gdbstub: Allow gdb_core_xml_file to be set at runtime

Currently the CPUClass:gdb_core_xml_file setting is a simple 'const
char *' which the CPU class must set to a fixed string.  Allow the
CPU class to instead set a new method gdb_get_core_xml_file() which
returns this string.

This will allow Arm CPUs to use different XML files for AArch32 vs
AArch64 without having to have an extra AArch64-specific class type
purely to give somewhere to set cc->gdb_core_xml_file differently.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250317142819.900029-3-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

2 files changed, 24 insertions, 4 deletions

diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 282e13e163..565f6b33a9 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -565,15 +565,30 @@ static void gdb_register_feature(CPUState *cpu, int base_reg,
     g_array_append_val(cpu->gdb_regs, s);
 }
 
+static const char *gdb_get_core_xml_file(CPUState *cpu)
+{
+    CPUClass *cc = cpu->cc;
+
+    /*
+     * The CPU class can provide the XML filename via a method,
+     * or as a simple fixed string field.
+     */
+    if (cc->gdb_get_core_xml_file) {
+        return cc->gdb_get_core_xml_file(cpu);
+    }
+    return cc->gdb_core_xml_file;
+}
+
 void gdb_init_cpu(CPUState *cpu)
 {
     CPUClass *cc = cpu->cc;
     const GDBFeature *feature;
+    const char *xmlfile = gdb_get_core_xml_file(cpu);
 
     cpu->gdb_regs = g_array_new(false, false, sizeof(GDBRegisterState));
 
-    if (cc->gdb_core_xml_file) {
-        feature = gdb_find_static_feature(cc->gdb_core_xml_file);
+    if (xmlfile) {
+        feature = gdb_find_static_feature(xmlfile);
         gdb_register_feature(cpu, 0,
                              cc->gdb_read_register, cc->gdb_write_register,
                              feature);
@@ -1644,7 +1659,7 @@ void gdb_extend_qsupported_features(char *qflags)
 static void handle_query_supported(GArray *params, void *user_ctx)
 {
     g_string_printf(gdbserver_state.str_buf, "PacketSize=%x", MAX_PACKET_LENGTH);
-    if (first_cpu->cc->gdb_core_xml_file) {
+    if (gdb_get_core_xml_file(first_cpu)) {
         g_string_append(gdbserver_state.str_buf, ";qXfer:features:read+");
     }
 
@@ -1701,7 +1716,7 @@ static void handle_query_xfer_features(GArray *params, void *user_ctx)
     }
 
     process = gdb_get_cpu_process(gdbserver_state.g_cpu);
-    if (!gdbserver_state.g_cpu->cc->gdb_core_xml_file) {
+    if (!gdb_get_core_xml_file(gdbserver_state.g_cpu)) {
         gdb_put_packet("");
         return;
     }
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 6ea246514e..2a02d4f078 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -131,6 +131,10 @@ struct SysemuCPUOps;
  * @gdb_num_core_regs: Number of core registers accessible to GDB or 0 to infer
  *                     from @gdb_core_xml_file.
  * @gdb_core_xml_file: File name for core registers GDB XML description.
+ * @gdb_get_core_xml_file: Optional callback that returns the file name for
+ * the core registers GDB XML description. The returned value is expected to
+ * be a simple constant string: the caller will not g_free() it. If this
+ * is NULL then @gdb_core_xml_file will be used instead.
  * @gdb_stop_before_watchpoint: Indicates whether GDB expects the CPU to stop
  *           before the insn which triggers a watchpoint rather than after it.
  * @gdb_arch_name: Optional callback that returns the architecture name known
@@ -166,6 +170,7 @@ struct CPUClass {
 
     const char *gdb_core_xml_file;
     const gchar * (*gdb_arch_name)(CPUState *cpu);
+    const char * (*gdb_get_core_xml_file)(CPUState *cpu);
 
     void (*disas_set_info)(CPUState *cpu, disassemble_info *info);