target/riscv: Use the RISCVException enum for CSR operations

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-id: 8566c4c271723f27f3ae8fc2429f906a459f17ce.1617290165.git.alistair.francis@wdc.com

target/riscv/cpu.h

@@ -474,12 +474,14 @@ static inline target_ulong riscv_csr_read(CPURISCVState *env, int csrno)
 
 typedef RISCVException (*riscv_csr_predicate_fn)(CPURISCVState *env,
                                                  int csrno);
-typedef int (*riscv_csr_read_fn)(CPURISCVState *env, int csrno,
-    target_ulong *ret_value);
-typedef int (*riscv_csr_write_fn)(CPURISCVState *env, int csrno,
-    target_ulong new_value);
-typedef int (*riscv_csr_op_fn)(CPURISCVState *env, int csrno,
-    target_ulong *ret_value, target_ulong new_value, target_ulong write_mask);
+typedef RISCVException (*riscv_csr_read_fn)(CPURISCVState *env, int csrno,
+                                            target_ulong *ret_value);
+typedef RISCVException (*riscv_csr_write_fn)(CPURISCVState *env, int csrno,
+                                             target_ulong new_value);
+typedef RISCVException (*riscv_csr_op_fn)(CPURISCVState *env, int csrno,
+                                          target_ulong *ret_value,
+                                          target_ulong new_value,
+                                          target_ulong write_mask);
 
 typedef struct {
     const char *name;