smp: Consolidate smp_prepare_boot_cpu()

There is no point in having seven architectures implementing the same empty
stub.

Provide a weak function in the init code and remove the stubs.

This also allows to utilize the function on UP which is required to
sanitize the per CPU handling on X86 UP.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240304005104.567671691@linutronix.de

9 files changed, 5 insertions, 35 deletions

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 7439b2377df5..8e9dd63b220c 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -467,11 +467,6 @@ smp_prepare_cpus(unsigned int max_cpus)
 	smp_num_cpus = smp_num_probed;
 }
 
-void
-smp_prepare_boot_cpu(void)
-{
-}
-
 int
 __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
index 8d9b188caa27..b2f2c59279a6 100644
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -39,11 +39,6 @@ struct plat_smp_ops  __weak plat_smp_ops;
 /* XXX: per cpu ? Only needed once in early secondary boot */
 struct task_struct *secondary_idle_tsk;
 
-/* Called from start_kernel */
-void __init smp_prepare_boot_cpu(void)
-{
-}
-
 static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
 {
 	unsigned long dt_root = of_get_flat_dt_root();
diff --git a/arch/csky/kernel/smp.c b/arch/csky/kernel/smp.c
index 8e42352cbf12..92dbbf3e0205 100644
--- a/arch/csky/kernel/smp.c
+++ b/arch/csky/kernel/smp.c
@@ -152,10 +152,6 @@ void arch_irq_work_raise(void)
 }
 #endif
 
-void __init smp_prepare_boot_cpu(void)
-{
-}
-
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 }
diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index 608884bc3396..65e1fdf9fdb2 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -114,10 +114,6 @@ void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 	local_irq_restore(flags);
 }
 
-void __init smp_prepare_boot_cpu(void)
-{
-}
-
 /*
  * interrupts should already be disabled from the VM
  * SP should already be correct; need to set THREADINFO_REG
diff --git a/arch/openrisc/kernel/smp.c b/arch/openrisc/kernel/smp.c
index 1c5a2d71d675..86da4bc5ee0b 100644
--- a/arch/openrisc/kernel/smp.c
+++ b/arch/openrisc/kernel/smp.c
@@ -57,10 +57,6 @@ static void boot_secondary(unsigned int cpu, struct task_struct *idle)
 	spin_unlock(&boot_lock);
 }
 
-void __init smp_prepare_boot_cpu(void)
-{
-}
-
 void __init smp_init_cpus(void)
 {
 	struct device_node *cpu;
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 519b6bd946e5..c4ed7d977f57 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -42,10 +42,6 @@
 
 static DECLARE_COMPLETION(cpu_running);
 
-void __init smp_prepare_boot_cpu(void)
-{
-}
-
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	int cpuid;
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index f3969a3600db..a0cc9bb41a92 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1206,10 +1206,6 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 }
 
-void smp_prepare_boot_cpu(void)
-{
-}
-
 void __init smp_setup_processor_id(void)
 {
 	if (tlb_type == spitfire)
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 4fab2ed454f3..31edeab5ee88 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -59,11 +59,6 @@ static inline void stop_other_cpus(void)
 	smp_ops.stop_other_cpus(1);
 }
 
-static inline void smp_prepare_boot_cpu(void)
-{
-	smp_ops.smp_prepare_boot_cpu();
-}
-
 static inline void smp_prepare_cpus(unsigned int max_cpus)
 {
 	smp_ops.smp_prepare_cpus(max_cpus);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3f57ce68a3f1..980782bd2c97 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1187,6 +1187,11 @@ void __init smp_prepare_cpus_common(void)
 	set_cpu_sibling_map(0);
 }
 
+void __init smp_prepare_boot_cpu(void)
+{
+	smp_ops.smp_prepare_boot_cpu();
+}
+
 #ifdef CONFIG_X86_64
 /* Establish whether parallel bringup can be supported. */
 bool __init arch_cpuhp_init_parallel_bringup(void)