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| author | Andy Lutomirski <luto@kernel.org> | 2018-01-28 10:38:50 -0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-01-30 15:30:36 +0100 |
| commit | 37a8f7c38339b22b69876d6f5a0ab851565284e3 (patch) | |
| tree | a4a7f97813a1adb6ec8b5ed1d441979498805b12 /arch/x86/entry/common.c | |
| parent | d1f7732009e0549eedf8ea1db948dc37be77fd46 (diff) | |
| download | linux-37a8f7c38339b22b69876d6f5a0ab851565284e3.tar.gz linux-37a8f7c38339b22b69876d6f5a0ab851565284e3.tar.bz2 linux-37a8f7c38339b22b69876d6f5a0ab851565284e3.zip | |
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
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index d7d3cc24baf4..99081340d19a 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -206,7 +206,7 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) * special case only applies after poking regs and before the * very next return to user mode. */ - current->thread.status &= ~(TS_COMPAT|TS_I386_REGS_POKED); + ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif user_enter_irqoff(); @@ -304,7 +304,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) unsigned int nr = (unsigned int)regs->orig_ax; #ifdef CONFIG_IA32_EMULATION - current->thread.status |= TS_COMPAT; + ti->status |= TS_COMPAT; #endif if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) { |