[PATCH 2/2] target/riscv: Add textra matching condition for the triggers

[Alvin Chang]

According to RISC-V Debug specification, the optional textra32 and
textra64 trigger CSRs can be used to configure additional matching
conditions for the triggers. For example, if the textra.MHSELECT field
is set to 4 (mcontext), this trigger will only match or fire if the low
bits of mcontext/hcontext equal textra.MHVALUE field.

This commit adds the aforementioned matching condition as common trigger
matching conditions. Currently, the only legal values of textra.MHSELECT
are 0 (ignore) and 4 (mcontext). When textra.MHSELECT is 0, we pass the
checking. When textra.MHSELECT is 4, we compare textra.MHVALUE with
mcontext CSR. The remaining fields, such as textra.SBYTEMASK,
textra.SVALUE, and textra.SSELECT, are hardwired to zero for now. Thus,
we skip checking them here.

Signed-off-by: Alvin Chang <alvinga@andestech.com>
---
 target/riscv/debug.c | 63 +++++++++++++++++++++++++++++++++++++++++++-
 target/riscv/debug.h |  3 +++
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/target/riscv/debug.c b/target/riscv/debug.c
index f7d8f5e320..58dd2f25ae 100644
--- a/target/riscv/debug.c
+++ b/target/riscv/debug.c
@@ -367,11 +367,72 @@ static bool trigger_priv_match(CPURISCVState *env, 
trigger_type_t type,
     return false;
 }
 
+static bool trigger_textra_match(CPURISCVState *env, trigger_type_t type,
+                                 int trigger_index)
+{
+    target_ulong textra = env->tdata3[trigger_index];
+    target_ulong mhvalue, mhselect;
+
+    if (type < TRIGGER_TYPE_AD_MATCH || type > TRIGGER_TYPE_AD_MATCH6) {
+        /* textra checking is only applicable when type is 2, 3, 4, 5, or 6 */
+        return true;
+    }
+
+    switch (riscv_cpu_mxl(env)) {
+    case MXL_RV32:
+        mhvalue  = get_field(textra, TEXTRA32_MHVALUE);
+        mhselect = get_field(textra, TEXTRA32_MHSELECT);
+        break;
+    case MXL_RV64:
+    case MXL_RV128:
+        mhvalue  = get_field(textra, TEXTRA64_MHVALUE);
+        mhselect = get_field(textra, TEXTRA64_MHSELECT);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    /* Check mhvalue and mhselect. */
+    switch (mhselect) {
+    case MHSELECT_IGNORE:
+        break;
+    case MHSELECT_MCONTEXT:
+        /* Match or fire if the low bits of mcontext/hcontext equal mhvalue. */
+        if (riscv_has_ext(env, RVH)) {
+            if (mhvalue != env->mcontext) {
+                return false;
+            }
+        } else {
+            switch (riscv_cpu_mxl(env)) {
+            case MXL_RV32:
+                if (mhvalue != (env->mcontext & MCONTEXT32)) {
+                    return false;
+                }
+                break;
+            case MXL_RV64:
+            case MXL_RV128:
+                if (mhvalue != (env->mcontext & MCONTEXT64)) {
+                    return false;
+                }
+                break;
+            default:
+                g_assert_not_reached();
+            }
+        }
+        break;
+    default:
+        break;
+    }
+
+    return true;
+}
+
 /* 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);
+    return trigger_priv_match(env, type, trigger_index) &&
+           trigger_textra_match(env, type, trigger_index);
 }
 
 /* type 2 trigger */
diff --git a/target/riscv/debug.h b/target/riscv/debug.h
index c347863578..f76b8f944a 100644
--- a/target/riscv/debug.h
+++ b/target/riscv/debug.h
@@ -131,6 +131,9 @@ enum {
 #define ITRIGGER_VU           BIT(25)
 #define ITRIGGER_VS           BIT(26)
 
+#define MHSELECT_IGNORE       0
+#define MHSELECT_MCONTEXT     4
+
 bool tdata_available(CPURISCVState *env, int tdata_index);
 
 target_ulong tselect_csr_read(CPURISCVState *env);
-- 
2.34.1