]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
arm64: restore get_current() optimisation
authorMark Rutland <mark.rutland@arm.com>
Tue, 3 Jan 2017 18:27:01 +0000 (18:27 +0000)
committerCatalin Marinas <catalin.marinas@arm.com>
Wed, 4 Jan 2017 16:26:18 +0000 (16:26 +0000)
commit9d84fb27fa135c99c9fe3de33628774a336a70a8
treec4fa86a746481b12cb6a23dfb407fb0638cead59
parent6ef4fb387d50fa8f3bffdffc868b57e981cdd709
arm64: restore get_current() optimisation

Commit c02433dd6de32f04 ("arm64: split thread_info from task stack")
inverted the relationship between get_current() and
current_thread_info(), with sp_el0 now holding the current task_struct
rather than the current thead_info. The new implementation of
get_current() prevents the compiler from being able to optimize repeated
calls to either, resulting in a noticeable penalty in some
microbenchmarks.

This patch restores the previous optimisation by implementing
get_current() in the same way as our old current_thread_info(), using a
non-volatile asm statement.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch/arm64/include/asm/current.h