Messages in this thread | | | Date | Fri, 5 Apr 2019 09:37:27 -0700 | From | Sean Christopherson <> | Subject | Re: [patch V2 03/29] x86/irq/64: Remove a hardcoded irq_stack_union access |
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On Fri, Apr 05, 2019 at 05:07:01PM +0200, Thomas Gleixner wrote: > From: Andy Lutomirski <luto@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 <luto@kernel.org> > Signed-off-by: Thomas Gleixner <tglx@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;
Not introduced in this patch, but the names for top and bottom are flipped, both for irq_stack and estack. STACK_TOP_MARGIN should also be STACK_BOTTOM_MARGIN. The actual checks are functionally correct, but holy hell does it make reading the code confusing, and the WARN prints backwards information.
E.g.:
swapper/10 has overflown the kernel stack
cur:ffffc900000bc000,sp:ffff888277b03f78 irq stk top-bottom:ffff888277b00080-ffff888277b04000 exception stk top-bottom:fffffe00001b4080-fffffe00001b9000
Printing out top-bottom for "cur" would also probably be helpful.
Let me know if you'd like me to send a patch, or if you'll fold a change into this series.
For this patch,
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom) > return; > > >
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