Messages in this thread Patch in this message | | | Date | Thu, 24 Dec 2015 15:17:17 +0000 (UTC) | From | Mathieu Desnoyers <> | Subject | Re: [RFC PATCH v2 2/3] thread_local_abi: wire up x86 32/64 system call |
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----- On Dec 23, 2015, at 10:42 PM, Josh Triplett josh@joshtriplett.org wrote:
> On December 22, 2015 10:02:12 AM PST, Mathieu Desnoyers > <mathieu.desnoyers@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.desnoyers@efficios.com> >>CC: Russell King <linux@arm.linux.org.uk> >>CC: Catalin Marinas <catalin.marinas@arm.com> >>CC: Will Deacon <will.deacon@arm.com> >>CC: Thomas Gleixner <tglx@linutronix.de> >>CC: Paul Turner <pjt@google.com> >>CC: Andrew Hunter <ahh@google.com> >>CC: Peter Zijlstra <peterz@infradead.org> >>CC: Andy Lutomirski <luto@amacapital.net> >>CC: Andi Kleen <andi@firstfloor.org> >>CC: Dave Watson <davejwatson@fb.com> >>CC: Chris Lameter <cl@linux.com> >>CC: Ingo Molnar <mingo@redhat.com> >>CC: Ben Maurer <bmaurer@fb.com> >>CC: Steven Rostedt <rostedt@goodmis.org> >>CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> >>CC: Josh Triplett <josh@joshtriplett.org> >>CC: Linus Torvalds <torvalds@linux-foundation.org> >>CC: Andrew Morton <akpm@linux-foundation.org> >>CC: Thomas Gleixner <tglx@linutronix.de> >>CC: linux-api@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
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