target/loongarch: Add gdb support.

Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220606124333.2060567-42-yangxiaojuan@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/loongarch/cpu.c

@@ -487,6 +487,8 @@ static void loongarch_cpu_realizefn(DeviceState *dev, Error **errp)
         return;
     }
 
+    loongarch_cpu_register_gdb_regs_for_features(cs);
+
     cpu_reset(cs);
     qemu_init_vcpu(cs);
 
@@ -640,6 +642,13 @@ static void loongarch_cpu_class_init(ObjectClass *c, void *data)
     dc->vmsd = &vmstate_loongarch_cpu;
     cc->sysemu_ops = &loongarch_sysemu_ops;
     cc->disas_set_info = loongarch_cpu_disas_set_info;
+    cc->gdb_read_register = loongarch_cpu_gdb_read_register;
+    cc->gdb_write_register = loongarch_cpu_gdb_write_register;
+    cc->disas_set_info = loongarch_cpu_disas_set_info;
+    cc->gdb_num_core_regs = 34;
+    cc->gdb_core_xml_file = "loongarch-base64.xml";
+    cc->gdb_stop_before_watchpoint = true;
+
 #ifdef CONFIG_TCG
     cc->tcg_ops = &loongarch_tcg_ops;
 #endif

target/loongarch/gdbstub.c

@@ -0,0 +1,81 @@
+/*
+ * LOONGARCH gdb server stub
+ *
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "internals.h"
+#include "exec/gdbstub.h"
+
+int loongarch_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
+{
+    LoongArchCPU *cpu = LOONGARCH_CPU(cs);
+    CPULoongArchState *env = &cpu->env;
+
+    if (0 <= n && n < 32) {
+        return gdb_get_regl(mem_buf, env->gpr[n]);
+    } else if (n == 32) {
+        return gdb_get_regl(mem_buf, env->pc);
+    } else if (n == 33) {
+        return gdb_get_regl(mem_buf, env->badaddr);
+    }
+    return 0;
+}
+
+int loongarch_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
+{
+    LoongArchCPU *cpu = LOONGARCH_CPU(cs);
+    CPULoongArchState *env = &cpu->env;
+    target_ulong tmp = ldtul_p(mem_buf);
+    int length = 0;
+
+    if (0 <= n && n < 32) {
+        env->gpr[n] = tmp;
+        length = sizeof(target_ulong);
+    } else if (n == 32) {
+        env->pc = tmp;
+        length = sizeof(target_ulong);
+    }
+    return length;
+}
+
+static int loongarch_gdb_get_fpu(CPULoongArchState *env,
+                                 GByteArray *mem_buf, int n)
+{
+    if (0 <= n && n < 32) {
+        return gdb_get_reg64(mem_buf, env->fpr[n]);
+    } else if (32 <= n && n < 40) {
+        return gdb_get_reg8(mem_buf, env->cf[n - 32]);
+    } else if (n == 40) {
+        return gdb_get_reg32(mem_buf, env->fcsr0);
+    }
+    return 0;
+}
+
+static int loongarch_gdb_set_fpu(CPULoongArchState *env,
+                                 uint8_t *mem_buf, int n)
+{
+    int length = 0;
+
+    if (0 <= n && n < 32) {
+        env->fpr[n] = ldq_p(mem_buf);
+        length = 8;
+    } else if (32 <= n && n < 40) {
+        env->cf[n - 32] = ldub_p(mem_buf);
+        length = 1;
+    } else if (n == 40) {
+        env->fcsr0 = ldl_p(mem_buf);
+        length = 4;
+    }
+    return length;
+}
+
+void loongarch_cpu_register_gdb_regs_for_features(CPUState *cs)
+{
+    gdb_register_coprocessor(cs, loongarch_gdb_get_fpu, loongarch_gdb_set_fpu,
+                             41, "loongarch-fpu64.xml", 0);
+}

target/loongarch/internals.h

@@ -49,4 +49,8 @@ bool loongarch_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 
 hwaddr loongarch_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 
+int loongarch_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n);
+int loongarch_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n);
+void loongarch_cpu_register_gdb_regs_for_features(CPUState *cs);
+
 #endif

target/loongarch/meson.build

@@ -11,6 +11,7 @@ loongarch_tcg_ss.add(files(
   'fpu_helper.c',
   'op_helper.c',
   'translate.c',
+  'gdbstub.c',
 ))
 loongarch_tcg_ss.add(zlib)