[Qemu-ppc] [PATCH 02/13] PPC: Fix lsxw bounds checks

[Mark Cave-Ayland]

From: Alexander Graf <address@hidden>

The lsxw 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 <address@hidden>
Signed-off-by: Mark Cave-Ayland <address@hidden>
---
 target-ppc/mem_helper.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/target-ppc/mem_helper.c b/target-ppc/mem_helper.c
index 6d37dae..7e1f234 100644
--- 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);
-- 
1.7.10.4