arch/x86/include/asm/irq_stack.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_IRQ_STACK_H
#define _ASM_X86_IRQ_STACK_H

#include <linux/ptrace.h>

#include <asm/processor.h>

#ifdef CONFIG_X86_64
static __always_inline bool irqstack_active(void)
{
	return __this_cpu_read(irq_count) != -1;
}

void asm_call_on_stack(void *sp, void *func, void *arg);

static __always_inline void __run_on_irqstack(void *func, void *arg)
{
	void *tos = __this_cpu_read(hardirq_stack_ptr);

	__this_cpu_add(irq_count, 1);
	asm_call_on_stack(tos - 8, func, arg);
	__this_cpu_sub(irq_count, 1);
}

#else /* CONFIG_X86_64 */
static inline bool irqstack_active(void) { return false; }
static inline void __run_on_irqstack(void *func, void *arg) { }
#endif /* !CONFIG_X86_64 */

static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs)
{
	if (IS_ENABLED(CONFIG_X86_32))
		return false;
	if (!regs)
		return !irqstack_active();
	return !user_mode(regs) && !irqstack_active();
}

static __always_inline void run_on_irqstack_cond(void *func, void *arg,
						 struct pt_regs *regs)
{
	void (*__func)(void *arg) = func;

	lockdep_assert_irqs_disabled();

	if (irq_needs_irq_stack(regs))
		__run_on_irqstack(__func, arg);
	else
		__func(arg);
}

#endif