Re: [PATCH] [7/31] Extract page table dumping code from i386 fault handler into dump_pagetable()

Harvey Harrison
2008-01-15T08:56:25Z

On Mon, 2008-01-14 at 23:16 +0100, Andi Kleen wrote:
> Similar to x86-64. This is useful in other situations where we want
> the page table dumped too.
>
> Besides anything that makes i386 do_page_fault shorter is good.
>
> Signed-off-by: Andi Kleen <ak@suse.de>
>
> ---
> arch/x86/mm/fault_32.c | 72 ++++++++++++++++++++++++++-----------------------
> 1 file changed, 39 insertions(+), 33 deletions(-)
>
> Index: linux/arch/x86/mm/fault_32.c
> ===================================================================
> --- linux.orig/arch/x86/mm/fault_32.c
> +++ linux/arch/x86/mm/fault_32.c
> @@ -28,6 +28,44 @@
> #include <asm/desc.h>
> #include <asm/segment.h>
>
> +void dump_pagetable(unsigned long address)

static?

> +{
> + typeof(pte_val(__pte(0))) page;

Is there any type that could be picked that would be nicer than
sprinkling ((__typeof__(page) *), typeof(pte_val(__pte(0))) etc
through here, I know it's just moving the code out to another
function, just wondering if you had any better ideas that someone
could follow-up on.

Maybe another helper printk_page()? could help here.

> +
> + page = read_cr3();
> + page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
> +#ifdef CONFIG_X86_PAE
> + printk("*pdpt = %016Lx ", page);
> + if ((page >> PAGE_SHIFT) < max_low_pfn
> + && page & _PAGE_PRESENT) {
> + page &= PAGE_MASK;
> + page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
> + & (PTRS_PER_PMD - 1)];
> + printk(KERN_CONT "*pde = %016Lx ", page);
> + page &= ~_PAGE_NX;
> + }
> +#else
> + printk("*pde = %08lx ", page);
> +#endif
> +
> + /*
> + * We must not directly access the pte in the highpte
> + * case if the page table is located in highmem.
> + * And let's rather not kmap-atomic the pte, just in case
> + * it's allocated already.
> + */
> + if ((page >> PAGE_SHIFT) < max_low_pfn
> + && (page & _PAGE_PRESENT)
> + && !(page & _PAGE_PSE)) {
> + page &= PAGE_MASK;
> + page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
> + & (PTRS_PER_PTE - 1)];
> + printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
> + }
> +
> + printk("\n");
> +}
> +

Cheers,

Harvey