target/arm: Enable MTE for user-only

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210212184902.1251044-31-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 70cfcbc9181f54907c869d13d094aa659055d53b..b8bc89e71fca117b4bc10e92dc27362f85d609b8 100644 (file)
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -209,6 +209,21 @@ static void arm_cpu_reset(DeviceState *dev)
          * Note that this must match useronly_clean_ptr.
          */
         env->cp15.tcr_el[1].raw_tcr = (1ULL << 37);
+
+        /* Enable MTE */
+        if (cpu_isar_feature(aa64_mte, cpu)) {
+            /* Enable tag access, but leave TCF0 as No Effect (0). */
+            env->cp15.sctlr_el[1] |= SCTLR_ATA0;
+            /*
+             * Exclude all tags, so that tag 0 is always used.
+             * This corresponds to Linux current->thread.gcr_incl = 0.
+             *
+             * Set RRND, so that helper_irg() will generate a seed later.
+             * Here in cpu_reset(), the crypto subsystem has not yet been
+             * initialized.
+             */
+            env->cp15.gcr_el1 = 0x1ffff;
+        }
 #else
         /* Reset into the highest available EL */
         if (arm_feature(env, ARM_FEATURE_EL3)) {