On Fri, Feb 07, 2020 at 05:20:57PM +0000, Christophe Leroy wrote:
> When CONFIG_PROVE_LOCKING is selected together with (now default)
> CONFIG_VMAP_STACK, kernel enter deadlock during boot.
>
> At the point of checking whether interrupts are enabled or not, the
> value of MSR saved on stack is read using the physical address of the
> stack. But at this point, when using VMAP stack the DATA MMU
> translation has already been re-enabled, leading to deadlock.
>
> Don't use the physical address of the stack when
> CONFIG_VMAP_STACK is set.
>
> Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
> Reported-by: Guenter Roeck <li...@roeck-us.net>
> Fixes: 028474876f47 ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Tested-by: Guenter Roeck <li...@roeck-us.net>
> ---
> arch/powerpc/kernel/entry_32.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
> index 77abbc34bbe0..0713daa651d9 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -214,7 +214,7 @@ transfer_to_handler_cont:
> * To speed up the syscall path where interrupts stay on, let's check
> * first if we are changing the MSR value at all.
> */
> - tophys(r12, r1)
> + tophys_novmstack r12, r1
> lwz r12,_MSR(r12)
> andi. r12,r12,MSR_EE
> bne 1f
> --
> 2.25.0
>
