Re: [PATCH v1 12/13] arm64: mm: Wrap flush_tlb_page() around ___flush_tlb_range()

[Linu Cherian <linu.cherian@arm.com>]

On Tue, Dec 16, 2025 at 02:45:57PM +0000, Ryan Roberts wrote:
> Flushing a page from the tlb is just a special case of flushing a range.
> So let's rework flush_tlb_page() so that it simply wraps
> ___flush_tlb_range(). While at it, let's also update the API to take the
> same flags that we use when flushing a range. This allows us to delete
> all the ugly "_nosync", "_local" and "_nonotify" variants.
> 
> Thanks to constant folding, all of the complex looping and tlbi-by-range
> options get eliminated so that the generated code for flush_tlb_page()
> looks very similar to the previous version.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
>  arch/arm64/include/asm/pgtable.h  |  6 +--
>  arch/arm64/include/asm/tlbflush.h | 81 ++++++++++---------------------
>  arch/arm64/mm/fault.c             |  2 +-
>  3 files changed, 29 insertions(+), 60 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 736747fbc843..b96a7ca465a1 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -136,10 +136,10 @@ static inline void arch_leave_lazy_mmu_mode(void)
>   * entries exist.
>   */
>  #define flush_tlb_fix_spurious_fault(vma, address, ptep)	\
> -	local_flush_tlb_page_nonotify(vma, address)
> +	__flush_tlb_page(vma, address, TLBF_NOBROADCAST | TLBF_NONOTIFY)
>  
>  #define flush_tlb_fix_spurious_fault_pmd(vma, address, pmdp)	\
> -	local_flush_tlb_page_nonotify(vma, address)
> +	__flush_tlb_page(vma, address, TLBF_NOBROADCAST | TLBF_NONOTIFY)
>  
>  /*
>   * ZERO_PAGE is a global shared page that is always zero: used
> @@ -1351,7 +1351,7 @@ static inline int __ptep_clear_flush_young(struct vm_area_struct *vma,
>  		 * context-switch, which provides a DSB to complete the TLB
>  		 * invalidation.
>  		 */
> -		flush_tlb_page_nosync(vma, address);
> +		__flush_tlb_page(vma, address, TLBF_NOSYNC);
>  	}
>  
>  	return young;
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index ee747e66bbef..fa5aee990742 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -256,10 +256,7 @@ static inline void __tlbi_level(tlbi_op op, u64 addr, u32 level)
>   *		unmapping pages from vmalloc/io space.
>   *
>   *	flush_tlb_page(vma, addr)
> - *		Invalidate a single user mapping for address 'addr' in the
> - *		address space corresponding to 'vma->mm'.  Note that this
> - *		operation only invalidates a single, last-level page-table
> - *		entry and therefore does not affect any walk-caches.
> + *		Equivalent to __flush_tlb_page(..., flags=TLBF_NONE)
>   *
>   *
>   *	Next, we have some undocumented invalidation routines that you probably
> @@ -287,13 +284,14 @@ static inline void __tlbi_level(tlbi_op op, u64 addr, u32 level)
>   *		TLBF_NOSYNC (don't issue trailing dsb) and TLBF_NOBROADCAST
>   *		(only perform the invalidation for the local cpu).
>   *
> - *	local_flush_tlb_page(vma, addr)
> - *		Local variant of flush_tlb_page().  Stale TLB entries may
> - *		remain in remote CPUs.
> - *
> - *	local_flush_tlb_page_nonotify(vma, addr)
> - *		Same as local_flush_tlb_page() except MMU notifier will not be
> - *		called.
> + *	__flush_tlb_page(vma, addr, flags)
> + *		Invalidate a single user mapping for address 'addr' in the
> + *		address space corresponding to 'vma->mm'.  Note that this
> + *		operation only invalidates a single, last-level page-table entry
> + *		and therefore does not affect any walk-caches. flags may contain
> + *		any combination of TLBF_NONOTIFY (don't call mmu notifiers),
> + *		TLBF_NOSYNC (don't issue trailing dsb) and TLBF_NOBROADCAST
> + *		(only perform the invalidation for the local cpu).
>   *
>   *	Finally, take a look at asm/tlb.h to see how tlb_flush() is implemented
>   *	on top of these routines, since that is our interface to the mmu_gather
> @@ -327,51 +325,6 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>  	mmu_notifier_arch_invalidate_secondary_tlbs(mm, 0, -1UL);
>  }
>  
> -static inline void __local_flush_tlb_page_nonotify_nosync(struct mm_struct *mm,
> -							  unsigned long uaddr)
> -{
> -	dsb(nshst);
> -	__tlbi_level_asid(vale1, uaddr, TLBI_TTL_UNKNOWN, ASID(mm));
> -}
> -
> -static inline void local_flush_tlb_page_nonotify(struct vm_area_struct *vma,
> -						 unsigned long uaddr)
> -{
> -	__local_flush_tlb_page_nonotify_nosync(vma->vm_mm, uaddr);
> -	dsb(nsh);
> -}
> -
> -static inline void local_flush_tlb_page(struct vm_area_struct *vma,
> -					unsigned long uaddr)
> -{
> -	__local_flush_tlb_page_nonotify_nosync(vma->vm_mm, uaddr);
> -	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, uaddr & PAGE_MASK,
> -						(uaddr & PAGE_MASK) + PAGE_SIZE);
> -	dsb(nsh);
> -}
> -
> -static inline void __flush_tlb_page_nosync(struct mm_struct *mm,
> -					   unsigned long uaddr)
> -{
> -	dsb(ishst);
> -	__tlbi_level_asid(vale1is, uaddr, TLBI_TTL_UNKNOWN, ASID(mm));
> -	mmu_notifier_arch_invalidate_secondary_tlbs(mm, uaddr & PAGE_MASK,
> -						(uaddr & PAGE_MASK) + PAGE_SIZE);
> -}
> -
> -static inline void flush_tlb_page_nosync(struct vm_area_struct *vma,
> -					 unsigned long uaddr)
> -{
> -	return __flush_tlb_page_nosync(vma->vm_mm, uaddr);
> -}
> -
> -static inline void flush_tlb_page(struct vm_area_struct *vma,
> -				  unsigned long uaddr)
> -{
> -	flush_tlb_page_nosync(vma, uaddr);
> -	dsb(ish);
> -}
> -
>  static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm)
>  {
>  	/*
> @@ -618,6 +571,22 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
>  	__flush_tlb_range(vma, start, end, PAGE_SIZE, TLBI_TTL_UNKNOWN, TLBF_NONE);
>  }
>  
> +static inline void __flush_tlb_page(struct vm_area_struct *vma,
> +				    unsigned long uaddr, tlbf_t flags)
> +{
> +	unsigned long start = round_down(uaddr, PAGE_SIZE);
> +	unsigned long end = start + PAGE_SIZE;
> +
> +	___flush_tlb_range(vma, start, end, PAGE_SIZE, TLBI_TTL_UNKNOWN,
> +			   TLBF_NOWALKCACHE | flags);
> +}
> +
> +static inline void flush_tlb_page(struct vm_area_struct *vma,
> +				  unsigned long uaddr)
> +{
> +	__flush_tlb_page(vma, uaddr, TLBF_NONE);
> +}
> +
>  static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end)
>  {
>  	const unsigned long stride = PAGE_SIZE;
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index be9dab2c7d6a..f91aa686f142 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -239,7 +239,7 @@ int __ptep_set_access_flags(struct vm_area_struct *vma,
>  	 * flush_tlb_fix_spurious_fault().
>  	 */
>  	if (dirty)
> -		local_flush_tlb_page(vma, address);
> +		__flush_tlb_page(vma, address, TLBF_NOBROADCAST);
>  	return 1;
>  }

Reviewed-by: Linu Cherian <linu.cherian@arm.com>