Re: port-m68k/55990: kernel stack leak in m68k cpu_setmcontext() and reenter_syscall()

[Jason Thorpe <thorpej%me.com@localhost>]

> On Feb 21, 2021, at 4:40 AM, Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost> wrote:
> 
> With this patch, the Xorg based servers both on sun3 and x68k survive
> over 24 hours without kernel crashes.
> (Note the similar x68k crashes were observed at least back in 2012.)
> 
> I wonder if we should also check frame->f_stackadj in trap0()
> but I would like to commit this fix (workaround?) for now.
> 
> Any comments (especially from m68k and siginfo gurus; kleink@? thorpej@?)
> are appreciated.

I'm really digging into archival section of by brain for this one, but this change seems perfectly reasonable.

-- thorpej