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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH -V3 03/11] arch/powerpc: Convert virtual address to vpn
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Date: Tue, 10 Jul 2012 11:45:36 +0530
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Stephen Rothwell <sfr@canb.auug.org.au> writes:

> Hi Aneesh,
>
> On Mon,  9 Jul 2012 18:43:33 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
>>
>> diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
>> index 660b8bb..308e29d 100644
>> --- a/arch/powerpc/mm/hash_native_64.c
>> +++ b/arch/powerpc/mm/hash_native_64.c
>> @@ -39,22 +39,33 @@
>>  
>>  DEFINE_RAW_SPINLOCK(native_tlbie_lock);
>>  
>> -static inline void __tlbie(unsigned long va, int psize, int ssize)
>> +static inline void __tlbie(unsigned long vpn, int psize, int ssize)
>>  {
>> +	unsigned long va;
>>  	unsigned int penc;
>>  
>> +	/*
>> +	 * We need 14 to 65 bits of va for a tlibe of 4K page
>> +	 * With vpn we ignore the lower VPN_SHIFT bits already.
>> +	 * And top two bits are already ignored because we can
>> +	 * only accomadate 76 bits in a 64 bit vpn with a VPN_SHIFT
>> +	 * of 12.
>> +	 */
>> +	BUG_ON((77 - 65) > VPN_SHIFT);
>
> BUILD_BUG_ON() ?

Yes. I also found a bug there. It should be updated as below

	BUILD_BUG_ON(VPN_SHIFT > (77 - 65));

We want to make sure we are not ignoring bits above 65th bit. 


>
>> -static inline void __tlbiel(unsigned long va, int psize, int ssize)
>> +static inline void __tlbiel(unsigned long vpn, int psize, int ssize)
>>  {
>> +	unsigned long va;
>>  	unsigned int penc;
>>  
>> +	BUG_ON((77 - 65) > VPN_SHIFT);
>
> BUILD_BUG_ON() ?

-aneesh