powerpc/64: Avoid panic during boot due to divide by zero in init_cache_info()
authorAnton Blanchard <anton@samba.org>
Sat, 4 Mar 2017 23:54:34 +0000 (10:54 +1100)
committerMichael Ellerman <mpe@ellerman.id.au>
Mon, 6 Mar 2017 10:44:09 +0000 (21:44 +1100)
commit6ba422c75facb1b1e0e206c464ee121b8073f7e0
tree5ab7573657019a678a3607d59a913be3cc86caa3
parent014d02cbf16b3106dc8e93281d2a9c189751ed5e
powerpc/64: Avoid panic during boot due to divide by zero in init_cache_info()

I see a panic in early boot when building with a recent gcc toolchain.
The issue is a divide by zero, which is undefined. Older toolchains
let us get away with it:

int foo(int a) { return a / 0; }

foo:
li 9,0
divw 3,3,9
extsw 3,3
blr

But newer ones catch it:

foo:
trap

Add a check to avoid the divide by zero.

Fixes: e2827fe5c156 ("powerpc/64: Clean up ppc64_caches using a struct per cache")
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/kernel/setup_64.c