----- On Dec 23, 2015, at 10:42 PM, Josh Triplett [email protected] wrote:
> On December 22, 2015 10:02:12 AM PST, Mathieu Desnoyers > <[email protected]> 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 <[email protected]> >>CC: Russell King <[email protected]> >>CC: Catalin Marinas <[email protected]> >>CC: Will Deacon <[email protected]> >>CC: Thomas Gleixner <[email protected]> >>CC: Paul Turner <[email protected]> >>CC: Andrew Hunter <[email protected]> >>CC: Peter Zijlstra <[email protected]> >>CC: Andy Lutomirski <[email protected]> >>CC: Andi Kleen <[email protected]> >>CC: Dave Watson <[email protected]> >>CC: Chris Lameter <[email protected]> >>CC: Ingo Molnar <[email protected]> >>CC: Ben Maurer <[email protected]> >>CC: Steven Rostedt <[email protected]> >>CC: "Paul E. McKenney" <[email protected]> >>CC: Josh Triplett <[email protected]> >>CC: Linus Torvalds <[email protected]> >>CC: Andrew Morton <[email protected]> >>CC: Thomas Gleixner <[email protected]> >>CC: [email protected] >>--- >> 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-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
