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https://github.com/edk2-porting/linux-next.git
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3cded41794
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>
48 lines
1.2 KiB
C
48 lines
1.2 KiB
C
/*
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* Split spinlock implementation out into its own file, so it can be
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* compiled in a FTRACE-compatible way.
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*/
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#include <linux/spinlock.h>
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#include <linux/export.h>
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#include <linux/jump_label.h>
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#include <asm/paravirt.h>
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__visible void __native_queued_spin_unlock(struct qspinlock *lock)
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{
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native_queued_spin_unlock(lock);
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}
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PV_CALLEE_SAVE_REGS_THUNK(__native_queued_spin_unlock);
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bool pv_is_native_spin_unlock(void)
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{
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return pv_lock_ops.queued_spin_unlock.func ==
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__raw_callee_save___native_queued_spin_unlock;
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}
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__visible bool __native_vcpu_is_preempted(int cpu)
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{
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return false;
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}
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PV_CALLEE_SAVE_REGS_THUNK(__native_vcpu_is_preempted);
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bool pv_is_native_vcpu_is_preempted(void)
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{
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return pv_lock_ops.vcpu_is_preempted.func ==
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__raw_callee_save___native_vcpu_is_preempted;
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}
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struct pv_lock_ops pv_lock_ops = {
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#ifdef CONFIG_SMP
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.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
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.queued_spin_unlock = PV_CALLEE_SAVE(__native_queued_spin_unlock),
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.wait = paravirt_nop,
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.kick = paravirt_nop,
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.vcpu_is_preempted = PV_CALLEE_SAVE(__native_vcpu_is_preempted),
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#endif /* SMP */
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};
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EXPORT_SYMBOL(pv_lock_ops);
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struct static_key paravirt_ticketlocks_enabled = STATIC_KEY_INIT_FALSE;
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EXPORT_SYMBOL(paravirt_ticketlocks_enabled);
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