Revisiting c0a454b9044f

[Nathan Chancellor]

Hi all,

I am looking to potentially bump the minimum version of LLVM for
building the kernel to 15.0.0 after the next merge window. In my quest
to look for workarounds that can be dropped, I noticed that
CONFIG_ARM64_BTI_KERNEL was disabled unconditionally for GCC in commit
c0a454b9044f ("arm64/bti: Disable in kernel BTI when cross section
thunks are broken") as a result of [1]. Looking at that GCC report, it
seems like the AArch64 ABI now documents [2] the GNU toolchain's
behavior as expected and LLVM has been adjusted [3][4][5] to match. Do I
need to block CONFIG_ARM64_BTI_KERNEL from being selected with LLVM
21.0.0? Or should the kernel adjust its expectations now that the ABI
and toolchains all agree?

Cheers,
Nathan

[1]: https://gcc.gnu.org/pr106671
[2]: https://github.com/ARM-software/abi-aa/commit/606ce44fe4d3419c15cd9ed598f18fb5d520fcfc
[3]: https://github.com/llvm/llvm-project/commit/7af2b51e761f49974a64c3009882239cea618f2a
[4]: https://github.com/llvm/llvm-project/commit/edf21314c98a4fe05d48f83dfab2b201ed8bfe9c
[5]: https://github.com/llvm/llvm-project/commit/098b0d18add97dea94e16006486b2fded65e228d