commit d4094b6a8883ae481c7644c5a210254efe92e9ad
Author: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Date:   Tue Feb 4 18:40:16 2014 +0100

    PowerPC64 ELFv2 ABI: no function descriptors
    
    This implements the most significant difference with the ELFv2 ABI:
    we no longer use function descriptors.  The patch consists mostly
    of switching off code to deal with descriptors :-)
    
    In addition, when calling an inferior function, we no longer need
    to provide its TOC in r2.  Instead, ELFv2 code expects to be called
    with r12 pointing to the code address itself.
    
    gdb/ChangeLog:
    
    	* ppc-linux-tdep.c (ppc_linux_init_abi): Only call
    	set_gdbarch_convert_from_func_ptr_addr and
    	set_gdbarch_elf_make_msymbol_special for ELFv1.
    	* ppc-sysv-tdep.c (ppc64_sysv_abi_push_param): Only handle
    	function descriptors on ELFv1.
    	(ppc64_sysv_abi_push_dummy_call): Likewise.  On ELFv2,
    	set up r12 at function entry.

Index: gdb-7.6.1/gdb/ppc-linux-tdep.c
===================================================================
--- gdb-7.6.1.orig/gdb/ppc-linux-tdep.c
+++ gdb-7.6.1/gdb/ppc-linux-tdep.c
@@ -1331,13 +1331,16 @@ ppc_linux_init_abi (struct gdbarch_info
   
   if (tdep->wordsize == 8)
     {
-      /* Handle PPC GNU/Linux 64-bit function pointers (which are really
-	 function descriptors).  */
-      set_gdbarch_convert_from_func_ptr_addr
-	(gdbarch, ppc64_convert_from_func_ptr_addr);
+      if (tdep->elf_abi == POWERPC_ELF_V1)
+	{
+	  /* Handle PPC GNU/Linux 64-bit function pointers (which are really
+	     function descriptors).  */
+	  set_gdbarch_convert_from_func_ptr_addr
+	    (gdbarch, ppc64_convert_from_func_ptr_addr);
 
-      set_gdbarch_elf_make_msymbol_special (gdbarch,
-					    ppc64_elf_make_msymbol_special);
+	  set_gdbarch_elf_make_msymbol_special
+	    (gdbarch, ppc64_elf_make_msymbol_special);
+	}
 
       /* Shared library handling.  */
       set_gdbarch_skip_trampoline_code (gdbarch, ppc64_skip_trampoline_code);
Index: gdb-7.6.1/gdb/ppc-sysv-tdep.c
===================================================================
--- gdb-7.6.1.orig/gdb/ppc-sysv-tdep.c
+++ gdb-7.6.1/gdb/ppc-sysv-tdep.c
@@ -1351,8 +1351,9 @@ ppc64_sysv_abi_push_param (struct gdbarc
 	  word = unpack_long (type, val);
 
 	  /* Convert any function code addresses into descriptors.  */
-	  if (TYPE_CODE (type) == TYPE_CODE_PTR
-	      || TYPE_CODE (type) == TYPE_CODE_REF)
+	  if (tdep->elf_abi == POWERPC_ELF_V1
+	      && (TYPE_CODE (type) == TYPE_CODE_PTR
+		  || TYPE_CODE (type) == TYPE_CODE_REF))
 	    {
 	      struct type *target_type
 		= check_typedef (TYPE_TARGET_TYPE (type));
@@ -1552,24 +1553,32 @@ ppc64_sysv_abi_push_dummy_call (struct g
      breakpoint.  */
   regcache_cooked_write_signed (regcache, tdep->ppc_lr_regnum, bp_addr);
 
-  /* Use the func_addr to find the descriptor, and use that to find
-     the TOC.  If we're calling via a function pointer, the pointer
-     itself identifies the descriptor.  */
-  {
-    struct type *ftype = check_typedef (value_type (function));
-    CORE_ADDR desc_addr = value_as_address (function);
-
-    if (TYPE_CODE (ftype) == TYPE_CODE_PTR
-	|| convert_code_addr_to_desc_addr (func_addr, &desc_addr))
-      {
-	/* The TOC is the second double word in the descriptor.  */
-	CORE_ADDR toc =
-	  read_memory_unsigned_integer (desc_addr + tdep->wordsize,
-					tdep->wordsize, byte_order);
-	regcache_cooked_write_unsigned (regcache,
-					tdep->ppc_gp0_regnum + 2, toc);
-      }
-  }
+  /* In the ELFv1 ABI, use the func_addr to find the descriptor, and use
+     that to find the TOC.  If we're calling via a function pointer,
+     the pointer itself identifies the descriptor.  */
+  if (tdep->elf_abi == POWERPC_ELF_V1)
+    {
+      struct type *ftype = check_typedef (value_type (function));
+      CORE_ADDR desc_addr = value_as_address (function);
+
+      if (TYPE_CODE (ftype) == TYPE_CODE_PTR
+	  || convert_code_addr_to_desc_addr (func_addr, &desc_addr))
+	{
+	  /* The TOC is the second double word in the descriptor.  */
+	  CORE_ADDR toc =
+	    read_memory_unsigned_integer (desc_addr + tdep->wordsize,
+					  tdep->wordsize, byte_order);
+
+	  regcache_cooked_write_unsigned (regcache,
+					  tdep->ppc_gp0_regnum + 2, toc);
+	}
+    }
+
+  /* In the ELFv2 ABI, we need to pass the target address in r12 since
+     we may be calling a global entry point.  */
+  if (tdep->elf_abi == POWERPC_ELF_V2)
+    regcache_cooked_write_unsigned (regcache,
+				    tdep->ppc_gp0_regnum + 12, func_addr);
 
   return sp;
 }