qemu/js2x/client: Support binutils >= 2.25.1

The recent binutils version introduces explicit definition of
a TOC symbol which points to the .toc section and enforces .toc
alignment to 256 rather than 8 bytes before.

For now the TOC symbol points to same location as it was before -
start of .toc + 0x8000; however as this might change, we should not
rely on that in the source code.

This changes __toc_start (for qemu and js2x boards), _got (for net-snk,
takeover, rtas) in linker scripts to use explicitely defined TOC if
defined and fall back to the older scheme if not.

This changes r2 (the register pointing to TOC) setup code not to add
0x8000 as linker scripts do that now.

Here is a bit more information about the change:
https://sourceware.org/ml/binutils/2015-10/msg00124.html
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=a27e685fa0a6480bdb07e3be359558524cec89b7

Tested on
1. gcc version 4.8.3 20140911 (Red Hat 4.8.3-7) (GCC)
   GNU ld version 2.23.2
2. gcc version 5.2.1 20151001 (GCC)
   GNU ld (GNU Binutils) 2.25.51.20150930

Reported-by: William Grant <wgrant@ubuntu.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

11 files changed, 14 insertions, 15 deletions

diff --git a/board-js2x/llfw/stage2.lds b/board-js2x/llfw/stage2.lds
index f91f065..e6315c3 100644
--- a/board-js2x/llfw/stage2.lds
+++ b/board-js2x/llfw/stage2.lds
@@ -45,7 +45,8 @@ SECTIONS {
 	__bss_end = .;
 	__bss_size = (__bss_end - __bss_start);
 
-	__toc_start = .;
+	. = ALIGN(256);
+	__toc_start = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
 	.got       :
 	{
 		 *(.toc .got)
diff --git a/board-js2x/llfw/stage2_head.S b/board-js2x/llfw/stage2_head.S
index 5460bfe..f3f5e0c 100644
--- a/board-js2x/llfw/stage2_head.S
+++ b/board-js2x/llfw/stage2_head.S
@@ -79,8 +79,6 @@ bsscdone:
 	/* ------------------------------------ */
 ASM_ENTRY(toc_init)	
 	LOAD64(r2, __toc_start)
-	addi	r2,r2,0x4000
-	addi	r2,r2,0x4000
 	blr
 
 	/* ------------------------------------ */
diff --git a/board-qemu/llfw/stage2.lds b/board-qemu/llfw/stage2.lds
index e060dd1..28c9dca 100644
--- a/board-qemu/llfw/stage2.lds
+++ b/board-qemu/llfw/stage2.lds
@@ -49,7 +49,8 @@ SECTIONS {
 	__bss_end = .;
 	__bss_size = (__bss_end - __bss_start);
 
-	__toc_start = .;
+	. = ALIGN(256);
+	__toc_start = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
 	.got :
 	{
 		 *(.toc .got)
diff --git a/board-qemu/llfw/stage2_head.S b/board-qemu/llfw/stage2_head.S
index c56b117..adf7554 100644
--- a/board-qemu/llfw/stage2_head.S
+++ b/board-qemu/llfw/stage2_head.S
@@ -77,8 +77,6 @@ bsscdone:
 	/* ------------------------------------ */
 ASM_ENTRY(toc_init)
 	LOAD64(r2, __toc_start)
-	addi	r2,r2,0x4000
-	addi	r2,r2,0x4000
 	blr
 
 	/* ------------------------------------ */
diff --git a/clients/net-snk/client.lds b/clients/net-snk/client.lds
index 39d0459..c208644 100644
--- a/clients/net-snk/client.lds
+++ b/clients/net-snk/client.lds
@@ -44,10 +44,10 @@ SECTIONS {
 	  *(.opd)
 	}
 
-	. = ALIGN(0x10);
+	. = ALIGN(256);
 	.got :
 	{
-	  _got = .;
+	  _got = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
           *(.got)
 	  *(.toc)
 	  _got_end = .;
diff --git a/clients/net-snk/kernel/entry.S b/clients/net-snk/kernel/entry.S
index 8849fb9..bf10542 100644
--- a/clients/net-snk/kernel/entry.S
+++ b/clients/net-snk/kernel/entry.S
@@ -44,7 +44,7 @@ C_ENTRY(_entry)
 	bcl	20,31,over	# branch after pointer table
 base:	
 	.align  3
-.LCgot:		.quad   _got-base+0x8000
+.LCgot:		.quad   _got-base
 .LCstack:	.quad   _stack+STACKSIZE-0x80-base
 over:	
 	mflr	r8		# gpr 8 is the base
diff --git a/clients/takeover/client.lds b/clients/takeover/client.lds
index 2701d8e..0ab428a 100644
--- a/clients/takeover/client.lds
+++ b/clients/takeover/client.lds
@@ -43,8 +43,8 @@ SECTIONS {
 
 	.got :
 	{
-	  . = ALIGN(8);
-	  _got = .;
+	  . = ALIGN(256);
+	  _got = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
           *(.got .toc)
 	  _got_end = .;
 	}  	
diff --git a/clients/takeover/entry.S b/clients/takeover/entry.S
index a1030eb..ff48273 100644
--- a/clients/takeover/entry.S
+++ b/clients/takeover/entry.S
@@ -21,7 +21,7 @@ _wrapclient:
 	bcl	20,31,over	# branch after pointer table
 base:
 	.align  3
-.LCgot:		.quad   _got-base+0x8000
+.LCgot:		.quad   _got-base
 over:
 	mflr	r8		# gpr 8 is the base
 	ld	r2, .LCgot-base(r8)	# load got pointer
diff --git a/rtas/reloc.S b/rtas/reloc.S
index e24d293..1b5b59a 100644
--- a/rtas/reloc.S
+++ b/rtas/reloc.S
@@ -61,7 +61,7 @@ _rtas_start:
 ._rtas_entry_offset:	.quad   rtas_entry-_rtas_start
 ._rtas_config_offset:	.quad   rtas_config-_rtas_start
 ._rtas_stack:	        .quad   .stack-_rtas_start+RTAS_STACKSIZE-0x60
-._rtas_toc:	        .quad   _got-_rtas_start+0x8000
+._rtas_toc:	        .quad   _got-_rtas_start
 
 .over:	
 	mflr r8			# gpr 8 is the base
diff --git a/rtas/rtas.lds b/rtas/rtas.lds
index a5ba1da..30b18dd 100644
--- a/rtas/rtas.lds
+++ b/rtas/rtas.lds
@@ -28,7 +28,8 @@ SECTIONS {
 	}
 	.got :
 	{
-	  _got = .;
+	  . = ALIGN(256);
+	  _got = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
 	  *(.got .toc)
 	}  	
 	.reloc :
diff --git a/rtas/rtas_entry.S b/rtas/rtas_entry.S
index 74693aa..424137b 100644
--- a/rtas/rtas_entry.S
+++ b/rtas/rtas_entry.S
@@ -39,7 +39,7 @@ rtas_entry:
 	bcl 20,31,.over		# branch to over 
 .base:	
 	.align  3
-..got:			.quad   _got-.base+0x8000
+..got:			.quad   _got-.base
 ..stack:		.quad   .stack+RTAS_STACKSIZE-0x60-.base
 .over:	
 	mflr r8			# gpr 8 is the base