x86/irq/64: Remove a hardcoded irq_stack_union access

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 <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.872549191@linutronix.de

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index b50ac9c7397bb25439b032a10a094233a7c77fd7..f6dcc8fea5c007cd77971a96bd43755f57eebe64 100644 (file)
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -55,9 +55,8 @@ static inline void stack_overflow_check(struct pt_regs *regs)
            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;