target/riscv: Add functions for common matching conditions of trigger

According to RISC-V Debug specification version 0.13 [1] (also applied
to version 1.0 [2] but it has not been ratified yet), there are several
common matching conditions before firing a trigger, including the
enabled privilege levels of the trigger.

This commit adds trigger_common_match() to prepare the common matching
conditions for the type 2/3/6 triggers. For now, we just implement
trigger_priv_match() to check if the enabled privilege levels of the
trigger match CPU's current privilege level.

Remove the related code in riscv_cpu_debug_check_breakpoint() and invoke
trigger_common_match() to check the privilege levels of the type 2 and
type 6 triggers for the breakpoints.

This commit also changes the behavior of looping the triggers. In
previous implementation, if we have a type 2 trigger and
env->virt_enabled is true, we directly return false to stop the loop.
Now we keep looping all the triggers until we find a matched trigger.

Only the execution bit and the executed PC should be futher checked in
riscv_cpu_debug_check_breakpoint().

[1]: https://github.com/riscv/riscv-debug-spec/releases/tag/task_group_vote
[2]: https://github.com/riscv/riscv-debug-spec/releases/tag/1.0.0-rc1-asciidoc

Signed-off-by: Alvin Chang <alvinga@andestech.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240626132247.2761286-2-alvinga@andestech.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 78 insertions, 23 deletions

diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index b110370..11125f3 100644
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -241,6 +241,76 @@ static void do_trigger_action(CPURISCVState *env, target_ulong trigger_index)
     }
 }
 
+/*
+ * Check the privilege level of specific trigger matches CPU's current privilege
+ * level.
+ */
+static bool trigger_priv_match(CPURISCVState *env, trigger_type_t type,
+                               int trigger_index)
+{
+    target_ulong ctrl = env->tdata1[trigger_index];
+
+    switch (type) {
+    case TRIGGER_TYPE_AD_MATCH:
+        /* type 2 trigger cannot be fired in VU/VS mode */
+        if (env->virt_enabled) {
+            return false;
+        }
+        /* check U/S/M bit against current privilege level */
+        if ((ctrl >> 3) & BIT(env->priv)) {
+            return true;
+        }
+        break;
+    case TRIGGER_TYPE_AD_MATCH6:
+        if (env->virt_enabled) {
+            /* check VU/VS bit against current privilege level */
+            if ((ctrl >> 23) & BIT(env->priv)) {
+                return true;
+            }
+        } else {
+            /* check U/S/M bit against current privilege level */
+            if ((ctrl >> 3) & BIT(env->priv)) {
+                return true;
+            }
+        }
+        break;
+    case TRIGGER_TYPE_INST_CNT:
+        if (env->virt_enabled) {
+            /* check VU/VS bit against current privilege level */
+            if ((ctrl >> 25) & BIT(env->priv)) {
+                return true;
+            }
+        } else {
+            /* check U/S/M bit against current privilege level */
+            if ((ctrl >> 6) & BIT(env->priv)) {
+                return true;
+            }
+        }
+        break;
+    case TRIGGER_TYPE_INT:
+    case TRIGGER_TYPE_EXCP:
+    case TRIGGER_TYPE_EXT_SRC:
+        qemu_log_mask(LOG_UNIMP, "trigger type: %d is not supported\n", type);
+        break;
+    case TRIGGER_TYPE_NO_EXIST:
+    case TRIGGER_TYPE_UNAVAIL:
+        qemu_log_mask(LOG_GUEST_ERROR, "trigger type: %d does not exist\n",
+                      type);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    return false;
+}
+
+/* Common matching conditions for all types of the triggers. */
+static bool trigger_common_match(CPURISCVState *env, trigger_type_t type,
+                                 int trigger_index)
+{
+    return trigger_priv_match(env, type, trigger_index);
+}
+
 /* type 2 trigger */
 
 static uint32_t type2_breakpoint_size(CPURISCVState *env, target_ulong ctrl)
@@ -785,22 +855,18 @@ bool riscv_cpu_debug_check_breakpoint(CPUState *cs)
         for (i = 0; i < RV_MAX_TRIGGERS; i++) {
             trigger_type = get_trigger_type(env, i);
 
+            if (!trigger_common_match(env, trigger_type, i)) {
+                continue;
+            }
+
             switch (trigger_type) {
             case TRIGGER_TYPE_AD_MATCH:
-                /* type 2 trigger cannot be fired in VU/VS mode */
-                if (env->virt_enabled) {
-                    return false;
-                }
-
                 ctrl = env->tdata1[i];
                 pc = env->tdata2[i];
 
                 if ((ctrl & TYPE2_EXEC) && (bp->pc == pc)) {
-                    /* check U/S/M bit against current privilege level */
-                    if ((ctrl >> 3) & BIT(env->priv)) {
-                        env->badaddr = pc;
-                        return true;
-                    }
+                    env->badaddr = pc;
+                    return true;
                 }
                 break;
             case TRIGGER_TYPE_AD_MATCH6:
@@ -808,19 +874,8 @@ bool riscv_cpu_debug_check_breakpoint(CPUState *cs)
                 pc = env->tdata2[i];
 
                 if ((ctrl & TYPE6_EXEC) && (bp->pc == pc)) {
-                    if (env->virt_enabled) {
-                        /* check VU/VS bit against current privilege level */
-                        if ((ctrl >> 23) & BIT(env->priv)) {
-                            env->badaddr = pc;
-                            return true;
-                        }
-                    } else {
-                        /* check U/S/M bit against current privilege level */
-                        if ((ctrl >> 3) & BIT(env->priv)) {
-                            env->badaddr = pc;
-                            return true;
-                        }
-                    }
+                    env->badaddr = pc;
+                    return true;
                 }
                 break;
             default: