On Wed, Jul 08, 2009 at 06:40:40PM +0100, Ralf Baechle wrote: > > The resume() implementation octeon_switch.S examines the saved > > cp0_status register. We were clobbering the entire pt_regs structure > > in kernel threads leading to random crashes. > > > > When switching away from a kernel thread, the saved cp0_status is > > examined and if bit 30 is set it is cleared and the CP2 state saved > > into the pt_regs structure. Since the kernel thread stack overlaid > > the pt_regs structure this resulted in a corrupt stack. When the > > kthread with the corrupt stack was resumed, it could crash if it used > > any of the data in the stack that was clobbered. > > > > We fix it by moving the kernel thread stack down so it doesn't overlay > > pt_regs. > > > > Differences from v1: Don't adjust the sp by an additional 32 bytes, it > > was not needed. Also fix up __KSTK_TOS and > > task_pt_regs. > > Thanks for fixing and testing the issues I raised on IRC. Next I'm wonding > what impact the uninitialized state of the stack frame we allocate may > have. I think we're ok - but I need to stare at this for a few more > minutes. Applied :) Ralf
