Re: [PATCH v3 2/2] ARM : change fixmap mapping region to support 32 CPUs

[Nicolas Pitre]

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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