tree 88bf4fbfa126ba8c66cf315d34f04913b6e05260
parent 7222f779acf94a123557c7bbbfbcc19424589f52
author Benjamin Herrenschmidt <benh@kernel.crashing.org> 1395974189 +1100
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> 1396830795 +1000

powerpc/ppc64: Gracefully handle early interrupts

If we take an interrupt such as a trap caused by a BUG_ON before the
MMU has been setup, the interrupt handlers try to enable virutal mode
and cause a recursive crash, making the original problem very hard
to debug.

This fixes it by adjusting the "kernel_msr" value in the PACA so that
it only has MSR_IR and MSR_DR (translation for instruction and data)
set after the MMU has been initialized for the processor.

We may still not have a console yet but at least we don't get into
a recursive fault (and early debug console or memory dump via JTAG
of the kernel buffer *will* give us the proper error).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>