On Sun, 2017-03-05 at 11:25 +1100, Benjamin Herrenschmidt wrote:
> On Sun, 2017-03-05 at 10:54 +1100, Anton Blanchard wrote:
> > From: Anton Blanchard <an...@samba.org>
> >
> > 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:
>
> Maybe we should panic though ... not having a valid cache block size
> is going to be fatal in other areas...
... Unless it's for L2/L3 caches. Of course...
Acked-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> > 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: bd067f83b084 ("powerpc/64: Fix naming of cache block vs.
> > cache
> > line")
> > Signed-off-by: Anton Blanchard <an...@samba.org>
> > ---
> > arch/powerpc/kernel/setup_64.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/kernel/setup_64.c
> > b/arch/powerpc/kernel/setup_64.c
> > index adf2084..afd1c26 100644
> > --- a/arch/powerpc/kernel/setup_64.c
> > +++ b/arch/powerpc/kernel/setup_64.c
> > @@ -408,7 +408,8 @@ 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;
> >
> > if (sets == 0)
> > info->assoc = 0xffff;
