target/riscv: fix counter-enable checks in ctr()

Access to a counter in U-mode is permitted only if the corresponding
bit is set in both mcounteren and scounteren.  The current code
ignores mcounteren and checks scounteren only for U-mode access.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index e72fcf1265d43157c80c248e97e4bd8d50fcaf84..960d2b0aa951f7ef7f15be31333663f8b0a1b046 100644 (file)
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -56,9 +56,15 @@ static int fs(CPURISCVState *env, int csrno)
 static int ctr(CPURISCVState *env, int csrno)
 {
 #if !defined(CONFIG_USER_ONLY)
-    target_ulong ctr_en = env->priv == PRV_U ? env->scounteren :
-                          env->priv == PRV_S ? env->mcounteren : -1U;
-    if (!(ctr_en & (1 << (csrno & 31)))) {
+    uint32_t ctr_en = ~0u;
+
+    if (env->priv < PRV_M) {
+        ctr_en &= env->mcounteren;
+    }
+    if (env->priv < PRV_S) {
+        ctr_en &= env->scounteren;
+    }
+    if (!(ctr_en & (1u << (csrno & 31)))) {
         return -1;
     }
 #endif