perf symbols: Export elf_section_by_name and reuse

Remove duplicated elf_section_by_name() functions from unwind.c and
probe-event.c and use one exported elf_section_by_name() instance
defined in symbol-elf.c.

Note that this also moves get_text_start_address() to merge
HAVE_DWARF_SUPPORT defined area.

Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20140116093949.24403.38093.stgit@kbuild-fedora.novalocal
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 37 insertions, 69 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index c68711c50f47..a8a9b6cd93a8 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -173,54 +173,6 @@ const char *kernel_get_module_path(const char *module)
         return (dso) ? dso->long_name : NULL;
 }
 
-#ifdef HAVE_DWARF_SUPPORT
-/* Copied from unwind.c */
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-                                    GElf_Shdr *shp, const char *name)
-{
-        Elf_Scn *sec = NULL;
-
-        while ((sec = elf_nextscn(elf, sec)) != NULL) {
-                char *str;
-
-                gelf_getshdr(sec, shp);
-                str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
-                if (!strcmp(name, str))
-                        break;
-        }
-
-        return sec;
-}
-
-static int get_text_start_address(const char *exec, unsigned long *address)
-{
-        Elf *elf;
-        GElf_Ehdr ehdr;
-        GElf_Shdr shdr;
-        int fd, ret = -ENOENT;
-
-        fd = open(exec, O_RDONLY);
-        if (fd < 0)
-                return -errno;
-
-        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
-        if (elf == NULL)
-                return -EINVAL;
-
-        if (gelf_getehdr(elf, &ehdr) == NULL)
-                goto out;
-
-        if (!elf_section_by_name(elf, &ehdr, &shdr, ".text"))
-                goto out;
-
-        *address = shdr.sh_addr - shdr.sh_offset;
-        ret = 0;
-out:
-        elf_end(elf);
-        return ret;
-}
-#endif
-
 static int init_user_exec(void)
 {
         int ret = 0;
@@ -341,6 +293,34 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
         return 0;
 }
 
+static int get_text_start_address(const char *exec, unsigned long *address)
+{
+        Elf *elf;
+        GElf_Ehdr ehdr;
+        GElf_Shdr shdr;
+        int fd, ret = -ENOENT;
+
+        fd = open(exec, O_RDONLY);
+        if (fd < 0)
+                return -errno;
+
+        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+        if (elf == NULL)
+                return -EINVAL;
+
+        if (gelf_getehdr(elf, &ehdr) == NULL)
+                goto out;
+
+        if (!elf_section_by_name(elf, &ehdr, &shdr, ".text", NULL))
+                goto out;
+
+        *address = shdr.sh_addr - shdr.sh_offset;
+        ret = 0;
+out:
+        elf_end(elf);
+        return ret;
+}
+
 static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
                                           int ntevs, const char *exec)
 {
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 4b0a127a4d3b..759456728703 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -136,9 +136,8 @@ static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
         return -1;
 }
 
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-                                    GElf_Shdr *shp, const char *name,
-                                    size_t *idx)
+Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+                             GElf_Shdr *shp, const char *name, size_t *idx)
 {
         Elf_Scn *sec = NULL;
         size_t cnt = 1;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index cbd680361806..fffe2888a1c7 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -52,6 +52,11 @@ static inline char *bfd_demangle(void __maybe_unused *v,
 # define PERF_ELF_C_READ_MMAP ELF_C_READ
 #endif
 
+#ifdef HAVE_LIBELF_SUPPORT
+extern Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+                                GElf_Shdr *shp, const char *name, size_t *idx);
+#endif
+
 #ifndef DMGL_PARAMS
 #define DMGL_PARAMS      (1 << 0)       /* Include function args */
 #define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */
diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
index 416f22bf3693..742f23bf35ff 100644
--- a/tools/perf/util/unwind.c
+++ b/tools/perf/util/unwind.c
@@ -28,6 +28,7 @@
 #include "session.h"
 #include "perf_regs.h"
 #include "unwind.h"
+#include "symbol.h"
 #include "util.h"
 
 extern int
@@ -158,23 +159,6 @@ static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
         __v;                                                    \
         })
 
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-                                    GElf_Shdr *shp, const char *name)
-{
-        Elf_Scn *sec = NULL;
-
-        while ((sec = elf_nextscn(elf, sec)) != NULL) {
-                char *str;
-
-                gelf_getshdr(sec, shp);
-                str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
-                if (!strcmp(name, str))
-                        break;
-        }
-
-        return sec;
-}
-
 static u64 elf_section_offset(int fd, const char *name)
 {
         Elf *elf;
@@ -190,7 +174,7 @@ static u64 elf_section_offset(int fd, const char *name)
                 if (gelf_getehdr(elf, &ehdr) == NULL)
                         break;
 
-                if (!elf_section_by_name(elf, &ehdr, &shdr, name))
+                if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
                         break;
 
                 offset = shdr.sh_offset;