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, 7 insertions, 8 deletions

diff --git a/elf/rtld.c b/elf/rtld.c
index 628245d..5eee9e1 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -501,13 +501,9 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
   return start_addr;
 }
 
-static ElfW(Addr) __attribute_used__
-_dl_start (void *arg)
-{
 #ifdef DONT_USE_BOOTSTRAP_MAP
 # define bootstrap_map GL(dl_rtld_map)
 #else
-  struct dl_start_final_info info;
 # define bootstrap_map info.l
 #endif
 
@@ -516,13 +512,16 @@ _dl_start (void *arg)
      Since ld.so must not have any undefined symbols the result
      is trivial: always the map of ld.so itself.  */
 #define RTLD_BOOTSTRAP
-#define BOOTSTRAP_MAP (&bootstrap_map)
-#define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP
+#define RESOLVE_MAP(map, scope, sym, version, flags) map
 #include "dynamic-link.h"
 
+static ElfW(Addr) __attribute_used__
+_dl_start (void *arg)
+{
 #ifdef DONT_USE_BOOTSTRAP_MAP
   rtld_timer_start (&start_time);
 #else
+  struct dl_start_final_info info;
   rtld_timer_start (&info.start_time);
 #endif
 
@@ -555,7 +554,7 @@ _dl_start (void *arg)
 #endif
 
 #ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
-  ELF_MACHINE_BEFORE_RTLD_RELOC (bootstrap_map.l_info);
+  ELF_MACHINE_BEFORE_RTLD_RELOC (&bootstrap_map, bootstrap_map.l_info);
 #endif
 
   if (bootstrap_map.l_addr || ! bootstrap_map.l_info[VALIDX(DT_GNU_PRELINKED)])
@@ -563,7 +562,7 @@ _dl_start (void *arg)
       /* Relocate ourselves so we can do normal function calls and
 	 data access using the global offset table.  */
 
-      ELF_DYNAMIC_RELOCATE (&bootstrap_map, 0, 0, 0);
+      ELF_DYNAMIC_RELOCATE (&bootstrap_map, NULL, 0, 0, 0);
     }
   bootstrap_map.l_relocated = 1;