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

From: Christoffer Dall <christoffer.dall@linaro.org>
To: Punit Agrawal <punit.agrawal@arm.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org,
	Mark Rutland <mark.rutland@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [RFC v2 PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro
Date: Tue, 6 Sep 2016 08:38:30 +0200	[thread overview]
Message-ID: <20160906063830.GC30513@cbox> (raw)
In-Reply-To: <1473093097-30932-5-git-send-email-punit.agrawal@arm.com>

On Mon, Sep 05, 2016 at 05:31:34PM +0100, Punit Agrawal wrote:
> From: Mark Rutland <mark.rutland@arm.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@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> [ rename helper to __tlbi, update commit log ]
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.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.

> + *
> + * 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
> 