linux-kernel - Re: [PATCH 05/18] asm-generic/tlb: Provide generic tlb

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Message-ID: <20180927121425.GC5028@brain-police>
Date:   Thu, 27 Sep 2018 13:14:26 +0100
From:   Will Deacon <will.deacon@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     aneesh.kumar@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        npiggin@...il.com, linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux@...linux.org.uk,
        heiko.carstens@...ibm.com, riel@...riel.com
Subject: Re: [PATCH 05/18] asm-generic/tlb: Provide generic tlb_flush

On Wed, Sep 26, 2018 at 08:07:27PM +0200, Peter Zijlstra wrote:
> --- a/include/asm-generic/tlb.h
> +++ b/include/asm-generic/tlb.h
> @@ -305,7 +305,8 @@ static inline void __tlb_reset_range(str
>  #error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma()
>  #endif
>  
> -#define tlb_flush tlb_flush
> +#define generic_tlb_flush
> +
>  static inline void tlb_flush(struct mmu_gather *tlb)
>  {
>  	if (tlb->fullmm || tlb->need_flush_all) {
> @@ -391,12 +392,12 @@ static inline unsigned long tlb_get_unma
>   * the vmas are adjusted to only cover the region to be torn down.
>   */
>  #ifndef tlb_start_vma
> -#define tlb_start_vma tlb_start_vma
>  static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
>  {
>  	if (tlb->fullmm)
>  		return;
>  
> +#ifdef generic_tlb_flush
>  	/*
>  	 * flush_tlb_range() implementations that look at VM_HUGETLB (tile,
>  	 * mips-4k) flush only large pages.
> @@ -410,13 +411,13 @@ static inline void tlb_start_vma(struct
>  	 */
>  	tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB);
>  	tlb->vma_exec = !!(vma->vm_flags & VM_EXEC);
> +#endif

Alternatively, we could wrap the two assignments above in a macro like:

	tlb_update_vma_flags(tlb, vma)

which could be empty if the generic tlb_flush isn't in use?

Anyway, as long as we resolve this one way or the other, you can add my Ack:

Acked-by: Will Deacon <will.deacon@....com>

Cheers,

Will