PowerPC64 undefined weak visibility vs GOT optimisation

Undefined weak symbols with non-default visibility are seen as local
by SYMBOL_REFERENCES_LOCAL.  This stops a got indirect to relative
optimisation for them, so that pies and dlls don't get non-zero values
when loading somewhere other than the address they are linked at
(which always happens).  The optimisation could be allowed for pdes,
but I thought it best not to allow it there too.

bfd/
	* elf64-ppc.c (ppc64_elf_relocate_section): Don't optimise got
	indirect to pc-relative or toc-relative for undefined symbols.
ld/
	* testsuite/ld-powerpc/weak1.d,
	* testsuite/ld-powerpc/weak1.r,
	* testsuite/ld-powerpc/weak1.s,
	* testsuite/ld-powerpc/weak1so.d,
	* testsuite/ld-powerpc/weak1so.r: New tests.
	* testsuite/ld-powerpc/powerpc.exp: Run them.

bfd/ChangeLog

@@ -1,3 +1,8 @@
+2021-03-02  Alan Modra  <amodra@gmail.com>
+
+	* elf64-ppc.c (ppc64_elf_relocate_section): Don't optimise got
+	indirect to pc-relative or toc-relative for undefined symbols.
+
 2021-03-01  Alan Modra  <amodra@gmail.com>
 	    Fangrui Song <maskray@google.com>
 

bfd/elf64-ppc.c

@@ -16081,6 +16081,9 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	    break;
 	  from = TOCstart + htab->sec_info[input_section->id].toc_off;
 	  if (relocation + addend - from + 0x8000 < 0x10000
+	      && sec != NULL
+	      && sec->output_section != NULL
+	      && !discarded_section (sec)
 	      && (h == NULL || SYMBOL_REFERENCES_LOCAL (info, &h->elf)))
 	    {
 	      insn = bfd_get_32 (input_bfd, contents + (rel->r_offset & ~3));
@@ -16101,6 +16104,9 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	    break;
 	  from = TOCstart + htab->sec_info[input_section->id].toc_off;
 	  if (relocation + addend - from + 0x80008000ULL < 0x100000000ULL
+	      && sec != NULL
+	      && sec->output_section != NULL
+	      && !discarded_section (sec)
 	      && (h == NULL || SYMBOL_REFERENCES_LOCAL (info, &h->elf)))
 	    {
 	      insn = bfd_get_32 (input_bfd, contents + (rel->r_offset & ~3));
@@ -16129,6 +16135,9 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 		  + input_section->output_section->vma
 		  + input_section->output_offset);
 	  if (!(relocation - from + (1ULL << 33) < 1ULL << 34
+		&& sec != NULL
+		&& sec->output_section != NULL
+		&& !discarded_section (sec)
 		&& (h == NULL || SYMBOL_REFERENCES_LOCAL (info, &h->elf))))
 	    break;
 

ld/ChangeLog

@@ -1,3 +1,12 @@
+2021-03-02  Alan Modra  <amodra@gmail.com>
+
+	* testsuite/ld-powerpc/weak1.d,
+	* testsuite/ld-powerpc/weak1.r,
+	* testsuite/ld-powerpc/weak1.s,
+	* testsuite/ld-powerpc/weak1so.d,
+	* testsuite/ld-powerpc/weak1so.r: New tests.
+	* testsuite/ld-powerpc/powerpc.exp: Run them.
+
 2021-03-01  Hannes Domani  <ssbssa@sourceware.org>
 	    Nick Clifton  <nickc@redhat.com>
 

ld/testsuite/ld-powerpc/powerpc.exp

@@ -344,6 +344,12 @@ set ppc64elftests {
     {"group3" "-melf64ppc -e foo" "" "-a64" {group3.s group2.s group1.s}
 	{{objdump {-d} group2.d}
 	 {readelf {-s} group3.sym}} "group3"}
+    {"weak1" "-melf64ppc --hash-style=both" ""
+	"-a64 -mpower10" {weak1.s}
+	{{objdump -d weak1.d} {readelf {-srW} weak1.r}} "weak1"}
+    {"weak1.so" "-shared -melf64ppc --hash-style=both" ""
+	"-a64 -mpower10" {weak1.s}
+	{{objdump -d weak1so.d} {readelf {-srW} weak1so.r}} "weak1.so"}
 }
 
 set ppceabitests {

ld/testsuite/ld-powerpc/weak1.d

@@ -0,0 +1,26 @@
+
+.*:     file format .*
+
+Disassembly of section \.text:
+
+.*0c0 <_start>:
+.*0c0:	(04 10 00 01|01 00 10 04) 	pld     r3,65888
+.*0c4:	(e4 60 01 60|60 01 60 e4) 
+.*0c8:	(04 10 00 01|01 00 10 04) 	pld     r3,65856
+.*0cc:	(e4 60 01 40|40 01 60 e4) 
+.*0d0:	(04 10 00 01|01 00 10 04) 	pld     r3,65864
+.*0d4:	(e4 60 01 48|48 01 60 e4) 
+.*0d8:	(04 10 00 01|01 00 10 04) 	pld     r3,65848
+.*0dc:	(e4 60 01 38|38 01 60 e4) 
+.*0e0:	(e8 62 80 20|20 80 62 e8) 	ld      r3,-32736\(r2\)
+.*0e4:	(e8 62 80 08|08 80 62 e8) 	ld      r3,-32760\(r2\)
+.*0e8:	(e8 62 80 18|18 80 62 e8) 	ld      r3,-32744\(r2\)
+.*0ec:	(e8 62 80 10|10 80 62 e8) 	ld      r3,-32752\(r2\)
+.*0f0:	(60 00 00 00|00 00 00 60) 	nop
+.*0f4:	(e8 62 80 20|20 80 62 e8) 	ld      r3,-32736\(r2\)
+.*0f8:	(60 00 00 00|00 00 00 60) 	nop
+.*0fc:	(e8 62 80 08|08 80 62 e8) 	ld      r3,-32760\(r2\)
+.*100:	(60 00 00 00|00 00 00 60) 	nop
+.*104:	(e8 62 80 18|18 80 62 e8) 	ld      r3,-32744\(r2\)
+.*108:	(60 00 00 00|00 00 00 60) 	nop
+.*10c:	(e8 62 80 10|10 80 62 e8) 	ld      r3,-32752\(r2\)

ld/testsuite/ld-powerpc/weak1.r

@@ -0,0 +1,5 @@
+
+There are no relocations in this file.
+
+Symbol table '\.symtab' .*
+#pass

ld/testsuite/ld-powerpc/weak1.s

@@ -0,0 +1,22 @@
+ .weak x1, x2, x3, x4
+ .protected x2
+ .hidden x3
+ .internal x4
+ .global _start
+_start:
+ pld 3,x1@got@pcrel
+ pld 3,x2@got@pcrel
+ pld 3,x3@got@pcrel
+ pld 3,x4@got@pcrel
+ ld 3,x1@got(2)
+ ld 3,x2@got(2)
+ ld 3,x3@got(2)
+ ld 3,x4@got(2)
+ addis 9,2,x1@got@ha
+ ld 3,x1@got@l(9)
+ addis 9,2,x2@got@ha
+ ld 3,x2@got@l(9)
+ addis 9,2,x3@got@ha
+ ld 3,x3@got@l(9)
+ addis 9,2,x4@got@ha
+ ld 3,x4@got@l(9)

ld/testsuite/ld-powerpc/weak1so.d

@@ -0,0 +1,26 @@
+
+.*:     file format .*
+
+Disassembly of section \.text:
+
+0+1c0 <_start>:
+ 1c0:	(04 10 00 01|01 00 10 04) 	pld     r3,66144
+ 1c4:	(e4 60 02 60|60 02 60 e4) 
+ 1c8:	(04 10 00 01|01 00 10 04) 	pld     r3,66112
+ 1cc:	(e4 60 02 40|40 02 60 e4) 
+ 1d0:	(04 10 00 01|01 00 10 04) 	pld     r3,66120
+ 1d4:	(e4 60 02 48|48 02 60 e4) 
+ 1d8:	(04 10 00 01|01 00 10 04) 	pld     r3,66104
+ 1dc:	(e4 60 02 38|38 02 60 e4) 
+ 1e0:	(e8 62 80 20|20 80 62 e8) 	ld      r3,-32736\(r2\)
+ 1e4:	(e8 62 80 08|08 80 62 e8) 	ld      r3,-32760\(r2\)
+ 1e8:	(e8 62 80 18|18 80 62 e8) 	ld      r3,-32744\(r2\)
+ 1ec:	(e8 62 80 10|10 80 62 e8) 	ld      r3,-32752\(r2\)
+ 1f0:	(60 00 00 00|00 00 00 60) 	nop
+ 1f4:	(e8 62 80 20|20 80 62 e8) 	ld      r3,-32736\(r2\)
+ 1f8:	(60 00 00 00|00 00 00 60) 	nop
+ 1fc:	(e8 62 80 08|08 80 62 e8) 	ld      r3,-32760\(r2\)
+ 200:	(60 00 00 00|00 00 00 60) 	nop
+ 204:	(e8 62 80 18|18 80 62 e8) 	ld      r3,-32744\(r2\)
+ 208:	(60 00 00 00|00 00 00 60) 	nop
+ 20c:	(e8 62 80 10|10 80 62 e8) 	ld      r3,-32752\(r2\)

ld/testsuite/ld-powerpc/weak1so.r

@@ -0,0 +1,7 @@
+#...
+.* R_PPC64_GLOB_DAT +0+ x1 \+ 0
+#...
+.* 0+ +0 NOTYPE +WEAK +DEFAULT +UND x1
+#...
+.* 0+ +0 NOTYPE +WEAK +DEFAULT +UND x1
+#pass