target/riscv: Return the exception from invalid CSR accesses

When performing a CSR access let's return a negative exception value on
an error instead of -1. This will allow us to specify the exception in
future patches.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: a487dad60c9b8fe7a2b992c5e0dcc2504a9000a7.1597259519.git.alistair.francis@wdc.com
Message-Id: <a487dad60c9b8fe7a2b992c5e0dcc2504a9000a7.1597259519.git.alistair.francis@wdc.com>

2 files changed, 35 insertions, 29 deletions

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 7dc50e6299..197ce97e95 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -51,7 +51,7 @@ static int fs(CPURISCVState *env, int csrno)
         return 0;
     }
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
     return 0;
@@ -73,7 +73,7 @@ static int ctr(CPURISCVState *env, int csrno)
 
     if (!cpu->cfg.ext_counters) {
         /* The Counters extensions is not enabled */
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
     return 0;
@@ -101,7 +101,7 @@ static int hmode(CPURISCVState *env, int csrno)
         }
     }
 
-    return -1;
+    return -RISCV_EXCP_ILLEGAL_INST;
 }
 
 static int pmp(CPURISCVState *env, int csrno)
@@ -115,7 +115,7 @@ static int read_fflags(CPURISCVState *env, int csrno, target_ulong *val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
     *val = riscv_cpu_get_fflags(env);
@@ -126,7 +126,7 @@ static int write_fflags(CPURISCVState *env, int csrno, target_ulong val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
     env->mstatus |= MSTATUS_FS;
 #endif
@@ -138,7 +138,7 @@ static int read_frm(CPURISCVState *env, int csrno, target_ulong *val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
     *val = env->frm;
@@ -149,7 +149,7 @@ static int write_frm(CPURISCVState *env, int csrno, target_ulong val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
     env->mstatus |= MSTATUS_FS;
 #endif
@@ -161,7 +161,7 @@ static int read_fcsr(CPURISCVState *env, int csrno, target_ulong *val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
     *val = (riscv_cpu_get_fflags(env) << FSR_AEXC_SHIFT)
@@ -177,7 +177,7 @@ static int write_fcsr(CPURISCVState *env, int csrno, target_ulong val)
 {
 #if !defined(CONFIG_USER_ONLY)
     if (!env->debugger && !riscv_cpu_fp_enabled(env)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
     env->mstatus |= MSTATUS_FS;
 #endif
@@ -291,7 +291,7 @@ static int read_time(CPURISCVState *env, int csrno, target_ulong *val)
     uint64_t delta = riscv_cpu_virt_enabled(env) ? env->htimedelta : 0;
 
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     *val = env->rdtime_fn() + delta;
@@ -304,7 +304,7 @@ static int read_timeh(CPURISCVState *env, int csrno, target_ulong *val)
     uint64_t delta = riscv_cpu_virt_enabled(env) ? env->htimedelta : 0;
 
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     *val = (env->rdtime_fn() + delta) >> 32;
@@ -570,7 +570,7 @@ static int write_mcounteren(CPURISCVState *env, int csrno, target_ulong val)
 static int read_mscounteren(CPURISCVState *env, int csrno, target_ulong *val)
 {
     if (env->priv_ver < PRIV_VERSION_1_11_0) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
     *val = env->mcounteren;
     return 0;
@@ -580,7 +580,7 @@ static int read_mscounteren(CPURISCVState *env, int csrno, target_ulong *val)
 static int write_mscounteren(CPURISCVState *env, int csrno, target_ulong val)
 {
     if (env->priv_ver < PRIV_VERSION_1_11_0) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
     env->mcounteren = val;
     return 0;
@@ -804,7 +804,7 @@ static int read_satp(CPURISCVState *env, int csrno, target_ulong *val)
     }
 
     if (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_TVM)) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     } else {
         *val = env->satp;
     }
@@ -821,7 +821,7 @@ static int write_satp(CPURISCVState *env, int csrno, target_ulong val)
         ((val ^ env->satp) & (SATP_MODE | SATP_ASID | SATP_PPN)))
     {
         if (env->priv == PRV_S && get_field(env->mstatus, MSTATUS_TVM)) {
-            return -1;
+            return -RISCV_EXCP_ILLEGAL_INST;
         } else {
             if((val ^ env->satp) & SATP_ASID) {
                 tlb_flush(env_cpu(env));
@@ -991,7 +991,7 @@ static int write_hgatp(CPURISCVState *env, int csrno, target_ulong val)
 static int read_htimedelta(CPURISCVState *env, int csrno, target_ulong *val)
 {
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
 #if defined(TARGET_RISCV32)
@@ -1005,7 +1005,7 @@ static int read_htimedelta(CPURISCVState *env, int csrno, target_ulong *val)
 static int write_htimedelta(CPURISCVState *env, int csrno, target_ulong val)
 {
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
 #if defined(TARGET_RISCV32)
@@ -1020,7 +1020,7 @@ static int write_htimedelta(CPURISCVState *env, int csrno, target_ulong val)
 static int read_htimedeltah(CPURISCVState *env, int csrno, target_ulong *val)
 {
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     *val = env->htimedelta >> 32;
@@ -1030,7 +1030,7 @@ static int read_htimedeltah(CPURISCVState *env, int csrno, target_ulong *val)
 static int write_htimedeltah(CPURISCVState *env, int csrno, target_ulong val)
 {
     if (!env->rdtime_fn) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     env->htimedelta = deposit64(env->htimedelta, 32, 32, (uint64_t)val);
@@ -1228,18 +1228,18 @@ int riscv_csrrw(CPURISCVState *env, int csrno, target_ulong *ret_value,
 
     if ((write_mask && read_only) ||
         (!env->debugger && (effective_priv < get_field(csrno, 0x300)))) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 #endif
 
     /* ensure the CSR extension is enabled. */
     if (!cpu->cfg.ext_icsr) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     /* check predicate */
     if (!csr_ops[csrno].predicate || csr_ops[csrno].predicate(env, csrno) < 0) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     /* execute combined read/write operation if it exists */
@@ -1249,7 +1249,7 @@ int riscv_csrrw(CPURISCVState *env, int csrno, target_ulong *ret_value,
 
     /* if no accessor exists then return failure */
     if (!csr_ops[csrno].read) {
-        return -1;
+        return -RISCV_EXCP_ILLEGAL_INST;
     }
 
     /* read old value */
diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index 4b64bfe7d2..948d204793 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -43,8 +43,10 @@ target_ulong helper_csrrw(CPURISCVState *env, target_ulong src,
         target_ulong csr)
 {
     target_ulong val = 0;
-    if (riscv_csrrw(env, csr, &val, src, -1) < 0) {
-        riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
+    int ret = riscv_csrrw(env, csr, &val, src, -1);
+
+    if (ret < 0) {
+        riscv_raise_exception(env, -ret, GETPC());
     }
     return val;
 }
@@ -53,8 +55,10 @@ target_ulong helper_csrrs(CPURISCVState *env, target_ulong src,
         target_ulong csr, target_ulong rs1_pass)
 {
     target_ulong val = 0;
-    if (riscv_csrrw(env, csr, &val, -1, rs1_pass ? src : 0) < 0) {
-        riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
+    int ret = riscv_csrrw(env, csr, &val, -1, rs1_pass ? src : 0);
+
+    if (ret < 0) {
+        riscv_raise_exception(env, -ret, GETPC());
     }
     return val;
 }
@@ -63,8 +67,10 @@ target_ulong helper_csrrc(CPURISCVState *env, target_ulong src,
         target_ulong csr, target_ulong rs1_pass)
 {
     target_ulong val = 0;
-    if (riscv_csrrw(env, csr, &val, 0, rs1_pass ? src : 0) < 0) {
-        riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
+    int ret = riscv_csrrw(env, csr, &val, 0, rs1_pass ? src : 0);
+
+    if (ret < 0) {
+        riscv_raise_exception(env, -ret, GETPC());
     }
     return val;
 }