	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
 	sec_off = 0;
 
 	for (i = 0; i < nr_syms; i++) {
-		if (!gelf_getsym(symbols, i, &sym))
-			continue;
-		if (sym.st_shndx != sec_idx)
+		sym = elf_sym_by_idx(obj, i);
+
+		if (sym->st_shndx != sec_idx)
 			continue;
-		if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
+		if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
 			continue;
 
-		prog_sz = sym.st_size;
-		sec_off = sym.st_value;
+		prog_sz = sym->st_size;
+		sec_off = sym->st_value;
 
-		name = elf_sym_str(obj, sym.st_name);
+		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);
@@ -730,7 +732,7 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		if (sec_idx != obj->efile.text_shndx && GELF_ST_BIND(sym.st_info) == STB_LOCAL) {
+		if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
 			pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
 			return -ENOTSUP;
 		}
@@ -763,9 +765,9 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
 		 * as static to enable more permissive BPF verification mode
 		 * with more outside context available to BPF verifier
 		 */
-		if (GELF_ST_BIND(sym.st_info) != STB_LOCAL
-		    && (GELF_ST_VISIBILITY(sym.st_other) == STV_HIDDEN
-			|| GELF_ST_VISIBILITY(sym.st_other) == STV_INTERNAL))
+		if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL
+		    && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
+			|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
 			prog->mark_btf_static = true;
 
 		nr_progs++;
@@ -1205,8 +1207,9 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
 
 static int bpf_object__elf_init(struct bpf_object *obj)
 {
+	Elf64_Ehdr *ehdr;
 	int err = 0;
-	GElf_Ehdr *ep;
+	Elf *elf;
 
 	if (obj->efile.elf) {
 		pr_warn("elf: init internal error\n");
@@ -1218,8 +1221,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 		 * obj_buf should have been validated by
 		 * bpf_object__open_buffer().
 		 */
-		obj->efile.elf = elf_memory((char *)obj->efile.obj_buf,
-					    obj->efile.obj_buf_sz);
+		elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
 	} else {
 		obj->efile.fd = open(obj->path, O_RDONLY);
 		if (obj->efile.fd < 0) {
@@ -1231,23 +1233,37 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 			return err;
 		}
 
-		obj->efile.elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
+		elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
 	}
 
-	if (!obj->efile.elf) {
+	if (!elf) {
 		pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
 		err = -LIBBPF_ERRNO__LIBELF;
 		goto errout;
 	}
 
-	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
+	obj->efile.elf = elf;
+
+	if (elf_kind(elf) != ELF_K_ELF) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
+		goto errout;
+	}
+
+	if (gelf_getclass(elf) != ELFCLASS64) {
+		err = -LIBBPF_ERRNO__FORMAT;
+		pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
+		goto errout;
+	}
+
+	obj->efile.ehdr = ehdr = elf64_getehdr(elf);
+	if (!obj->efile.ehdr) {
 		pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
 	}
-	ep = &obj->efile.ehdr;
 
-	if (elf_getshdrstrndx(obj->efile.elf, &obj->efile.shstrndx)) {
+	if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
 		pr_warn("elf: failed to get section names section index for %s: %s\n",
 			obj->path, elf_errmsg(-1));
 		err = -LIBBPF_ERRNO__FORMAT;
@@ -1255,7 +1271,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	}
 
 	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
-	if (!elf_rawdata(elf_getscn(obj->efile.elf, obj->efile.shstrndx), NULL)) {
+	if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
 		pr_warn("elf: failed to get section names strings from %s: %s\n",
 			obj->path, elf_errmsg(-1));
 		err = -LIBBPF_ERRNO__FORMAT;
@@ -1263,8 +1279,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 	}
 
 	/* Old LLVM set e_machine to EM_NONE */
-	if (ep->e_type != ET_REL ||
-	    (ep->e_machine && ep->e_machine != EM_BPF)) {
+	if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
 		pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
 		err = -LIBBPF_ERRNO__FORMAT;
 		goto errout;
@@ -1279,10 +1294,10 @@ static int bpf_object__elf_init(struct bpf_object *obj)
 static int bpf_object__check_endianness(struct bpf_object *obj)
 {
 #if __BYTE_ORDER == __LITTLE_ENDIAN
-	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
 		return 0;
 #elif __BYTE_ORDER == __BIG_ENDIAN
-	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
+	if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
 		return 0;
 #else
 # error "Unrecognized __BYTE_ORDER__"
@@ -1363,23 +1378,20 @@ static int find_elf_var_offset(const struct bpf_object *obj, const char *name, _
 	if (!name || !off)
 		return -EINVAL;
 
-	for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) {
-		GElf_Sym sym;
+	for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
+		Elf64_Sym *sym = elf_sym_by_idx(obj, si);
 
-		if (!gelf_getsym(symbols, si, &sym))
-			continue;
-		if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL ||
-		    GELF_ST_TYPE(sym.st_info) != STT_OBJECT)
+		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL ||
+		    ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
 			continue;
 
-		sname = elf_sym_str(obj, sym.st_name);
+		sname = elf_sym_str(obj, sym->st_name);
 		if (!sname) {
-			pr_warn("failed to get sym name string for var %s\n",
-				name);
+			pr_warn("failed to get sym name string for var %s\n", name);
 			return -EIO;
 		}
 		if (strcmp(name, sname) == 0) {
-			*off = sym.st_value;
+			*off = sym->st_value;
 			return 0;
 		}
 	}
@@ -1866,15 +1878,13 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 	 *
 	 * TODO: Detect array of map and report error.
 	 */
-	nr_syms = symbols->d_size / sizeof(GElf_Sym);
+	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
 	for (i = 0; i < nr_syms; i++) {
-		GElf_Sym sym;
+		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
 
-		if (!gelf_getsym(symbols, i, &sym))
+		if (sym->st_shndx != obj->efile.maps_shndx)
 			continue;
-		if (sym.st_shndx != obj->efile.maps_shndx)
-			continue;
-		if (GELF_ST_TYPE(sym.st_info) == STT_SECTION)
+		if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION)
 			continue;
 		nr_maps++;
 	}
@@ -1891,40 +1901,38 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 
 	/* Fill obj->maps using data in "maps" section.  */
 	for (i = 0; i < nr_syms; i++) {
-		GElf_Sym sym;
+		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
 		const char *map_name;
 		struct bpf_map_def *def;
 		struct bpf_map *map;
 
-		if (!gelf_getsym(symbols, i, &sym))
-			continue;
-		if (sym.st_shndx != obj->efile.maps_shndx)
+		if (sym->st_shndx != obj->efile.maps_shndx)
 			continue;
-		if (GELF_ST_TYPE(sym.st_info) == STT_SECTION)
+		if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION)
 			continue;
 
 		map = bpf_object__add_map(obj);
 		if (IS_ERR(map))
 			return PTR_ERR(map);
 
-		map_name = elf_sym_str(obj, sym.st_name);
+		map_name = elf_sym_str(obj, sym->st_name);
 		if (!map_name) {
 			pr_warn("failed to get map #%d name sym string for obj %s\n",
 				i, obj->path);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		if (GELF_ST_BIND(sym.st_info) == STB_LOCAL) {
+		if (ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
 			pr_warn("map '%s' (legacy): static maps are not supported\n", map_name);
 			return -ENOTSUP;
 		}
 
 		map->libbpf_type = LIBBPF_MAP_UNSPEC;
-		map->sec_idx = sym.st_shndx;
-		map->sec_offset = sym.st_value;
+		map->sec_idx = sym->st_shndx;
+		map->sec_offset = sym->st_value;
 		pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n",
 			 map_name, map->sec_idx, map->sec_offset);
-		if (sym.st_value + map_def_sz > data->d_size) {
+		if (sym->st_value + map_def_sz > data->d_size) {
 			pr_warn("corrupted maps section in %s: last map \"%s\" too small\n",
 				obj->path, map_name);
 			return -EINVAL;
@@ -1936,7 +1944,7 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 			return -ENOMEM;
 		}
 		pr_debug("map %d is \"%s\"\n", i, map->name);
-		def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
+		def = (struct bpf_map_def *)(data->d_buf + sym->st_value);
 		/*
 		 * If the definition of the map in the object file fits in
 		 * bpf_map_def, copy it.  Any extra fields in our version
@@ -2506,12 +2514,13 @@ static int bpf_object__init_maps(struct bpf_object *obj,
 
 static bool section_have_execinstr(struct bpf_object *obj, int idx)
 {
-	GElf_Shdr sh;
+	Elf64_Shdr *sh;
 
-	if (elf_sec_hdr(obj, elf_sec_by_idx(obj, idx), &sh))
+	sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
+	if (!sh)
 		return false;
 
-	return sh.sh_flags & SHF_EXECINSTR;
+	return sh->sh_flags & SHF_EXECINSTR;
 }
 
 static bool btf_needs_sanitization(struct bpf_object *obj)
@@ -2987,32 +2996,36 @@ static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
 	return NULL;
 }
 
-static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr)
+static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
 {
+	Elf64_Shdr *shdr;
+
 	if (!scn)
-		return -EINVAL;
+		return NULL;
 
-	if (gelf_getshdr(scn, hdr) != hdr) {
+	shdr = elf64_getshdr(scn);
+	if (!shdr) {
 		pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
 			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
-		return -EINVAL;
+		return NULL;
 	}
 
-	return 0;
+	return shdr;
 }
 
 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
 {
 	const char *name;
-	GElf_Shdr sh;
+	Elf64_Shdr *sh;
 
 	if (!scn)
 		return NULL;
 
-	if (elf_sec_hdr(obj, scn, &sh))
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh)
 		return NULL;
 
-	name = elf_sec_str(obj, sh.sh_name);
+	name = elf_sec_str(obj, sh->sh_name);
 	if (!name) {
 		pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
 			elf_ndxscn(scn), obj->path, elf_errmsg(-1));
@@ -3040,13 +3053,29 @@ static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
 	return data;
 }
 
+static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
+{
+	if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
+		return NULL;
+
+	return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
+}
+
+static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
+{
+	if (idx >= data->d_size / sizeof(Elf64_Rel))
+		return NULL;
+
+	return (Elf64_Rel *)data->d_buf + idx;
+}
+
 static bool is_sec_name_dwarf(const char *name)
 {
 	/* approximation, but the actual list is too long */
 	return str_has_pfx(name, ".debug_");
 }
 
-static bool ignore_elf_section(GElf_Shdr *hdr, const char *name)
+static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
 {
 	/* no special handling of .strtab */
 	if (hdr->sh_type == SHT_STRTAB)
@@ -3101,17 +3130,18 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 	const char *name;
 	Elf_Data *data;
 	Elf_Scn *scn;
-	GElf_Shdr sh;
+	Elf64_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) {
-		if (elf_sec_hdr(obj, scn, &sh))
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
 			return -LIBBPF_ERRNO__FORMAT;
 
-		if (sh.sh_type == SHT_SYMTAB) {
+		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;
@@ -3123,7 +3153,7 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 
 			obj->efile.symbols = data;
 			obj->efile.symbols_shndx = elf_ndxscn(scn);
-			obj->efile.strtabidx = sh.sh_link;
+			obj->efile.strtabidx = sh->sh_link;
 		}
 	}
 
@@ -3137,14 +3167,15 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
 		idx++;
 
-		if (elf_sec_hdr(obj, scn, &sh))
+		sh = elf_sec_hdr(obj, scn);
+		if (!sh)
 			return -LIBBPF_ERRNO__FORMAT;
 
-		name = elf_sec_str(obj, sh.sh_name);
+		name = elf_sec_str(obj, sh->sh_name);
 		if (!name)
 			return -LIBBPF_ERRNO__FORMAT;
 
-		if (ignore_elf_section(&sh, name))
+		if (ignore_elf_section(sh, name))
 			continue;
 
 		data = elf_sec_data(obj, scn);
@@ -3153,8 +3184,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 
 		pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
 			 idx, name, (unsigned long)data->d_size,
-			 (int)sh.sh_link, (unsigned long)sh.sh_flags,
-			 (int)sh.sh_type);
+			 (int)sh->sh_link, (unsigned long)sh->sh_flags,
+			 (int)sh->sh_type);
 
 		if (strcmp(name, "license") == 0) {
 			err = bpf_object__init_license(obj, data->d_buf, data->d_size);
@@ -3172,10 +3203,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 			btf_data = data;
 		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
 			btf_ext_data = data;
-		} else if (sh.sh_type == SHT_SYMTAB) {
+		} else if (sh->sh_type == SHT_SYMTAB) {
 			/* already processed during the first pass above */
-		} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
-			if (sh.sh_flags & SHF_EXECINSTR) {
+		} 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_programs(obj, data, name, idx);
@@ -3194,10 +3225,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 				pr_info("elf: skipping unrecognized data section(%d) %s\n",
 					idx, name);
 			}
-		} else if (sh.sh_type == SHT_REL) {
+		} else if (sh->sh_type == SHT_REL) {
 			int nr_sects = obj->efile.nr_reloc_sects;
 			void *sects = obj->efile.reloc_sects;
-			int sec = sh.sh_info; /* points to other section */
+			int sec = sh->sh_info; /* points to other section */
 
 			/* Only do relo for section with exec instructions */
 			if (!section_have_execinstr(obj, sec) &&
@@ -3219,12 +3250,12 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 
 			obj->efile.reloc_sects[nr_sects].shdr = sh;
 			obj->efile.reloc_sects[nr_sects].data = data;
-		} else if (sh.sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
+		} else if (sh->sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
 			obj->efile.bss = data;
 			obj->efile.bss_shndx = idx;
 		} else {
 			pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
-				(size_t)sh.sh_size);
+				(size_t)sh->sh_size);
 		}
 	}
 
@@ -3240,19 +3271,19 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 	return bpf_object__init_btf(obj, btf_data, btf_ext_data);
 }
 
-static bool sym_is_extern(const GElf_Sym *sym)
+static bool sym_is_extern(const Elf64_Sym *sym)
 {
-	int bind = GELF_ST_BIND(sym->st_info);
+	int bind = ELF64_ST_BIND(sym->st_info);
 	/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
 	return sym->st_shndx == SHN_UNDEF &&
 	       (bind == STB_GLOBAL || bind == STB_WEAK) &&
-	       GELF_ST_TYPE(sym->st_info) == STT_NOTYPE;
+	       ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
 }
 
-static bool sym_is_subprog(const GElf_Sym *sym, int text_shndx)
+static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
 {
-	int bind = GELF_ST_BIND(sym->st_info);
-	int type = GELF_ST_TYPE(sym->st_info);
+	int bind = ELF64_ST_BIND(sym->st_info);
+	int type = ELF64_ST_TYPE(sym->st_info);
 
 	/* in .text section */
 	if (sym->st_shndx != text_shndx)
@@ -3450,30 +3481,31 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
 	int i, n, off, dummy_var_btf_id;
 	const char *ext_name, *sec_name;
 	Elf_Scn *scn;
-	GElf_Shdr sh;
+	Elf64_Shdr *sh;
 
 	if (!obj->efile.symbols)
 		return 0;
 
 	scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
-	if (elf_sec_hdr(obj, scn, &sh))
+	sh = elf_sec_hdr(obj, scn);
+	if (!sh)
 		return -LIBBPF_ERRNO__FORMAT;
 
 	dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
 	if (dummy_var_btf_id < 0)
 		return dummy_var_btf_id;
 
-	n = sh.sh_size / sh.sh_entsize;
+	n = sh->sh_size / sh->sh_entsize;
 	pr_debug("looking for externs among %d symbols...\n", n);
 
 	for (i = 0; i < n; i++) {
-		GElf_Sym sym;
+		Elf64_Sym *sym = elf_sym_by_idx(obj, i);
 
-		if (!gelf_getsym(obj->efile.symbols, i, &sym))
+		if (!sym)
 			return -LIBBPF_ERRNO__FORMAT;
-		if (!sym_is_extern(&sym))
+		if (!sym_is_extern(sym))
 			continue;
-		ext_name = elf_sym_str(obj, sym.st_name);
+		ext_name = elf_sym_str(obj, sym->st_name);
 		if (!ext_name || !ext_name[0])
 			continue;
 
@@ -3495,7 +3527,7 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
 		t = btf__type_by_id(obj->btf, ext->btf_id);
 		ext->name = btf__name_by_offset(obj->btf, t->name_off);
 		ext->sym_idx = i;
-		ext->is_weak = GELF_ST_BIND(sym.st_info) == STB_WEAK;
+		ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
 
 		ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
 		if (ext->sec_btf_id <= 0) {
@@ -3730,7 +3762,7 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
 static int bpf_program__record_reloc(struct bpf_program *prog,
 				     struct reloc_desc *reloc_desc,
 				     __u32 insn_idx, const char *sym_name,
-				     const GElf_Sym *sym, const GElf_Rel *rel)
+				     const Elf64_Sym *sym, const Elf64_Rel *rel)
 {
 	struct bpf_insn *insn = &prog->insns[insn_idx];
 	size_t map_idx, nr_maps = prog->obj->nr_maps;
@@ -3747,7 +3779,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 	}
 
 	if (sym_is_extern(sym)) {
-		int sym_idx = GELF_R_SYM(rel->r_info);
+		int sym_idx = ELF64_R_SYM(rel->r_info);
 		int i, n = obj->nr_extern;
 		struct extern_desc *ext;
 
@@ -3912,9 +3944,8 @@ static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
 }
 
 static int
-bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data)
+bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_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;
@@ -3924,8 +3955,8 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data
 	__u32 insn_idx;
 	Elf_Scn *scn;
 	Elf_Data *scn_data;
-	GElf_Sym sym;
-	GElf_Rel rel;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
 
 	scn = elf_sec_by_idx(obj, sec_idx);
 	scn_data = elf_sec_data(obj, scn);
@@ -3940,33 +3971,36 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data
 	nrels = shdr->sh_size / shdr->sh_entsize;
 
 	for (i = 0; i < nrels; i++) {
-		if (!gelf_getrel(data, i, &rel)) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
 			pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
-		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
 			pr_warn("sec '%s': symbol 0x%zx not found for relo #%d\n",
-				relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i);
+				relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		if (rel.r_offset % BPF_INSN_SZ || rel.r_offset >= scn_data->d_size) {
+		if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
 			pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
-				relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i);
+				relo_sec_name, (size_t)ELF64_R_SYM(rel->r_info), i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		insn_idx = rel.r_offset / BPF_INSN_SZ;
+		insn_idx = rel->r_offset / BPF_INSN_SZ;
 		/* 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));
+		if (ELF64_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 = elf_sym_str(obj, sym->st_name);
 		sym_name = sym_name ?: "<?";
 
 		pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
@@ -3988,7 +4022,7 @@ bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data
 		/* 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);
+						insn_idx, sym_name, sym, rel);
 		if (err)
 			return err;
 
@@ -6036,10 +6070,10 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
 }
 
 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
-					    GElf_Shdr *shdr, Elf_Data *data);
+					    Elf64_Shdr *shdr, Elf_Data *data);
 
 static int bpf_object__collect_map_relos(struct bpf_object *obj,
-					 GElf_Shdr *shdr, Elf_Data *data)
+					 Elf64_Shdr *shdr, Elf_Data *data)
 {
 	const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
 	int i, j, nrels, new_sz;
@@ -6048,10 +6082,9 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 	struct bpf_map *map = NULL, *targ_map;
 	const struct btf_member *member;
 	const char *name, *mname;
-	Elf_Data *symbols;
 	unsigned int moff;
-	GElf_Sym sym;
-	GElf_Rel rel;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
 	void *tmp;
 
 	if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
@@ -6060,28 +6093,30 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 	if (!sec)
 		return -EINVAL;
 
-	symbols = obj->efile.symbols;
 	nrels = shdr->sh_size / shdr->sh_entsize;
 	for (i = 0; i < nrels; i++) {
-		if (!gelf_getrel(data, i, &rel)) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
 			pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
-		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
+
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
 			pr_warn(".maps relo #%d: symbol %zx not found\n",
-				i, (size_t)GELF_R_SYM(rel.r_info));
+				i, (size_t)ELF64_R_SYM(rel->r_info));
 			return -LIBBPF_ERRNO__FORMAT;
 		}
-		name = elf_sym_str(obj, sym.st_name) ?: "<?>";
-		if (sym.st_shndx != obj->efile.btf_maps_shndx) {
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+		if (sym->st_shndx != obj->efile.btf_maps_shndx) {
 			pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
 				i, name);
 			return -LIBBPF_ERRNO__RELOC;
 		}
 
-		pr_debug(".maps relo #%d: for %zd value %zd rel.r_offset %zu name %d ('%s')\n",
-			 i, (ssize_t)(rel.r_info >> 32), (size_t)sym.st_value,
-			 (size_t)rel.r_offset, sym.st_name, name);
+		pr_debug(".maps relo #%d: for %zd value %zd rel->r_offset %zu name %d ('%s')\n",
+			 i, (ssize_t)(rel->r_info >> 32), (size_t)sym->st_value,
+			 (size_t)rel->r_offset, sym->st_name, name);
 
 		for (j = 0; j < obj->nr_maps; j++) {
 			map = &obj->maps[j];
@@ -6089,13 +6124,13 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 				continue;
 
 			vi = btf_var_secinfos(sec) + map->btf_var_idx;
-			if (vi->offset <= rel.r_offset &&
-			    rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size)
+			if (vi->offset <= rel->r_offset &&
+			    rel->r_offset + bpf_ptr_sz <= vi->offset + vi->size)
 				break;
 		}
 		if (j == obj->nr_maps) {
-			pr_warn(".maps relo #%d: cannot find map '%s' at rel.r_offset %zu\n",
-				i, name, (size_t)rel.r_offset);
+			pr_warn(".maps relo #%d: cannot find map '%s' at rel->r_offset %zu\n",
+				i, name, (size_t)rel->r_offset);
 			return -EINVAL;
 		}
 
@@ -6122,10 +6157,10 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
 			return -EINVAL;
 
 		moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
-		if (rel.r_offset - vi->offset < moff)
+		if (rel->r_offset - vi->offset < moff)
 			return -EINVAL;
 
-		moff = rel.r_offset - vi->offset - moff;
+		moff = rel->r_offset - vi->offset - moff;
 		/* here we use BPF pointer size, which is always 64 bit, as we
 		 * are parsing ELF that was built for BPF target
 		 */
@@ -6171,7 +6206,7 @@ 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;
+		Elf64_Shdr *shdr = obj->efile.reloc_sects[i].shdr;
 		Elf_Data *data = obj->efile.reloc_sects[i].data;
 		int idx = shdr->sh_info;
 
@@ -8362,7 +8397,7 @@ static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
 
 /* Collect the reloc from ELF and populate the st_ops->progs[] */
 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
-					    GElf_Shdr *shdr, Elf_Data *data)
+					    Elf64_Shdr *shdr, Elf_Data *data)
 {
 	const struct btf_member *member;
 	struct bpf_struct_ops *st_ops;
@@ -8370,58 +8405,58 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
 	unsigned int shdr_idx;
 	const struct btf *btf;
 	struct bpf_map *map;
-	Elf_Data *symbols;
 	unsigned int moff, insn_idx;
 	const char *name;
 	__u32 member_idx;
-	GElf_Sym sym;
-	GElf_Rel rel;
+	Elf64_Sym *sym;
+	Elf64_Rel *rel;
 	int i, nrels;
 
-	symbols = obj->efile.symbols;
 	btf = obj->btf;
 	nrels = shdr->sh_size / shdr->sh_entsize;
 	for (i = 0; i < nrels; i++) {
-		if (!gelf_getrel(data, i, &rel)) {
+		rel = elf_rel_by_idx(data, i);
+		if (!rel) {
 			pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
+		sym = elf_sym_by_idx(obj, ELF64_R_SYM(rel->r_info));
+		if (!sym) {
 			pr_warn("struct_ops reloc: symbol %zx not found\n",
-				(size_t)GELF_R_SYM(rel.r_info));
+				(size_t)ELF64_R_SYM(rel->r_info));
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
-		name = elf_sym_str(obj, sym.st_name) ?: "<?>";
-		map = find_struct_ops_map_by_offset(obj, rel.r_offset);
+		name = elf_sym_str(obj, sym->st_name) ?: "<?>";
+		map = find_struct_ops_map_by_offset(obj, rel->r_offset);
 		if (!map) {
-			pr_warn("struct_ops reloc: cannot find map at rel.r_offset %zu\n",
-				(size_t)rel.r_offset);
+			pr_warn("struct_ops reloc: cannot find map at rel->r_offset %zu\n",
+				(size_t)rel->r_offset);
 			return -EINVAL;
 		}
 
-		moff = rel.r_offset - map->sec_offset;
-		shdr_idx = sym.st_shndx;
+		moff = rel->r_offset - map->sec_offset;
+		shdr_idx = sym->st_shndx;
 		st_ops = map->st_ops;
-		pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel.r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
+		pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel->r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
 			 map->name,
-			 (long long)(rel.r_info >> 32),
-			 (long long)sym.st_value,
-			 shdr_idx, (size_t)rel.r_offset,
-			 map->sec_offset, sym.st_name, name);
+			 (long long)(rel->r_info >> 32),
+			 (long long)sym->st_value,
+			 shdr_idx, (size_t)rel->r_offset,
+			 map->sec_offset, sym->st_name, name);
 
 		if (shdr_idx >= SHN_LORESERVE) {
-			pr_warn("struct_ops reloc %s: rel.r_offset %zu shdr_idx %u unsupported non-static function\n",
-				map->name, (size_t)rel.r_offset, shdr_idx);
+			pr_warn("struct_ops reloc %s: rel->r_offset %zu shdr_idx %u unsupported non-static function\n",
+				map->name, (size_t)rel->r_offset, shdr_idx);
 			return -LIBBPF_ERRNO__RELOC;
 		}
-		if (sym.st_value % BPF_INSN_SZ) {
+		if (sym->st_value % BPF_INSN_SZ) {
 			pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
-				map->name, (unsigned long long)sym.st_value);
+				map->name, (unsigned long long)sym->st_value);
 			return -LIBBPF_ERRNO__FORMAT;
 		}
-		insn_idx = sym.st_value / BPF_INSN_SZ;
+		insn_idx = sym->st_value / BPF_INSN_SZ;
 
 		member = find_member_by_offset(st_ops->type, moff * 8);
 		if (!member) {
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 4bbd327a4ce9..13bc7950e304 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -52,8 +52,8 @@
 #endif
 
 /* Older libelf all end up in this expression, for both 32 and 64 bit */
-#ifndef GELF_ST_VISIBILITY
-#define GELF_ST_VISIBILITY(o) ((o) & 0x03)
+#ifndef ELF64_ST_VISIBILITY
+#define ELF64_ST_VISIBILITY(o) ((o) & 0x03)
 #endif
 
 #define BTF_INFO_ENC(kind, kind_flag, vlen) \
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 2df880cefdae..13e6fdc7d8cb 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -15,7 +15,6 @@
 #include <linux/btf.h>
 #include <elf.h>
 #include <libelf.h>
-#include <gelf.h>
 #include <fcntl.h>
 #include "libbpf.h"
 #include "btf.h"
-- 
2.30.2

[PATCH v2 bpf-next 04/10] libbpf: remove assumptions about uniqueness of .rodata/.data/.bss maps

[Andrii Nakryiko]

Remove internal libbpf assumption that there can be only one .rodata,
.data, and .bss map per BPF object. To achieve that, extend and
generalize the scheme that was used for keeping track of relocation ELF
sections. Now each ELF section has a temporary extra index that keeps
track of logical type of ELF section (relocations, data, read-only data,
BSS). Switch relocation to this scheme, as well as .rodata/.data/.bss
handling.

We don't yet allow multiple .rodata, .data, and .bss sections, but no
libbpf internal code makes an assumption that there can be only one of
each and thus they can be explicitly referenced by a single index. Next
patches will actually allow multiple .rodata and .data sections.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 260 ++++++++++++++++++++++-------------------
 1 file changed, 140 insertions(+), 120 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 74f7d9252d13..a7320d272b34 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -462,6 +462,20 @@ struct module_btf {
 	int fd_array_idx;
 };
 
+enum sec_type {
+	SEC_UNUSED = 0,
+	SEC_RELO,
+	SEC_BSS,
+	SEC_DATA,
+	SEC_RODATA,
+};
+
+struct elf_sec_desc {
+	enum sec_type sec_type;
+	Elf64_Shdr *shdr;
+	Elf_Data *data;
+};
+
 struct elf_state {
 	int fd;
 	const void *obj_buf;
@@ -469,25 +483,16 @@ struct elf_state {
 	Elf *elf;
 	Elf64_Ehdr *ehdr;
 	Elf_Data *symbols;
-	Elf_Data *data;
-	Elf_Data *rodata;
-	Elf_Data *bss;
 	Elf_Data *st_ops_data;
 	size_t shstrndx; /* section index for section name strings */
 	size_t strtabidx;
-	struct {
-		Elf64_Shdr *shdr;
-		Elf_Data *data;
-	} *reloc_sects;
-	int nr_reloc_sects;
+	struct elf_sec_desc *secs;
+	int sec_cnt;
 	int maps_shndx;
 	int btf_maps_shndx;
 	__u32 btf_maps_sec_btf_id;
 	int text_shndx;
 	int symbols_shndx;
-	int data_shndx;
-	int rodata_shndx;
-	int bss_shndx;
 	int st_ops_shndx;
 };
 
@@ -506,10 +511,10 @@ struct bpf_object {
 	struct extern_desc *externs;
 	int nr_extern;
 	int kconfig_map_idx;
-	int rodata_map_idx;
 
 	bool loaded;
 	bool has_subcalls;
+	bool has_rodata;
 
 	struct bpf_gen *gen_loader;
 
@@ -1168,12 +1173,8 @@ static struct bpf_object *bpf_object__new(const char *path,
 	obj->efile.obj_buf_sz = obj_buf_sz;
 	obj->efile.maps_shndx = -1;
 	obj->efile.btf_maps_shndx = -1;
-	obj->efile.data_shndx = -1;
-	obj->efile.rodata_shndx = -1;
-	obj->efile.bss_shndx = -1;
 	obj->efile.st_ops_shndx = -1;
 	obj->kconfig_map_idx = -1;
-	obj->rodata_map_idx = -1;
 
 	obj->kern_version = get_kernel_version();
 	obj->loaded = false;
@@ -1193,13 +1194,10 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
 		obj->efile.elf = NULL;
 	}
 	obj->efile.symbols = NULL;
-	obj->efile.data = NULL;
-	obj->efile.rodata = NULL;
-	obj->efile.bss = NULL;
 	obj->efile.st_ops_data = NULL;
 
-	zfree(&obj->efile.reloc_sects);
-	obj->efile.nr_reloc_sects = 0;
+	zfree(&obj->efile.secs);
+	obj->efile.sec_cnt = 0;
 	zclose(obj->efile.fd);
 	obj->efile.obj_buf = NULL;
 	obj->efile.obj_buf_sz = 0;
@@ -1340,30 +1338,18 @@ static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
 static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
 {
 	int ret = -ENOENT;
+	Elf_Data *data;
+	Elf_Scn *scn;
 
 	*size = 0;
-	if (!name) {
+	if (!name)
 		return -EINVAL;
-	} else if (!strcmp(name, DATA_SEC)) {
-		if (obj->efile.data)
-			*size = obj->efile.data->d_size;
-	} else if (!strcmp(name, BSS_SEC)) {
-		if (obj->efile.bss)
-			*size = obj->efile.bss->d_size;
-	} else if (!strcmp(name, RODATA_SEC)) {
-		if (obj->efile.rodata)
-			*size = obj->efile.rodata->d_size;
-	} else if (!strcmp(name, STRUCT_OPS_SEC)) {
-		if (obj->efile.st_ops_data)
-			*size = obj->efile.st_ops_data->d_size;
-	} else {
-		Elf_Scn *scn = elf_sec_by_name(obj, name);
-		Elf_Data *data = elf_sec_data(obj, scn);
 
-		if (data) {
-			ret = 0; /* found it */
-			*size = data->d_size;
-		}
+	scn = elf_sec_by_name(obj, name);
+	data = elf_sec_data(obj, scn);
+	if (data) {
+		ret = 0; /* found it */
+		*size = data->d_size;
 	}
 
 	return *size ? 0 : ret;
@@ -1516,34 +1502,39 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 
 static int bpf_object__init_global_data_maps(struct bpf_object *obj)
 {
-	int err;
+	struct elf_sec_desc *sec_desc;
+	int err = 0, sec_idx;
 
 	/*
 	 * Populate obj->maps with libbpf internal maps.
 	 */
-	if (obj->efile.data_shndx >= 0) {
-		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
-						    obj->efile.data_shndx,
-						    obj->efile.data->d_buf,
-						    obj->efile.data->d_size);
-		if (err)
-			return err;
-	}
-	if (obj->efile.rodata_shndx >= 0) {
-		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
-						    obj->efile.rodata_shndx,
-						    obj->efile.rodata->d_buf,
-						    obj->efile.rodata->d_size);
-		if (err)
-			return err;
-
-		obj->rodata_map_idx = obj->nr_maps - 1;
-	}
-	if (obj->efile.bss_shndx >= 0) {
-		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
-						    obj->efile.bss_shndx,
-						    NULL,
-						    obj->efile.bss->d_size);
+	for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
+		sec_desc = &obj->efile.secs[sec_idx];
+
+		switch (sec_desc->sec_type) {
+		case SEC_DATA:
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+							    sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_RODATA:
+			obj->has_rodata = true;
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+							    sec_idx,
+							    sec_desc->data->d_buf,
+							    sec_desc->data->d_size);
+			break;
+		case SEC_BSS:
+			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+							    sec_idx,
+							    NULL,
+							    sec_desc->data->d_size);
+			break;
+		default:
+			/* skip */
+			break;
+		}
 		if (err)
 			return err;
 	}
@@ -3123,6 +3114,7 @@ static int cmp_progs(const void *_a, const void *_b)
 
 static int bpf_object__elf_collect(struct bpf_object *obj)
 {
+	struct elf_sec_desc *sec_desc;
 	Elf *elf = obj->efile.elf;
 	Elf_Data *btf_ext_data = NULL;
 	Elf_Data *btf_data = NULL;
@@ -3132,6 +3124,15 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 	Elf_Scn *scn;
 	Elf64_Shdr *sh;
 
+	/* ELF section indices are 1-based, so allocate +1 element to keep
+	 * indexing simple. Also include 0th invalid section into sec_cnt for
+	 * simpler and more traditional iteration logic.
+	 */
+	obj->efile.sec_cnt = 1 + obj->efile.ehdr->e_shnum;
+	obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
+	if (!obj->efile.secs)
+		return -ENOMEM;
+
 	/* a bunch of ELF parsing functionality depends on processing symbols,
 	 * so do the first pass and find the symbol table
 	 */
@@ -3151,8 +3152,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 			if (!data)
 				return -LIBBPF_ERRNO__FORMAT;
 
+			idx = elf_ndxscn(scn);
+
 			obj->efile.symbols = data;
-			obj->efile.symbols_shndx = elf_ndxscn(scn);
+			obj->efile.symbols_shndx = idx;
 			obj->efile.strtabidx = sh->sh_link;
 		}
 	}
@@ -3165,7 +3168,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 
 	scn = NULL;
 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
-		idx++;
+		idx = elf_ndxscn(scn);
+		sec_desc = &obj->efile.secs[idx];
 
 		sh = elf_sec_hdr(obj, scn);
 		if (!sh)
@@ -3213,11 +3217,13 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 				if (err)
 					return err;
 			} else if (strcmp(name, DATA_SEC) == 0) {
-				obj->efile.data = data;
-				obj->efile.data_shndx = idx;
+				sec_desc->sec_type = SEC_DATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
 			} else if (strcmp(name, RODATA_SEC) == 0) {
-				obj->efile.rodata = data;
-				obj->efile.rodata_shndx = idx;
+				sec_desc->sec_type = SEC_RODATA;
+				sec_desc->shdr = sh;
+				sec_desc->data = data;
 			} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
 				obj->efile.st_ops_data = data;
 				obj->efile.st_ops_shndx = idx;
@@ -3226,33 +3232,25 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 					idx, name);
 			}
 		} else if (sh->sh_type == SHT_REL) {
-			int nr_sects = obj->efile.nr_reloc_sects;
-			void *sects = obj->efile.reloc_sects;
-			int sec = sh->sh_info; /* points to other section */
+			int targ_sec_idx = sh->sh_info; /* points to other section */
 
 			/* Only do relo for section with exec instructions */
-			if (!section_have_execinstr(obj, sec) &&
+			if (!section_have_execinstr(obj, targ_sec_idx) &&
 			    strcmp(name, ".rel" STRUCT_OPS_SEC) &&
 			    strcmp(name, ".rel" MAPS_ELF_SEC)) {
 				pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
-					idx, name, sec,
-					elf_sec_name(obj, elf_sec_by_idx(obj, sec)) ?: "<?>");
+					idx, name, targ_sec_idx,
+					elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
 				continue;
 			}
 
-			sects = libbpf_reallocarray(sects, nr_sects + 1,
-						    sizeof(*obj->efile.reloc_sects));
-			if (!sects)
-				return -ENOMEM;
-
-			obj->efile.reloc_sects = sects;
-			obj->efile.nr_reloc_sects++;
-
-			obj->efile.reloc_sects[nr_sects].shdr = sh;
-			obj->efile.reloc_sects[nr_sects].data = data;
+			sec_desc->sec_type = SEC_RELO;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
 		} else if (sh->sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
-			obj->efile.bss = data;
-			obj->efile.bss_shndx = idx;
+			sec_desc->sec_type = SEC_BSS;
+			sec_desc->shdr = sh;
+			sec_desc->data = data;
 		} else {
 			pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
 				(size_t)sh->sh_size);
@@ -3732,9 +3730,14 @@ bpf_object__find_program_by_name(const struct bpf_object *obj,
 static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
 				      int shndx)
 {
-	return shndx == obj->efile.data_shndx ||
-	       shndx == obj->efile.bss_shndx ||
-	       shndx == obj->efile.rodata_shndx;
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
+	case SEC_DATA:
+	case SEC_RODATA:
+		return true;
+	default:
+		return false;
+	}
 }
 
 static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
@@ -3747,16 +3750,19 @@ static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
 static enum libbpf_map_type
 bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
 {
-	if (shndx == obj->efile.data_shndx)
-		return LIBBPF_MAP_DATA;
-	else if (shndx == obj->efile.bss_shndx)
+	if (shndx == obj->efile.symbols_shndx)
+		return LIBBPF_MAP_KCONFIG;
+
+	switch (obj->efile.secs[shndx].sec_type) {
+	case SEC_BSS:
 		return LIBBPF_MAP_BSS;
-	else if (shndx == obj->efile.rodata_shndx)
+	case SEC_DATA:
+		return LIBBPF_MAP_DATA;
+	case SEC_RODATA:
 		return LIBBPF_MAP_RODATA;
-	else if (shndx == obj->efile.symbols_shndx)
-		return LIBBPF_MAP_KCONFIG;
-	else
+	default:
 		return LIBBPF_MAP_UNSPEC;
+	}
 }
 
 static int bpf_program__record_reloc(struct bpf_program *prog,
@@ -3892,7 +3898,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 	}
 	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
 		map = &obj->maps[map_idx];
-		if (map->libbpf_type != type)
+		if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
 			continue;
 		pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
 			 prog->name, map_idx, map->name, map->sec_idx,
@@ -6205,10 +6211,18 @@ static int bpf_object__collect_relos(struct bpf_object *obj)
 {
 	int i, err;
 
-	for (i = 0; i < obj->efile.nr_reloc_sects; i++) {
-		Elf64_Shdr *shdr = obj->efile.reloc_sects[i].shdr;
-		Elf_Data *data = obj->efile.reloc_sects[i].data;
-		int idx = shdr->sh_info;
+	for (i = 0; i < obj->efile.sec_cnt; i++) {
+		struct elf_sec_desc *sec_desc = &obj->efile.secs[i];
+		Elf64_Shdr *shdr;
+		Elf_Data *data;
+		int idx;
+
+		if (sec_desc->sec_type != SEC_RELO)
+			continue;
+
+		shdr = sec_desc->shdr;
+		data = sec_desc->data;
+		idx = shdr->sh_info;
 
 		if (shdr->sh_type != SHT_REL) {
 			pr_warn("internal error at %d\n", __LINE__);
@@ -6331,6 +6345,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	     char *license, __u32 kern_version, int *pfd)
 {
 	struct bpf_prog_load_params load_attr = {};
+	struct bpf_object *obj = prog->obj;
 	char *cp, errmsg[STRERR_BUFSIZE];
 	size_t log_buf_size = 0;
 	char *log_buf = NULL;
@@ -6351,7 +6366,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 
 	load_attr.prog_type = prog->type;
 	load_attr.expected_attach_type = prog->expected_attach_type;
-	if (kernel_supports(prog->obj, FEAT_PROG_NAME))
+	if (kernel_supports(obj, FEAT_PROG_NAME))
 		load_attr.name = prog->name;
 	load_attr.insns = insns;
 	load_attr.insn_cnt = insns_cnt;
@@ -6364,8 +6379,8 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.prog_ifindex = prog->prog_ifindex;
 
 	/* specify func_info/line_info only if kernel supports them */
-	btf_fd = bpf_object__btf_fd(prog->obj);
-	if (btf_fd >= 0 && kernel_supports(prog->obj, FEAT_BTF_FUNC)) {
+	btf_fd = bpf_object__btf_fd(obj);
+	if (btf_fd >= 0 && kernel_supports(obj, FEAT_BTF_FUNC)) {
 		load_attr.prog_btf_fd = btf_fd;
 		load_attr.func_info = prog->func_info;
 		load_attr.func_info_rec_size = prog->func_info_rec_size;
@@ -6376,7 +6391,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	}
 	load_attr.log_level = prog->log_level;
 	load_attr.prog_flags = prog->prog_flags;
-	load_attr.fd_array = prog->obj->fd_array;
+	load_attr.fd_array = obj->fd_array;
 
 	/* adjust load_attr if sec_def provides custom preload callback */
 	if (prog->sec_def && prog->sec_def->preload_fn) {
@@ -6388,9 +6403,9 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 		}
 	}
 
-	if (prog->obj->gen_loader) {
-		bpf_gen__prog_load(prog->obj->gen_loader, &load_attr,
-				   prog - prog->obj->programs);
+	if (obj->gen_loader) {
+		bpf_gen__prog_load(obj->gen_loader, &load_attr,
+				   prog - obj->programs);
 		*pfd = -1;
 		return 0;
 	}
@@ -6411,16 +6426,21 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 		if (log_buf && load_attr.log_level)
 			pr_debug("verifier log:\n%s", log_buf);
 
-		if (prog->obj->rodata_map_idx >= 0 &&
-		    kernel_supports(prog->obj, FEAT_PROG_BIND_MAP)) {
-			struct bpf_map *rodata_map =
-				&prog->obj->maps[prog->obj->rodata_map_idx];
+		if (obj->has_rodata && kernel_supports(obj, FEAT_PROG_BIND_MAP)) {
+			struct bpf_map *map;
+			int i;
+
+			for (i = 0; i < obj->nr_maps; i++) {
+				map = &prog->obj->maps[i];
+				if (map->libbpf_type != LIBBPF_MAP_RODATA)
+					continue;
 
-			if (bpf_prog_bind_map(ret, bpf_map__fd(rodata_map), NULL)) {
-				cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
-				pr_warn("prog '%s': failed to bind .rodata map: %s\n",
-					prog->name, cp);
-				/* Don't fail hard if can't bind rodata. */
+				if (bpf_prog_bind_map(ret, bpf_map__fd(map), NULL)) {
+					cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+					pr_warn("prog '%s': failed to bind .rodata map: %s\n",
+						prog->name, cp);
+					/* Don't fail hard if can't bind rodata. */
+				}
 			}
 		}
 
-- 
2.30.2

[PATCH v2 bpf-next 05/10] bpftool: support multiple .rodata/.data internal maps in skeleton

[Andrii Nakryiko]

Remove the assumption about only single instance of each of .rodata and
.data internal maps. Nothing changes for '.rodata' and '.data' maps, but new
'.rodata.something' map will get 'rodata_something' section in BPF
skeleton for them (as well as having struct bpf_map * field in maps
section with the same field name).

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/bpf/bpftool/gen.c | 107 ++++++++++++++++++++++------------------
 1 file changed, 60 insertions(+), 47 deletions(-)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index b2ffc18eafc1..59afe9a2ca3c 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -33,6 +33,11 @@ static void sanitize_identifier(char *name)
 			name[i] = '_';
 }
 
+static bool str_has_prefix(const char *str, const char *prefix)
+{
+	return strncmp(str, prefix, strlen(prefix)) == 0;
+}
+
 static bool str_has_suffix(const char *str, const char *suffix)
 {
 	size_t i, n1 = strlen(str), n2 = strlen(suffix);
@@ -67,23 +72,47 @@ static void get_header_guard(char *guard, const char *obj_name)
 		guard[i] = toupper(guard[i]);
 }
 
-static const char *get_map_ident(const struct bpf_map *map)
+static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz)
 {
+	static const char *sfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
 	const char *name = bpf_map__name(map);
+	int i, n;
+
+	if (!bpf_map__is_internal(map)) {
+		snprintf(buf, buf_sz, "%s", name);
+		return true;
+	}
+
+	for  (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) {
+		const char *sfx = sfxs[i], *p;
+
+		p = strstr(name, sfx);
+		if (p) {
+			snprintf(buf, buf_sz, "%s", p + 1);
+			sanitize_identifier(buf);
+			return true;
+		}
+	}
 
-	if (!bpf_map__is_internal(map))
-		return name;
-
-	if (str_has_suffix(name, ".data"))
-		return "data";
-	else if (str_has_suffix(name, ".rodata"))
-		return "rodata";
-	else if (str_has_suffix(name, ".bss"))
-		return "bss";
-	else if (str_has_suffix(name, ".kconfig"))
-		return "kconfig";
-	else
-		return NULL;
+	return false;
+}
+
+static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz)
+{
+	static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
+	int i, n;
+
+	for  (i = 0, n = ARRAY_SIZE(pfxs); i < n; i++) {
+		const char *pfx = pfxs[i];
+
+		if (str_has_prefix(sec_name, pfx)) {
+			snprintf(buf, buf_sz, "%s", sec_name + 1);
+			sanitize_identifier(buf);
+			return true;
+		}
+	}
+
+	return false;
 }
 
 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
@@ -100,24 +129,14 @@ static int codegen_datasec_def(struct bpf_object *obj,
 	const char *sec_name = btf__name_by_offset(btf, sec->name_off);
 	const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
 	int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
-	const char *sec_ident;
-	char var_ident[256];
+	char var_ident[256], sec_ident[256];
 	bool strip_mods = false;
 
-	if (strcmp(sec_name, ".data") == 0) {
-		sec_ident = "data";
-		strip_mods = true;
-	} else if (strcmp(sec_name, ".bss") == 0) {
-		sec_ident = "bss";
-		strip_mods = true;
-	} else if (strcmp(sec_name, ".rodata") == 0) {
-		sec_ident = "rodata";
-		strip_mods = true;
-	} else if (strcmp(sec_name, ".kconfig") == 0) {
-		sec_ident = "kconfig";
-	} else {
+	if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
 		return 0;
-	}
+
+	if (strcmp(sec_name, ".kconfig") != 0)
+		strip_mods = true;
 
 	printf("	struct %s__%s {\n", obj_name, sec_ident);
 	for (i = 0; i < vlen; i++, sec_var++) {
@@ -385,6 +404,7 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
 {
 	struct bpf_program *prog;
 	struct bpf_map *map;
+	char ident[256];
 
 	codegen("\
 		\n\
@@ -405,10 +425,7 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
 	}
 
 	bpf_object__for_each_map(map, obj) {
-		const char *ident;
-
-		ident = get_map_ident(map);
-		if (!ident)
+		if (!get_map_ident(map, ident, sizeof(ident)))
 			continue;
 		if (bpf_map__is_internal(map) &&
 		    (bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
@@ -432,6 +449,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 	struct bpf_object_load_attr load_attr = {};
 	DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
 	struct bpf_map *map;
+	char ident[256];
 	int err = 0;
 
 	err = bpf_object__gen_loader(obj, &opts);
@@ -477,12 +495,10 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 		",
 		obj_name, opts.data_sz);
 	bpf_object__for_each_map(map, obj) {
-		const char *ident;
 		const void *mmap_data = NULL;
 		size_t mmap_size = 0;
 
-		ident = get_map_ident(map);
-		if (!ident)
+		if (!get_map_ident(map, ident, sizeof(ident)))
 			continue;
 
 		if (!bpf_map__is_internal(map) ||
@@ -544,15 +560,15 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
 				return err;				    \n\
 		", obj_name);
 	bpf_object__for_each_map(map, obj) {
-		const char *ident, *mmap_flags;
+		const char *mmap_flags;
 
-		ident = get_map_ident(map);
-		if (!ident)
+		if (!get_map_ident(map, ident, sizeof(ident)))
 			continue;
 
 		if (!bpf_map__is_internal(map) ||
 		    !(bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
 			continue;
+
 		if (bpf_map__def(map)->map_flags & BPF_F_RDONLY_PROG)
 			mmap_flags = "PROT_READ";
 		else
@@ -602,7 +618,8 @@ static int do_skeleton(int argc, char **argv)
 	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 	char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
 	struct bpf_object *obj = NULL;
-	const char *file, *ident;
+	const char *file;
+	char ident[256];
 	struct bpf_program *prog;
 	int fd, err = -1;
 	struct bpf_map *map;
@@ -673,8 +690,7 @@ static int do_skeleton(int argc, char **argv)
 	}
 
 	bpf_object__for_each_map(map, obj) {
-		ident = get_map_ident(map);
-		if (!ident) {
+		if (!get_map_ident(map, ident, sizeof(ident))) {
 			p_err("ignoring unrecognized internal map '%s'...",
 			      bpf_map__name(map));
 			continue;
@@ -727,8 +743,7 @@ static int do_skeleton(int argc, char **argv)
 	if (map_cnt) {
 		printf("\tstruct {\n");
 		bpf_object__for_each_map(map, obj) {
-			ident = get_map_ident(map);
-			if (!ident)
+			if (!get_map_ident(map, ident, sizeof(ident)))
 				continue;
 			if (use_loader)
 				printf("\t\tstruct bpf_map_desc %s;\n", ident);
@@ -897,9 +912,7 @@ static int do_skeleton(int argc, char **argv)
 		);
 		i = 0;
 		bpf_object__for_each_map(map, obj) {
-			ident = get_map_ident(map);
-
-			if (!ident)
+			if (!get_map_ident(map, ident, sizeof(ident)))
 				continue;
 
 			codegen("\
-- 
2.30.2

[PATCH v2 bpf-next 06/10] bpftool: improve skeleton generation for data maps without DATASEC type

[Andrii Nakryiko]

It can happen that some data sections (e.g., .rodata.cst16, containing
compiler populated string constants) won't have a corresponding BTF
DATASEC type. Now that libbpf supports .rodata.* and .data.* sections,
situation like that will cause invalid BPF skeleton to be generated that
won't compile successfully, as some parts of skeleton would assume
memory-mapped struct definitions for each special data section.

Fix this by generating empty struct definitions for such data sections.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/bpf/bpftool/gen.c | 51 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 59afe9a2ca3c..c446405ab73f 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -213,22 +213,61 @@ static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 	struct btf *btf = bpf_object__btf(obj);
 	int n = btf__get_nr_types(btf);
 	struct btf_dump *d;
+	struct bpf_map *map;
+	const struct btf_type *sec;
+	char sec_ident[256], map_ident[256];
 	int i, err = 0;
 
 	d = btf_dump__new(btf, NULL, NULL, codegen_btf_dump_printf);
 	if (IS_ERR(d))
 		return PTR_ERR(d);
 
-	for (i = 1; i <= n; i++) {
-		const struct btf_type *t = btf__type_by_id(btf, i);
+	bpf_object__for_each_map(map, obj) {
+		/* only generate definitions for memory-mapped internal maps */
+		if (!bpf_map__is_internal(map))
+			continue;
+		if (!(bpf_map__def(map)->map_flags & BPF_F_MMAPABLE))
+			continue;
 
-		if (!btf_is_datasec(t))
+		if (!get_map_ident(map, map_ident, sizeof(map_ident)))
 			continue;
 
-		err = codegen_datasec_def(obj, btf, d, t, obj_name);
-		if (err)
-			goto out;
+		sec = NULL;
+		for (i = 1; i <= n; i++) {
+			const struct btf_type *t = btf__type_by_id(btf, i);
+			const char *name;
+
+			if (!btf_is_datasec(t))
+				continue;
+
+			name = btf__str_by_offset(btf, t->name_off);
+			if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident)))
+				continue;
+
+			if (strcmp(sec_ident, map_ident) == 0) {
+				sec = t;
+				break;
+			}
+		}
+
+		/* In some cases (e.g., sections like .rodata.cst16 containing
+		 * compiler allocated string constants only) there will be
+		 * special internal maps with no corresponding DATASEC BTF
+		 * type. In such case, generate empty structs for each such
+		 * map. It will still be memory-mapped and its contents
+		 * accessible from user-space through BPF skeleton.
+		 */
+		if (!sec) {
+			printf("	struct %s__%s {\n", obj_name, map_ident);
+			printf("	} *%s;\n", map_ident);
+		} else {
+			err = codegen_datasec_def(obj, btf, d, sec, obj_name);
+			if (err)
+				goto out;
+		}
 	}
+
+
 out:
 	btf_dump__free(d);
 	return err;
-- 
2.30.2

[PATCH v2 bpf-next 07/10] libbpf: support multiple .rodata.* and .data.* BPF maps

[Andrii Nakryiko]

Add support for having multiple .rodata and .data data sections ([0]).
.rodata/.data are supported like the usual, but now also
.rodata.<whatever> and .data.<whatever> are also supported. Each such
section will get its own backing BPF_MAP_TYPE_ARRAY, just like
.rodata and .data.

Multiple .bss maps are not supported, as the whole '.bss' name is
confusing and might be deprecated soon, as well as user would need to
specify custom ELF section with SEC() attribute anyway, so might as well
stick to just .data.* and .rodata.* convention.

User-visible map name for such new maps is going to be just their ELF
section names.

  [0] https://github.com/libbpf/libbpf/issues/274

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 130 ++++++++++++++++++++++++++++++++---------
 1 file changed, 101 insertions(+), 29 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a7320d272b34..031f4611e0ff 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -370,15 +370,14 @@ enum libbpf_map_type {
 	LIBBPF_MAP_KCONFIG,
 };
 
-static const char * const libbpf_type_to_btf_name[] = {
-	[LIBBPF_MAP_DATA]	= DATA_SEC,
-	[LIBBPF_MAP_BSS]	= BSS_SEC,
-	[LIBBPF_MAP_RODATA]	= RODATA_SEC,
-	[LIBBPF_MAP_KCONFIG]	= KCONFIG_SEC,
-};
-
 struct bpf_map {
 	char *name;
+	/* real_name is defined for special internal maps (.rodata*,
+	 * .data*, .bss, .kconfig) and preserves their original ELF section
+	 * name. This is important to be be able to find corresponding BTF
+	 * DATASEC information.
+	 */
+	char *real_name;
 	int fd;
 	int sec_idx;
 	size_t sec_offset;
@@ -1429,17 +1428,55 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map)
 	return map_sz;
 }
 
-static char *internal_map_name(struct bpf_object *obj,
-			       enum libbpf_map_type type)
+static char *internal_map_name(struct bpf_object *obj, const char *real_name)
 {
 	char map_name[BPF_OBJ_NAME_LEN], *p;
-	const char *sfx = libbpf_type_to_btf_name[type];
-	int sfx_len = max((size_t)7, strlen(sfx));
-	int pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1,
-			  strlen(obj->name));
+	int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
+
+	/* This is one of the more confusing parts of libbpf for various
+	 * reasons, some of which are historical. The original idea for naming
+	 * internal names was to include as much of BPF object name prefix as
+	 * possible, so that it can be distinguished from similar internal
+	 * maps of a different BPF object.
+	 * As an example, let's say we have bpf_object named 'my_object_name'
+	 * and internal map corresponding to '.rodata' ELF section. The final
+	 * map name advertised to user and to the kernel will be
+	 * 'my_objec.rodata', taking first 8 characters of object name and
+	 * entire 7 characters of '.rodata'.
+	 * Somewhat confusingly, if internal map ELF section name is shorter
+	 * than 7 characters, e.g., '.bss', we still reserve 7 characters
+	 * for the suffix, even though we only have 4 actual characters, and
+	 * resulting map will be called 'my_objec.bss', not even using all 15
+	 * characters allowed by the kernel. Oh well, at least the truncated
+	 * object name is somewhat consistent in this case. But if the map
+	 * name is '.kconfig', we'll still have entirety of '.kconfig' added
+	 * (8 chars) and thus will be left with only first 7 characters of the
+	 * object name ('my_obje'). Happy guessing, user, that the final map
+	 * name will be "my_obje.kconfig".
+	 * Now, with libbpf starting to support arbitrarily named .rodata.*
+	 * and .data.* data sections, it's possible that ELF section name is
+	 * longer than allowed 15 chars, so we now need to be careful to take
+	 * only up to 15 first characters of ELF name, taking no BPF object
+	 * name characters at all. So '.rodata.abracadabra' will result in
+	 * '.rodata.abracad' kernel and user-visible name.
+	 * We need to keep this convoluted logic intact for .data, .bss and
+	 * .rodata maps, but for new custom .data.custom and .rodata.custom
+	 * maps we use their ELF names as is, not prepending bpf_object name
+	 * in front. We still need to truncate them to 15 characters for the
+	 * kernel. Full name can be recovered for such maps by using DATASEC
+	 * BTF type associated with such map's value type, though.
+	 */
+	if (sfx_len >= BPF_OBJ_NAME_LEN)
+		sfx_len = BPF_OBJ_NAME_LEN - 1;
+
+	/* if there are two or more dots in map name, it's a custom dot map */
+	if (strchr(real_name + 1, '.') != NULL)
+		pfx_len = 0;
+	else
+		pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
 
 	snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
-		 sfx_len, libbpf_type_to_btf_name[type]);
+		 sfx_len, real_name);
 
 	/* sanitise map name to characters allowed by kernel */
 	for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
@@ -1451,7 +1488,7 @@ static char *internal_map_name(struct bpf_object *obj,
 
 static int
 bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
-			      int sec_idx, void *data, size_t data_sz)
+			      const char *real_name, int sec_idx, void *data, size_t data_sz)
 {
 	struct bpf_map_def *def;
 	struct bpf_map *map;
@@ -1464,9 +1501,11 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 	map->libbpf_type = type;
 	map->sec_idx = sec_idx;
 	map->sec_offset = 0;
-	map->name = internal_map_name(obj, type);
-	if (!map->name) {
-		pr_warn("failed to alloc map name\n");
+	map->real_name = strdup(real_name);
+	map->name = internal_map_name(obj, real_name);
+	if (!map->real_name || !map->name) {
+		zfree(&map->real_name);
+		zfree(&map->name);
 		return -ENOMEM;
 	}
 
@@ -1489,6 +1528,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 		map->mmaped = NULL;
 		pr_warn("failed to alloc map '%s' content buffer: %d\n",
 			map->name, err);
+		zfree(&map->real_name);
 		zfree(&map->name);
 		return err;
 	}
@@ -1503,6 +1543,7 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
 static int bpf_object__init_global_data_maps(struct bpf_object *obj)
 {
 	struct elf_sec_desc *sec_desc;
+	const char *sec_name;
 	int err = 0, sec_idx;
 
 	/*
@@ -1513,21 +1554,24 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
 
 		switch (sec_desc->sec_type) {
 		case SEC_DATA:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
-							    sec_idx,
+							    sec_name, sec_idx,
 							    sec_desc->data->d_buf,
 							    sec_desc->data->d_size);
 			break;
 		case SEC_RODATA:
 			obj->has_rodata = true;
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
-							    sec_idx,
+							    sec_name, sec_idx,
 							    sec_desc->data->d_buf,
 							    sec_desc->data->d_size);
 			break;
 		case SEC_BSS:
+			sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
 			err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
-							    sec_idx,
+							    sec_name, sec_idx,
 							    NULL,
 							    sec_desc->data->d_size);
 			break;
@@ -1831,7 +1875,7 @@ static int bpf_object__init_kconfig_map(struct bpf_object *obj)
 
 	map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
 	err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
-					    obj->efile.symbols_shndx,
+					    ".kconfig", obj->efile.symbols_shndx,
 					    NULL, map_sz);
 	if (err)
 		return err;
@@ -1931,7 +1975,7 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
 
 		map->name = strdup(map_name);
 		if (!map->name) {
-			pr_warn("failed to alloc map name\n");
+			pr_warn("map '%s': failed to alloc map name\n", map_name);
 			return -ENOMEM;
 		}
 		pr_debug("map %d is \"%s\"\n", i, map->name);
@@ -3216,11 +3260,13 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 				err = bpf_object__add_programs(obj, data, name, idx);
 				if (err)
 					return err;
-			} else if (strcmp(name, DATA_SEC) == 0) {
+			} else if (strcmp(name, DATA_SEC) == 0 ||
+				   str_has_pfx(name, DATA_SEC ".")) {
 				sec_desc->sec_type = SEC_DATA;
 				sec_desc->shdr = sh;
 				sec_desc->data = data;
-			} else if (strcmp(name, RODATA_SEC) == 0) {
+			} else if (strcmp(name, RODATA_SEC) == 0 ||
+				   str_has_pfx(name, RODATA_SEC ".")) {
 				sec_desc->sec_type = SEC_RODATA;
 				sec_desc->shdr = sh;
 				sec_desc->data = data;
@@ -4060,8 +4106,7 @@ static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
 		 * LLVM annotates global data differently in BTF, that is,
 		 * only as '.data', '.bss' or '.rodata'.
 		 */
-		ret = btf__find_by_name(obj->btf,
-				libbpf_type_to_btf_name[map->libbpf_type]);
+		ret = btf__find_by_name(obj->btf, map->real_name);
 	}
 	if (ret < 0)
 		return ret;
@@ -7831,6 +7876,7 @@ static void bpf_map__destroy(struct bpf_map *map)
 	}
 
 	zfree(&map->name);
+	zfree(&map->real_name);
 	zfree(&map->pin_path);
 
 	if (map->fd >= 0)
@@ -8755,9 +8801,30 @@ const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
 	return map ? &map->def : libbpf_err_ptr(-EINVAL);
 }
 
+static bool map_uses_real_name(const struct bpf_map *map)
+{
+	/* Since libbpf started to support custom .data.* and .rodata.* maps,
+	 * their user-visible name differs from kernel-visible name. Users see
+	 * such map's corresponding ELF section name as a map name.
+	 * This check distinguishes .data/.rodata from .data.* and .rodata.*
+	 * maps to know which name has to be returned to the user.
+	 */
+	if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, DATA_SEC) != 0)
+		return true;
+	if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, RODATA_SEC) != 0)
+		return true;
+	return false;
+}
+
 const char *bpf_map__name(const struct bpf_map *map)
 {
-	return map ? map->name : NULL;
+	if (!map)
+		return NULL;
+
+	if (map_uses_real_name(map))
+		return map->real_name;
+
+	return map->name;
 }
 
 enum bpf_map_type bpf_map__type(const struct bpf_map *map)
@@ -8976,7 +9043,12 @@ bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
 	struct bpf_map *pos;
 
 	bpf_object__for_each_map(pos, obj) {
-		if (pos->name && !strcmp(pos->name, name))
+		if (map_uses_real_name(pos)) {
+			if (strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		if (strcmp(pos->name, name) == 0)
 			return pos;
 	}
 	return errno = ENOENT, NULL;
-- 
2.30.2

[PATCH v2 bpf-next 08/10] selftests/bpf: demonstrate use of custom .rodata/.data sections

[Andrii Nakryiko]

Enhance existing selftests to demonstrate the use of custom
.data/.rodata sections.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 .../selftests/bpf/prog_tests/skeleton.c       | 29 +++++++++++++++++++
 .../selftests/bpf/progs/test_skeleton.c       | 18 ++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/skeleton.c b/tools/testing/selftests/bpf/prog_tests/skeleton.c
index fe1e204a65c6..180afd632f4c 100644
--- a/tools/testing/selftests/bpf/prog_tests/skeleton.c
+++ b/tools/testing/selftests/bpf/prog_tests/skeleton.c
@@ -16,10 +16,13 @@ void test_skeleton(void)
 	struct test_skeleton* skel;
 	struct test_skeleton__bss *bss;
 	struct test_skeleton__data *data;
+	struct test_skeleton__data_dyn *data_dyn;
 	struct test_skeleton__rodata *rodata;
+	struct test_skeleton__rodata_dyn *rodata_dyn;
 	struct test_skeleton__kconfig *kcfg;
 	const void *elf_bytes;
 	size_t elf_bytes_sz = 0;
+	int i;
 
 	skel = test_skeleton__open();
 	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
@@ -30,7 +33,12 @@ void test_skeleton(void)
 
 	bss = skel->bss;
 	data = skel->data;
+	data_dyn = skel->data_dyn;
 	rodata = skel->rodata;
+	rodata_dyn = skel->rodata_dyn;
+
+	ASSERT_STREQ(bpf_map__name(skel->maps.rodata_dyn), ".rodata.dyn", "rodata_dyn_name");
+	ASSERT_STREQ(bpf_map__name(skel->maps.data_dyn), ".data.dyn", "data_dyn_name");
 
 	/* validate values are pre-initialized correctly */
 	CHECK(data->in1 != -1, "in1", "got %d != exp %d\n", data->in1, -1);
@@ -46,6 +54,12 @@ void test_skeleton(void)
 	CHECK(rodata->in.in6 != 0, "in6", "got %d != exp %d\n", rodata->in.in6, 0);
 	CHECK(bss->out6 != 0, "out6", "got %d != exp %d\n", bss->out6, 0);
 
+	ASSERT_EQ(rodata_dyn->in_dynarr_sz, 0, "in_dynarr_sz");
+	for (i = 0; i < 4; i++)
+		ASSERT_EQ(rodata_dyn->in_dynarr[i], -(i + 1), "in_dynarr");
+	for (i = 0; i < 4; i++)
+		ASSERT_EQ(data_dyn->out_dynarr[i], i + 1, "out_dynarr");
+
 	/* validate we can pre-setup global variables, even in .bss */
 	data->in1 = 10;
 	data->in2 = 11;
@@ -53,6 +67,10 @@ void test_skeleton(void)
 	bss->in4 = 13;
 	rodata->in.in6 = 14;
 
+	rodata_dyn->in_dynarr_sz = 4;
+	for (i = 0; i < 4; i++)
+		rodata_dyn->in_dynarr[i] = i + 10;
+
 	err = test_skeleton__load(skel);
 	if (CHECK(err, "skel_load", "failed to load skeleton: %d\n", err))
 		goto cleanup;
@@ -64,6 +82,10 @@ void test_skeleton(void)
 	CHECK(bss->in4 != 13, "in4", "got %lld != exp %lld\n", bss->in4, 13LL);
 	CHECK(rodata->in.in6 != 14, "in6", "got %d != exp %d\n", rodata->in.in6, 14);
 
+	ASSERT_EQ(rodata_dyn->in_dynarr_sz, 4, "in_dynarr_sz");
+	for (i = 0; i < 4; i++)
+		ASSERT_EQ(rodata_dyn->in_dynarr[i], i + 10, "in_dynarr");
+
 	/* now set new values and attach to get them into outX variables */
 	data->in1 = 1;
 	data->in2 = 2;
@@ -73,6 +95,8 @@ void test_skeleton(void)
 	bss->in5.b = 6;
 	kcfg = skel->kconfig;
 
+	skel->data_read_mostly->read_mostly_var = 123;
+
 	err = test_skeleton__attach(skel);
 	if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
 		goto cleanup;
@@ -93,6 +117,11 @@ void test_skeleton(void)
 	CHECK(bss->kern_ver != kcfg->LINUX_KERNEL_VERSION, "ext2",
 	      "got %d != exp %d\n", bss->kern_ver, kcfg->LINUX_KERNEL_VERSION);
 
+	for (i = 0; i < 4; i++)
+		ASSERT_EQ(data_dyn->out_dynarr[i], i + 10, "out_dynarr");
+
+	ASSERT_EQ(skel->bss->out_mostly_var, 123, "out_mostly_var");
+
 	elf_bytes = test_skeleton__elf_bytes(&elf_bytes_sz);
 	ASSERT_OK_PTR(elf_bytes, "elf_bytes");
 	ASSERT_GE(elf_bytes_sz, 0, "elf_bytes_sz");
diff --git a/tools/testing/selftests/bpf/progs/test_skeleton.c b/tools/testing/selftests/bpf/progs/test_skeleton.c
index 441fa1c552c8..1b1187d2967b 100644
--- a/tools/testing/selftests/bpf/progs/test_skeleton.c
+++ b/tools/testing/selftests/bpf/progs/test_skeleton.c
@@ -5,6 +5,8 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 
+#define __read_mostly SEC(".data.read_mostly")
+
 struct s {
 	int a;
 	long long b;
@@ -40,9 +42,20 @@ int kern_ver = 0;
 
 struct s out5 = {};
 
+
+const volatile int in_dynarr_sz SEC(".rodata.dyn");
+const volatile int in_dynarr[4] SEC(".rodata.dyn") = { -1, -2, -3, -4 };
+
+int out_dynarr[4] SEC(".data.dyn") = { 1, 2, 3, 4 };
+
+int read_mostly_var __read_mostly;
+int out_mostly_var;
+
 SEC("raw_tp/sys_enter")
 int handler(const void *ctx)
 {
+	int i;
+
 	out1 = in1;
 	out2 = in2;
 	out3 = in3;
@@ -53,6 +66,11 @@ int handler(const void *ctx)
 	bpf_syscall = CONFIG_BPF_SYSCALL;
 	kern_ver = LINUX_KERNEL_VERSION;
 
+	for (i = 0; i < in_dynarr_sz; i++)
+		out_dynarr[i] = in_dynarr[i];
+
+	out_mostly_var = read_mostly_var;
+
 	return 0;
 }
 
-- 
2.30.2

[PATCH v2 bpf-next 09/10] libbpf: simplify look up by name of internal maps

[Andrii Nakryiko]

Map name that's assigned to internal maps (.rodata, .data, .bss, etc)
consist of a small prefix of bpf_object's name and ELF section name as
a suffix. This makes it hard for users to "guess" the name to use for
looking up by name with bpf_object__find_map_by_name() API.

One proposal was to drop object name prefix from the map name and just
use ".rodata", ".data", etc, names. One downside called out was that
when multiple BPF applications are active on the host, it will be hard
to distinguish between multiple instances of .rodata and know which BPF
object (app) they belong to. Having few first characters, while quite
limiting, still can give a bit of a clue, in general.

Note, though, that btf_value_type_id for such global data maps (ARRAY)
points to DATASEC type, which encodes full ELF name, so tools like
bpftool can take advantage of this fact to "recover" full original name
of the map. This is also the reason why for custom .data.* and .rodata.*
maps libbpf uses only their ELF names and doesn't prepend object name at
all.

Another downside of such approach is that it is not backwards compatible
and, among direct use of bpf_object__find_map_by_name() API, will break
any BPF skeleton generated using bpftool that was compiled with older
libbpf version.

Instead of causing all this pain, libbpf will still generate map name
using a combination of object name and ELF section name, but it will
allow looking such maps up by their natural names, which correspond to
their respective ELF section names. This means non-truncated ELF section
names longer than 15 characters are going to be expected and supported.

With such set up, we get the best of both worlds: leave small bits of
a clue about BPF application that instantiated such maps, as well as
making it easy for user apps to lookup such maps at runtime. In this
sense it closes corresponding libbpf 1.0 issue ([0]).

BPF skeletons will continue using full names for lookups.

  [0] Closes: https://github.com/libbpf/libbpf/issues/275

Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Stanislav Fomichev <sdf@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 031f4611e0ff..db6e48014839 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9043,6 +9043,16 @@ bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
 	struct bpf_map *pos;
 
 	bpf_object__for_each_map(pos, obj) {
+		/* if it's a special internal map name (which always starts
+		 * with dot) then check if that special name matches the
+		 * real map name (ELF section name)
+		 */
+		if (name[0] == '.') {
+			if (pos->real_name && strcmp(pos->real_name, name) == 0)
+				return pos;
+			continue;
+		}
+		/* otherwise map name has to be an exact match */
 		if (map_uses_real_name(pos)) {
 			if (strcmp(pos->real_name, name) == 0)
 				return pos;
-- 
2.30.2

[PATCH v2 bpf-next 10/10] selftests/bpf: switch to ".bss"/".rodata"/".data" lookups for internal maps

[Andrii Nakryiko]

Utilize libbpf's feature of allowing to lookup internal maps by their
ELF section names. No need to guess or calculate the exact truncated
prefix taken from the object name.

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 .../testing/selftests/bpf/prog_tests/core_autosize.c  |  2 +-
 tools/testing/selftests/bpf/prog_tests/core_reloc.c   |  2 +-
 tools/testing/selftests/bpf/prog_tests/global_data.c  | 11 +++++++++--
 .../selftests/bpf/prog_tests/global_data_init.c       |  2 +-
 tools/testing/selftests/bpf/prog_tests/kfree_skb.c    |  2 +-
 tools/testing/selftests/bpf/prog_tests/rdonly_maps.c  |  2 +-
 6 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/core_autosize.c b/tools/testing/selftests/bpf/prog_tests/core_autosize.c
index 3d4b2a358d47..2a0dac6394ef 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_autosize.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_autosize.c
@@ -163,7 +163,7 @@ void test_core_autosize(void)
 
 	usleep(1);
 
-	bss_map = bpf_object__find_map_by_name(skel->obj, "test_cor.bss");
+	bss_map = bpf_object__find_map_by_name(skel->obj, ".bss");
 	if (!ASSERT_OK_PTR(bss_map, "bss_map_find"))
 		goto cleanup;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index 763302e63a29..cc50f8feeca3 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -867,7 +867,7 @@ void test_core_reloc(void)
 			goto cleanup;
 		}
 
-		data_map = bpf_object__find_map_by_name(obj, "test_cor.bss");
+		data_map = bpf_object__find_map_by_name(obj, ".bss");
 		if (CHECK(!data_map, "find_data_map", "data map not found\n"))
 			goto cleanup;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/global_data.c b/tools/testing/selftests/bpf/prog_tests/global_data.c
index 9efa7e50eab2..afd8639f9a94 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data.c
@@ -103,11 +103,18 @@ static void test_global_data_struct(struct bpf_object *obj, __u32 duration)
 static void test_global_data_rdonly(struct bpf_object *obj, __u32 duration)
 {
 	int err = -ENOMEM, map_fd, zero = 0;
-	struct bpf_map *map;
+	struct bpf_map *map, *map2;
 	__u8 *buff;
 
 	map = bpf_object__find_map_by_name(obj, "test_glo.rodata");
-	if (CHECK_FAIL(!map || !bpf_map__is_internal(map)))
+	if (!ASSERT_OK_PTR(map, "map"))
+		return;
+	if (!ASSERT_TRUE(bpf_map__is_internal(map), "is_internal"))
+		return;
+
+	/* ensure we can lookup internal maps by their ELF names */
+	map2 = bpf_object__find_map_by_name(obj, ".rodata");
+	if (!ASSERT_EQ(map, map2, "same_maps"))
 		return;
 
 	map_fd = bpf_map__fd(map);
diff --git a/tools/testing/selftests/bpf/prog_tests/global_data_init.c b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
index ee46b11f1f9a..1db86eab101b 100644
--- a/tools/testing/selftests/bpf/prog_tests/global_data_init.c
+++ b/tools/testing/selftests/bpf/prog_tests/global_data_init.c
@@ -16,7 +16,7 @@ void test_global_data_init(void)
 	if (CHECK_FAIL(err))
 		return;
 
-	map = bpf_object__find_map_by_name(obj, "test_glo.rodata");
+	map = bpf_object__find_map_by_name(obj, ".rodata");
 	if (CHECK_FAIL(!map || !bpf_map__is_internal(map)))
 		goto out;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/kfree_skb.c b/tools/testing/selftests/bpf/prog_tests/kfree_skb.c
index 032a322d51f2..01e51d16c8b8 100644
--- a/tools/testing/selftests/bpf/prog_tests/kfree_skb.c
+++ b/tools/testing/selftests/bpf/prog_tests/kfree_skb.c
@@ -93,7 +93,7 @@ void serial_test_kfree_skb(void)
 	if (CHECK(!fexit, "find_prog", "prog eth_type_trans not found\n"))
 		goto close_prog;
 
-	global_data = bpf_object__find_map_by_name(obj2, "kfree_sk.bss");
+	global_data = bpf_object__find_map_by_name(obj2, ".bss");
 	if (CHECK(!global_data, "find global data", "not found\n"))
 		goto close_prog;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c b/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
index 5f9eaa3ab584..fd5d2ddfb062 100644
--- a/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
+++ b/tools/testing/selftests/bpf/prog_tests/rdonly_maps.c
@@ -37,7 +37,7 @@ void test_rdonly_maps(void)
 	if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
 		goto cleanup;
 
-	bss_map = bpf_object__find_map_by_name(obj, "test_rdo.bss");
+	bss_map = bpf_object__find_map_by_name(obj, ".bss");
 	if (CHECK(!bss_map, "find_bss_map", "failed\n"))
 		goto cleanup;
 
-- 
2.30.2