On Fri, Apr 05, 2019 at 09:37:27AM -0700, Sean Christopherson wrote: > On Fri, Apr 05, 2019 at 05:07:01PM +0200, Thomas Gleixner wrote: > > 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; > > 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.
I agree, but... one man's top is another man's bottom. Especially when stacks grow physically down (as defined by Intel) but conceptually up (as defined by every CS algorithms class ever). -- Josh
