Re: [PATCH v1 01/13] arm64: mm: Re-implement the __tlbi_level macro as a C function

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

Happy new year!


On 16/12/2025 17:53, Jonathan Cameron wrote:
> On Tue, 16 Dec 2025 14:45:46 +0000
> Ryan Roberts <ryan.roberts@arm.com> wrote:
> 
>> As part of efforts to reduce our reliance on complex preprocessor macros
>> for TLB invalidation routines, convert the __tlbi_level macro to a C
>> function for by-level TLB invalidation.
>>
>> Each specific tlbi level op is implemented as a C function and the
>> appropriate function pointer is passed to __tlbi_level(). Since
>> everything is declared inline and is statically resolvable, the compiler
>> will convert the indirect function call to a direct inline execution.
>>
>> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
>> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
>> ---
> 
>> +static __always_inline void __tlbi_level(tlbi_op op, u64 addr, u32 level)
>> +{
>> +	u64 arg = addr;
>> +
>> +	if (alternative_has_cap_unlikely(ARM64_HAS_ARMv8_4_TTL) && level <= 3) {
>> +		u64 ttl = level | (get_trans_granule() << 2);
>> +
>> +		arg &= ~TLBI_TTL_MASK;
>> +		arg |= FIELD_PREP(TLBI_TTL_MASK, ttl);
> 
> Probably don't care, but I think you could do
> 		FIELD_MODIFY(TLBI_TTL_MASK, &arg, ttl);
> instead of those two lines. Code generation hopefully similar?
> So depends on which macros you find more readable.

Yeah that's probably slightly neater - I'll switch to this for the next version.

Thanks,
Ryan

> 
>> +	}
>> +
>> +	op(arg);
>> +}
>>  
>>  #define __tlbi_user_level(op, arg, level) do {				\
>>  	if (arm64_kernel_unmapped_at_el0())				\
>