target/riscv: Add itrigger support when icount is not enabled

When icount is not enabled, there is no API in QEMU that can get the
guest instruction number.

Translate the guest code in a way that each TB only has one instruction.
After executing the instruction, decrease the count by 1 until it reaches 0
where the itrigger fires.

Note that only when priviledge matches the itrigger configuration,
the count will decrease.

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221013062946.7530-2-zhiwei_liu@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index e44848d0d7..036161649f 100644
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -29,6 +29,7 @@
 #include "cpu.h"
 #include "trace.h"
 #include "exec/exec-all.h"
+#include "exec/helper-proto.h"
 
 /*
  * The following M-mode trigger CSRs are implemented:
@@ -496,6 +497,76 @@ static void type6_reg_write(CPURISCVState *env, target_ulong index,
     return;
 }
 
+/* icount trigger type */
+static inline int
+itrigger_get_count(CPURISCVState *env, int index)
+{
+    return get_field(env->tdata1[index], ITRIGGER_COUNT);
+}
+
+static inline void
+itrigger_set_count(CPURISCVState *env, int index, int value)
+{
+    env->tdata1[index] = set_field(env->tdata1[index],
+                                   ITRIGGER_COUNT, value);
+}
+
+static bool check_itrigger_priv(CPURISCVState *env, int index)
+{
+    target_ulong tdata1 = env->tdata1[index];
+    if (riscv_cpu_virt_enabled(env)) {
+        /* check VU/VS bit against current privilege level */
+        return (get_field(tdata1, ITRIGGER_VS) == env->priv) ||
+               (get_field(tdata1, ITRIGGER_VU) == env->priv);
+    } else {
+        /* check U/S/M bit against current privilege level */
+        return (get_field(tdata1, ITRIGGER_M) == env->priv) ||
+               (get_field(tdata1, ITRIGGER_S) == env->priv) ||
+               (get_field(tdata1, ITRIGGER_U) == env->priv);
+    }
+}
+
+bool riscv_itrigger_enabled(CPURISCVState *env)
+{
+    int count;
+    for (int i = 0; i < RV_MAX_TRIGGERS; i++) {
+        if (get_trigger_type(env, i) != TRIGGER_TYPE_INST_CNT) {
+            continue;
+        }
+        if (check_itrigger_priv(env, i)) {
+            continue;
+        }
+        count = itrigger_get_count(env, i);
+        if (!count) {
+            continue;
+        }
+        return true;
+    }
+
+    return false;
+}
+
+void helper_itrigger_match(CPURISCVState *env)
+{
+    int count;
+    for (int i = 0; i < RV_MAX_TRIGGERS; i++) {
+        if (get_trigger_type(env, i) != TRIGGER_TYPE_INST_CNT) {
+            continue;
+        }
+        if (check_itrigger_priv(env, i)) {
+            continue;
+        }
+        count = itrigger_get_count(env, i);
+        if (!count) {
+            continue;
+        }
+        itrigger_set_count(env, i, count--);
+        if (!count) {
+            do_trigger_action(env, i);
+        }
+    }
+}
+
 target_ulong tdata_csr_read(CPURISCVState *env, int tdata_index)
 {
     switch (tdata_index) {