Re: [RFC PATCH v1 1/2] arm64: tlbflush: Move invocation of __flush_tlb_range_op() to a macro

[Ryan Roberts <ryan.roberts@arm.com>]

On 11/09/2025 06:50, Anshuman Khandual wrote:
> 
> 
> On 29/08/25 9:05 PM, Ryan Roberts wrote:
>> __flush_tlb_range_op() is a pre-processor macro that takes the TLBI
>> operation as a string, and builds the instruction from it. This prevents
>> passing the TLBI operation around as a variable. __flush_tlb_range_op()
>> also takes 7 other arguments.
>>
>> Adding extra invocations for different TLB operations means duplicating
>> the whole thing, but those 7 extra arguments are the same each time.
>>
>> Add an enum for the TLBI operations that __flush_tlb_range() uses, and a
>> macro to pass the operation name as a string to __flush_tlb_range_op(),
>> and the rest of the arguments using __VA_ARGS_.
>>
>> The result is easier to add new TLBI operations to, and to modify any of
>> the other arguments as they only appear once.
>>
>> Suggested-by: James Morse <james.morse@arm.com>
>> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
>> ---
>>  arch/arm64/include/asm/tlbflush.h | 30 ++++++++++++++++++++++++------
>>  1 file changed, 24 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
>> index 18a5dc0c9a54..f66b8c4696d0 100644
>> --- a/arch/arm64/include/asm/tlbflush.h
>> +++ b/arch/arm64/include/asm/tlbflush.h
>> @@ -11,6 +11,7 @@
>>  #ifndef __ASSEMBLY__
>>  
>>  #include <linux/bitfield.h>
>> +#include <linux/build_bug.h>
>>  #include <linux/mm_types.h>
>>  #include <linux/sched.h>
>>  #include <linux/mmu_notifier.h>
>> @@ -433,12 +434,32 @@ static inline bool __flush_tlb_range_limit_excess(unsigned long start,
>>  	return false;
>>  }
>>  
>> +enum tlbi_op {
>> +	TLBI_VALE1IS,
>> +	TLBI_VAE1IS,
>> +};
>> +
>> +#define flush_tlb_range_op(op, ...)					\
>> +do {									\
>> +	switch (op) {							\
>> +	case TLBI_VALE1IS:						\
>> +		__flush_tlb_range_op(vale1is, __VA_ARGS__);		\
>> +		break;							\
>> +	case TLBI_VAE1IS:						\
>> +		__flush_tlb_range_op(vae1is, __VA_ARGS__);		\
>> +		break;							\
>> +	default:							\
>> +		BUILD_BUG_ON_MSG(1, "Unknown TLBI op");			\
>> +	}								\
>> +} while (0)
>> +
>>  static inline void __flush_tlb_range_nosync(struct mm_struct *mm,
>>  				     unsigned long start, unsigned long end,
>>  				     unsigned long stride, bool last_level,
>>  				     int tlb_level)
>>  {
>>  	unsigned long asid, pages;
>> +	enum tlbi_op tlbi_op;
>>  
>>  	start = round_down(start, stride);
>>  	end = round_up(end, stride);
>> @@ -452,12 +473,9 @@ static inline void __flush_tlb_range_nosync(struct mm_struct *mm,
>>  	dsb(ishst);
>>  	asid = ASID(mm);
>>  
>> -	if (last_level)
>> -		__flush_tlb_range_op(vale1is, start, pages, stride, asid,
>> -				     tlb_level, true, lpa2_is_enabled());
>> -	else
>> -		__flush_tlb_range_op(vae1is, start, pages, stride, asid,
>> -				     tlb_level, true, lpa2_is_enabled());
>> +	tlbi_op = last_level ? TLBI_VALE1IS : TLBI_VAE1IS;
>> +	flush_tlb_range_op(tlbi_op, start, pages, stride, asid, tlb_level,
>> +			   true, lpa2_is_enabled());
>>  
>>  	mmu_notifier_arch_invalidate_secondary_tlbs(mm, start, end);
>>  }
> 
> Should the remaining __flush_tlb_range_op() in flush_tlb_kernel_range()
> converted into flush_tlb_range_op() adding another similar enum variable
> i.e TLBI_VAALE1IS ? Because this will ensure that there is one variant
> helper i.e flush_tlb_range_op() that gets called.

Yeah maybe. I don't really have a strong opinion.

Will posted an RFC for converting all this to functions a while ago. That's the
better baseline to build this all on I think.

> 
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index f66b8c4696d0..a23169751deb 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -437,6 +437,7 @@ static inline bool __flush_tlb_range_limit_excess(unsigned long start,
>  enum tlbi_op {
>         TLBI_VALE1IS,
>         TLBI_VAE1IS,
> +       TLBI_VAALE1IS,
>  };
> 
>  #define flush_tlb_range_op(op, ...)                                    \
> @@ -448,6 +449,9 @@ do {                                                                        \
>         case TLBI_VAE1IS:                                               \
>                 __flush_tlb_range_op(vae1is, __VA_ARGS__);              \
>                 break;                                                  \
> +       case TLBI_VAALE1IS:                                             \
> +               __flush_tlb_range_op(vaale1is, __VA_ARGS__);            \
> +               break;                                                  \
>         default:                                                        \
>                 BUILD_BUG_ON_MSG(1, "Unknown TLBI op");                 \
>         }                                                               \
> @@ -517,7 +521,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
>         }
> 
>         dsb(ishst);
> -       __flush_tlb_range_op(vaale1is, start, pages, stride, 0,
> +       flush_tlb_range_op(TLBI_VAALE1IS, start, pages, stride, 0,
>                              TLBI_TTL_UNKNOWN, false, lpa2_is_enabled());
>         dsb(ish);
>         isb();