[patch V2 03/29] x86/irq/64: Remove a hardcoded irq_stack_union access

[Thomas Gleixner]

From: Andy Lutomirski <l...@kernel.org>

stack_overflow_check() is using both irq_stack_ptr and irq_stack_union to
find the IRQ stack. That's going to break when vmapped irq stacks are
introduced.

Change it to just use irq_stack_ptr.

Signed-off-by: Andy Lutomirski <l...@kernel.org>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>

---
 arch/x86/kernel/irq_64.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -55,9 +55,8 @@ static inline void stack_overflow_check(
            regs->sp <= curbase + THREAD_SIZE)
                return;
 
-       irq_stack_top = (u64)this_cpu_ptr(irq_stack_union.irq_stack) +
-                       STACK_TOP_MARGIN;
        irq_stack_bottom = (u64)__this_cpu_read(irq_stack_ptr);
+       irq_stack_top = irq_stack_bottom - IRQ_STACK_SIZE + STACK_TOP_MARGIN;
        if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
                return;