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
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index cfff1b5..74392fa 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1985,6 +1985,7 @@
ARM_FEATURE_VBAR, /* has cp15 VBAR */
ARM_FEATURE_M_SECURITY, /* M profile Security Extension */
ARM_FEATURE_M_MAIN, /* M profile Main Extension */
+ ARM_FEATURE_V8_1M, /* M profile extras only in v8.1M and later */
};
static inline int arm_feature(CPUARMState *env, int feature)
diff --git a/target/arm/m-nocp.decode b/target/arm/m-nocp.decode
index 7182d7d..28c8ac6 100644
--- a/target/arm/m-nocp.decode
+++ b/target/arm/m-nocp.decode
@@ -29,14 +29,16 @@
# If the coprocessor is not present or disabled then we will generate
# the NOCP exception; otherwise we let the insn through to the main decode.
+&nocp cp
+
{
# Special cases which do not take an early NOCP: VLLDM and VLSTM
VLLDM_VLSTM 1110 1100 001 l:1 rn:4 0000 1010 0000 0000
# TODO: VSCCLRM (new in v8.1M) is similar:
#VSCCLRM 1110 1100 1-01 1111 ---- 1011 ---- ---0
- NOCP 111- 1110 ---- ---- ---- cp:4 ---- ----
- NOCP 111- 110- ---- ---- ---- cp:4 ---- ----
- # TODO: From v8.1M onwards we will also want this range to NOCP
- #NOCP_8_1 111- 1111 ---- ---- ---- ---- ---- ---- cp=10
+ NOCP 111- 1110 ---- ---- ---- cp:4 ---- ---- &nocp
+ NOCP 111- 110- ---- ---- ---- cp:4 ---- ---- &nocp
+ # From v8.1M onwards this range will also NOCP:
+ NOCP_8_1 111- 1111 ---- ---- ---- ---- ---- ---- &nocp cp=10
}
diff --git a/target/arm/translate-vfp.c.inc b/target/arm/translate-vfp.c.inc
index 9b11b81..a7ed9bc 100644
--- a/target/arm/translate-vfp.c.inc
+++ b/target/arm/translate-vfp.c.inc
@@ -3459,7 +3459,7 @@
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 @@
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 @@
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;
