[rtems commit] Revert "bsps/powerpc: Fix potential relocation truncation"

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    c1072919fa328d0400a76c29d47cf2c74052a87a
Changeset: http://git.rtems.org/rtems/commit/?id=c1072919fa328d0400a76c29d47cf2c74052a87a

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Fri Jun  6 14:54:37 2014 +0200

Revert "bsps/powerpc: Fix potential relocation truncation"

This reverts commit d9ff8b3e687a0ec56cac6463ba01ba7775eccd41.

It is not that simple:

https://sourceware.org/ml/binutils/2014-06/msg00062.html

On Fri, Jun 06, 2014 at 01:31:48PM +0200, Sebastian Huber wrote:
> On 2014-06-06 13:23, Sebastian Huber wrote:
> >Ok, so this "cmplwi cr0, rX, ppc_exc_lock_std at sdarel" is illegal,
> >since
> >ppc_exc_lock_std at sdarel is signed and the immediate is unsigned
> >16-bit?  The
> >assembler doesn't issue a warning about this.
> >
> >Exists there a way to rescue this cmplwi hack without relaxing the
> >overflow
> >checks?
>
> Hm, sorry, it was surprisingly simple.  This works:
>
> "cmplwi cr0, rX, ppc_exc_lock_std at sdarel@l"
>
> I was not aware that you can add several @ in a row.

That is the wrong thing to use here.  sdarel at l translates to a VLE
reloc which applies to a split 16-bit field in VLE insns.

You want
 cmpwi cr0, rX, ppc_exc_lock_std at sdarel
to properly compare a 16-bit signed number from sym at sdarel.

Note that the assembler does error if you write something like
 cmplwi 3,-30000
or
 cmpwi 3,40000
so what the linker is now doing is extending this behaviour to link
time.

---

 .../new-exceptions/bspsupport/ppc_exc_asm_macros.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_asm_macros.h b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_asm_macros.h
index 9a303f7..0e3bc96 100644
--- a/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_asm_macros.h
+++ b/c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_asm_macros.h
@@ -168,7 +168,7 @@ ppc_exc_min_prolog_sync_\_NAME:
 	 * if what's left compares against the 'ppc_exc_lock_std at sdarel'
 	 * address offset then we have a match...
 	 */
-	cmplwi	cr0, \_REG, ppc_exc_lock_std at sdarel@l
+	cmplwi	cr0, \_REG, ppc_exc_lock_std at sdarel
 
 	.endm