On Wed, Apr 30, 2014 at 05:55:56PM -0400, David Miller wrote:
>
> Instead of returning false we should at least check the most basic
> things, otherwise page table corruptions will be very difficult to
> debug.
>
> PMD and PTE tables are of size PAGE_SIZE, so none of the sub-PAGE_SIZE
> bits should be set.
>
> We also complement this with a check that the physical address the
> pud/pmd points to is valid memory.
>
> PowerPC was used as a guide while implementating this.
>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> ---
> arch/sparc/include/asm/pgtable_64.h | 46 +++++++++++++++++++++++++------------
> 1 file changed, 31 insertions(+), 15 deletions(-)
>
> diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> index ff97960..fd4dbdd 100644
> --- a/arch/sparc/include/asm/pgtable_64.h
> +++ b/arch/sparc/include/asm/pgtable_64.h
> @@ -71,6 +71,23 @@
>
> #include <linux/sched.h>
>
> +extern unsigned long sparc64_valid_addr_bitmap[];
> +
> +/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
> +static inline bool __kern_addr_valid(unsigned long paddr)
It would had been self-documenting if the type is changed to phys_addr_t here.
But I see that we do not use phys_addr_t much (only one place) in sparc code today.
> +{
> + if ((paddr >> MAX_PHYS_ADDRESS_BITS) != 0UL)
> + return false;
> + return test_bit(paddr >> 22, sparc64_valid_addr_bitmap);
> +}
I assume it is a coincidence that we have the same block size
in sparc64_valid_addr_bitmapi (22) as we have for REAL_HPAGE_SHIFT.
Sam
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