mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-18 01:34:14 +08:00
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>
55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
#ifndef _ASM_X86_SPINLOCK_H
|
|
#define _ASM_X86_SPINLOCK_H
|
|
|
|
#include <linux/jump_label.h>
|
|
#include <linux/atomic.h>
|
|
#include <asm/page.h>
|
|
#include <asm/processor.h>
|
|
#include <linux/compiler.h>
|
|
#include <asm/paravirt.h>
|
|
#include <asm/bitops.h>
|
|
|
|
/*
|
|
* Your basic SMP spinlocks, allowing only a single CPU anywhere
|
|
*
|
|
* Simple spin lock operations. There are two variants, one clears IRQ's
|
|
* on the local processor, one does not.
|
|
*
|
|
* These are fair FIFO ticket locks, which support up to 2^16 CPUs.
|
|
*
|
|
* (the type definitions are in asm/spinlock_types.h)
|
|
*/
|
|
|
|
/* How long a lock should spin before we consider blocking */
|
|
#define SPIN_THRESHOLD (1 << 15)
|
|
|
|
extern struct static_key paravirt_ticketlocks_enabled;
|
|
static __always_inline bool static_key_false(struct static_key *key);
|
|
|
|
#include <asm/qspinlock.h>
|
|
|
|
/*
|
|
* Read-write spinlocks, allowing multiple readers
|
|
* but only one writer.
|
|
*
|
|
* NOTE! it is quite common to have readers in interrupts
|
|
* but no interrupt writers. For those circumstances we
|
|
* can "mix" irq-safe locks - any writer needs to get a
|
|
* irq-safe write-lock, but readers can get non-irqsafe
|
|
* read-locks.
|
|
*
|
|
* On x86, we implement read-write locks using the generic qrwlock with
|
|
* x86 specific optimization.
|
|
*/
|
|
|
|
#include <asm/qrwlock.h>
|
|
|
|
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
|
|
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
|
|
|
|
#define arch_spin_relax(lock) cpu_relax()
|
|
#define arch_read_relax(lock) cpu_relax()
|
|
#define arch_write_relax(lock) cpu_relax()
|
|
|
|
#endif /* _ASM_X86_SPINLOCK_H */
|