linux-kernel - Re: [RFC v2 PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro

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Message-ID: <87d1khjqci.fsf@e105922-lin.cambridge.arm.com>
Date:   Tue, 06 Sep 2016 11:05:17 +0100
From:   Punit Agrawal <punit.agrawal@....com>
To:     Christoffer Dall <christoffer.dall@...aro.org>
Cc:     kvm@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC v2 PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro

Christoffer Dall <christoffer.dall@...aro.org> writes:

> On Mon, Sep 05, 2016 at 05:31:34PM +0100, Punit Agrawal wrote:
>> From: Mark Rutland <mark.rutland@....com>
>> 
>> As with dsb() and isb(), add a __tlbi() helper so that we can avoid
>> distracting asm boilerplate every time we want a TLBI. As some TLBI
>> operations take an argument while others do not, some pre-processor is
>> used to handle these two cases with different assembly blocks.
>> 
>> The existing tlbflush.h code is moved over to use the helper.
>> 
>> Signed-off-by: Mark Rutland <mark.rutland@....com>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> Cc: Will Deacon <will.deacon@....com>
>> [ rename helper to __tlbi, update commit log ]
>> Signed-off-by: Punit Agrawal <punit.agrawal@....com>
>> ---
>>  arch/arm64/include/asm/tlbflush.h | 31 +++++++++++++++++++++++--------
>>  1 file changed, 23 insertions(+), 8 deletions(-)
>> 
>> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
>> index b460ae2..e9e42a7 100644
>> --- a/arch/arm64/include/asm/tlbflush.h
>> +++ b/arch/arm64/include/asm/tlbflush.h
>> @@ -25,6 +25,21 @@
>>  #include <asm/cputype.h>
>>  
>>  /*
>> + * Raw TLBI operations. Drivers and most kernel code should use the TLB
>> + * management routines below in preference to these. Where necessary, these can
>
> in preference to these?
>
>> + * be used to avoid asm() boilerplate.
>
> 'these' seem to be a bit overloaded in this commentary.
>

I've locally updated the comment to - 

"Raw TLBI operations.

Where necessary, use the __tlbi macro to avoid asm()
boilerplate. *Note:* Drivers and most kernel code should use the
TLB management routines in preference to the macros."

Is that better?

>> + *
>> + * Can be used as __tlbi(op) or __tlbi(op, arg), depending on whether a
>> + * particular TLBI op takes an argument or not. The macros below handle invoking
>> + * the asm with or without the register argument as appropriate.
>> + */
>> +#define __TLBI_0(op, arg)		asm ("tlbi " #op)
>> +#define __TLBI_1(op, arg)		asm ("tlbi " #op ", %0" : : "r" (arg))
>> +#define __TLBI_N(op, arg, n, ...)	__TLBI_##n(op, arg)
>> +
>> +#define __tlbi(op, ...)		__TLBI_N(op, ##__VA_ARGS__, 1, 0)
>> +
>> +/*
>>   *	TLB Management
>>   *	==============
>>   *
>> @@ -66,7 +81,7 @@
>>  static inline void local_flush_tlb_all(void)
>>  {
>>  	dsb(nshst);
>> -	asm("tlbi	vmalle1");
>> +	__tlbi(vmalle1);
>>  	dsb(nsh);
>>  	isb();
>>  }
>> @@ -74,7 +89,7 @@ static inline void local_flush_tlb_all(void)
>>  static inline void flush_tlb_all(void)
>>  {
>>  	dsb(ishst);
>> -	asm("tlbi	vmalle1is");
>> +	__tlbi(vmalle1is);
>>  	dsb(ish);
>>  	isb();
>>  }
>> @@ -84,7 +99,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>>  	unsigned long asid = ASID(mm) << 48;
>>  
>>  	dsb(ishst);
>> -	asm("tlbi	aside1is, %0" : : "r" (asid));
>> +	__tlbi(aside1is, asid);
>>  	dsb(ish);
>>  }
>>  
>> @@ -94,7 +109,7 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
>>  	unsigned long addr = uaddr >> 12 | (ASID(vma->vm_mm) << 48);
>>  
>>  	dsb(ishst);
>> -	asm("tlbi	vale1is, %0" : : "r" (addr));
>> +	__tlbi(vale1is, addr);
>>  	dsb(ish);
>>  }
>>  
>> @@ -122,9 +137,9 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
>>  	dsb(ishst);
>>  	for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12)) {
>>  		if (last_level)
>> -			asm("tlbi vale1is, %0" : : "r"(addr));
>> +			__tlbi(vale1is, addr);
>>  		else
>> -			asm("tlbi vae1is, %0" : : "r"(addr));
>> +			__tlbi(vae1is, addr);
>>  	}
>>  	dsb(ish);
>>  }
>> @@ -149,7 +164,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
>>  
>>  	dsb(ishst);
>>  	for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
>> -		asm("tlbi vaae1is, %0" : : "r"(addr));
>> +		__tlbi(vaae1is, addr);
>>  	dsb(ish);
>>  	isb();
>>  }
>> @@ -163,7 +178,7 @@ static inline void __flush_tlb_pgtable(struct mm_struct *mm,
>>  {
>>  	unsigned long addr = uaddr >> 12 | (ASID(mm) << 48);
>>  
>> -	asm("tlbi	vae1is, %0" : : "r" (addr));
>> +	__tlbi(vae1is, addr);
>>  	dsb(ish);
>>  }
>>  
>> -- 
>> 2.8.1
>> 
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> kvmarm@...ts.cs.columbia.edu
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