Re: [Xen-devel] [PATCH 2 of 4] get_page_type: Print out extra information when failing to get page_type

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 08/21/12 10:22 PM >>>
>get_page_type: Print out extra information when failing to get page_type.
>
>When any reference to __get_page_type is called and it fails, we get:
>
>(XEN) mm.c:2429:d0 Bad type (saw 1400000000000002 != exp 7000000000000000) for 
>mfn 10e392 (pfn 1bf6c)
>
>with this patch we get some extra details such as:
>(XEN) debug.c:127:d0 cr3: 10d80b000, searching for 10e392
>(XEN) debug.c:111:d0 cr3(10d80b000) has mfn(10e392) in level PUD/L3: [258][272]
>(XEN) debug.c:111:d0 cr3(10d80b000) has mfn(10e392) in level PMD/L2: 
>[258][511][511]
>(XEN) debug.c:111:d0 cr3(10d80b000) has mfn(10e392) in level PGD/L4: [272]
>(XEN) debug.c:111:d0 cr3(10d80b000) has mfn(10e392) in level PUD/L3: [511][511]
>
>where it actually is in the pagetable of the guest. This is useful
>b/c we can figure out where it is, and use that to figure out where
>the OS thinks it is.

Hmm, not sure how useful this is: To me, it is first of all non-obvious why
there are two instances of L3 here, what the non-consistent indexes really
mean, and what the repeated printing of CR3 is good for.

>--- a/xen/arch/x86/debug.c    Tue Aug 21 16:08:29 2012 -0400
>+++ b/xen/arch/x86/debug.c    Tue Aug 21 16:08:29 2012 -0400

Further, putting the code in this file is likely wrong - as it says close to its
top, its a helper file for debuggers.

>--- a/xen/arch/x86/mm.c    Tue Aug 21 16:08:29 2012 -0400
>+++ b/xen/arch/x86/mm.c    Tue Aug 21 16:08:29 2012 -0400
>@@ -2422,6 +2422,8 @@ static int __put_page_type(struct page_i
>}
 >
 >
>+extern void dbg_pv_mfn(unsigned long mfn, struct domain *d);
>+
>static int __get_page_type(struct page_info *page, unsigned long type,
>int preemptible)
>{

No extern declarations in C files please.

Jan


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