target/arm: Honour HCR_EL2.TGE when raising synchronous exceptions

Whene we raise a synchronous exception, if HCR_EL2.TGE is set then
exceptions targeting NS EL1 must be redirected to EL2.  Implement
this in raise_exception() -- all synchronous exceptions go through
this function.

(Asynchronous exceptions go via arm_cpu_exec_interrupt(), which
already honours HCR_EL2.TGE when it determines the target EL
in arm_phys_excp_target_el().)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180724115950.17316-4-peter.maydell@linaro.org

target/arm/op_helper.c

@@ -33,6 +33,20 @@ static void raise_exception(CPUARMState *env, uint32_t excp,
 {
     CPUState *cs = CPU(arm_env_get_cpu(env));
 
+    if ((env->cp15.hcr_el2 & HCR_TGE) &&
+        target_el == 1 && !arm_is_secure(env)) {
+        /*
+         * Redirect NS EL1 exceptions to NS EL2. These are reported with
+         * their original syndrome register value, with the exception of
+         * SIMD/FP access traps, which are reported as uncategorized
+         * (see DDI0478C.a D1.10.4)
+         */
+        target_el = 2;
+        if (syndrome >> ARM_EL_EC_SHIFT == EC_ADVSIMDFPACCESSTRAP) {
+            syndrome = syn_uncategorized();
+        }
+    }
+
     assert(!excp_is_internal(excp));
     cs->exception_index = excp;
     env->exception.syndrome = syndrome;