libbpf: Add BPF_EMBED_OBJ macro for embedding BPF .o files

Add a convenience macro BPF_EMBED_OBJ, which allows to embed other files
(typically used to embed BPF .o files) into a hosting userspace programs. To
C program it is exposed as struct bpf_embed_data, containing a pointer to
raw data and its size in bytes.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191214014341.3442258-5-andriin@fb.com

tools/lib/bpf/libbpf.h

@@ -615,6 +615,41 @@ bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear);
  */
 LIBBPF_API int libbpf_num_possible_cpus(void);
 
+struct bpf_embed_data {
+	void *data;
+	size_t size;
+};
+
+#define BPF_EMBED_OBJ_DECLARE(NAME)					\
+extern struct bpf_embed_data NAME##_embed;				\
+extern char NAME##_data[];						\
+extern char NAME##_data_end[];
+
+#define __BPF_EMBED_OBJ(NAME, PATH, SZ, ASM_TYPE)			\
+asm (									\
+"	.pushsection \".rodata\", \"a\", @progbits		\n"	\
+"	.global "#NAME"_data					\n"	\
+#NAME"_data:							\n"	\
+"	.incbin \"" PATH "\"					\n"	\
+"	.global "#NAME"_data_end				\n"	\
+#NAME"_data_end:						\n"	\
+"	.global "#NAME"_embed					\n"	\
+"	.type "#NAME"_embed, @object				\n"	\
+"	.size "#NAME"_size, "#SZ"				\n"	\
+"	.align 8,						\n"	\
+#NAME"_embed:							\n"	\
+"	"ASM_TYPE" "#NAME"_data					\n"	\
+"	"ASM_TYPE" "#NAME"_data_end - "#NAME"_data 		\n"	\
+"	.popsection						\n"	\
+);									\
+BPF_EMBED_OBJ_DECLARE(NAME)
+
+#if __SIZEOF_POINTER__ == 4
+#define BPF_EMBED_OBJ(NAME, PATH) __BPF_EMBED_OBJ(NAME, PATH, 8, ".long")
+#else
+#define BPF_EMBED_OBJ(NAME, PATH) __BPF_EMBED_OBJ(NAME, PATH, 16, ".quad")
+#endif
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

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

 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
 
-#define EMBED_FILE(NAME, PATH)						    \
-asm (									    \
-"      .pushsection \".rodata\", \"a\", @progbits              \n"	    \
-"      .global "#NAME"_data                                    \n"	    \
-#NAME"_data:                                                   \n"	    \
-"      .incbin \"" PATH "\"                                    \n"	    \
-#NAME"_data_end:                                               \n"	    \
-"      .global "#NAME"_size                                    \n"	    \
-"      .type "#NAME"_size, @object                             \n"	    \
-"      .size "#NAME"_size, 4                                   \n"	    \
-"      .align 4,                                               \n"	    \
-#NAME"_size:                                                   \n"	    \
-"      .int "#NAME"_data_end - "#NAME"_data                    \n"	    \
-"      .popsection                                             \n"	    \
-);									    \
-extern char NAME##_data[];						    \
-extern int NAME##_size;
-
 ssize_t get_base_addr() {
 	size_t start;
 	char buf[256];
@@ -39,7 +21,7 @@ ssize_t get_base_addr() {
 	return -EINVAL;
 }
 
-EMBED_FILE(probe, "test_attach_probe.o");
+BPF_EMBED_OBJ(probe, "test_attach_probe.o");
 
 void test_attach_probe(void)
 {
@@ -73,7 +55,8 @@ void test_attach_probe(void)
 	uprobe_offset = (size_t)&get_base_addr - base_addr;
 
 	/* open object */
-	obj = bpf_object__open_mem(probe_data, probe_size, &open_opts);
+	obj = bpf_object__open_mem(probe_embed.data, probe_embed.size,
+				   &open_opts);
 	if (CHECK(IS_ERR(obj), "obj_open_mem", "err %ld\n", PTR_ERR(obj)))
 		return;