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/*
* Out of line spinlock code.
*
* Copyright IBM Corp. 2004, 2006
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <linux/types.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <asm/io.h>
int spin_retry = -1;
static int __init spin_retry_init(void)
{
if (spin_retry < 0)
spin_retry = 1000;
return 0;
}
early_initcall(spin_retry_init);
/**
* spin_retry= parameter
*/
static int __init spin_retry_setup(char *str)
{
spin_retry = simple_strtoul(str, &str, 0);
return 1;
}
__setup("spin_retry=", spin_retry_setup);
static inline int arch_load_niai4(int *lock)
{
int owner;
asm volatile(
#ifdef CONFIG_HAVE_MARCH_ZEC12_FEATURES
" .long 0xb2fa0040\n" /* NIAI 4 */
#endif
" l %0,%1\n"
: "=d" (owner) : "Q" (*lock) : "memory");
return owner;
}
static inline int arch_cmpxchg_niai8(int *lock, int old, int new)
{
int expected = old;
asm volatile(
#ifdef CONFIG_HAVE_MARCH_ZEC12_FEATURES
" .long 0xb2fa0080\n" /* NIAI 8 */
#endif
" cs %0,%3,%1\n"
: "=d" (old), "=Q" (*lock)
: "0" (old), "d" (new), "Q" (*lock)
: "cc", "memory");
return expected == old;
}
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int cpu = SPINLOCK_LOCKVAL;
int owner, count;
/* Pass the virtual CPU to the lock holder if it is not running */
owner = arch_load_niai4(&lp->lock);
if (owner && arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
count = spin_retry;
while (1) {
owner = arch_load_niai4(&lp->lock);
/* Try to get the lock if it is free. */
if (!owner) {
if (arch_cmpxchg_niai8(&lp->lock, 0, cpu))
return;
continue;
}
if (count-- >= 0)
continue;
count = spin_retry;
/*
* For multiple layers of hypervisors, e.g. z/VM + LPAR
* yield the CPU unconditionally. For LPAR rely on the
* sense running status.
*/
if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
}
}
EXPORT_SYMBOL(arch_spin_lock_wait);
void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
int cpu = SPINLOCK_LOCKVAL;
int owner, count;
local_irq_restore(flags);
/* Pass the virtual CPU to the lock holder if it is not running */
owner = arch_load_niai4(&lp->lock);
if (owner && arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
count = spin_retry;
while (1) {
owner = arch_load_niai4(&lp->lock);
/* Try to get the lock if it is free. */
if (!owner) {
local_irq_disable();
if (arch_cmpxchg_niai8(&lp->lock, 0, cpu))
return;
local_irq_restore(flags);
continue;
}
if (count-- >= 0)
continue;
count = spin_retry;
/*
* For multiple layers of hypervisors, e.g. z/VM + LPAR
* yield the CPU unconditionally. For LPAR rely on the
* sense running status.
*/
if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
}
}
EXPORT_SYMBOL(arch_spin_lock_wait_flags);
int arch_spin_trylock_retry(arch_spinlock_t *lp)
{
int cpu = SPINLOCK_LOCKVAL;
int owner, count;
for (count = spin_retry; count > 0; count--) {
owner = READ_ONCE(lp->lock);
/* Try to get the lock if it is free. */
if (!owner) {
if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
return 1;
}
}
return 0;
}
EXPORT_SYMBOL(arch_spin_trylock_retry);
void _raw_read_lock_wait(arch_rwlock_t *rw)
{
int count = spin_retry;
int owner, old;
#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
__RAW_LOCK(&rw->lock, -1, __RAW_OP_ADD);
#endif
owner = 0;
while (1) {
if (count-- <= 0) {
if (owner && arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
count = spin_retry;
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
if (old < 0)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return;
}
}
EXPORT_SYMBOL(_raw_read_lock_wait);
int _raw_read_trylock_retry(arch_rwlock_t *rw)
{
int count = spin_retry;
int old;
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
if (old < 0)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return 1;
}
return 0;
}
EXPORT_SYMBOL(_raw_read_trylock_retry);
#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
void _raw_write_lock_wait(arch_rwlock_t *rw, int prev)
{
int count = spin_retry;
int owner, old;
owner = 0;
while (1) {
if (count-- <= 0) {
if (owner && arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
count = spin_retry;
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
smp_mb();
if (old >= 0) {
prev = __RAW_LOCK(&rw->lock, 0x80000000, __RAW_OP_OR);
old = prev;
}
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
void _raw_write_lock_wait(arch_rwlock_t *rw)
{
int count = spin_retry;
int owner, old, prev;
prev = 0x80000000;
owner = 0;
while (1) {
if (count-- <= 0) {
if (owner && arch_vcpu_is_preempted(~owner))
smp_yield_cpu(~owner);
count = spin_retry;
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
if (old >= 0 &&
__atomic_cmpxchg_bool(&rw->lock, old, old | 0x80000000))
prev = old;
else
smp_mb();
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
int _raw_write_trylock_retry(arch_rwlock_t *rw)
{
int count = spin_retry;
int old;
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
if (old)
continue;
if (__atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000))
return 1;
}
return 0;
}
EXPORT_SYMBOL(_raw_write_trylock_retry);
void arch_lock_relax(int cpu)
{
if (!cpu)
return;
if (MACHINE_IS_LPAR && !arch_vcpu_is_preempted(~cpu))
return;
smp_yield_cpu(~cpu);
}
EXPORT_SYMBOL(arch_lock_relax);
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