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

Jonathan Cameron
2025-12-16T18:12:48Z

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.

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