Re: [Xen-devel] [PATCH 4/4] x86: check for canonical address before doing page walks

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.10.13 at 16:01, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 10/10/13 14:55, Jan Beulich wrote:
>> --- a/xen/arch/x86/x86_64/traps.c
>> +++ b/xen/arch/x86/x86_64/traps.c
>> @@ -170,6 +170,8 @@ void show_page_walk(unsigned long addr)
>>      l1_pgentry_t l1e, *l1t;
>>  
>>      printk("Pagetable walk from %016lx:\n", addr);
>> +    if ( !is_canonical_address(addr) )
>> +        return;
>>  
>>      l4t = map_domain_page(mfn);
>>      l4e = l4t[l4_table_offset(addr)];
>>
> 
> I was intending something a little more like
> 
> if ( !is_canonical_address(addr) )
> {
>     printk(" Not canonical\n");
>     return;
> }
> 
> So it doesn't appear on the console that show_page_walk() got stuck
> somewhere.

Seems pretty pointless - the address is being printed, and anyone
(I would hope) can easily see whether it is non-canonical.

Jan


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