target/riscv: Add User CSRs read-only check

For U-mode CSRs, read-only check is also needed.

Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-id: 20210810014552.4884-1-zhiwei_liu@c-sky.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index e747fbe0e91aca3dc5e51dc06c5cad05a1468114..6d7f2c2a95ddd146a0d164be685ea0a7797ac234 100644 (file)
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1422,11 +1422,11 @@ RISCVException riscv_csrrw(CPURISCVState *env, int csrno,
     RISCVException ret;
     target_ulong old_value;
     RISCVCPU *cpu = env_archcpu(env);
+    int read_only = get_field(csrno, 0xC00) == 3;
 
     /* check privileges and return RISCV_EXCP_ILLEGAL_INST if check fails */
 #if !defined(CONFIG_USER_ONLY)
     int effective_priv = env->priv;
-    int read_only = get_field(csrno, 0xC00) == 3;
 
     if (riscv_has_ext(env, RVH) &&
         env->priv == PRV_S &&
@@ -1439,11 +1439,13 @@ RISCVException riscv_csrrw(CPURISCVState *env, int csrno,
         effective_priv++;
     }
 
-    if ((write_mask && read_only) ||
-        (!env->debugger && (effective_priv < get_field(csrno, 0x300)))) {
+    if (!env->debugger && (effective_priv < get_field(csrno, 0x300))) {
         return RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
+    if (write_mask && read_only) {
+        return RISCV_EXCP_ILLEGAL_INST;
+    }
 
     /* ensure the CSR extension is enabled. */
     if (!cpu->cfg.ext_icsr) {