[RFC PATCH v3 02/12] powerpc/book3s: Introduce exclusive emergency stack for machine check exception.

[Paul Mackerras]

On Tue, Aug 27, 2013 at 01:01:32AM +0530, Mahesh J Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> 
> This patch introduces exclusive emergency stack for machine check exception.
> We use emergency stack to handle machine check exception so that we can save
> MCE information (srr1, srr0, dar and dsisr) before turning on ME bit and be
> ready for re-entrancy. This helps us to prevent clobbering of MCE information
> in case of nested machine checks.
> 
> The reason for using emergency stack over normal kernel stack is that the
> machine check might occur in the middle of setting up a stack frame which may
> result into improper use of kernel stack.
> 
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

Acked-by: Paul Mackerras <paulus at samba.org>