tree 10563ebf4b7536a781eef24ce2e09025f519d275
parent b14a7253cf999412e5a0dd39d58b0a42d19fd73a
author Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> 1383143640 +0530
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> 1386219725 +1100

powerpc/book3s: Introduce exclusive emergency stack for machine check exception.

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@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>