[PATCH] Avoid GOT relocations in ld.so on powerpc
Carlos O'Donell
carlos@systemhalted.org
Thu May 17 03:59:00 GMT 2012
On Wed, May 16, 2012 at 6:01 PM, Andreas Schwab <schwab@linux-m68k.org> wrote:
> This removes GOT relocations in ld.so referring to dl_argv, _rtld_global
> and _rtld_global_ro, by using their internal aliases instead.
>
> Andreas.
>
> * sysdeps/powerpc/powerpc32/dl-start.S (_dl_start_user): Use
> INTUSE on _dl_argv, and _rtld_local instead of _rtld_global.
> * sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S [IS_IN_rtld]:
> Refer to _rtld_local_ro instead of _rtld_global_ro.
> * sysdeps/powerpc/powerpc32/fpu/setjmp-common.S [IS_IN_rtld]:
> Likewise.
> * sysdeps/powerpc/powerpc64/__longjmp-common.S [IS_IN_rtld]:
> Likewise.
> * sysdeps/powerpc/powerpc64/setjmp-common.S [IS_IN_rtld]:
> Likewise.
> * sysdeps/powerpc/powerpc64/dl-trampoline.S [SHARED]: Likewise.
> * sysdeps/powerpc/powerpc64/dl-machine.h: Use _rtld_local instead
> of _rtld_global, and rtld_progname instead of _dl_argv[0].
> ---
> sysdeps/powerpc/powerpc32/dl-start.S | 7 +++----
> sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S | 7 +++++--
> sysdeps/powerpc/powerpc32/fpu/setjmp-common.S | 6 +++++-
> sysdeps/powerpc/powerpc64/__longjmp-common.S | 6 +++++-
> sysdeps/powerpc/powerpc64/dl-machine.h | 6 +++---
> sysdeps/powerpc/powerpc64/dl-trampoline.S | 4 ++--
> sysdeps/powerpc/powerpc64/setjmp-common.S | 6 +++++-
> 7 files changed, 28 insertions(+), 14 deletions(-)
Looks good to me, a couple of minor nits.
We should be consistent about the use of _rtld_local in comments and
derivative symbol names e.g. __rtld_local.
> diff --git a/sysdeps/powerpc/powerpc32/dl-start.S b/sysdeps/powerpc/powerpc32/dl-start.S
> index 2546fa5..b2d0194 100644
> --- a/sysdeps/powerpc/powerpc32/dl-start.S
> +++ b/sysdeps/powerpc/powerpc32/dl-start.S
> @@ -1,6 +1,5 @@
> /* Machine-dependent ELF startup code. PowerPC version.
> - Copyright (C) 1995-2000, 2002, 2004, 2005, 2006, 2011
> - Free Software Foundation, Inc.
> + Copyright (C) 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -53,9 +52,9 @@ _dl_start_user:
> /* the address of _start in r30, */
> mr r30,r3
> /* &_dl_argc in 29, &_dl_argv in 27, and _dl_loaded in 28. */
> - lwz r28,_rtld_global@got(r31)
> + lwz r28,_rtld_local@got(r31)
> lwz r29,_dl_argc@got(r31)
> - lwz r27,_dl_argv@got(r31)
> + lwz r27,INTUSE(_dl_argv)@got(r31)
>
> /* Call _dl_init (_dl_loaded, _dl_argc, _dl_argv, _dl_argv+_dl_argc+1). */
> lwz r3,0(r28)
> diff --git a/sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S b/sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S
> index 4cfde6b..8246e45 100644
> --- a/sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S
> +++ b/sysdeps/powerpc/powerpc32/fpu/__longjmp-common.S
> @@ -1,6 +1,5 @@
> /* longjmp for PowerPC.
> - Copyright (C) 1995-99, 2000, 2003-2006, 2009, 2011
> - Free Software Foundation, Inc.
> + Copyright (C) 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -38,7 +37,11 @@ ENTRY (BP_SYM (__longjmp))
> addis r5,r5,_GLOBAL_OFFSET_TABLE_-got_label@ha
> addi r5,r5,_GLOBAL_OFFSET_TABLE_-got_label@l
> # ifdef SHARED
> +# ifdef IS_IN_rtld
> + lwz r5,_rtld_local_ro@got(r5)
> +# else
> lwz r5,_rtld_global_ro@got(r5)
> +# endif
> mtlr r6
> cfi_same_value (lr)
> lwz r5,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET+4(r5)
> diff --git a/sysdeps/powerpc/powerpc32/fpu/setjmp-common.S b/sysdeps/powerpc/powerpc32/fpu/setjmp-common.S
> index b3c9f56..8b7bc60 100644
> --- a/sysdeps/powerpc/powerpc32/fpu/setjmp-common.S
> +++ b/sysdeps/powerpc/powerpc32/fpu/setjmp-common.S
> @@ -1,5 +1,5 @@
> /* setjmp for PowerPC.
> - Copyright (C) 1995-2000, 2003-2005, 2006, 2011 Free Software Foundation, Inc.
> + Copyright (C) 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -90,7 +90,11 @@ ENTRY (BP_SYM (__sigsetjmp))
> mtlr r6
> cfi_same_value (lr)
> # ifdef SHARED
> +# ifdef IS_IN_rtld
> + lwz r5,_rtld_local_ro@got(r5)
> +# else
> lwz r5,_rtld_global_ro@got(r5)
> +# endif
> lwz r5,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET+4(r5)
> # else
> lwz r5,_dl_hwcap@got(r5)
> diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
> index 2ff9078..3804b39 100644
> --- a/sysdeps/powerpc/powerpc64/__longjmp-common.S
> +++ b/sysdeps/powerpc/powerpc64/__longjmp-common.S
> @@ -1,5 +1,5 @@
> /* longjmp for PowerPC64.
> - Copyright (C) 1995, 1996,1997,1999-2006,2009 Free Software Foundation, Inc.
> + Copyright (C) 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -31,7 +31,11 @@
> .section ".toc","aw"
> .LC__dl_hwcap:
> # ifdef SHARED
> +# ifdef IS_IN_rtld
> + .tc _rtld_local_ro[TC],_rtld_local_ro
> +# else
> .tc _rtld_global_ro[TC],_rtld_global_ro
> +# endif
Same comment as below about RTLD_GLOBAL_RO_DL_HWCAP_OFFSET.
> # else
> .tc _dl_hwcap[TC],_dl_hwcap
> # endif
> diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
> index 7c04757..f0cad57 100644
> --- a/sysdeps/powerpc/powerpc64/dl-machine.h
> +++ b/sysdeps/powerpc/powerpc64/dl-machine.h
> @@ -1,6 +1,6 @@
> /* Machine-dependent ELF dynamic relocation inline functions.
> PowerPC64 version.
> - Copyright 1995-2005, 2006, 2008, 2010, 2011 Free Software Foundation, Inc.
> + Copyright 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -162,7 +162,7 @@ BODY_PREFIX "_start:\n" \
> " .pushsection \".toc\",\"aw\"\n" \
> DL_STARTING_UP_DEF \
> ".LC__rtld_global:\n"
Call it __rtld_local and fixup the reference?
\
> -" .tc _rtld_global[TC],_rtld_global\n" \
> +" .tc _rtld_local[TC],_rtld_local\n" \
> ".LC__dl_argc:\n" \
> " .tc _dl_argc[TC],_dl_argc\n" \
> ".LC__dl_argv:\n" \
> @@ -734,7 +734,7 @@ elf_machine_rela (struct link_map *map,
> _dl_error_printf ("%s: Symbol `%s' has different size" \
> " in shared object," \
> " consider re-linking\n",
> - _dl_argv[0] ?: "<program name unknown>",
> + rtld_progname ?: "<program name unknown>",
> strtab + refsym->st_name);
> }
> memcpy (reloc_addr_arg, (char *) value,
> diff --git a/sysdeps/powerpc/powerpc64/dl-trampoline.S b/sysdeps/powerpc/powerpc64/dl-trampoline.S
> index 266efe3..6435f46 100644
> --- a/sysdeps/powerpc/powerpc64/dl-trampoline.S
> +++ b/sysdeps/powerpc/powerpc64/dl-trampoline.S
> @@ -1,5 +1,5 @@
> /* PLT trampolines. PPC64 version.
> - Copyright (C) 2005, 2006 Free Software Foundation, Inc.
> + Copyright (C) 2005-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -169,7 +169,7 @@ END(_dl_runtime_resolve)
> .section ".toc","aw"
> .LC__dl_hwcap:
> # ifdef SHARED
> - .tc _rtld_global_ro[TC],_rtld_global_ro
> + .tc _rtld_local_ro[TC],_rtld_local_ro
> # else
> .tc _dl_hwcap[TC],_dl_hwcap
> # endif
Same comment as below about RTLD_GLOBAL_RO_DL_HWCAP_OFFSET.
> diff --git a/sysdeps/powerpc/powerpc64/setjmp-common.S b/sysdeps/powerpc/powerpc64/setjmp-common.S
> index 1a1326e..ab017b7 100644
> --- a/sysdeps/powerpc/powerpc64/setjmp-common.S
> +++ b/sysdeps/powerpc/powerpc64/setjmp-common.S
> @@ -1,5 +1,5 @@
> /* setjmp for PowerPC64.
> - Copyright (C) 1995-2003, 2004, 2005, 2006 Free Software Foundation, Inc.
> + Copyright (C) 1995-2012 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> The GNU C Library is free software; you can redistribute it and/or
> @@ -30,7 +30,11 @@
> .section ".toc","aw"
> .LC__dl_hwcap:
> # ifdef SHARED
> +# ifdef IS_IN_rtld
> + .tc _rtld_local_ro[TC],_rtld_local_ro
> +# else
> .tc _rtld_global_ro[TC],_rtld_global_ro
> +# endif
> # else
> .tc _dl_hwcap[TC],_dl_hwcap
> # endif
Could you adjust the comments that use the macro RTLD_GLOBAL_RO_DL_HWCAP_OFFSET?
e.g.
#ifdef SHARED
/* Load _rtld_local._dl_hwcap. We use the offset
for _rtld_global because they are the same and
we already have them computed for the *context
routines. */
ld r12,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r12)
#else
ld r12,0(r12) /* Load extern _dl_hwcap. */
#endif
Perhaps that comment is too verbose, but it should at least say "Load
_rtld_local._dl_hwcap."
Cheers,
Carlos.
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