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Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions inline

Started byChristophe Leroy <christophe.leroy@c-s.fr>
First post2015-10-08 03:10 +0200
Last post2015-10-12 20:10 +0200
Articles 3 — 3 participants

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  Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions  inline Christophe Leroy <christophe.leroy@c-s.fr> - 2015-10-08 03:10 +0200
    Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions  inline Scott Wood <scottwood@freescale.com> - 2015-10-08 21:20 +0200
      Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions  inline christophe leroy <christophe.leroy@c-s.fr> - 2015-10-12 20:10 +0200

#1241915 — Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions inline

FromChristophe Leroy <christophe.leroy@c-s.fr>
Date2015-10-08 03:10 +0200
SubjectRe: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions inline
Message-ID<qh7Sx-51D-3@gated-at.bofh.it>

Le 29/09/2015 02:29, Scott Wood a écrit :
> On Tue, Sep 22, 2015 at 06:51:13PM +0200, Christophe Leroy wrote:
>> flush/clean/invalidate _dcache_range() functions are all very
>> similar and are quite short. They are mainly used in __dma_sync()
>> perf_event locate them in the top 3 consumming functions during
>> heavy ethernet activity
>>
>> They are good candidate for inlining, as __dma_sync() does
>> almost nothing but calling them
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> New in v2
>>
>>   arch/powerpc/include/asm/cacheflush.h | 55 +++++++++++++++++++++++++++--
>>   arch/powerpc/kernel/misc_32.S         | 65 -----------------------------------
>>   arch/powerpc/kernel/ppc_ksyms.c       |  2 ++
>>   3 files changed, 54 insertions(+), 68 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
>> index 6229e6b..6169604 100644
>> --- a/arch/powerpc/include/asm/cacheflush.h
>> +++ b/arch/powerpc/include/asm/cacheflush.h
>> @@ -47,12 +47,61 @@ static inline void __flush_dcache_icache_phys(unsigned long physaddr)
>>   }
>>   #endif
>>   
>> -extern void flush_dcache_range(unsigned long start, unsigned long stop);
>>   #ifdef CONFIG_PPC32
>> -extern void clean_dcache_range(unsigned long start, unsigned long stop);
>> -extern void invalidate_dcache_range(unsigned long start, unsigned long stop);
>> +/*
>> + * Write any modified data cache blocks out to memory and invalidate them.
>> + * Does not invalidate the corresponding instruction cache blocks.
>> + */
>> +static inline void flush_dcache_range(unsigned long start, unsigned long stop)
>> +{
>> +	void *addr = (void *)(start & ~(L1_CACHE_BYTES - 1));
>> +	unsigned int size = stop - (unsigned long)addr + (L1_CACHE_BYTES - 1);
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < size >> L1_CACHE_SHIFT; i++, addr += L1_CACHE_BYTES)
>> +		dcbf(addr);
>> +	if (i)
>> +		mb();	/* sync */
>> +}
> I know this is 32-bit-specific code, but it's still bad practice to use
> "unsigned int" for addresses or sizes thereof.
>
>
Ok, I can fix size, but what about start and stop ? If I change that, it 
means I also have to fix all caller. Do you expect me to do that ?

And it is very unlykely, but what if for some reason someone wants to 
invalidate the entire user address space which is 3Gbytes size ? A 
signed size would be negative here.

Christophe
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#1242695

FromScott Wood <scottwood@freescale.com>
Date2015-10-08 21:20 +0200
Message-ID<qhoTo-4d2-17@gated-at.bofh.it>
In reply to#1241915
On Wed, 2015-10-07 at 14:49 +0200, Christophe Leroy wrote:
> Le 29/09/2015 02:29, Scott Wood a écrit :
> > On Tue, Sep 22, 2015 at 06:51:13PM +0200, Christophe Leroy wrote:
> > > flush/clean/invalidate _dcache_range() functions are all very
> > > similar and are quite short. They are mainly used in __dma_sync()
> > > perf_event locate them in the top 3 consumming functions during
> > > heavy ethernet activity
> > > 
> > > They are good candidate for inlining, as __dma_sync() does
> > > almost nothing but calling them
> > > 
> > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> > > ---
> > > New in v2
> > > 
> > >   arch/powerpc/include/asm/cacheflush.h | 55 
> > > +++++++++++++++++++++++++++--
> > >   arch/powerpc/kernel/misc_32.S         | 65 ---------------------------
> > > --------
> > >   arch/powerpc/kernel/ppc_ksyms.c       |  2 ++
> > >   3 files changed, 54 insertions(+), 68 deletions(-)
> > > 
> > > diff --git a/arch/powerpc/include/asm/cacheflush.h 
> > > b/arch/powerpc/include/asm/cacheflush.h
> > > index 6229e6b..6169604 100644
> > > --- a/arch/powerpc/include/asm/cacheflush.h
> > > +++ b/arch/powerpc/include/asm/cacheflush.h
> > > @@ -47,12 +47,61 @@ static inline void 
> > > __flush_dcache_icache_phys(unsigned long physaddr)
> > >   }
> > >   #endif
> > >   
> > > -extern void flush_dcache_range(unsigned long start, unsigned long 
> > > stop);
> > >   #ifdef CONFIG_PPC32
> > > -extern void clean_dcache_range(unsigned long start, unsigned long 
> > > stop);
> > > -extern void invalidate_dcache_range(unsigned long start, unsigned long 
> > > stop);
> > > +/*
> > > + * Write any modified data cache blocks out to memory and invalidate 
> > > them.
> > > + * Does not invalidate the corresponding instruction cache blocks.
> > > + */
> > > +static inline void flush_dcache_range(unsigned long start, unsigned 
> > > long stop)
> > > +{
> > > + void *addr = (void *)(start & ~(L1_CACHE_BYTES - 1));
> > > + unsigned int size = stop - (unsigned long)addr + (L1_CACHE_BYTES - 1);
> > > + unsigned int i;
> > > +
> > > + for (i = 0; i < size >> L1_CACHE_SHIFT; i++, addr += L1_CACHE_BYTES)
> > > +         dcbf(addr);
> > > + if (i)
> > > +         mb();   /* sync */
> > > +}
> > I know this is 32-bit-specific code, but it's still bad practice to use
> > "unsigned int" for addresses or sizes thereof.
> > 
> > 
> Ok, I can fix size, but what about start and stop ? If I change that, it 
> means I also have to fix all caller. Do you expect me to do that ?

start and stop are already unsigned long.

> And it is very unlykely, but what if for some reason someone wants to 
> invalidate the entire user address space which is 3Gbytes size ? A 
> signed size would be negative here.

Why would size be signed?

-Scott

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#1244973

Fromchristophe leroy <christophe.leroy@c-s.fr>
Date2015-10-12 20:10 +0200
Message-ID<qiPHQ-6Go-9@gated-at.bofh.it>
In reply to#1242695

Le 08/10/2015 21:12, Scott Wood a écrit :
> On Wed, 2015-10-07 at 14:49 +0200, Christophe Leroy wrote:
>> Le 29/09/2015 02:29, Scott Wood a écrit :
>>> On Tue, Sep 22, 2015 at 06:51:13PM +0200, Christophe Leroy wrote:
>>>> flush/clean/invalidate _dcache_range() functions are all very
>>>> similar and are quite short. They are mainly used in __dma_sync()
>>>> perf_event locate them in the top 3 consumming functions during
>>>> heavy ethernet activity
>>>>
>>>> They are good candidate for inlining, as __dma_sync() does
>>>> almost nothing but calling them
>>>>
>>>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>>> ---
>>>> New in v2
>>>>
>>>>    arch/powerpc/include/asm/cacheflush.h | 55
>>>> +++++++++++++++++++++++++++--
>>>>    arch/powerpc/kernel/misc_32.S         | 65 ---------------------------
>>>> --------
>>>>    arch/powerpc/kernel/ppc_ksyms.c       |  2 ++
>>>>    3 files changed, 54 insertions(+), 68 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/include/asm/cacheflush.h
>>>> b/arch/powerpc/include/asm/cacheflush.h
>>>> index 6229e6b..6169604 100644
>>>> --- a/arch/powerpc/include/asm/cacheflush.h
>>>> +++ b/arch/powerpc/include/asm/cacheflush.h
>>>> @@ -47,12 +47,61 @@ static inline void
>>>> __flush_dcache_icache_phys(unsigned long physaddr)
>>>>    }
>>>>    #endif
>>>>    
>>>> -extern void flush_dcache_range(unsigned long start, unsigned long
>>>> stop);
>>>>    #ifdef CONFIG_PPC32
>>>> -extern void clean_dcache_range(unsigned long start, unsigned long
>>>> stop);
>>>> -extern void invalidate_dcache_range(unsigned long start, unsigned long
>>>> stop);
>>>> +/*
>>>> + * Write any modified data cache blocks out to memory and invalidate
>>>> them.
>>>> + * Does not invalidate the corresponding instruction cache blocks.
>>>> + */
>>>> +static inline void flush_dcache_range(unsigned long start, unsigned
>>>> long stop)
>>>> +{
>>>> + void *addr = (void *)(start & ~(L1_CACHE_BYTES - 1));
>>>> + unsigned int size = stop - (unsigned long)addr + (L1_CACHE_BYTES - 1);
>>>> + unsigned int i;
>>>> +
>>>> + for (i = 0; i < size >> L1_CACHE_SHIFT; i++, addr += L1_CACHE_BYTES)
>>>> +         dcbf(addr);
>>>> + if (i)
>>>> +         mb();   /* sync */
>>>> +}
>>> I know this is 32-bit-specific code, but it's still bad practice to use
>>> "unsigned int" for addresses or sizes thereof.
>>>
>>>
>> Ok, I can fix size, but what about start and stop ? If I change that, it
>> means I also have to fix all caller. Do you expect me to do that ?
> start and stop are already unsigned long.
>
>> And it is very unlykely, but what if for some reason someone wants to
>> invalidate the entire user address space which is 3Gbytes size ? A
>> signed size would be negative here.
> Why would size be signed?

Oops, indeed I misunderstood your comment, thought you said:
* size has to be signed int instead of unsigned int
* addresses have to be void *

I understand now that size and addresses should be unsigned long instead

Christophe


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