[glibc/maskray/lld] csu: Skip ARCH_SETUP_IREL if _dl_relocate_static_pie applied IRELATIVE relocations

[Fangrui Song <maskray@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c67127a88540f6de4b92370158b5da61bec23f4f

commit c67127a88540f6de4b92370158b5da61bec23f4f
Author: Siva Chandra Reddy <sivachandra@google.com>
Date:   Fri Jan 29 10:42:50 2021 -0800

    csu: Skip ARCH_SETUP_IREL if _dl_relocate_static_pie applied IRELATIVE relocations
    
    For static pie, _dl_relocate_static_pie applies IRELATIVE relocations so
    ARCH_SETUP_IREL should not apply relocations again.
    
    LLD defines __rela_iplt_start/__rela_iplt_end regardless of -no-pie or
    -pie, so in an LLD linked static pie, ARCH_SETUP_IREL would otherwise
    apply the relocations in the range of [__rela_iplt_start,
    __rela_iplt_end).
    
    Co-authored-by: Fangrui Song <maskray@google.com>

Diff:
---
 csu/libc-start.c           | 8 +++++---
 csu/static-reloc.c         | 3 ++-
 elf/dl-reloc-static-pie.c  | 4 +++-
 sysdeps/generic/ldsodefs.h | 4 ++--
 4 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/csu/libc-start.c b/csu/libc-start.c
index feb0d7ce11..44d9d875d2 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -200,10 +200,11 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
   /* Do static pie self relocation after tunables and cpu features
      are setup for ifunc resolvers. Before this point relocations
      must be avoided.  */
-  _dl_relocate_static_pie ();
+  int irel_applied = _dl_relocate_static_pie ();
 
   /* Perform IREL{,A} relocations.  */
-  ARCH_SETUP_IREL ();
+  if (!irel_applied)
+    ARCH_SETUP_IREL ();
 
   /* The stack guard goes into the TCB, so initialize it early.  */
   ARCH_SETUP_TLS ();
@@ -211,7 +212,8 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
   /* In some architectures, IREL{,A} relocations happen after TLS setup in
      order to let IFUNC resolvers benefit from TCB information, e.g. powerpc's
      hwcap and platform fields available in the TCB.  */
-  ARCH_APPLY_IREL ();
+  if (!irel_applied)
+    ARCH_APPLY_IREL ();
 
   /* Set up the stack checker's canary.  */
   uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
diff --git a/csu/static-reloc.c b/csu/static-reloc.c
index 972c524f28..9046d9f6a3 100644
--- a/csu/static-reloc.c
+++ b/csu/static-reloc.c
@@ -19,8 +19,9 @@
 #if ENABLE_STATIC_PIE
 #include <ldsodefs.h>
 
-void
+int
 _dl_relocate_static_pie (void)
 {
+  return 0;
 }
 #endif
diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c
index d5bd2f31e9..b707ef4bf1 100644
--- a/elf/dl-reloc-static-pie.c
+++ b/elf/dl-reloc-static-pie.c
@@ -25,7 +25,7 @@
 
 /* Relocate static executable with PIE.  */
 
-void
+int
 _dl_relocate_static_pie (void)
 {
   struct link_map *main_map = _dl_get_dl_main_map ();
@@ -66,5 +66,7 @@ _dl_relocate_static_pie (void)
        with the run-time address of the r_debug structure  */
     main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
 # endif
+
+  return 1;
 }
 #endif
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index aab7245e93..a0b1e3a34e 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1148,13 +1148,13 @@ void __libc_setup_tls (void);
 
 # if ENABLE_STATIC_PIE
 /* Relocate static executable with PIE.  */
-extern void _dl_relocate_static_pie (void) attribute_hidden;
+extern int _dl_relocate_static_pie (void) attribute_hidden;
 
 /* Get a pointer to _dl_main_map.  */
 extern struct link_map * _dl_get_dl_main_map (void)
   __attribute__ ((visibility ("hidden")));
 # else
-#  define _dl_relocate_static_pie()
+#  define _dl_relocate_static_pie() 0
 # endif
 #endif