So this is the result of me doing some profiling on my 128-core Altra box. I've sent out versions of this before, but they've all been fairly ugly partial series. This is the full cleaned-up series with patches split up to be logical, and with fixes from some of the commentary from previous patches. The first four patches are for the 'runtime constant' code, where I did the initial implementation on x86-64 just because I was more comfy with that, and the arm64 version of it came once I had the x86-64 side working. The horror that is __d_lookup_rcu() shows up a lot more on my Altra box because of the relatively pitiful caches, but it's something that I've wanted on x86-64 before. The arm64 numbers just made me bite the bullet on the whole runtime constant thing. The last three patches are purely arm64-specific, and just fix up some nasty code generation in the user access functions. I just noticed that I will need to implement 'user_access_save()' for KCSAN now that I do the unsafe user access functions. Anyway, that 'user_access_save/restore()' issue only shows up with KCSAN. And it would be a no-op thanks to arm64 doing SMAP the right way (pet peeve: arm64 did what I told the x86 designers to do originally, but they claimed was too hard, so we ended up with that CLAC/STAC instead)... Sadly that "no-op for KCSAN" would is except for the horrid CONFIG_ARM64_SW_TTBR0_PAN case, which is why I'm not touching it. I'm hoping some hapless^Whelpful arm64 person is willing to tackle this (or maybe make KCSAN and ARM64_SW_TTBR0_PAN incompatible in the Kconfig). Note: the final access_ok() change in 7/7 is a API relaxation and cleanup, and as such much more worrisome than the other patches. It's _simpler_ than the other patches, but the others aren't intended to really change behavior. That one does. Linus Torvalds (7): vfs: dcache: move hashlen_hash() from callers into d_hash() add default dummy 'runtime constant' infrastructure x86: add 'runtime constant' support arm64: add 'runtime constant' support arm64: start using 'asm goto' for get_user() when available arm64: start using 'asm goto' for put_user() when available arm64: access_ok() optimization arch/arm64/include/asm/runtime-const.h | 75 ++++++++++ arch/arm64/include/asm/uaccess.h | 191 +++++++++++++++++-------- arch/arm64/kernel/mte.c | 12 +- arch/arm64/kernel/vmlinux.lds.S | 3 + arch/x86/include/asm/runtime-const.h | 61 ++++++++ arch/x86/kernel/vmlinux.lds.S | 3 + fs/dcache.c | 17 ++- include/asm-generic/Kbuild | 1 + include/asm-generic/runtime-const.h | 15 ++ include/asm-generic/vmlinux.lds.h | 8 ++ 10 files changed, 319 insertions(+), 67 deletions(-) create mode 100644 arch/arm64/include/asm/runtime-const.h create mode 100644 arch/x86/include/asm/runtime-const.h create mode 100644 include/asm-generic/runtime-const.h -- 2.45.1.209.gc6f12300df
