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Support for R_ARM_IRELATIVE relocations


ARM have allocated R_ARM_IRELATIVE the relocation number 160 (thanks).
This patch adds GLIBC support for it.  Like PPC, the relocation is only
allowed in the normal DT_REL(A) table, not in DT_JMPREL.

Tested on arm-linux-gnueabi with --enable-multi-arch.  All ifunc* tests
passed.  (I actually cross-tested using EGLIBC, with a local patch to
make the ifunc tests cross-testing friendly.  I also used a dummy
arm/multiarch/Makefile, so that --enable-multi-arch was honoured.)

Please install if OK.

Richard


2011-03-14  Richard Sandiford  <richard.sandiford@linaro.org>

libc/
	* elf/elf.h (R_ARM_IRELATIVE): Define.

ports/
	* sysdeps/arm/dl-machine.h (elf_machine_rel): Handle STT_GNU_IFUNC
	and R_ARM_IRELATIVE.
	(elf_machine_rela): Likewise.
	* sysdeps/arm/dl-irel.h: New file.

Index: libc/elf/elf.h
===================================================================
--- libc/elf/elf.h	2011-03-14 16:12:41.000000000 +0000
+++ libc/elf/elf.h	2011-03-14 16:12:56.000000000 +0000
@@ -2353,6 +2353,7 @@ #define R_ARM_TLS_IE32		107	/* PC-rel 32
 					   static TLS block offset */
 #define R_ARM_TLS_LE32		108	/* 32 bit offset relative to static
 					   TLS block */
+#define R_ARM_IRELATIVE		160
 #define R_ARM_RXPC25		249
 #define R_ARM_RSBREL32		250
 #define R_ARM_THM_RPC22		251
Index: ports/sysdeps/arm/dl-irel.h
===================================================================
--- /dev/null	2011-03-14 08:51:58.266827044 +0000
+++ ports/sysdeps/arm/dl-irel.h	2011-03-14 16:12:56.000000000 +0000
@@ -0,0 +1,45 @@
+/* Machine-dependent ELF indirect relocation inline functions.
+   ARM version.
+   Copyright (C) 2009, 2010 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
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _DL_IREL_H
+#define _DL_IREL_H
+
+#include <stdio.h>
+#include <unistd.h>
+
+#define ELF_MACHINE_IREL	1
+
+static inline void
+__attribute ((always_inline))
+elf_irel (const Elf32_Rel *reloc)
+{
+  Elf32_Addr *const reloc_addr = (void *) reloc->r_offset;
+  const unsigned long int r_type = ELF32_R_TYPE (reloc->r_info);
+
+  if (__builtin_expect (r_type == R_ARM_IRELATIVE, 1))
+    {
+      Elf32_Addr value = ((Elf32_Addr (*) (void)) (*reloc_addr)) ();
+      *reloc_addr = value;
+    }
+  else
+    __libc_fatal ("unexpected reloc type in static binary");
+}
+
+#endif /* dl-irel.h */
Index: ports/sysdeps/arm/dl-machine.h
===================================================================
--- ports/sysdeps/arm/dl-machine.h	2011-03-14 16:12:41.000000000 +0000
+++ ports/sysdeps/arm/dl-machine.h	2011-03-14 16:12:56.000000000 +0000
@@ -367,6 +367,12 @@ elf_machine_rel (struct link_map *map, c
       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
       Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value;
 
+      if (sym != NULL
+	  && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC,
+			       0)
+	  && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1))
+	value = ((Elf32_Addr (*) (void)) value) ();
+
       switch (r_type)
 	{
 	case R_ARM_COPY:
@@ -447,7 +453,8 @@ elf_machine_rel (struct link_map *map, c
 	     *reloc_addr = value;
 	  }
 	  break;
-#if defined USE_TLS && !defined RTLD_BOOTSTRAP
+#if !defined RTLD_BOOTSTRAP
+#if defined USE_TLS
 	case R_ARM_TLS_DTPMOD32:
 	  /* Get the information from the link map returned by the
 	     resolv function.  */
@@ -468,6 +475,12 @@ elf_machine_rel (struct link_map *map, c
 	    }
 	  break;
 #endif
+	case R_ARM_IRELATIVE:
+	  value = map->l_addr + *reloc_addr;
+	  value = ((Elf32_Addr (*) (void)) value) ();
+	  *reloc_addr = value;
+	  break;
+#endif
 	default:
 	  _dl_reloc_bad_type (map, r_type, 0);
 	  break;
@@ -497,6 +510,12 @@ elf_machine_rela (struct link_map *map, 
       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
       Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value;
 
+      if (sym != NULL
+	  && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC,
+			       0)
+	  && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1))
+	value = ((Elf32_Addr (*) (void)) value) ();
+
       switch (r_type)
 	{
 #  ifndef RESOLVE_CONFLICT_FIND_MAP
@@ -548,7 +567,8 @@ elf_machine_rela (struct link_map *map, 
 	     *reloc_addr = value;
 	  }
 	  break;
-#if defined USE_TLS && !defined RTLD_BOOTSTRAP
+#if !defined RTLD_BOOTSTRAP
+#if defined USE_TLS
 	case R_ARM_TLS_DTPMOD32:
 	  /* Get the information from the link map returned by the
 	     resolv function.  */
@@ -569,6 +589,12 @@ elf_machine_rela (struct link_map *map, 
 	    }
 	  break;
 #endif
+	case R_ARM_IRELATIVE:
+	  value = map->l_addr + *reloc_addr;
+	  value = ((Elf32_Addr (*) (void)) value) ();
+	  *reloc_addr = value;
+	  break;
+#endif
 	default:
 	  _dl_reloc_bad_type (map, r_type, 0);
 	  break;


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