From c7b6b7f8bf31a6387e0bd1eab0d1ac9741999523 Mon Sep 17 00:00:00 2001
From: Alibek Omarov <a1ba.omarov@gmail.com>
Date: Mon, 16 Nov 2020 21:54:23 +0300
Subject: [PATCH] target: e2k: initial gdb support

---
 linux-user/e2k/cpu_loop.c | 21 +++++++++++++++++
 target/e2k/cpu.c          |  4 ++++
 target/e2k/cpu.h          |  2 ++
 target/e2k/gdbstub.c      | 47 +++++++++++++++++++++++++++++++++++++++
 target/e2k/meson.build    |  1 +
 5 files changed, 75 insertions(+)
 create mode 100644 target/e2k/gdbstub.c

diff --git a/linux-user/e2k/cpu_loop.c b/linux-user/e2k/cpu_loop.c
index e2112c7ee1..91ef2d244d 100644
--- a/linux-user/e2k/cpu_loop.c
+++ b/linux-user/e2k/cpu_loop.c
@@ -66,6 +66,27 @@ void cpu_loop(CPUE2KState *env)
             env->ip = env->nip;
             break;
         }
+        /* QEMU common interrupts */
+        case EXCP_INTERRUPT:
+            /* just indicate that signals should be handled asap */
+            break;
+        case EXCP_DEBUG:
+        {
+            target_siginfo_t info;
+            info.si_signo = TARGET_SIGTRAP;
+            info.si_errno = 0;
+            info.si_code = TARGET_TRAP_BRKPT;
+            queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
+            break;
+        }
+        case EXCP_ATOMIC:
+            cpu_exec_step_atomic(cs);
+            break;
+        case EXCP_HLT:
+        case EXCP_HALTED:
+        case EXCP_YIELD:
+            fprintf(stderr, "Unhandled QEMU trap: 0x%x\n", trapnr);
+            break;
         default:
             fprintf(stderr, "Unhandled trap: 0x%x\n", trapnr);
             cpu_dump_state(cs, stderr, 0);
diff --git a/target/e2k/cpu.c b/target/e2k/cpu.c
index 876af1dd2d..e6ffd860d4 100644
--- a/target/e2k/cpu.c
+++ b/target/e2k/cpu.c
@@ -224,6 +224,10 @@ static void e2k_cpu_class_init(ObjectClass *oc, void *data)
     cc->class_by_name = e2k_cpu_class_by_name;
     cc->disas_set_info = cpu_e2k_disas_set_info;
     cc->tcg_initialize = e2k_tcg_initialize;
+
+    cc->gdb_read_register  = e2k_cpu_gdb_read_register;
+    cc->gdb_write_register = e2k_cpu_gdb_write_register;
+    cc->gdb_num_core_regs  = 300; /* TODO: bogus value, depends on e2k-linux-gdb */
 }
 
 static const TypeInfo e2k_cpu_type_info = {
diff --git a/target/e2k/cpu.h b/target/e2k/cpu.h
index 4387caf505..ad652f316d 100644
--- a/target/e2k/cpu.h
+++ b/target/e2k/cpu.h
@@ -266,6 +266,8 @@ static inline void cpu_get_tb_cpu_state(CPUE2KState *env, target_ulong *pc,
 }
 
 int e2k_cpu_signal_handler(int host_signum, void *pinfo, void *puc);
+int e2k_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n);
+int e2k_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n);
 
 #define cpu_signal_handler e2k_cpu_signal_handler
 
diff --git a/target/e2k/gdbstub.c b/target/e2k/gdbstub.c
new file mode 100644
index 0000000000..33b5d86bb4
--- /dev/null
+++ b/target/e2k/gdbstub.c
@@ -0,0 +1,47 @@
+/*
+ * Elbrus 2000 gdb server stub
+ *
+ * Copyright (c) 2003-2005 Fabrice Bellard
+ * Copyright (c) 2013 SUSE LINUX Products GmbH
+ * Copyright (c) 2020 Alibek Omarov
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "exec/gdbstub.h"
+
+/* TODO: reverse engineer e2k-linux-gdb register ids */
+
+int e2k_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
+{
+    E2KCPU *cpu = E2K_CPU(cs);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    CPUE2KState *env = &cpu->env;
+
+    fprintf(stderr, "%s: unknown register %d\n", __FUNCTION__, n);
+    return 0;
+}
+
+int e2k_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
+{
+    E2KCPU *cpu = E2K_CPU(cs);
+    CPUClass *cc = CPU_GET_CLASS(cs);
+    CPUE2KState *env = &cpu->env;
+
+    fprintf(stderr, "%s: unknown register %d\n", __FUNCTION__, n);
+
+    /* TODO */
+    return 0;
+}
diff --git a/target/e2k/meson.build b/target/e2k/meson.build
index b400b79222..86927d4688 100644
--- a/target/e2k/meson.build
+++ b/target/e2k/meson.build
@@ -1,6 +1,7 @@
 e2k_ss = ss.source_set()
 e2k_ss.add(files(
   'cpu.c',
+  'gdbstub.c',
   'helper.c',
   'helper_int.c',
   'translate.c',