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| author | Peter Zijlstra <peterz@infradead.org> | 2016-11-15 16:47:06 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-22 12:48:11 +0100 |
| commit | 3cded41794818d788aa1dc028ede4a1c1222d937 (patch) | |
| tree | b38f7540e28ee21ccec1e2fb850ff4235041984e /arch/x86/xen/spinlock.c | |
| parent | locking/mutex: Break out of expensive busy-loop on {mutex,rwsem}_spin_on_owne... (diff) | |
| download | linux-3cded41794818d788aa1dc028ede4a1c1222d937.tar.xz linux-3cded41794818d788aa1dc028ede4a1c1222d937.zip | |
x86/paravirt: Optimize native pv_lock_ops.vcpu_is_preempted()
Avoid the pointless function call to pv_lock_ops.vcpu_is_preempted()
when a paravirt spinlock enabled kernel is ran on native hardware.
Do this by patching out the CALL instruction with "XOR %RAX,%RAX"
which has the same effect (0 return value).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: borntraeger@de.ibm.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/xen/spinlock.c')
| -rw-r--r-- | arch/x86/xen/spinlock.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 74756bbd28c4..e8a9ea7d7a21 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -114,6 +114,8 @@ void xen_uninit_lock_cpu(int cpu) per_cpu(irq_name, cpu) = NULL; } +PV_CALLEE_SAVE_REGS_THUNK(xen_vcpu_stolen); + /* * Our init of PV spinlocks is split in two init functions due to us * using paravirt patching and jump labels patching and having to do @@ -136,8 +138,7 @@ void __init xen_init_spinlocks(void) pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); pv_lock_ops.wait = xen_qlock_wait; pv_lock_ops.kick = xen_qlock_kick; - - pv_lock_ops.vcpu_is_preempted = xen_vcpu_stolen; + pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen); } /* |