x86/irq: Move irq stacks to percpu hot section

No functional change.

Signed-off-by: Brian Gerst <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Acked-by: Uros Bizjak <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/x86/include/asm/current.h

···
 struct pcpu_hot {
 	struct task_struct	*current_task;
 	unsigned long		top_of_stack;
-	void			*hardirq_stack_ptr;
-#ifdef CONFIG_X86_64
-	bool			hardirq_stack_inuse;
-#else
-	void			*softirq_stack_ptr;
-#endif
 };
 
 DECLARE_PER_CPU_CACHE_HOT(struct pcpu_hot, pcpu_hot);

arch/x86/include/asm/irq_stack.h

···
 	ASM_CALL_ARG2
 
 #define call_on_irqstack(func, asm_call, argconstr...)			\
-	call_on_stack(__this_cpu_read(pcpu_hot.hardirq_stack_ptr),	\
+	call_on_stack(__this_cpu_read(hardirq_stack_ptr),		\
 		      func, asm_call, argconstr)
 
 /* Macros to assert type correctness for run_*_on_irqstack macros */
···
 	 * User mode entry and interrupt on the irq stack do not	\
 	 * switch stacks. If from user mode the task stack is empty.	\
 	 */								\
-	if (user_mode(regs) || __this_cpu_read(pcpu_hot.hardirq_stack_inuse)) { \
+	if (user_mode(regs) || __this_cpu_read(hardirq_stack_inuse)) {	\
 		irq_enter_rcu();					\
 		func(c_args);						\
 		irq_exit_rcu();						\
···
 		 * places. Invoke the stack switch macro with the call	\
 		 * sequence which matches the above direct invocation.	\
 		 */							\
-		__this_cpu_write(pcpu_hot.hardirq_stack_inuse, true);	\
+		__this_cpu_write(hardirq_stack_inuse, true);		\
 		call_on_irqstack(func, asm_call, constr);		\
-		__this_cpu_write(pcpu_hot.hardirq_stack_inuse, false);	\
+		__this_cpu_write(hardirq_stack_inuse, false);		\
 	}								\
 }
 
···
  */
 #define do_softirq_own_stack()						\
 {									\
-	__this_cpu_write(pcpu_hot.hardirq_stack_inuse, true);		\
+	__this_cpu_write(hardirq_stack_inuse, true);			\
 	call_on_irqstack(__do_softirq, ASM_CALL_ARG0);			\
-	__this_cpu_write(pcpu_hot.hardirq_stack_inuse, false);		\
+	__this_cpu_write(hardirq_stack_inuse, false);			\
 }
 
 #endif

arch/x86/include/asm/processor.h

···
 	char		stack[IRQ_STACK_SIZE];
 } __aligned(IRQ_STACK_SIZE);
 
+DECLARE_PER_CPU_CACHE_HOT(struct irq_stack *, hardirq_stack_ptr);
+#ifdef CONFIG_X86_64
+DECLARE_PER_CPU_CACHE_HOT(bool, hardirq_stack_inuse);
+#else
+DECLARE_PER_CPU_CACHE_HOT(struct irq_stack *, softirq_stack_ptr);
+#endif
+
 #ifdef CONFIG_X86_64
 static inline unsigned long cpu_kernelmode_gs_base(int cpu)
 {

arch/x86/kernel/dumpstack_32.c

···
 
 static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
 {
-	unsigned long *begin = (unsigned long *)this_cpu_read(pcpu_hot.hardirq_stack_ptr);
+	unsigned long *begin = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
 	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));
 
 	/*
···
 
 static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
 {
-	unsigned long *begin = (unsigned long *)this_cpu_read(pcpu_hot.softirq_stack_ptr);
+	unsigned long *begin = (unsigned long *)this_cpu_read(softirq_stack_ptr);
 	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));
 
 	/*

arch/x86/kernel/dumpstack_64.c

···
 
 static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)
 {
-	unsigned long *end = (unsigned long *)this_cpu_read(pcpu_hot.hardirq_stack_ptr);
+	unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
 	unsigned long *begin;
 
 	/*

arch/x86/kernel/irq.c

···
 DEFINE_PER_CPU_CACHE_HOT(u16, __softirq_pending);
 EXPORT_PER_CPU_SYMBOL(__softirq_pending);
 
+DEFINE_PER_CPU_CACHE_HOT(struct irq_stack *, hardirq_stack_ptr);
+
 atomic_t irq_err_count;
 
 /*

arch/x86/kernel/irq_32.c

···
 static inline void print_stack_overflow(void) { }
 #endif
 
+DEFINE_PER_CPU_CACHE_HOT(struct irq_stack *, softirq_stack_ptr);
+
 static void call_on_stack(void *func, void *stack)
 {
 	asm volatile("xchgl %[sp], %%esp\n"
···
 	u32 *isp, *prev_esp;
 
 	curstk = (struct irq_stack *) current_stack();
-	irqstk = __this_cpu_read(pcpu_hot.hardirq_stack_ptr);
+	irqstk = __this_cpu_read(hardirq_stack_ptr);
 
 	/*
 	 * this is where we switch to the IRQ stack. However, if we are
···
 	int node = cpu_to_node(cpu);
 	struct page *ph, *ps;
 
-	if (per_cpu(pcpu_hot.hardirq_stack_ptr, cpu))
+	if (per_cpu(hardirq_stack_ptr, cpu))
 		return 0;
 
 	ph = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER);
···
 		return -ENOMEM;
 	}
 
-	per_cpu(pcpu_hot.hardirq_stack_ptr, cpu) = page_address(ph);
-	per_cpu(pcpu_hot.softirq_stack_ptr, cpu) = page_address(ps);
+	per_cpu(hardirq_stack_ptr, cpu) = page_address(ph);
+	per_cpu(softirq_stack_ptr, cpu) = page_address(ps);
 	return 0;
 }
 
···
 	struct irq_stack *irqstk;
 	u32 *isp, *prev_esp;
 
-	irqstk = __this_cpu_read(pcpu_hot.softirq_stack_ptr);
+	irqstk = __this_cpu_read(softirq_stack_ptr);
 
 	/* build the stack frame on the softirq stack */
 	isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));

arch/x86/kernel/irq_64.c

···
 #include <asm/io_apic.h>
 #include <asm/apic.h>
 
+DEFINE_PER_CPU_CACHE_HOT(bool, hardirq_stack_inuse);
 DEFINE_PER_CPU_PAGE_ALIGNED(struct irq_stack, irq_stack_backing_store) __visible;
 
 #ifdef CONFIG_VMAP_STACK
···
 		return -ENOMEM;
 
 	/* Store actual TOS to avoid adjustment in the hotpath */
-	per_cpu(pcpu_hot.hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE - 8;
+	per_cpu(hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE - 8;
 	return 0;
 }
 #else
···
 	void *va = per_cpu_ptr(&irq_stack_backing_store, cpu);
 
 	/* Store actual TOS to avoid adjustment in the hotpath */
-	per_cpu(pcpu_hot.hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE - 8;
+	per_cpu(hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE - 8;
 	return 0;
 }
 #endif
 
 int irq_init_percpu_irqstack(unsigned int cpu)
 {
-	if (per_cpu(pcpu_hot.hardirq_stack_ptr, cpu))
+	if (per_cpu(hardirq_stack_ptr, cpu))
 		return 0;
 	return map_irq_stack(cpu);
 }

arch/x86/kernel/process_64.c

···
 	int cpu = smp_processor_id();
 
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) &&
-		     this_cpu_read(pcpu_hot.hardirq_stack_inuse));
+		     this_cpu_read(hardirq_stack_inuse));
 
 	if (!test_tsk_thread_flag(prev_p, TIF_NEED_FPU_LOAD))
 		switch_fpu_prepare(prev_p, cpu);