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-rw-r--r--target/riscv/cpu.h4
-rw-r--r--target/riscv/csr.c57
-rw-r--r--target/riscv/op_helper.c6
3 files changed, 58 insertions, 9 deletions
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 093c86b8b9..1619c3acb6 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -751,6 +751,8 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc,
 void riscv_cpu_update_mask(CPURISCVState *env);
 bool riscv_cpu_is_32bit(RISCVCPU *cpu);
 
+RISCVException riscv_csrr(CPURISCVState *env, int csrno,
+                          target_ulong *ret_value);
 RISCVException riscv_csrrw(CPURISCVState *env, int csrno,
                            target_ulong *ret_value,
                            target_ulong new_value, target_ulong write_mask);
@@ -783,6 +785,8 @@ typedef RISCVException (*riscv_csr_op_fn)(CPURISCVState *env, int csrno,
                                           target_ulong new_value,
                                           target_ulong write_mask);
 
+RISCVException riscv_csrr_i128(CPURISCVState *env, int csrno,
+                               Int128 *ret_value);
 RISCVException riscv_csrrw_i128(CPURISCVState *env, int csrno,
                                 Int128 *ret_value,
                                 Int128 new_value, Int128 write_mask);
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 781ef27eba..ea3560342c 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -4624,7 +4624,7 @@ static RISCVException rmw_seed(CPURISCVState *env, int csrno,
 
 static inline RISCVException riscv_csrrw_check(CPURISCVState *env,
                                                int csrno,
-                                               bool write_mask)
+                                               bool write)
 {
     /* check privileges and return RISCV_EXCP_ILLEGAL_INST if check fails */
     bool read_only = get_field(csrno, 0xC00) == 3;
@@ -4646,7 +4646,7 @@ static inline RISCVException riscv_csrrw_check(CPURISCVState *env,
     }
 
     /* read / write check */
-    if (write_mask && read_only) {
+    if (write && read_only) {
         return RISCV_EXCP_ILLEGAL_INST;
     }
 
@@ -4733,11 +4733,22 @@ static RISCVException riscv_csrrw_do64(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+RISCVException riscv_csrr(CPURISCVState *env, int csrno,
+                           target_ulong *ret_value)
+{
+    RISCVException ret = riscv_csrrw_check(env, csrno, false);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
+    return riscv_csrrw_do64(env, csrno, ret_value, 0, 0);
+}
+
 RISCVException riscv_csrrw(CPURISCVState *env, int csrno,
                            target_ulong *ret_value,
                            target_ulong new_value, target_ulong write_mask)
 {
-    RISCVException ret = riscv_csrrw_check(env, csrno, write_mask);
+    RISCVException ret = riscv_csrrw_check(env, csrno, true);
     if (ret != RISCV_EXCP_NONE) {
         return ret;
     }
@@ -4785,13 +4796,45 @@ static RISCVException riscv_csrrw_do128(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+RISCVException riscv_csrr_i128(CPURISCVState *env, int csrno,
+                               Int128 *ret_value)
+{
+    RISCVException ret;
+
+    ret = riscv_csrrw_check(env, csrno, false);
+    if (ret != RISCV_EXCP_NONE) {
+        return ret;
+    }
+
+    if (csr_ops[csrno].read128) {
+        return riscv_csrrw_do128(env, csrno, ret_value,
+                                 int128_zero(), int128_zero());
+    }
+
+    /*
+     * Fall back to 64-bit version for now, if the 128-bit alternative isn't
+     * at all defined.
+     * Note, some CSRs don't need to extend to MXLEN (64 upper bits non
+     * significant), for those, this fallback is correctly handling the
+     * accesses
+     */
+    target_ulong old_value;
+    ret = riscv_csrrw_do64(env, csrno, &old_value,
+                           (target_ulong)0,
+                           (target_ulong)0);
+    if (ret == RISCV_EXCP_NONE && ret_value) {
+        *ret_value = int128_make64(old_value);
+    }
+    return ret;
+}
+
 RISCVException riscv_csrrw_i128(CPURISCVState *env, int csrno,
                                 Int128 *ret_value,
                                 Int128 new_value, Int128 write_mask)
 {
     RISCVException ret;
 
-    ret = riscv_csrrw_check(env, csrno, int128_nz(write_mask));
+    ret = riscv_csrrw_check(env, csrno, true);
     if (ret != RISCV_EXCP_NONE) {
         return ret;
     }
@@ -4830,7 +4873,11 @@ RISCVException riscv_csrrw_debug(CPURISCVState *env, int csrno,
 #if !defined(CONFIG_USER_ONLY)
     env->debugger = true;
 #endif
-    ret = riscv_csrrw(env, csrno, ret_value, new_value, write_mask);
+    if (!write_mask) {
+        ret = riscv_csrr(env, csrno, ret_value);
+    } else {
+        ret = riscv_csrrw(env, csrno, ret_value, new_value, write_mask);
+    }
 #if !defined(CONFIG_USER_ONLY)
     env->debugger = false;
 #endif
diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index ec1408ba0f..25a5263573 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -51,7 +51,7 @@ target_ulong helper_csrr(CPURISCVState *env, int csr)
     }
 
     target_ulong val = 0;
-    RISCVException ret = riscv_csrrw(env, csr, &val, 0, 0);
+    RISCVException ret = riscv_csrr(env, csr, &val);
 
     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());
@@ -84,9 +84,7 @@ target_ulong helper_csrrw(CPURISCVState *env, int csr,
 target_ulong helper_csrr_i128(CPURISCVState *env, int csr)
 {
     Int128 rv = int128_zero();
-    RISCVException ret = riscv_csrrw_i128(env, csr, &rv,
-                                          int128_zero(),
-                                          int128_zero());
+    RISCVException ret = riscv_csrr_i128(env, csr, &rv);
 
     if (ret != RISCV_EXCP_NONE) {
         riscv_raise_exception(env, ret, GETPC());