]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
x86/asm: Move 'status' from thread_struct to thread_info
authorAndy Lutomirski <luto@kernel.org>
Sun, 28 Jan 2018 18:38:50 +0000 (10:38 -0800)
committerThomas Gleixner <tglx@linutronix.de>
Tue, 30 Jan 2018 14:30:36 +0000 (15:30 +0100)
commit37a8f7c38339b22b69876d6f5a0ab851565284e3
treea4a7f97813a1adb6ec8b5ed1d441979498805b12
parentd1f7732009e0549eedf8ea1db948dc37be77fd46
x86/asm: Move 'status' from thread_struct to thread_info

The TS_COMPAT bit is very hot and is accessed from code paths that mostly
also touch thread_info::flags.  Move it into struct thread_info to improve
cache locality.

The only reason it was in thread_struct is that there was a brief period
during which arch-specific fields were not allowed in struct thread_info.

Linus suggested further changing:

  ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);

to:

  if (unlikely(ti->status & (TS_COMPAT|TS_I386_REGS_POKED)))
          ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);

on the theory that frequently dirtying the cacheline even in pure 64-bit
code that never needs to modify status hurts performance.  That could be a
reasonable followup patch, but I suspect it matters less on top of this
patch.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Link: https://lkml.kernel.org/r/03148bcc1b217100e6e8ecf6a5468c45cf4304b6.1517164461.git.luto@kernel.org
arch/x86/entry/common.c
arch/x86/include/asm/processor.h
arch/x86/include/asm/syscall.h
arch/x86/include/asm/thread_info.h
arch/x86/kernel/process_64.c
arch/x86/kernel/ptrace.c
arch/x86/kernel/signal.c