cpu: Introduce env_archcpu

This will replace foo_env_get_cpu with a generic definition.
No changes to the target specific code so far.
Reviewed-by: NAlistair Francis <alistair.francis@wdc.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>

include/exec/cpu-all.h

@@ -371,6 +371,17 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
 
 int cpu_exec(CPUState *cpu);
 
+/**
+ * env_archcpu(env)
+ * @env: The architecture environment
+ *
+ * Return the ArchCPU associated with the environment.
+ */
+static inline ArchCPU *env_archcpu(CPUArchState *env)
+{
+    return container_of(env, ArchCPU, env);
+}
+
 /**
  * env_cpu(env)
  * @env: The architecture environment
@@ -379,8 +390,7 @@ int cpu_exec(CPUState *cpu);
  */
 static inline CPUState *env_cpu(CPUArchState *env)
 {
-    ArchCPU *arch_cpu = container_of(env, ArchCPU, env);
-    return &arch_cpu->parent_obj;
+    return &env_archcpu(env)->parent_obj;
 }
 
 #endif /* CPU_ALL_H */