[tip: x86/boot] init: Provide arch_cpu_finalize_init()

["tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     7725acaa4f0c04fbefb0e0d342635b967bb7d414
Gitweb:        https://git.kernel.org/tip/7725acaa4f0c04fbefb0e0d342635b967bb7d414
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Wed, 14 Jun 2023 01:39:22 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 16 Jun 2023 10:15:59 +02:00

init: Provide arch_cpu_finalize_init()

check_bugs() has become a dumping ground for all sorts of activities to
finalize the CPU initialization before running the rest of the init code.

Most are empty, a few do actual bug checks, some do alternative patching
and some cobble a CPU advertisement string together....

Aside of that the current implementation requires duplicated function
declaration and mostly empty header files for them.

Provide a new function arch_cpu_finalize_init(). Provide a generic
declaration if CONFIG_ARCH_HAS_CPU_FINALIZE_INIT is selected and a stub
inline otherwise.

This requires a temporary #ifdef in start_kernel() which will be removed
along with check_bugs() once the architectures are converted over.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230613224544.957805717@linutronix.de

---
 arch/Kconfig        | 3 +++
 include/linux/cpu.h | 6 ++++++
 init/main.c         | 4 ++++
 3 files changed, 13 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 205fd23..171e6b5 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -285,6 +285,9 @@ config ARCH_HAS_DMA_SET_UNCACHED
 config ARCH_HAS_DMA_CLEAR_UNCACHED
 	bool
 
+config ARCH_HAS_CPU_FINALIZE_INIT
+	bool
+
 # Select if arch init_task must go in the __init_task_data section
 config ARCH_TASK_STRUCT_ON_STACK
 	bool
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 8582a71..4893c4a 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -184,6 +184,12 @@ void arch_cpu_idle_enter(void);
 void arch_cpu_idle_exit(void);
 void __noreturn arch_cpu_idle_dead(void);
 
+#ifdef CONFIG_ARCH_HAS_CPU_FINALIZE_INIT
+void arch_cpu_finalize_init(void);
+#else
+static inline void arch_cpu_finalize_init(void) { }
+#endif
+
 int cpu_report_state(int cpu);
 int cpu_check_up_prepare(int cpu);
 void cpu_set_state_online(int cpu);
diff --git a/init/main.c b/init/main.c
index af50044..77d5316 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1078,7 +1078,11 @@ asmlinkage __visible void __init __no_sanitize_address __noreturn start_kernel(v
 	taskstats_init_early();
 	delayacct_init();
 
+	arch_cpu_finalize_init();
+	/* Temporary conditional until everything has been converted */
+#ifndef CONFIG_ARCH_HAS_CPU_FINALIZE_INIT
 	check_bugs();
+#endif
 
 	acpi_subsystem_init();
 	arch_post_acpi_subsys_init();