init: Invoke arch_cpu_finalize_init() earlier

X86 is reworking the boot process so that initializations which are not
required during early boot can be moved into the late boot process and out
of the fragile and restricted initial boot phase.

arch_cpu_finalize_init() is the obvious place to do such initializations,
but arch_cpu_finalize_init() is invoked too late in start_kernel() e.g. for
initializing the FPU completely. fork_init() requires that the FPU is
initialized as the size of task_struct on X86 depends on the size of the
required FPU register buffer.

Fortunately none of the init calls between calibrate_delay() and
arch_cpu_finalize_init() is relevant for the functionality of
arch_cpu_finalize_init().

Invoke it right after calibrate_delay() where everything which is relevant
for arch_cpu_finalize_init() has been set up already.

No functional change intended.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Rick Edgecombe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

init/main.c

@@ -1041,6 +1041,8 @@ asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(v
 	sched_clock_init();
 	calibrate_delay();
 
+	arch_cpu_finalize_init();
+
 	/*
 	 * This needs to be called before any devices perform DMA
 	 * operations that might use the SWIOTLB bounce buffers. It will
@@ -1077,8 +1079,6 @@ asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(v
 	taskstats_init_early();
 	delayacct_init();
 
-	arch_cpu_finalize_init();
-
 	acpi_subsystem_init();
 	arch_post_acpi_subsys_init();
 	kcsan_init();