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Re: ppc476 linker workaround shared lib fixes

From: Alan Modra <amodra at gmail dot com>
To: binutils at sourceware dot org
Date: Tue, 16 Jun 2015 18:00:47 +0930
Subject: Re: ppc476 linker workaround shared lib fixes
Authentication-results: sourceware.org; auth=none
References: <20150605104130 dot GY14752 at bubble dot grove dot modra dot org>

On Fri, Jun 05, 2015 at 08:11:30PM +0930, Alan Modra wrote:
> When building a shared lib from non-PIC objects, we'll get dynamic
> text relocations.  These need to move with any insns we move.

Huh, I can't even write a binary search properly.  Also, when the
original objects aren't made available to test a linker fix, it pays
to write something a little more than the simplest testcase.

bfd/
	* elf32-ppc.c (ppc_elf_relocate_section): Correct binary search of
	dynamic relocs.
ld/testsuite/
	* ld-powerpc/ppc476-shared.s: Repeat dynamic reloc generating insns.
	* ld-powerpc/ppc476-shared.d: Update.
	* ld-powerpc/ppc476-shared2.d: Update.

diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c
index a947e8e..f1fbc66 100644
--- a/bfd/elf32-ppc.c
+++ b/bfd/elf32-ppc.c
@@ -9642,32 +9642,33 @@ ppc_elf_relocate_section (bfd *output_bfd,
 	      sreloc = elf_section_data (input_section)->sreloc;
 	      if (sreloc != NULL)
 		{
-		  bfd_byte *slo, *shi, *srelend;
+		  Elf32_External_Rela *slo, *shi, *srelend;
 		  bfd_vma soffset;
 
-		  slo = sreloc->contents;
-		  shi = srelend
-		    = slo + sreloc->reloc_count * sizeof (Elf32_External_Rela);
+		  slo = (Elf32_External_Rela *) sreloc->contents;
+		  shi = srelend = slo + sreloc->reloc_count;
 		  soffset = (offset + input_section->output_section->vma
 			     + input_section->output_offset);
 		  while (slo < shi)
 		    {
-		      bfd_byte *srel = slo + (shi - slo) / 2;
-		      bfd_elf32_swap_reloca_in (output_bfd, srel, &outrel);
+		      Elf32_External_Rela *srel = slo + (shi - slo) / 2;
+		      bfd_elf32_swap_reloca_in (output_bfd, (bfd_byte *) srel,
+						&outrel);
 		      if (outrel.r_offset < soffset)
 			slo = srel + 1;
 		      else if (outrel.r_offset > soffset + 3)
 			shi = srel;
 		      else
 			{
-			  bfd_byte *nextr = srel + sizeof (Elf32_External_Rela);
-			  if (nextr != srelend)
+			  if (srel + 1 != srelend)
 			    {
-			      memmove (srel, nextr, srelend - nextr);
-			      srel = srelend - sizeof (Elf32_External_Rela);
+			      memmove (srel, srel + 1,
+				       (srelend - (srel + 1)) * sizeof (*srel));
+			      srel = srelend - 1;
 			    }
 			  outrel.r_offset += patch_off - offset;
-			  bfd_elf32_swap_reloca_out (output_bfd, &outrel, srel);
+			  bfd_elf32_swap_reloca_out (output_bfd, &outrel,
+						     (bfd_byte *) srel);
 			  break;
 			}
 		    }
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared.d b/ld/testsuite/ld-powerpc/ppc476-shared.d
index 8fda847..fe438f4 100644
--- a/ld/testsuite/ld-powerpc/ppc476-shared.d
+++ b/ld/testsuite/ld-powerpc/ppc476-shared.d
@@ -8,23 +8,41 @@
 
 Disassembly of section \.text:
 
-0+fffc <\.text>:
-    fffc:	(48 01 00 04|04 00 01 48) 	b       20000 .*
+0000fffc <\.text>:
+    fffc:	(48 03 00 04|04 00 03 48) 	b       40000 .*
    10000:	(38 63 00 00|00 00 63 38) 	addi    r3,r3,0
-			1000[02]: R_PPC_ADDR16_LO	.bss
+			1000[02]: R_PPC_ADDR16_LO	\.bss
 	\.\.\.
-   1fff0:	(42 9f 00 05|05 00 9f 42) 	bcl     .*
-   1fff4:	(7d 28 02 a6|a6 02 28 7d) 	mflr    r9
-   1fff8:	(3d 29 00 00|00 00 29 3d) 	addis   r9,r9,0
-			1fff[8a]: R_PPC_REL16_HA	.bss\+0x[46]
-   1fffc:	(48 00 00 14|14 00 00 48) 	b       20010 .*
-   20000:	(3c 60 00 00|00 00 60 3c) 	lis     r3,0
-			2000[02]: R_PPC_ADDR16_HA	.bss
-   20004:	(4b fe ff fc|fc ff fe 4b) 	b       10000 .*
-   20008:	(48 00 00 02|02 00 00 48) 	ba      0 .*
-   2000c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
-   20010:	(39 29 01 00|00 01 29 39) 	addi    r9,r9,256
-			2001[02]: R_PPC_REL16_LO	.bss\+0x1[ce]
-   20014:	(4b ff ff ec|ec ff ff 4b) 	b       20000 .*
-   20018:	(48 00 00 02|02 00 00 48) 	ba      0 .*
-   2001c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   1fffc:	(48 02 00 14|14 00 02 48) 	b       40010 .*
+   20000:	(38 63 00 00|00 00 63 38) 	addi    r3,r3,0
+			2000[02]: R_PPC_ADDR16_LO	\.bss
+	\.\.\.
+   2fffc:	(48 01 00 24|24 00 01 48) 	b       40020 .*
+   30000:	(38 63 00 00|00 00 63 38) 	addi    r3,r3,0
+			3000[02]: R_PPC_ADDR16_LO	\.bss
+	\.\.\.
+   3fff0:	(42 9f 00 05|05 00 9f 42) 	bcl     .*
+   3fff4:	(7d 28 02 a6|a6 02 28 7d) 	mflr    r9
+   3fff8:	(3d 29 00 00|00 00 29 3d) 	addis   r9,r9,0
+			3fff[8a]: R_PPC_REL16_HA	\.bss\+0x[46]
+   3fffc:	(48 00 00 34|34 00 00 48) 	b       40030 .*
+   40000:	(3c 60 00 00|00 00 60 3c) 	lis     r3,0
+			4000[02]: R_PPC_ADDR16_HA	\.bss
+   40004:	(4b fc ff fc|fc ff fc 4b) 	b       10000 .*
+   40008:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   4000c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   40010:	(3c 60 00 00|00 00 60 3c) 	lis     r3,0
+			4001[02]: R_PPC_ADDR16_HA	\.bss
+   40014:	(4b fd ff ec|ec ff fd 4b) 	b       20000 .*
+   40018:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   4001c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   40020:	(3c 60 00 00|00 00 60 3c) 	lis     r3,0
+			4002[02]: R_PPC_ADDR16_HA	\.bss
+   40024:	(4b fe ff dc|dc ff fe 4b) 	b       30000 .*
+   40028:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   4002c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   40030:	(39 29 01 50|50 01 29 39) 	addi    r9,r9,336
+			4003[02]: R_PPC_REL16_LO	\.bss\+0x3[ce]
+   40034:	(4b ff ff cc|cc ff ff 4b) 	b       40000 .*
+   40038:	(48 00 00 02|02 00 00 48) 	ba      0 .*
+   4003c:	(48 00 00 02|02 00 00 48) 	ba      0 .*
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared.s b/ld/testsuite/ld-powerpc/ppc476-shared.s
index 6774bad..e23b78a 100644
--- a/ld/testsuite/ld-powerpc/ppc476-shared.s
+++ b/ld/testsuite/ld-powerpc/ppc476-shared.s
@@ -1,8 +1,14 @@
  .text
  lis 3,x@ha
  addi 3,3,x@l
+ .org 0x10000
+ lis 3,x@ha
+ addi 3,3,x@l
+ .org 0x20000
+ lis 3,x@ha
+ addi 3,3,x@l
 
- .org 0xfff4
+ .org 0x2fff4
  bcl 20,31,.+4
 0:
  mflr 9
diff --git a/ld/testsuite/ld-powerpc/ppc476-shared2.d b/ld/testsuite/ld-powerpc/ppc476-shared2.d
index ebb8bf1..813ea2e 100644
--- a/ld/testsuite/ld-powerpc/ppc476-shared2.d
+++ b/ld/testsuite/ld-powerpc/ppc476-shared2.d
@@ -8,5 +8,9 @@
 
 DYNAMIC RELOCATION RECORDS
 OFFSET   TYPE              VALUE 
-0001000[02] R_PPC_ADDR16_LO   \.text\+0x000200f4
-0002000[02] R_PPC_ADDR16_HA   \.text\+0x000200f4
+0001000[02] R_PPC_ADDR16_LO   \.text\+0x00040144
+0002000[02] R_PPC_ADDR16_LO   \.text\+0x00040144
+0003000[02] R_PPC_ADDR16_LO   \.text\+0x00040144
+0004000[02] R_PPC_ADDR16_HA   \.text\+0x00040144
+0004001[02] R_PPC_ADDR16_HA   \.text\+0x00040144
+0004002[02] R_PPC_ADDR16_HA   \.text\+0x00040144

-- 
Alan Modra
Australia Development Lab, IBM

References:
- ppc476 linker workaround shared lib fixes
  - From: Alan Modra

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