target/arm: Implement v8.1M NOCP handling

From v8.1M, disabled-coprocessor handling changes slightly:
 * coprocessors 8, 9, 14 and 15 are also governed by the
   cp10 enable bit, like cp11
 * an extra range of instruction patterns is considered
   to be inside the coprocessor space

We previously marked these up with TODO comments; implement the
correct behaviour.

Unfortunately there is no ID register field which indicates this
behaviour.  We could in theory test an unrelated ID register which
indicates guaranteed-to-be-in-v8.1M behaviour like ID_ISAR0.CmpBranch
>= 3 (low-overhead-loops), but it seems better to simply define a new
ARM_FEATURE_V8_1M feature flag and use it for this and other
new-in-v8.1M behaviour that isn't identifiable from the ID registers.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201019151301.2046-3-peter.maydell@linaro.org

1 files changed, 15 insertions, 2 deletions

diff --git a/target/arm/translate-vfp.c.inc b/target/arm/translate-vfp.c.inc
index 9b11b81f80..a7ed9bc81b 100644
--- a/target/arm/translate-vfp.c.inc
+++ b/target/arm/translate-vfp.c.inc
@@ -3459,7 +3459,7 @@ static bool trans_VLLDM_VLSTM(DisasContext *s, arg_VLLDM_VLSTM *a)
     return true;
 }
 
-static bool trans_NOCP(DisasContext *s, arg_NOCP *a)
+static bool trans_NOCP(DisasContext *s, arg_nocp *a)
 {
     /*
      * Handle M-profile early check for disabled coprocessor:
@@ -3472,7 +3472,11 @@ static bool trans_NOCP(DisasContext *s, arg_NOCP *a)
     if (a->cp == 11) {
         a->cp = 10;
     }
-    /* TODO: in v8.1M cp 8, 9, 14, 15 also are governed by the cp10 enable */
+    if (arm_dc_feature(s, ARM_FEATURE_V8_1M) &&
+        (a->cp == 8 || a->cp == 9 || a->cp == 14 || a->cp == 15)) {
+        /* in v8.1M cp 8, 9, 14, 15 also are governed by the cp10 enable */
+        a->cp = 10;
+    }
 
     if (a->cp != 10) {
         gen_exception_insn(s, s->pc_curr, EXCP_NOCP,
@@ -3489,6 +3493,15 @@ static bool trans_NOCP(DisasContext *s, arg_NOCP *a)
     return false;
 }
 
+static bool trans_NOCP_8_1(DisasContext *s, arg_nocp *a)
+{
+    /* This range needs a coprocessor check for v8.1M and later only */
+    if (!arm_dc_feature(s, ARM_FEATURE_V8_1M)) {
+        return false;
+    }
+    return trans_NOCP(s, a);
+}
+
 static bool trans_VINS(DisasContext *s, arg_VINS *a)
 {
     TCGv_i32 rd, rm;