PPC: Fix lswx bounds checks

The lswx instruction checks whether the desired string actually fits
into all defined registers. Unfortunately it does the calculation wrong,
resulting in illegal instruction traps for loads that really should fit.

Fix it up, making Mac OS happier.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/target-ppc/mem_helper.c b/target-ppc/mem_helper.c
index 6d37dae7b0fb594a199a753766cb929c21a259c2..7e1f234aa53c2550778236d4a1972718f80b54fc 100644 (file)
--- a/target-ppc/mem_helper.c
+++ b/target-ppc/mem_helper.c
@@ -100,8 +100,9 @@ void helper_lswx(CPUPPCState *env, target_ulong addr, uint32_t reg,
                  uint32_t ra, uint32_t rb)
 {
     if (likely(xer_bc != 0)) {
-        if (unlikely((ra != 0 && reg < ra && (reg + xer_bc) > ra) ||
-                     (reg < rb && (reg + xer_bc) > rb))) {
+        int num_used_regs = (xer_bc + 3) / 4;
+        if (unlikely((ra != 0 && reg < ra && (reg + num_used_regs) > ra) ||
+                     (reg < rb && (reg + num_used_regs) > rb))) {
             helper_raise_exception_err(env, POWERPC_EXCP_PROGRAM,
                                        POWERPC_EXCP_INVAL |
                                        POWERPC_EXCP_INVAL_LSWX);