elf: Avoid nested functions in the loader [BZ #27220]

dynamic-link.h is included more than once in some elf/ files (rtld.c,
dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested
functions. This harms readability and the nested functions usage
is the biggest obstacle prevents Clang build (Clang doesn't support GCC
nested functions).

The key idea for unnesting is to add extra parameters (struct link_map
*and struct r_scope_elm *[]) to RESOLVE_MAP,
ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a],
elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired
by Stan Shebs' ppc64/x86-64 implementation in the
google/grte/v5-2.27/master which uses mixed extra parameters and static
variables.)

Future simplification:
* If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM,
  elf_machine_runtime_setup can drop the `scope` parameter.
* If TLSDESC no longer need to be in elf_machine_lazy_rel,
  elf_machine_lazy_rel can drop the `scope` parameter.

Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32,
sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64.
In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu
and riscv64-linux-gnu-rv64imafdc-lp64d.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 27 insertions, 30 deletions

diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
index 6c957456b8..0d5b727c64 100644
--- a/elf/dl-reloc.c
+++ b/elf/dl-reloc.c
@@ -162,6 +162,32 @@ _dl_nothread_init_static_tls (struct link_map *map)
 }
 #endif /* !PTHREAD_IN_LIBC */
 
+/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code.  */
+#define RESOLVE_MAP(l, scope, ref, version, r_type)			      \
+    ((ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL			      \
+      && __glibc_likely (!dl_symbol_visibility_binds_local_p (*ref)))	      \
+     ? ((__glibc_unlikely ((*ref) == l->l_lookup_cache.sym)		      \
+	 && elf_machine_type_class (r_type) == l->l_lookup_cache.type_class)  \
+	? (bump_num_cache_relocations (),				      \
+	   (*ref) = l->l_lookup_cache.ret,				      \
+	   l->l_lookup_cache.value)					      \
+	: ({ lookup_t _lr;						      \
+	     int _tc = elf_machine_type_class (r_type);			      \
+	     l->l_lookup_cache.type_class = _tc;			      \
+	     l->l_lookup_cache.sym = (*ref);				      \
+	     const struct r_found_version *v = NULL;			      \
+	     if ((version) != NULL && (version)->hash != 0)		      \
+	       v = (version);						      \
+	     _lr = _dl_lookup_symbol_x ((const char *) D_PTR (l, l_info[DT_STRTAB]) + (*ref)->st_name, \
+					l, (ref), scope, v, _tc,	      \
+					DL_LOOKUP_ADD_DEPENDENCY	      \
+					| DL_LOOKUP_FOR_RELOCATE, NULL);      \
+	     l->l_lookup_cache.ret = (*ref);				      \
+	     l->l_lookup_cache.value = _lr; }))				      \
+     : l)
+
+#include "dynamic-link.h"
+
 void
 _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
 		     int reloc_mode, int consider_profiling)
@@ -243,36 +269,7 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
   {
     /* Do the actual relocation of the object's GOT and other data.  */
 
-    /* String table object symbols.  */
-    const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
-
-    /* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code.  */
-#define RESOLVE_MAP(ref, version, r_type) \
-    ((ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL			      \
-      && __glibc_likely (!dl_symbol_visibility_binds_local_p (*ref)))	      \
-     ? ((__builtin_expect ((*ref) == l->l_lookup_cache.sym, 0)		      \
-	 && elf_machine_type_class (r_type) == l->l_lookup_cache.type_class)  \
-	? (bump_num_cache_relocations (),				      \
-	   (*ref) = l->l_lookup_cache.ret,				      \
-	   l->l_lookup_cache.value)					      \
-	: ({ lookup_t _lr;						      \
-	     int _tc = elf_machine_type_class (r_type);			      \
-	     l->l_lookup_cache.type_class = _tc;			      \
-	     l->l_lookup_cache.sym = (*ref);				      \
-	     const struct r_found_version *v = NULL;			      \
-	     if ((version) != NULL && (version)->hash != 0)		      \
-	       v = (version);						      \
-	     _lr = _dl_lookup_symbol_x (strtab + (*ref)->st_name, l, (ref),   \
-					scope, v, _tc,			      \
-					DL_LOOKUP_ADD_DEPENDENCY	      \
-					| DL_LOOKUP_FOR_RELOCATE, NULL);      \
-	     l->l_lookup_cache.ret = (*ref);				      \
-	     l->l_lookup_cache.value = _lr; }))				      \
-     : l)
-
-#include "dynamic-link.h"
-
-    ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling, skip_ifunc);
+    ELF_DYNAMIC_RELOCATE (l, scope, lazy, consider_profiling, skip_ifunc);
 
 #ifndef PROF
     if (__glibc_unlikely (consider_profiling)