target/arm: Implement HSTR.TJDBX

In v7A, the HSTR register has a TJDBX bit which traps NS EL0/EL1
access to the JOSCR and JMCR trivial Jazelle registers, and also BXJ.
Implement these traps. In v8A this HSTR bit doesn't exist, so don't
trap for v8A CPUs.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210816180305.20137-3-peter.maydell@linaro.org

1 files changed, 17 insertions, 0 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 54ac8c54b1..d2dd4aa0b8 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7602,6 +7602,21 @@ static CPAccessResult access_jazelle(CPUARMState *env, const ARMCPRegInfo *ri,
     return CP_ACCESS_OK;
 }
 
+static CPAccessResult access_joscr_jmcr(CPUARMState *env,
+                                        const ARMCPRegInfo *ri, bool isread)
+{
+    /*
+     * HSTR.TJDBX traps JOSCR and JMCR accesses, but it exists only
+     * in v7A, not in v8A.
+     */
+    if (!arm_feature(env, ARM_FEATURE_V8) &&
+        arm_current_el(env) < 2 && !arm_is_secure_below_el3(env) &&
+        (env->cp15.hstr_el2 & HSTR_TJDBX)) {
+        return CP_ACCESS_TRAP_EL2;
+    }
+    return CP_ACCESS_OK;
+}
+
 static const ARMCPRegInfo jazelle_regs[] = {
     { .name = "JIDR",
       .cp = 14, .crn = 0, .crm = 0, .opc1 = 7, .opc2 = 0,
@@ -7609,9 +7624,11 @@ static const ARMCPRegInfo jazelle_regs[] = {
       .type = ARM_CP_CONST, .resetvalue = 0 },
     { .name = "JOSCR",
       .cp = 14, .crn = 1, .crm = 0, .opc1 = 7, .opc2 = 0,
+      .accessfn = access_joscr_jmcr,
       .access = PL1_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
     { .name = "JMCR",
       .cp = 14, .crn = 2, .crm = 0, .opc1 = 7, .opc2 = 0,
+      .accessfn = access_joscr_jmcr,
       .access = PL1_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
     REGINFO_SENTINEL
 };