powerpc: Fix unsafe accesses to parameter area in ELFv2

Some of the assembler files in lib/ make use of the fact that in the
ELFv1 ABI, the caller guarantees to provide stack space to save the
parameter registers r3 ... r10.  This guarantee is no longer present
in ELFv2 for functions that have no variable argument list and no
more than 8 arguments.

Change the affected routines to temporarily store registers in the
red zone and/or the top of their own stack frame (in the space
provided to save r31 .. r29, which is actually not used in these
routines).

In opal_query_takeover, simply always allocate a stack frame;
the routine is not performance critical.

Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/powerpc/lib/copypage_power7.S b/arch/powerpc/lib/copypage_power7.S
index affc6d308e13..d7dafb3777ac 100644
--- a/arch/powerpc/lib/copypage_power7.S
+++ b/arch/powerpc/lib/copypage_power7.S
@@ -56,15 +56,15 @@ _GLOBAL(copypage_power7)
 
 #ifdef CONFIG_ALTIVEC
         mflr    r0
-        std     r3,STK_PARAM(R3)(r1)
-        std     r4,STK_PARAM(R4)(r1)
+        std     r3,-STACKFRAMESIZE+STK_REG(R31)(r1)
+        std     r4,-STACKFRAMESIZE+STK_REG(R30)(r1)
         std     r0,16(r1)
         stdu    r1,-STACKFRAMESIZE(r1)
         bl      enter_vmx_copy
         cmpwi   r3,0
         ld      r0,STACKFRAMESIZE+16(r1)
-        ld      r3,STACKFRAMESIZE+STK_PARAM(R3)(r1)
-        ld      r4,STACKFRAMESIZE+STK_PARAM(R4)(r1)
+        ld      r3,STK_REG(R31)(r1)
+        ld      r4,STK_REG(R30)(r1)
         mtlr    r0
 
         li      r0,(PAGE_SIZE/128)