diff options
| 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/kernel/paravirt_patch_32.c | |
| parent | 05ffc951392df57edecc2519327b169210c3df75 (diff) | |
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/kernel/paravirt_patch_32.c')
| -rw-r--r-- | arch/x86/kernel/paravirt_patch_32.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c index 920c6ae08592..ff03dbd28625 100644 --- a/arch/x86/kernel/paravirt_patch_32.c +++ b/arch/x86/kernel/paravirt_patch_32.c @@ -12,6 +12,7 @@ DEF_NATIVE(pv_cpu_ops, clts, "clts"); #if defined(CONFIG_PARAVIRT_SPINLOCKS) DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)"); +DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %eax, %eax"); #endif unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len) @@ -27,6 +28,7 @@ unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len) } extern bool pv_is_native_spin_unlock(void); +extern bool pv_is_native_vcpu_is_preempted(void); unsigned native_patch(u8 type, u16 clobbers, void *ibuf, unsigned long addr, unsigned len) @@ -56,6 +58,12 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, end = end_pv_lock_ops_queued_spin_unlock; goto patch_site; } + case PARAVIRT_PATCH(pv_lock_ops.vcpu_is_preempted): + if (pv_is_native_vcpu_is_preempted()) { + start = start_pv_lock_ops_vcpu_is_preempted; + end = end_pv_lock_ops_vcpu_is_preempted; + goto patch_site; + } #endif default: |