ppc: Fix the range check in the LSWI instruction

There are two issues: First, the number of registers that are used has
to be calculated with "(nb + 3) / 4" (i.e. round always up, not down).
Second, the "start <= ra && (start + nr - 32) > ra" condition for the
wrap-around case is wrong: It has to be tested with "||" instead of "&&".
Since we can reuse this check later for the LSWX instruction, let's
place the fixed code into a helper function, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 2 insertions, 4 deletions

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index e229723..30b8953 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -3235,10 +3235,8 @@ static void gen_lswi(DisasContext *ctx)
 
     if (nb == 0)
         nb = 32;
-    nr = nb / 4;
-    if (unlikely(((start + nr) > 32  &&
-                  start <= ra && (start + nr - 32) > ra) ||
-                 ((start + nr) <= 32 && start <= ra && (start + nr) > ra))) {
+    nr = (nb + 3) / 4;
+    if (unlikely(lsw_reg_in_range(start, nr, ra))) {
         gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX);
         return;
     }