----- On Dec 23, 2015, at 10:42 PM, Josh Triplett j...@joshtriplett.org wrote:
> On December 22, 2015 10:02:12 AM PST, Mathieu Desnoyers
> <mathieu.desnoy...@efficios.com> wrote:
>>Wire up the thread local ABI on x86 32/64. Call the
>>thread_local_abi_handle_notify_resume() function on return to
>>userspace if TIF_NOTIFY_RESUME thread flag is set.
>>
>>This provides an ABI improving the speed of a getcpu operation
>>on x86 by removing the need to perform a function call, "lsl"
>>instruction, or system call on the fast path.
>>
>>Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
>>CC: Russell King <li...@arm.linux.org.uk>
>>CC: Catalin Marinas <catalin.mari...@arm.com>
>>CC: Will Deacon <will.dea...@arm.com>
>>CC: Thomas Gleixner <t...@linutronix.de>
>>CC: Paul Turner <p...@google.com>
>>CC: Andrew Hunter <a...@google.com>
>>CC: Peter Zijlstra <pet...@infradead.org>
>>CC: Andy Lutomirski <l...@amacapital.net>
>>CC: Andi Kleen <a...@firstfloor.org>
>>CC: Dave Watson <davejwat...@fb.com>
>>CC: Chris Lameter <c...@linux.com>
>>CC: Ingo Molnar <mi...@redhat.com>
>>CC: Ben Maurer <bmau...@fb.com>
>>CC: Steven Rostedt <rost...@goodmis.org>
>>CC: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
>>CC: Josh Triplett <j...@joshtriplett.org>
>>CC: Linus Torvalds <torva...@linux-foundation.org>
>>CC: Andrew Morton <a...@linux-foundation.org>
>>CC: Thomas Gleixner <t...@linutronix.de>
>>CC: linux-...@vger.kernel.org
>>---
>> arch/x86/entry/common.c | 2 ++
>> arch/x86/entry/syscalls/syscall_32.tbl | 1 +
>> arch/x86/entry/syscalls/syscall_64.tbl | 1 +
>> 3 files changed, 4 insertions(+)
>>
>>diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
>>index a89fdbc..222cacf 100644
>>--- a/arch/x86/entry/common.c
>>+++ b/arch/x86/entry/common.c
>>@@ -249,6 +249,8 @@ static void exit_to_usermode_loop(struct pt_regs
>>*regs, u32 cached_flags)
>> if (cached_flags & _TIF_NOTIFY_RESUME) {
>> clear_thread_flag(TIF_NOTIFY_RESUME);
>> tracehook_notify_resume(regs);
>>+ if (thread_local_abi_active(current))
>>+ thread_local_abi_handle_notify_resume(current);
>
> Every caller seems likely to duplicate this pattern; why not make the call
> itself a static inline containing this check and call (or no-op if compiled
> out)?
Very good point, I'll do that.
Thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
