Commit-ID:  4f44b8f0b33b7111216f0fad353315f796b81617
Gitweb:     https://git.kernel.org/tip/4f44b8f0b33b7111216f0fad353315f796b81617
Author:     Andy Lutomirski <[email protected]>
AuthorDate: Sun, 14 Apr 2019 17:59:40 +0200
Committer:  Borislav Petkov <[email protected]>
CommitDate: Wed, 17 Apr 2019 12:31:38 +0200

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Sean Christopherson <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Nicolai Stange <[email protected]>
Cc: x86-ml <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
 arch/x86/kernel/irq_64.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index b50ac9c7397b..f6dcc8fea5c0 100644
--- 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;
 

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