On Tue, May 28, 2013 at 02:05:02PM +0100, Will Deacon wrote:
> On Tue, May 28, 2013 at 11:48:20AM +0100, Po-Yu Chuang wrote:
> > This bug was introduced in commit e651eab0.
> > Some v4/v5 platforms failed to boot due to this.
> >
> > Signed-off-by: Po-Yu Chuang <ratbert.chu...@gmail.com>
> > ---
> > arch/arm/mm/mmu.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> > index e0d8565..19a43f8 100644
> > --- a/arch/arm/mm/mmu.c
> > +++ b/arch/arm/mm/mmu.c
> > @@ -620,6 +620,8 @@ static void __init map_init_section(pmd_t *pmd,
> > unsigned long addr,
> > unsigned long end, phys_addr_t phys,
> > const struct mem_type *type)
> > {
> > + pmd_t *p = pmd;
> > +
> > #ifndef CONFIG_ARM_LPAE
> > /*
> > * In classic MMU format, puds and pmds are folded in to
> > @@ -638,7 +640,7 @@ static void __init map_init_section(pmd_t *pmd,
> > unsigned long addr,
> > phys += SECTION_SIZE;
> > } while (pmd++, addr += SECTION_SIZE, addr != end);
> >
> > - flush_pmd_entry(pmd);
> > + flush_pmd_entry(p);
>
> Wait, shouldn't this flush be *inside* the loop anyway? Otherwise we just
> flush the cacheline containing the first pmd. The flushing code could also
> flush to PoU instead of PoC for UP ARMv7, but that's an unrelated
> optimisation.
With LPAE, map_init_section() is called once per section from
alloc_init_pmd(). The loop is there for classic MMU to allow setting two
pmd entries (maximum) and flush_pmd_entry() takes care of both (it
flushes a full cache line anyway).
--
Catalin
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