arm64: Introduce get_cpu_ops() helper function

This introduces get_cpu_ops() to return the CPU operations according to
the given CPU index. For now, it simply returns the @cpu_ops[cpu] as
before. Also, helper function __cpu_try_die() is introduced to be shared
by cpu_die() and ipi_cpu_crash_stop(). So it shouldn't introduce any
functional changes.
Signed-off-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>

arch/arm64/include/asm/cpu_ops.h

@@ -55,8 +55,8 @@ struct cpu_operations {
 #endif
 };
 
-extern const struct cpu_operations *cpu_ops[NR_CPUS];
 int __init init_cpu_ops(int cpu);
+extern const struct cpu_operations *get_cpu_ops(int cpu);
 
 static inline void __init init_bootcpu_ops(void)
 {

arch/arm64/kernel/cpu_ops.c

@@ -20,7 +20,7 @@ extern const struct cpu_operations acpi_parking_protocol_ops;
 #endif
 extern const struct cpu_operations cpu_psci_ops;
 
-const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
+static const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
 
 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
 	&smp_spin_table_ops,
@@ -111,3 +111,8 @@ int __init init_cpu_ops(int cpu)
 
 	return 0;
 }
+
+const struct cpu_operations *get_cpu_ops(int cpu)
+{
+	return cpu_ops[cpu];
+}

arch/arm64/kernel/cpuidle.c

@@ -18,11 +18,11 @@
 
 int arm_cpuidle_init(unsigned int cpu)
 {
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
 	int ret = -EOPNOTSUPP;
 
-	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_suspend &&
-			cpu_ops[cpu]->cpu_init_idle)
-		ret = cpu_ops[cpu]->cpu_init_idle(cpu);
+	if (ops && ops->cpu_suspend && ops->cpu_init_idle)
+		ret = ops->cpu_init_idle(cpu);
 
 	return ret;
 }
@@ -37,8 +37,9 @@ int arm_cpuidle_init(unsigned int cpu)
 int arm_cpuidle_suspend(int index)
 {
 	int cpu = smp_processor_id();
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
 
-	return cpu_ops[cpu]->cpu_suspend(index);
+	return ops->cpu_suspend(index);
 }
 
 #ifdef CONFIG_ACPI

arch/arm64/kernel/setup.c

@@ -371,8 +371,10 @@ void __init setup_arch(char **cmdline_p)
 static inline bool cpu_can_disable(unsigned int cpu)
 {
 #ifdef CONFIG_HOTPLUG_CPU
-	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_can_disable)
-		return cpu_ops[cpu]->cpu_can_disable(cpu);
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
+
+	if (ops && ops->cpu_can_disable)
+		return ops->cpu_can_disable(cpu);
 #endif
 	return false;
 }

arch/arm64/kernel/smp.c

@@ -93,8 +93,10 @@ static inline int op_cpu_kill(unsigned int cpu)
  */
 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
-	if (cpu_ops[cpu]->cpu_boot)
-		return cpu_ops[cpu]->cpu_boot(cpu);
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
+
+	if (ops->cpu_boot)
+		return ops->cpu_boot(cpu);
 
 	return -EOPNOTSUPP;
 }
@@ -196,6 +198,7 @@ asmlinkage notrace void secondary_start_kernel(void)
 {
 	u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
 	struct mm_struct *mm = &init_mm;
+	const struct cpu_operations *ops;
 	unsigned int cpu;
 
 	cpu = task_cpu(current);
@@ -227,8 +230,9 @@ asmlinkage notrace void secondary_start_kernel(void)
 	 */
 	check_local_cpu_capabilities();
 
-	if (cpu_ops[cpu]->cpu_postboot)
-		cpu_ops[cpu]->cpu_postboot();
+	ops = get_cpu_ops(cpu);
+	if (ops->cpu_postboot)
+		ops->cpu_postboot();
 
 	/*
 	 * Log the CPU info before it is marked online and might get read.
@@ -266,19 +270,21 @@ asmlinkage notrace void secondary_start_kernel(void)
 #ifdef CONFIG_HOTPLUG_CPU
 static int op_cpu_disable(unsigned int cpu)
 {
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
+
 	/*
 	 * If we don't have a cpu_die method, abort before we reach the point
 	 * of no return. CPU0 may not have an cpu_ops, so test for it.
 	 */
-	if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
+	if (!ops || !ops->cpu_die)
 		return -EOPNOTSUPP;
 
 	/*
 	 * We may need to abort a hot unplug for some other mechanism-specific
 	 * reason.
 	 */
-	if (cpu_ops[cpu]->cpu_disable)
-		return cpu_ops[cpu]->cpu_disable(cpu);
+	if (ops->cpu_disable)
+		return ops->cpu_disable(cpu);
 
 	return 0;
 }
@@ -314,15 +320,17 @@ int __cpu_disable(void)
 
 static int op_cpu_kill(unsigned int cpu)
 {
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
+
 	/*
 	 * If we have no means of synchronising with the dying CPU, then assume
 	 * that it is really dead. We can only wait for an arbitrary length of
 	 * time and hope that it's dead, so let's skip the wait and just hope.
 	 */
-	if (!cpu_ops[cpu]->cpu_kill)
+	if (!ops->cpu_kill)
 		return 0;
 
-	return cpu_ops[cpu]->cpu_kill(cpu);
+	return ops->cpu_kill(cpu);
 }
 
 /*
@@ -357,6 +365,7 @@ void __cpu_die(unsigned int cpu)
 void cpu_die(void)
 {
 	unsigned int cpu = smp_processor_id();
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
 
 	idle_task_exit();
 
@@ -370,12 +379,22 @@ void cpu_die(void)
 	 * mechanism must perform all required cache maintenance to ensure that
 	 * no dirty lines are lost in the process of shutting down the CPU.
 	 */
-	cpu_ops[cpu]->cpu_die(cpu);
+	ops->cpu_die(cpu);
 
 	BUG();
 }
 #endif
 
+static void __cpu_try_die(int cpu)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+	const struct cpu_operations *ops = get_cpu_ops(cpu);
+
+	if (ops && ops->cpu_die)
+		ops->cpu_die(cpu);
+#endif
+}
+
 /*
  * Kill the calling secondary CPU, early in bringup before it is turned
  * online.
@@ -389,12 +408,11 @@ void cpu_die_early(void)
 	/* Mark this CPU absent */
 	set_cpu_present(cpu, 0);
 
-#ifdef CONFIG_HOTPLUG_CPU
+	if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) {
 		update_cpu_boot_status(CPU_KILL_ME);
-	/* Check if we can park ourselves */
-	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
-		cpu_ops[cpu]->cpu_die(cpu);
-#endif
+		__cpu_try_die(cpu);
+	}
+
 	update_cpu_boot_status(CPU_STUCK_IN_KERNEL);
 
 	cpu_park_loop();
@@ -488,10 +506,13 @@ static bool __init is_mpidr_duplicate(unsigned int cpu, u64 hwid)
  */
 static int __init smp_cpu_setup(int cpu)
 {
+	const struct cpu_operations *ops;
+
 	if (init_cpu_ops(cpu))
 		return -ENODEV;
 
-	if (cpu_ops[cpu]->cpu_init(cpu))
+	ops = get_cpu_ops(cpu);
+	if (ops->cpu_init(cpu))
 		return -ENODEV;
 
 	set_cpu_possible(cpu, true);
@@ -714,6 +735,7 @@ void __init smp_init_cpus(void)
 
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+	const struct cpu_operations *ops;
 	int err;
 	unsigned int cpu;
 	unsigned int this_cpu;
@@ -744,10 +766,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 		if (cpu == smp_processor_id())
 			continue;
 
-		if (!cpu_ops[cpu])
+		ops = get_cpu_ops(cpu);
+		if (!ops)
 			continue;
 
-		err = cpu_ops[cpu]->cpu_prepare(cpu);
+		err = ops->cpu_prepare(cpu);
 		if (err)
 			continue;
 
@@ -863,10 +886,8 @@ static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 	local_irq_disable();
 	sdei_mask_local_cpu();
 
-#ifdef CONFIG_HOTPLUG_CPU
-	if (cpu_ops[cpu]->cpu_die)
-		cpu_ops[cpu]->cpu_die(cpu);
-#endif
+	if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
+		__cpu_try_die(cpu);
 
 	/* just in case */
 	cpu_park_loop();
@@ -1044,8 +1065,9 @@ static bool have_cpu_die(void)
 {
 #ifdef CONFIG_HOTPLUG_CPU
 	int any_cpu = raw_smp_processor_id();
+	const struct cpu_operations *ops = get_cpu_ops(any_cpu);
 
-	if (cpu_ops[any_cpu] && cpu_ops[any_cpu]->cpu_die)
+	if (ops && ops->cpu_die)
 		return true;
 #endif
 	return false;