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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: e2827fe5c1 ("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>
This commit is contained in:
Anton Blanchard 2017-03-05 10:54:34 +11:00 committed by Michael Ellerman
parent 014d02cbf1
commit 6ba422c75f
1 changed files with 4 additions and 1 deletions
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5
arch/powerpc/kernel/setup_64.c
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@ -408,7 +408,10 @@ static void init_cache_info(struct ppc_cache_info *info, u32 size, u32 lsize,
info->line_size = lsize;
info->block_size = bsize;
info->log_block_size = __ilog2(bsize);
info->blocks_per_page = PAGE_SIZE / bsize;
if (bsize)
info->blocks_per_page = PAGE_SIZE / bsize;
else
info->blocks_per_page = 0;
if (sets == 0)
info->assoc = 0xffff;