target/m68k: fix gdb for m68xxx

Currently "cf-core.xml" is sent to GDB when using any m68k flavor.  Thing is
it uses the "org.gnu.gdb.coldfire.core" feature name and gdb 8.3 then expects
a coldfire FPU instead of the default m68881 FPU.

This is not OK because the m68881 floats registers are 96 bits wide so it
crashes GDB with the following error message:

(gdb) target remote localhost:7960
Remote debugging using localhost:7960
warning: Register "fp0" has an unsupported size (96 bits)
warning: Register "fp1" has an unsupported size (96 bits)
...
Remote 'g' packet reply is too long (expected 148 bytes, got 180 bytes):    \
  00000000000[...]0000

With this patch: qemu-system-m68k -M none -cpu m68020 -s -S

(gdb) tar rem :1234
Remote debugging using :1234
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.
0x00000000 in ?? ()
(gdb) p $fp0
$1 = nan(0xffffffffffffffff)

Signed-off-by: KONRAD Frederic <frederic.konrad@adacore.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <1588094279-17913-3-git-send-email-frederic.konrad@adacore.com>
Message-Id: <20200430190122.4592-10-alex.bennee@linaro.org>

configure

@@ -7825,7 +7825,7 @@ case "$target_name" in
   ;;
   m68k)
     bflt="yes"
-    gdb_xml_files="cf-core.xml cf-fp.xml m68k-fp.xml"
+    gdb_xml_files="cf-core.xml cf-fp.xml m68k-core.xml m68k-fp.xml"
     TARGET_SYSTBL_ABI=common
   ;;
   microblaze|microblazeel)

gdb-xml/m68k-core.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<!-- Copyright (C) 2008 Free Software Foundation, Inc.
+
+     Copying and distribution of this file, with or without modification,
+     are permitted in any medium without royalty provided the copyright
+     notice and this notice are preserved.  -->
+<!DOCTYPE feature SYSTEM "gdb-target.dtd">
+<feature name="org.gnu.gdb.m68k.core">
+  <reg name="d0" bitsize="32"/>
+  <reg name="d1" bitsize="32"/>
+  <reg name="d2" bitsize="32"/>
+  <reg name="d3" bitsize="32"/>
+  <reg name="d4" bitsize="32"/>
+  <reg name="d5" bitsize="32"/>
+  <reg name="d6" bitsize="32"/>
+  <reg name="d7" bitsize="32"/>
+  <reg name="a0" bitsize="32" type="data_ptr"/>
+  <reg name="a1" bitsize="32" type="data_ptr"/>
+  <reg name="a2" bitsize="32" type="data_ptr"/>
+  <reg name="a3" bitsize="32" type="data_ptr"/>
+  <reg name="a4" bitsize="32" type="data_ptr"/>
+  <reg name="a5" bitsize="32" type="data_ptr"/>
+  <reg name="fp" bitsize="32" type="data_ptr"/>
+  <reg name="sp" bitsize="32" type="data_ptr"/>
+
+  <reg name="ps" bitsize="32"/>
+  <reg name="pc" bitsize="32" type="code_ptr"/>
+
+</feature>

target/m68k/cpu.c

@@ -292,16 +292,38 @@ static void m68k_cpu_class_init(ObjectClass *c, void *data)
     cc->tcg_initialize = m68k_tcg_init;
 
     cc->gdb_num_core_regs = 18;
-    cc->gdb_core_xml_file = "cf-core.xml";
 
     dc->vmsd = &vmstate_m68k_cpu;
 }
 
-#define DEFINE_M68K_CPU_TYPE(cpu_model, initfn) \
-    {                                           \
-        .name = M68K_CPU_TYPE_NAME(cpu_model),  \
-        .instance_init = initfn,                \
-        .parent = TYPE_M68K_CPU,                \
+static void m68k_cpu_class_init_cf_core(ObjectClass *c, void *data)
+{
+    CPUClass *cc = CPU_CLASS(c);
+
+    cc->gdb_core_xml_file = "cf-core.xml";
+}
+
+#define DEFINE_M68K_CPU_TYPE_CF(model)               \
+    {                                                \
+        .name = M68K_CPU_TYPE_NAME(#model),          \
+        .instance_init = model##_cpu_initfn,         \
+        .parent = TYPE_M68K_CPU,                     \
+        .class_init = m68k_cpu_class_init_cf_core    \
+    }
+
+static void m68k_cpu_class_init_m68k_core(ObjectClass *c, void *data)
+{
+    CPUClass *cc = CPU_CLASS(c);
+
+    cc->gdb_core_xml_file = "m68k-core.xml";
+}
+
+#define DEFINE_M68K_CPU_TYPE_M68K(model)             \
+    {                                                \
+        .name = M68K_CPU_TYPE_NAME(#model),          \
+        .instance_init = model##_cpu_initfn,         \
+        .parent = TYPE_M68K_CPU,                     \
+        .class_init = m68k_cpu_class_init_m68k_core  \
     }
 
 static const TypeInfo m68k_cpus_type_infos[] = {
@@ -314,15 +336,15 @@ static const TypeInfo m68k_cpus_type_infos[] = {
         .class_size = sizeof(M68kCPUClass),
         .class_init = m68k_cpu_class_init,
     },
-    DEFINE_M68K_CPU_TYPE("m68000", m68000_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m68020", m68020_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m68030", m68030_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m68040", m68040_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m68060", m68060_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m5206", m5206_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("m5208", m5208_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("cfv4e", cfv4e_cpu_initfn),
-    DEFINE_M68K_CPU_TYPE("any", any_cpu_initfn),
+    DEFINE_M68K_CPU_TYPE_M68K(m68000),
+    DEFINE_M68K_CPU_TYPE_M68K(m68020),
+    DEFINE_M68K_CPU_TYPE_M68K(m68030),
+    DEFINE_M68K_CPU_TYPE_M68K(m68040),
+    DEFINE_M68K_CPU_TYPE_M68K(m68060),
+    DEFINE_M68K_CPU_TYPE_CF(m5206),
+    DEFINE_M68K_CPU_TYPE_CF(m5208),
+    DEFINE_M68K_CPU_TYPE_CF(cfv4e),
+    DEFINE_M68K_CPU_TYPE_CF(any),
 };
 
 DEFINE_TYPES(m68k_cpus_type_infos)