[PATCH 02/13] hw/riscv/trace-encoder.c: add trace ntrace/etrace selection logic

Selecting trace message format rely on `TraceEncoder->ntrace` flag.
This flag mirrors trTeFormat bit.

For now only two values supported:

 - E-Trace (trTeFormat = 0), trace format, described by Efficient trace spec.

 - N-Trace (trTeFormat = 1), trace format, described by Nexus trace spec.

For now we not yet implemented any N-Trace messages, so currently
`ntrace` field only disables E-Trace messages competely. We will reuse
this field in following commits, when N-Trace messages added.

Signed-off-by: Konstantin Semichastnov <[email protected]>
---
 hw/riscv/trace-encoder.c    | 29 +++++++++++++++++++++++++----
 target/riscv/trace_helper.c |  8 ++++++--
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/hw/riscv/trace-encoder.c b/hw/riscv/trace-encoder.c
index 53345a478c..34c8f60ce1 100644
--- a/hw/riscv/trace-encoder.c
+++ b/hw/riscv/trace-encoder.c
@@ -254,7 +254,11 @@ static void trencoder_te_ctrl_postw(RegisterInfo *reg, uint64_t val)
 
     if (!te->trace_running && trTeInstTracing) {
         /* Starting trace. Ask the CPU for the first trace insn */
-        te->trace_next_insn = true;
+        if (te->ntrace) {
+            /* send ProgTraceSync message */
+        } else {
+            te->trace_next_insn = true;
+        }
 
         te->ramsink_ramstart = trencoder_read_ramsink_writep(te);
         te->ramsink_ramlimit = trencoder_read_ramsink_ramlimit(te);
@@ -442,6 +446,8 @@ static void trencoder_send_sync_msg(Object *trencoder_obj, uint64_t pc)
     uint8_t msg_size;
     bool is_branch_taken;
 
+    g_assert(!trencoder->ntrace);
+
     trencoder->first_pc = pc;
     is_branch_taken = trencoder_addr_is_branch_taken(trencoder, pc);
     msg_size = rv_etrace_gen_encoded_sync_msg(msg, pc, priv,
@@ -458,6 +464,8 @@ static void trencoder_send_updiscon(TraceEncoder *trencoder, uint64_t pc)
     bool updiscon = !notify;
     uint8_t msg_size;
 
+    g_assert(!trencoder->ntrace);
+
     if (trencoder->branches > 0) {
         msg_size = rv_etrace_gen_encoded_format1(format2_msg,
                                                  trencoder->branches,
@@ -485,6 +493,8 @@ void trencoder_set_first_trace_insn(Object *trencoder_obj, uint64_t pc)
     uint8_t msg_size;
     bool is_branch_taken;
 
+    g_assert(!trencoder->ntrace);
+
     if (trencoder->updiscon_pending) {
         trencoder_send_updiscon(trencoder, pc);
     }
@@ -508,6 +518,11 @@ void trencoder_trace_trap_insn(Object *trencoder_obj,
     g_autofree uint8_t *msg = g_malloc0(TRACE_MSG_MAX_SIZE);
     uint8_t msg_size;
 
+    if (trencoder->ntrace) {
+        /* send IndirectBranchHist message */
+        return;
+    }
+
     if (trencoder->updiscon_pending) {
         trencoder_send_updiscon(trencoder, pc);
     }
@@ -525,9 +540,15 @@ static void trencoder_send_branch_map(Object *trencoder_obj)
     g_autofree uint8_t *msg = g_malloc0(TRACE_MSG_MAX_SIZE);
     uint8_t msg_size;
 
-    msg_size = rv_etrace_gen_encoded_format1_noaddr(msg,
-                                                    te->branches,
-                                                    te->branch_map);
+    if (te->ntrace) {
+        /* send ResourceFull message */
+        return;
+    } else {
+        msg_size = rv_etrace_gen_encoded_format1_noaddr(msg,
+                                                        te->branches,
+                                                        te->branch_map);
+    }
+
     trencoder_send_message_smem(te, msg, msg_size);
 }
 
diff --git a/target/riscv/trace_helper.c b/target/riscv/trace_helper.c
index cd57641d9b..9b43aeac09 100644
--- a/target/riscv/trace_helper.c
+++ b/target/riscv/trace_helper.c
@@ -34,8 +34,12 @@ void helper_trace_updiscon(CPURISCVState *env)
     RISCVCPU *cpu = env_archcpu(env);
     TraceEncoder *te = TRACE_ENCODER(cpu->trencoder);
 
-    te->updiscon_pending = true;
-    te->trace_next_insn = true;
+    if (te->ntrace) {
+        /* send IndirectBranchHist message */
+    } else {
+        te->updiscon_pending = true;
+        te->trace_next_insn = true;
+    }
 }
 
 void helper_trace_branch(CPURISCVState *env, target_ulong pc, int taken)

-- 
2.43.0