On Wed, 6 Aug 2014, Kees Cook wrote:
> With the original code, there is (I think) a page table entry for the
> fixmap range. For the latter, there isn't. I see a NULL pgd entry
> fault when trying to use it, and noticed that this only exists under
> highmem:
>
> static void __init kmap_init(void)
> {
> #ifdef CONFIG_HIGHMEM
> pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
> PKMAP_BASE, _PAGE_KERNEL_TABLE);
>
> fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
> FIXADDR_START, _PAGE_KERNEL_TABLE);
> #endif
> }
The above is wrong. The fixmap PTEs must be allocated unconditionally
irrespective of highmem. So the #endif should be moved up by 3 lines.
Nicolas
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