diff mbox series

[PULL,03/58] hw/core/cpu-common: Don't init gdbstub until cpu_exec_realizefn()

Message ID 20250515102546.2149601-4-peter.maydell@linaro.org
State New
Headers show
Series [PULL,01/58] target/microblaze: Use 'obj' in DEVICE() casts in mb_cpu_initfn() | expand

Commit Message

Peter Maydell May 15, 2025, 10:24 a.m. UTC 
Currently we call gdb_init_cpu() in cpu_common_initfn(), which is
very early in the CPU object's init->realize creation sequence.  In
particular this happens before the architecture-specific subclass's
init fn has even run.  This means that gdb_init_cpu() can only do
things that depend strictly on the class, not on the object, because
the CPUState* that it is passed is currently half-initialized.

In commit a1f728ecc90cf6c6 we accidentally broke this rule, by adding
a call to the gdb_get_core_xml_file method which takes the CPUState.
At the moment we get away with this because the only implementation
doesn't actually look at the pointer it is passed.  However the whole
reason we created that method was so that we could make the "which
XML file?" decision based on a property of the CPU object, and we
currently can't change the Arm implementation of the method to do
what we want without causing wrong behaviour or a crash.

The ordering restrictions here are:
 * we must call gdb_init_cpu before:
   - any call to gdb_register_coprocessor()
   - any use of the gdb_num_regs field (this is only used
     in code that's about to call gdb_register_coprocessor()
     and wants to know the first register number of the
     set of registers it's about to add)
 * we must call gdb_init_cpu after CPU properties have been
   set, which is to say somewhere in realize

The function cpu_exec_realizefn() meets both of these requirements,
as it is called by the architecture-specific CPU realize function
early in realize, before any calls ot gdb_register_coprocessor().
Move the gdb_init_cpu() call to there.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250429132200.605611-4-peter.maydell@linaro.org
---
 hw/core/cpu-common.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index 92c40b6bf83..39e674aca21 100644
--- a/hw/core/cpu-common.c
+++ b/hw/core/cpu-common.c
@@ -234,6 +234,8 @@  bool cpu_exec_realizefn(CPUState *cpu, Error **errp)
         return false;
     }
 
+    gdb_init_cpu(cpu);
+
     /* Wait until cpu initialization complete before exposing cpu. */
     cpu_list_add(cpu);
 
@@ -304,7 +306,6 @@  static void cpu_common_initfn(Object *obj)
     /* cache the cpu class for the hotpath */
     cpu->cc = CPU_GET_CLASS(cpu);
 
-    gdb_init_cpu(cpu);
     cpu->cpu_index = UNASSIGNED_CPU_INDEX;
     cpu->cluster_index = UNASSIGNED_CLUSTER_INDEX;
     cpu->as = NULL;