target/arm: Clear CPSR.IL and CPSR.J on 32-bit exception entry

On 32-bit exception entry, CPSR.J must always be set to 0
(see v7A Arm ARM DDI0406C.c B1.8.5). CPSR.IL must also
be cleared on 32-bit exception entry (see v8A Arm ARM
DDI0487C.a G1.10).

Clear these bits. (This fixes a bug which will never be noticed
by non-buggy guests.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: NLuc Michel <luc.michel@greensocs.com>
Message-id: 20180820153020.21478-6-peter.maydell@linaro.org

target/arm/helper.c

@@ -8054,6 +8054,8 @@ static void take_aarch32_exception(CPUARMState *env, int new_mode,
     if (env->cp15.sctlr_el[arm_current_el(env)] & SCTLR_EE) {
         env->uncached_cpsr |= CPSR_E;
     }
+    /* J and IL must always be cleared for exception entry */
+    env->uncached_cpsr &= ~(CPSR_IL | CPSR_J);
     env->daif |= mask;
 
     if (new_mode == ARM_CPU_MODE_HYP) {