diff mbox series

[v2,3/4] powerpc: Relocate stinfo->main

Message ID 20220228064052.3413334-4-amodra@gmail.com
State New
Headers show
Series PowerPC64 static-pie | expand

Commit Message

Alan Modra Feb. 28, 2022, 6:40 a.m. UTC 
start_addresses in sysdeps/powerpc/powerpc64/start.S is historical
baggage that should disappear.  Until someone does that, relocating
stinfo->main by hand is one solution to the fact that the field may be
unrelocated at the time it is accessed.  This is similar to what is
done for dynamic tags via the D_PTR macro.  stinfo->init and
stinfo->fini are zero in both powerpc64/start.S and powerpc32/start.S,
so make it a little more obvious they are unused by passing NULLs to
LIBC_START_MAIN.  The makefile change is needed to pick up
elf/dl-static-tls.h from dl-machine.h.

Comments

Tulio Magno Quites Machado Filho April 8, 2022, 10:32 p.m. UTC | #1 
Alan Modra via Libc-alpha <libc-alpha@sourceware.org> writes:

> diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
> index bb97d16145..8f0d3a0eac 100644
> --- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c
> +++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
> @@ -23,6 +23,10 @@
>  #ifndef SHARED
>  #include <hwcapinfo.h>
>  #endif
> +#if ENABLE_STATIC_PIE && !defined SHARED
> +/* For elf_machine_load_address.  */
> +#include <dl-machine.h>
> +#endif
>  
>  /* The main work is done in the generic function.  */
>  #define LIBC_START_MAIN generic_start_main
> @@ -95,8 +99,15 @@ __libc_start_main_impl (int argc, char **argv,
>    __tcb_parse_hwcap_and_convert_at_platform ();
>  #endif
>  
> -  return generic_start_main (stinfo->main, argc, argv, auxvec,
> -			     stinfo->init, stinfo->fini, rtld_fini,
> +  void *main = stinfo->main;

Some GCC versions (e.g. GCC 8) complain about the name of this variable:

../sysdeps/unix/sysv/linux/powerpc/libc-start.c: In function ‘__libc_start_main_impl’:
../sysdeps/unix/sysv/linux/powerpc/libc-start.c:102:9: error: ‘main’ is usually a function [-Werror=main]

Looks good to me if this variable is either renamed or if this part of the code
is built with -Wno-main.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile
index fc7c29c695..93783cae00 100644
--- a/sysdeps/unix/sysv/linux/powerpc/Makefile
+++ b/sysdeps/unix/sysv/linux/powerpc/Makefile
@@ -27,3 +27,9 @@  tests += $(tests-static)
 tests += test-gettimebasefreq
 tests += test-powerpc-linux-sysconf
 endif
+
+ifeq ($(subdir),csu)
+# to relocate stinfo->main
+CPPFLAGS-libc-start.o += -I../elf
+CPPFLAGS-libc-start.op += -I../elf
+endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
index bb97d16145..8f0d3a0eac 100644
--- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c
+++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c
@@ -23,6 +23,10 @@ 
 #ifndef SHARED
 #include <hwcapinfo.h>
 #endif
+#if ENABLE_STATIC_PIE && !defined SHARED
+/* For elf_machine_load_address.  */
+#include <dl-machine.h>
+#endif
 
 /* The main work is done in the generic function.  */
 #define LIBC_START_MAIN generic_start_main
@@ -95,8 +99,15 @@  __libc_start_main_impl (int argc, char **argv,
   __tcb_parse_hwcap_and_convert_at_platform ();
 #endif
 
-  return generic_start_main (stinfo->main, argc, argv, auxvec,
-			     stinfo->init, stinfo->fini, rtld_fini,
+  void *main = stinfo->main;
+#if ENABLE_STATIC_PIE && !defined SHARED
+  struct link_map *map = _dl_get_dl_main_map ();
+  if (!map->l_relocated)
+    main = (char *) main + elf_machine_load_address ();
+#endif
+
+  return generic_start_main (main, argc, argv, auxvec,
+			     NULL, NULL, rtld_fini,
 			     stack_on_entry);
 }
 DEFINE_LIBC_START_MAIN_VERSION