perf symbol: Add filename__has_section()

The filename__has_section() is to check if the given section name is in
the binary. It'd be used for checking debug info for srcline.

Committer notes:

Added missing __maybe_unused to the unused filename__has_section()
arguments in tools/perf/util/symbol-minimal.c.

Signed-off-by: Namhyung Kim <[e-mail]>
Acked-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Milian Wolff <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/symbol-elf.c

···
 	return NULL;
 }
 
+bool filename__has_section(const char *filename, const char *sec)
+{
+	int fd;
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	GElf_Shdr shdr;
+	bool found = false;
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0)
+		return false;
+
+	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+	if (elf == NULL)
+		goto out;
+
+	if (gelf_getehdr(elf, &ehdr) == NULL)
+		goto elf_out;
+
+	found = !!elf_section_by_name(elf, &ehdr, &shdr, sec, NULL);
+
+elf_out:
+	elf_end(elf);
+out:
+	close(fd);
+	return found;
+}
+
 static int elf_read_program_header(Elf *elf, u64 vaddr, GElf_Phdr *phdr)
 {
 	size_t i, phdrnum;

tools/perf/util/symbol-minimal.c

···
 {
 	return NULL;
 }
+
+bool filename__has_section(const char *filename __maybe_unused, const char *sec __maybe_unused)
+{
+	return false;
+}

tools/perf/util/symbol.h

···
 					 u64 start, u64 size));
 int filename__read_debuglink(const char *filename, char *debuglink,
 			     size_t size);
+bool filename__has_section(const char *filename, const char *sec);
 
 struct perf_env;
 int symbol__init(struct perf_env *env);