tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_X86_QSPINLOCK_H
3#define _ASM_X86_QSPINLOCK_H
4
5#include <linux/jump_label.h>
6#include <asm/cpufeature.h>
7#include <asm-generic/qspinlock_types.h>
8#include <asm/paravirt.h>
9#include <asm/rmwcc.h>
10
11#define _Q_PENDING_LOOPS (1 << 9)
12
13#define queued_fetch_set_pending_acquire queued_fetch_set_pending_acquire
14static __always_inline u32 queued_fetch_set_pending_acquire(struct qspinlock *lock)
15{
16 u32 val;
17
18 /*
19 * We can't use GEN_BINARY_RMWcc() inside an if() stmt because asm goto
20 * and CONFIG_PROFILE_ALL_BRANCHES=y results in a label inside a
21 * statement expression, which GCC doesn't like.
22 */
23 val = GEN_BINARY_RMWcc(LOCK_PREFIX "btsl", lock->val.counter, c,
24 "I", _Q_PENDING_OFFSET) * _Q_PENDING_VAL;
25 val |= atomic_read(&lock->val) & ~_Q_PENDING_MASK;
26
27 return val;
28}
29
30#ifdef CONFIG_PARAVIRT_SPINLOCKS
31extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
32extern void __pv_init_lock_hash(void);
33extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
34extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
35
36#define queued_spin_unlock queued_spin_unlock
37/**
38 * queued_spin_unlock - release a queued spinlock
39 * @lock : Pointer to queued spinlock structure
40 *
41 * A smp_store_release() on the least-significant byte.
42 */
43static inline void native_queued_spin_unlock(struct qspinlock *lock)
44{
45 smp_store_release(&lock->locked, 0);
46}
47
48static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
49{
50 pv_queued_spin_lock_slowpath(lock, val);
51}
52
53static inline void queued_spin_unlock(struct qspinlock *lock)
54{
55 pv_queued_spin_unlock(lock);
56}
57
58#define vcpu_is_preempted vcpu_is_preempted
59static inline bool vcpu_is_preempted(long cpu)
60{
61 return pv_vcpu_is_preempted(cpu);
62}
63#endif
64
65#ifdef CONFIG_PARAVIRT
66DECLARE_STATIC_KEY_TRUE(virt_spin_lock_key);
67
68void native_pv_lock_init(void) __init;
69
70#define virt_spin_lock virt_spin_lock
71static inline bool virt_spin_lock(struct qspinlock *lock)
72{
73 if (!static_branch_likely(&virt_spin_lock_key))
74 return false;
75
76 /*
77 * On hypervisors without PARAVIRT_SPINLOCKS support we fall
78 * back to a Test-and-Set spinlock, because fair locks have
79 * horrible lock 'holder' preemption issues.
80 */
81
82 do {
83 while (atomic_read(&lock->val) != 0)
84 cpu_relax();
85 } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);
86
87 return true;
88}
89#else
90static inline void native_pv_lock_init(void)
91{
92}
93#endif /* CONFIG_PARAVIRT */
94
95#include <asm-generic/qspinlock.h>
96
97#endif /* _ASM_X86_QSPINLOCK_H */