Taking an undefined function's address in an executable

doesn't always mean you need to define a function symbol on plt code.
If all references are in read-write sections, then using dynamic relocs
is OK.

bfd/
	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Clear
	pointer_equality_needed when !readonly_dynrelocs.
	* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
ld/testsuite/
	* ld-powerpc/ambiguousv1.d: Match symbol table too.
	* ld-powerpc/ambiguousv2.d: Likewise.
	* ld-powerpc/ambiguousv1b.d: New.
	* ld-powerpc/ambiguousv2b.d: New.
	* ld-powerpc/powerpc.exp: Run new tests.

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2014-07-02  Alan Modra  <amodra@gmail.com>
+
+	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Clear
+	pointer_equality_needed when !readonly_dynrelocs.
+	* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
+
 2014-07-02  Alan Modra  <amodra@gmail.com>
 
 	* elf32-ppc.c (ppc_elf_check_relocs): Set DF_STATIC_TLS for PIEs too.

bfd/elf32-ppc.c

@@ -5506,9 +5506,21 @@ ppc_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	     will go to this object, or will remain undefined.  */
 	  h->plt.plist = NULL;
 	  h->needs_plt = 0;
+	  h->pointer_equality_needed = 0;
 	}
       else
 	{
+	  /* Taking a function's address in a read/write section
+	     doesn't require us to define the function symbol in the
+	     executable on a global entry stub.  A dynamic reloc can
+	     be used instead.  */
+	  if (h->pointer_equality_needed
+	      && !readonly_dynrelocs (h))
+	    {
+	      h->pointer_equality_needed = 0;
+	      h->non_got_ref = 0;
+	    }
+
 	  /* After adjust_dynamic_symbol, non_got_ref set in the
 	     non-shared case means that we have allocated space in
 	     .dynbss for the symbol and thus dyn_relocs for this
@@ -5518,7 +5530,7 @@ ppc_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	     relocations against this symbol to the PLT entry.  Allow
 	     dynamic relocs if the reference is weak, and the dynamic
 	     relocs will not cause text relocation.  */
-	  if (!h->ref_regular_nonweak
+	  else if (!h->ref_regular_nonweak
 		   && h->non_got_ref
 		   && h->type != STT_GNU_IFUNC
 		   && !htab->is_vxworks

bfd/elf64-ppc.c

@@ -6993,9 +6993,21 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	{
 	  h->plt.plist = NULL;
 	  h->needs_plt = 0;
+	  h->pointer_equality_needed = 0;
 	}
       else if (abiversion (info->output_bfd) == 2)
 	{
+	  /* Taking a function's address in a read/write section
+	     doesn't require us to define the function symbol in the
+	     executable on a global entry stub.  A dynamic reloc can
+	     be used instead.  */
+	  if (h->pointer_equality_needed
+	      && !readonly_dynrelocs (h))
+	    {
+	      h->pointer_equality_needed = 0;
+	      h->non_got_ref = 0;
+	    }
+
 	  /* After adjust_dynamic_symbol, non_got_ref set in the
 	     non-shared case means that we have allocated space in
 	     .dynbss for the symbol and thus dyn_relocs for this
@@ -7005,7 +7017,7 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
 	     relocations against this symbol to the PLT entry.  Allow
 	     dynamic relocs if the reference is weak, and the dynamic
 	     relocs will not cause text relocation.  */
-	  if (!h->ref_regular_nonweak
+	  else if (!h->ref_regular_nonweak
 		   && h->non_got_ref
 		   && h->type != STT_GNU_IFUNC
 		   && !readonly_dynrelocs (h))

ld/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2014-07-02  Alan Modra  <amodra@gmail.com>
+
+	* ld-powerpc/ambiguousv1.d: Match symbol table too.
+	* ld-powerpc/ambiguousv2.d: Likewise.
+	* ld-powerpc/ambiguousv1b.d: New.
+	* ld-powerpc/ambiguousv2b.d: New.
+	* ld-powerpc/powerpc.exp: Run new tests.
+
 2014-06-25  Kyle McMartin  <kyle@redhat.com>
 
 	* ld-arm/tls-gdierelax2.d: Fix expected offsets.

ld/testsuite/ld-powerpc/ambiguousv1.d

@@ -1,12 +1,44 @@
 #source: startv1.s
 #source: funref.s
 #as: -a64
-#ld: -melf64ppc
+#ld: -melf64ppc --emit-stub-syms
 #ld_after_inputfiles: tmpdir/funv1.so
-#readelf: -r --wide
+#readelf: -rs --wide
-# check that we do the right thing with funref.s that doesn't have
+# Check that we do the right thing with funref.s that doesn't have
-# anything to mark it as ELFv1 or ELFv2
+# anything to mark it as ELFv1 or ELFv2.  We should get a dynamic
+# reloc on the function address, and my_func should be undefined
+# dynamic with value zero.
 
 Relocation section .* contains 1 entries:
 .*
 .* R_PPC64_ADDR64 +0+ my_func \+ 0
+
+Symbol table '\.dynsym' contains 5 entries:
+.*
+     0: .*
+     1: 0+00000000     0 FUNC    GLOBAL DEFAULT  UND my_func
+     2: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 __bss_start
+     3: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+     4: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _end
+
+Symbol table '\.symtab' contains 19 entries:
+   Num:    Value          Size Type    Bind   Vis      Ndx Name
+     0: .*
+     1: 0+10000158     0 SECTION LOCAL  DEFAULT    1 
+     2: 0+10000170     0 SECTION LOCAL  DEFAULT    2 
+     3: 0+10000198     0 SECTION LOCAL  DEFAULT    3 
+     4: 0+10000210     0 SECTION LOCAL  DEFAULT    4 
+     5: 0+10000248     0 SECTION LOCAL  DEFAULT    5 
+     6: 0+10000260     0 SECTION LOCAL  DEFAULT    6 
+     7: 0+10000264     0 SECTION LOCAL  DEFAULT    7 
+     8: 0+10010268     0 SECTION LOCAL  DEFAULT    8 
+     9: 0+10010368     0 SECTION LOCAL  DEFAULT    9 
+    10: 0+10010370     0 SECTION LOCAL  DEFAULT   10 
+    11: 0+10010388     0 SECTION LOCAL  DEFAULT   11 
+    12: 0+10010268     0 OBJECT  LOCAL  DEFAULT    8 _DYNAMIC
+    13: 0+10010368     0 NOTYPE  GLOBAL DEFAULT    9 func_tab
+    14: 0+00000000     0 FUNC    GLOBAL DEFAULT  UND my_func
+    15: 0+10010370     0 FUNC    GLOBAL DEFAULT   10 _start
+    16: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 __bss_start
+    17: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+    18: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _end

ld/testsuite/ld-powerpc/ambiguousv1b.d

@@ -0,0 +1,45 @@
+#source: startv1.s
+#source: funref2.s
+#as: -a64
+#ld: -melf64ppc --emit-stub-syms
+#ld_after_inputfiles: tmpdir/funv1.so
+#readelf: -rs --wide
+# Check that we do the right thing with funref2.s that doesn't have
+# anything to mark it as ELFv1 or ELFv2.  Since my_func address is
+# taken in a read-only section we should get a copy reloc for the OPD
+# entry.
+
+Relocation section .* contains 1 entries:
+.*
+.* R_PPC64_COPY .* my_func \+ 0
+
+Symbol table '\.dynsym' contains 5 entries:
+.*
+     0: .*
+     1: 0+10010390     4 FUNC    GLOBAL DEFAULT   12 my_func
+     2: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   12 __bss_start
+     3: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+     4: 0+10010398     0 NOTYPE  GLOBAL DEFAULT   12 _end
+
+Symbol table '\.symtab' contains 20 entries:
+.*
+     0: .*
+     1: 0+10000158     0 SECTION LOCAL  DEFAULT    1 
+     2: 0+10000170     0 SECTION LOCAL  DEFAULT    2 
+     3: 0+10000198     0 SECTION LOCAL  DEFAULT    3 
+     4: 0+10000210     0 SECTION LOCAL  DEFAULT    4 
+     5: 0+10000248     0 SECTION LOCAL  DEFAULT    5 
+     6: 0+10000260     0 SECTION LOCAL  DEFAULT    6 
+     7: 0+10000264     0 SECTION LOCAL  DEFAULT    7 
+     8: 0+1000026c     0 SECTION LOCAL  DEFAULT    8 
+     9: 0+10010270     0 SECTION LOCAL  DEFAULT    9 
+    10: 0+10010370     0 SECTION LOCAL  DEFAULT   10 
+    11: 0+10010388     0 SECTION LOCAL  DEFAULT   11 
+    12: 0+10010390     0 SECTION LOCAL  DEFAULT   12 
+    13: 0+10010270     0 OBJECT  LOCAL  DEFAULT    9 _DYNAMIC
+    14: 0+10000264     0 NOTYPE  GLOBAL DEFAULT    7 func_tab
+    15: 0+10010390     4 FUNC    GLOBAL DEFAULT   12 my_func
+    16: 0+10010370     0 FUNC    GLOBAL DEFAULT   10 _start
+    17: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   12 __bss_start
+    18: 0+10010390     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+    19: 0+10010398     0 NOTYPE  GLOBAL DEFAULT   12 _end

ld/testsuite/ld-powerpc/ambiguousv2.d

@@ -1,12 +1,51 @@
 #source: startv2.s
 #source: funref.s
 #as: -a64
-#ld: -melf64ppc
+#ld: -melf64ppc --emit-stub-syms
 #ld_after_inputfiles: tmpdir/funv2.so
-#readelf: -r --wide
+#readelf: -rs --wide
-# check that we do the right thing with funref.s that doesn't have
+# Check that we do the right thing with funref.s that doesn't have
-# anything to mark it as ELFv1 or ELFv2
+# anything to mark it as ELFv1 or ELFv2.  We should get a dynamic
+# reloc on the function address, not have a global entry stub, and
+# my_func should be undefined dynamic with value zero.
+# FIXME someday: No need for a plt entry.
+
+Relocation section .* contains 1 entries:
+.*
+.* R_PPC64_ADDR64 .* my_func \+ 0
 
 Relocation section .* contains 1 entries:
 .*
 .* R_PPC64_JMP_SLOT .* my_func \+ 0
+
+Symbol table '\.dynsym' contains 5 entries:
+.*
+     0: .*
+     1: 0+00000000     0 FUNC    GLOBAL DEFAULT  UND my_func
+     2: 0+10010438     0 NOTYPE  GLOBAL DEFAULT   12 __bss_start
+     3: 0+10010438     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+     4: 0+10010450     0 NOTYPE  GLOBAL DEFAULT   12 _end
+
+Symbol table '\.symtab' contains 21 entries:
+.*
+     0: .*
+     1: 0+10000158     0 SECTION LOCAL  DEFAULT    1 
+     2: 0+10000170     0 SECTION LOCAL  DEFAULT    2 
+     3: 0+10000198     0 SECTION LOCAL  DEFAULT    3 
+     4: 0+10000210     0 SECTION LOCAL  DEFAULT    4 
+     5: 0+10000248     0 SECTION LOCAL  DEFAULT    5 
+     6: 0+10000260     0 SECTION LOCAL  DEFAULT    6 
+     7: 0+10000278     0 SECTION LOCAL  DEFAULT    7 
+     8: 0+100002c4     0 SECTION LOCAL  DEFAULT    8 
+     9: 0+100102c8     0 SECTION LOCAL  DEFAULT    9 
+    10: 0+10010428     0 SECTION LOCAL  DEFAULT   10 
+    11: 0+10010430     0 SECTION LOCAL  DEFAULT   11 
+    12: 0+10010438     0 SECTION LOCAL  DEFAULT   12 
+    13: 0+100102c8     0 OBJECT  LOCAL  DEFAULT    9 _DYNAMIC
+    14: 0+10000288     0 NOTYPE  LOCAL  DEFAULT    7 __glink_PLTresolve
+    15: 0+10010428     0 NOTYPE  GLOBAL DEFAULT   10 func_tab
+    16: 0+00000000     0 FUNC    GLOBAL DEFAULT  UND my_func
+    17: 0+10000278     0 NOTYPE  GLOBAL DEFAULT    7 _start
+    18: 0+10010438     0 NOTYPE  GLOBAL DEFAULT   12 __bss_start
+    19: 0+10010438     0 NOTYPE  GLOBAL DEFAULT   11 _edata
+    20: 0+10010450     0 NOTYPE  GLOBAL DEFAULT   12 _end

ld/testsuite/ld-powerpc/ambiguousv2b.d

@@ -0,0 +1,47 @@
+#source: startv2.s
+#source: funref2.s
+#as: -a64
+#ld: -melf64ppc --emit-stub-syms
+#ld_after_inputfiles: tmpdir/funv2.so
+#readelf: -rs --wide
+# Check that we do the right thing with funref2.s that doesn't have
+# anything to mark it as ELFv1 or ELFv2.  Since my_func address is
+# taken in a read-only section we should get a plt entry, a global
+# entry stub, and my_func should be undefined dynamic with non-zero
+# value.
+
+Relocation section .* contains 1 entries:
+.*
+.* R_PPC64_JMP_SLOT .* my_func \+ 0
+
+Symbol table '\.dynsym' contains 5 entries:
+.*
+     0: .*
+     1: 0+100002b8     0 FUNC    GLOBAL DEFAULT  UND my_func
+     2: 0+10010408     0 NOTYPE  GLOBAL DEFAULT   11 __bss_start
+     3: 0+10010408     0 NOTYPE  GLOBAL DEFAULT   10 _edata
+     4: 0+10010420     0 NOTYPE  GLOBAL DEFAULT   11 _end
+
+Symbol table '\.symtab' contains 21 entries:
+.*
+     0: .*
+     1: 0+10000158     0 SECTION LOCAL  DEFAULT    1 
+     2: 0+10000170     0 SECTION LOCAL  DEFAULT    2 
+     3: 0+10000198     0 SECTION LOCAL  DEFAULT    3 
+     4: 0+10000210     0 SECTION LOCAL  DEFAULT    4 
+     5: 0+10000248     0 SECTION LOCAL  DEFAULT    5 
+     6: 0+10000260     0 SECTION LOCAL  DEFAULT    6 
+     7: 0+100002c8     0 SECTION LOCAL  DEFAULT    7 
+     8: 0+100002d0     0 SECTION LOCAL  DEFAULT    8 
+     9: 0+100102d0     0 SECTION LOCAL  DEFAULT    9 
+    10: 0+10010400     0 SECTION LOCAL  DEFAULT   10 
+    11: 0+10010408     0 SECTION LOCAL  DEFAULT   11 
+    12: 0+100102d0     0 OBJECT  LOCAL  DEFAULT    9 _DYNAMIC
+    13: 0+100002b8     0 NOTYPE  LOCAL  DEFAULT    6 00000011\.global_entry\.my_func
+    14: 0+10000270     0 NOTYPE  LOCAL  DEFAULT    6 __glink_PLTresolve
+    15: 0+100002c8     0 NOTYPE  GLOBAL DEFAULT    7 func_tab
+    16: 0+100002b8     0 FUNC    GLOBAL DEFAULT  UND my_func
+    17: 0+10000260     0 NOTYPE  GLOBAL DEFAULT    6 _start
+    18: 0+10010408     0 NOTYPE  GLOBAL DEFAULT   11 __bss_start
+    19: 0+10010408     0 NOTYPE  GLOBAL DEFAULT   10 _edata
+    20: 0+10010420     0 NOTYPE  GLOBAL DEFAULT   11 _end

ld/testsuite/ld-powerpc/funref2.s

@@ -0,0 +1,4 @@
+ .section .rodata,"a",@progbits
+ .globl func_tab
+func_tab:
+ .dc.a my_func

ld/testsuite/ld-powerpc/powerpc.exp

@@ -275,7 +275,9 @@ if [ supports_ppc64 ] then {
     run_dump_test "elfv2-2so"
     run_dump_test "elfv2-2exe"
     run_dump_test "ambiguousv1"
+    run_dump_test "ambiguousv1b"
     run_dump_test "ambiguousv2"
+    run_dump_test "ambiguousv2b"
 }
 
 if { [istarget "powerpc*-eabi*"] } {