target/arm: Tidy sve_exception_el for CPACR_EL1 access

Extract entire fields for ZEN and FPEN, rather than testing specific bits.
This makes it easier to follow the code versus the ARM spec.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Message-id: 20220127063428.30212-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 649958a727d913476eee7eee793655bbcb728f77..e474ab2e1de452322d95d789172d4ce6215416f0 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6154,30 +6154,28 @@ int sve_exception_el(CPUARMState *env, int el)
     uint64_t hcr_el2 = arm_hcr_el2_eff(env);
 
     if (el <= 1 && (hcr_el2 & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) {
-        bool disabled = false;
-
-        /* The CPACR.ZEN controls traps to EL1:
-         * 0, 2 : trap EL0 and EL1 accesses
-         * 1    : trap only EL0 accesses
-         * 3    : trap no accesses
-         */
-        if (!extract32(env->cp15.cpacr_el1, 16, 1)) {
-            disabled = true;
-        } else if (!extract32(env->cp15.cpacr_el1, 17, 1)) {
-            disabled = el == 0;
-        }
-        if (disabled) {
+        /* Check CPACR.ZEN.  */
+        switch (extract32(env->cp15.cpacr_el1, 16, 2)) {
+        case 1:
+            if (el != 0) {
+                break;
+            }
+            /* fall through */
+        case 0:
+        case 2:
             /* route_to_el2 */
             return hcr_el2 & HCR_TGE ? 2 : 1;
         }
 
         /* Check CPACR.FPEN.  */
-        if (!extract32(env->cp15.cpacr_el1, 20, 1)) {
-            disabled = true;
-        } else if (!extract32(env->cp15.cpacr_el1, 21, 1)) {
-            disabled = el == 0;
-        }
-        if (disabled) {
+        switch (extract32(env->cp15.cpacr_el1, 20, 2)) {
+        case 1:
+            if (el != 0) {
+                break;
+            }
+            /* fall through */
+        case 0:
+        case 2:
             return 0;
         }
     }