libbpf: Move elf_find_func_offset* functions to elf object

Adding new elf object that will contain elf related functions.
There's no functional change.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-9-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 0 insertions, 185 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7da15d878618..c05dd32910e0 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11004,191 +11004,6 @@ err_clean_legacy:
 	return err;
 }
 
-/* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
-static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
-{
-	while ((scn = elf_nextscn(elf, scn)) != NULL) {
-		GElf_Shdr sh;
-
-		if (!gelf_getshdr(scn, &sh))
-			continue;
-		if (sh.sh_type == sh_type)
-			return scn;
-	}
-	return NULL;
-}
-
-/* Find offset of function name in the provided ELF object. "binary_path" is
- * the path to the ELF binary represented by "elf", and only used for error
- * reporting matters. "name" matches symbol name or name@@LIB for library
- * functions.
- */
-static long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name)
-{
-	int i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
-	bool is_shared_lib, is_name_qualified;
-	long ret = -ENOENT;
-	size_t name_len;
-	GElf_Ehdr ehdr;
-
-	if (!gelf_getehdr(elf, &ehdr)) {
-		pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
-		ret = -LIBBPF_ERRNO__FORMAT;
-		goto out;
-	}
-	/* for shared lib case, we do not need to calculate relative offset */
-	is_shared_lib = ehdr.e_type == ET_DYN;
-
-	name_len = strlen(name);
-	/* Does name specify "@@LIB"? */
-	is_name_qualified = strstr(name, "@@") != NULL;
-
-	/* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
-	 * a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
-	 * linked binary may not have SHT_DYMSYM, so absence of a section should not be
-	 * reported as a warning/error.
-	 */
-	for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
-		size_t nr_syms, strtabidx, idx;
-		Elf_Data *symbols = NULL;
-		Elf_Scn *scn = NULL;
-		int last_bind = -1;
-		const char *sname;
-		GElf_Shdr sh;
-
-		scn = elf_find_next_scn_by_type(elf, sh_types[i], NULL);
-		if (!scn) {
-			pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
-				 binary_path);
-			continue;
-		}
-		if (!gelf_getshdr(scn, &sh))
-			continue;
-		strtabidx = sh.sh_link;
-		symbols = elf_getdata(scn, 0);
-		if (!symbols) {
-			pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
-				binary_path, elf_errmsg(-1));
-			ret = -LIBBPF_ERRNO__FORMAT;
-			goto out;
-		}
-		nr_syms = symbols->d_size / sh.sh_entsize;
-
-		for (idx = 0; idx < nr_syms; idx++) {
-			int curr_bind;
-			GElf_Sym sym;
-			Elf_Scn *sym_scn;
-			GElf_Shdr sym_sh;
-
-			if (!gelf_getsym(symbols, idx, &sym))
-				continue;
-
-			if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
-				continue;
-
-			sname = elf_strptr(elf, strtabidx, sym.st_name);
-			if (!sname)
-				continue;
-
-			curr_bind = GELF_ST_BIND(sym.st_info);
-
-			/* User can specify func, func@@LIB or func@@LIB_VERSION. */
-			if (strncmp(sname, name, name_len) != 0)
-				continue;
-			/* ...but we don't want a search for "foo" to match 'foo2" also, so any
-			 * additional characters in sname should be of the form "@@LIB".
-			 */
-			if (!is_name_qualified && sname[name_len] != '\0' && sname[name_len] != '@')
-				continue;
-
-			if (ret >= 0) {
-				/* handle multiple matches */
-				if (last_bind != STB_WEAK && curr_bind != STB_WEAK) {
-					/* Only accept one non-weak bind. */
-					pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
-						sname, name, binary_path);
-					ret = -LIBBPF_ERRNO__FORMAT;
-					goto out;
-				} else if (curr_bind == STB_WEAK) {
-					/* already have a non-weak bind, and
-					 * this is a weak bind, so ignore.
-					 */
-					continue;
-				}
-			}
-
-			/* Transform symbol's virtual address (absolute for
-			 * binaries and relative for shared libs) into file
-			 * offset, which is what kernel is expecting for
-			 * uprobe/uretprobe attachment.
-			 * See Documentation/trace/uprobetracer.rst for more
-			 * details.
-			 * This is done by looking up symbol's containing
-			 * section's header and using it's virtual address
-			 * (sh_addr) and corresponding file offset (sh_offset)
-			 * to transform sym.st_value (virtual address) into
-			 * desired final file offset.
-			 */
-			sym_scn = elf_getscn(elf, sym.st_shndx);
-			if (!sym_scn)
-				continue;
-			if (!gelf_getshdr(sym_scn, &sym_sh))
-				continue;
-
-			ret = sym.st_value - sym_sh.sh_addr + sym_sh.sh_offset;
-			last_bind = curr_bind;
-		}
-		if (ret > 0)
-			break;
-	}
-
-	if (ret > 0) {
-		pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
-			 ret);
-	} else {
-		if (ret == 0) {
-			pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
-				is_shared_lib ? "should not be 0 in a shared library" :
-						"try using shared library path instead");
-			ret = -ENOENT;
-		} else {
-			pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
-		}
-	}
-out:
-	return ret;
-}
-
-/* Find offset of function name in ELF object specified by path. "name" matches
- * symbol name or name@@LIB for library functions.
- */
-static long elf_find_func_offset_from_file(const char *binary_path, const char *name)
-{
-	char errmsg[STRERR_BUFSIZE];
-	long ret = -ENOENT;
-	Elf *elf;
-	int fd;
-
-	fd = open(binary_path, O_RDONLY | O_CLOEXEC);
-	if (fd < 0) {
-		ret = -errno;
-		pr_warn("failed to open %s: %s\n", binary_path,
-			libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
-		return ret;
-	}
-	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
-	if (!elf) {
-		pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
-		close(fd);
-		return -LIBBPF_ERRNO__FORMAT;
-	}
-
-	ret = elf_find_func_offset(elf, binary_path, name);
-	elf_end(elf);
-	close(fd);
-	return ret;
-}
-
 /* Find offset of function name in archive specified by path. Currently
  * supported are .zip files that do not compress their contents, as used on
  * Android in the form of APKs, for example. "file_name" is the name of the ELF