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-rw-r--r--arch/arc/include/asm/spinlock.h382
1 files changed, 382 insertions, 0 deletions
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
new file mode 100644
index 0000000000..1928716089
--- /dev/null
+++ b/arch/arc/include/asm/spinlock.h
@@ -0,0 +1,382 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ */
+
+#ifndef __ASM_SPINLOCK_H
+#define __ASM_SPINLOCK_H
+
+#include <asm/spinlock_types.h>
+#include <asm/processor.h>
+#include <asm/barrier.h>
+
+#define arch_spin_is_locked(x) ((x)->slock != __ARCH_SPIN_LOCK_UNLOCKED__)
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+ unsigned int val;
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[slock]] \n"
+ " breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */
+ " scond %[LOCKED], [%[slock]] \n" /* acquire */
+ " bnz 1b \n"
+ " \n"
+ : [val] "=&r" (val)
+ : [slock] "r" (&(lock->slock)),
+ [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
+ : "memory", "cc");
+
+ /*
+ * ACQUIRE barrier to ensure load/store after taking the lock
+ * don't "bleed-up" out of the critical section (leak-in is allowed)
+ * http://www.spinics.net/lists/kernel/msg2010409.html
+ *
+ * ARCv2 only has load-load, store-store and all-all barrier
+ * thus need the full all-all barrier
+ */
+ smp_mb();
+}
+
+/* 1 - lock taken successfully */
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+ unsigned int val, got_it = 0;
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[slock]] \n"
+ " breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */
+ " scond %[LOCKED], [%[slock]] \n" /* acquire */
+ " bnz 1b \n"
+ " mov %[got_it], 1 \n"
+ "4: \n"
+ " \n"
+ : [val] "=&r" (val),
+ [got_it] "+&r" (got_it)
+ : [slock] "r" (&(lock->slock)),
+ [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
+ : "memory", "cc");
+
+ smp_mb();
+
+ return got_it;
+}
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+ smp_mb();
+
+ WRITE_ONCE(lock->slock, __ARCH_SPIN_LOCK_UNLOCKED__);
+}
+
+/*
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ * Unfair locking as Writers could be starved indefinitely by Reader(s)
+ */
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+ unsigned int val;
+
+ /*
+ * zero means writer holds the lock exclusively, deny Reader.
+ * Otherwise grant lock to first/subseq reader
+ *
+ * if (rw->counter > 0) {
+ * rw->counter--;
+ * ret = 1;
+ * }
+ */
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[rwlock]] \n"
+ " brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */
+ " sub %[val], %[val], 1 \n" /* reader lock */
+ " scond %[val], [%[rwlock]] \n"
+ " bnz 1b \n"
+ " \n"
+ : [val] "=&r" (val)
+ : [rwlock] "r" (&(rw->counter)),
+ [WR_LOCKED] "ir" (0)
+ : "memory", "cc");
+
+ smp_mb();
+}
+
+/* 1 - lock taken successfully */
+static inline int arch_read_trylock(arch_rwlock_t *rw)
+{
+ unsigned int val, got_it = 0;
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[rwlock]] \n"
+ " brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */
+ " sub %[val], %[val], 1 \n" /* counter-- */
+ " scond %[val], [%[rwlock]] \n"
+ " bnz 1b \n" /* retry if collided with someone */
+ " mov %[got_it], 1 \n"
+ " \n"
+ "4: ; --- done --- \n"
+
+ : [val] "=&r" (val),
+ [got_it] "+&r" (got_it)
+ : [rwlock] "r" (&(rw->counter)),
+ [WR_LOCKED] "ir" (0)
+ : "memory", "cc");
+
+ smp_mb();
+
+ return got_it;
+}
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+ unsigned int val;
+
+ /*
+ * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
+ * deny writer. Otherwise if unlocked grant to writer
+ * Hence the claim that Linux rwlocks are unfair to writers.
+ * (can be starved for an indefinite time by readers).
+ *
+ * if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
+ * rw->counter = 0;
+ * ret = 1;
+ * }
+ */
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[rwlock]] \n"
+ " brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */
+ " mov %[val], %[WR_LOCKED] \n"
+ " scond %[val], [%[rwlock]] \n"
+ " bnz 1b \n"
+ " \n"
+ : [val] "=&r" (val)
+ : [rwlock] "r" (&(rw->counter)),
+ [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
+ [WR_LOCKED] "ir" (0)
+ : "memory", "cc");
+
+ smp_mb();
+}
+
+/* 1 - lock taken successfully */
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+ unsigned int val, got_it = 0;
+
+ __asm__ __volatile__(
+ "1: llock %[val], [%[rwlock]] \n"
+ " brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */
+ " mov %[val], %[WR_LOCKED] \n"
+ " scond %[val], [%[rwlock]] \n"
+ " bnz 1b \n" /* retry if collided with someone */
+ " mov %[got_it], 1 \n"
+ " \n"
+ "4: ; --- done --- \n"
+
+ : [val] "=&r" (val),
+ [got_it] "+&r" (got_it)
+ : [rwlock] "r" (&(rw->counter)),
+ [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
+ [WR_LOCKED] "ir" (0)
+ : "memory", "cc");
+
+ smp_mb();
+
+ return got_it;
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+ unsigned int val;
+
+ smp_mb();
+
+ /*
+ * rw->counter++;
+ */
+ __asm__ __volatile__(
+ "1: llock %[val], [%[rwlock]] \n"
+ " add %[val], %[val], 1 \n"
+ " scond %[val], [%[rwlock]] \n"
+ " bnz 1b \n"
+ " \n"
+ : [val] "=&r" (val)
+ : [rwlock] "r" (&(rw->counter))
+ : "memory", "cc");
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+ smp_mb();
+
+ WRITE_ONCE(rw->counter, __ARCH_RW_LOCK_UNLOCKED__);
+}
+
+#else /* !CONFIG_ARC_HAS_LLSC */
+
+static inline void arch_spin_lock(arch_spinlock_t *lock)
+{
+ unsigned int val = __ARCH_SPIN_LOCK_LOCKED__;
+
+ /*
+ * Per lkmm, smp_mb() is only required after _lock (and before_unlock)
+ * for ACQ and REL semantics respectively. However EX based spinlocks
+ * need the extra smp_mb to workaround a hardware quirk.
+ */
+ smp_mb();
+
+ __asm__ __volatile__(
+ "1: ex %0, [%1] \n"
+ " breq %0, %2, 1b \n"
+ : "+&r" (val)
+ : "r"(&(lock->slock)), "ir"(__ARCH_SPIN_LOCK_LOCKED__)
+ : "memory");
+
+ smp_mb();
+}
+
+/* 1 - lock taken successfully */
+static inline int arch_spin_trylock(arch_spinlock_t *lock)
+{
+ unsigned int val = __ARCH_SPIN_LOCK_LOCKED__;
+
+ smp_mb();
+
+ __asm__ __volatile__(
+ "1: ex %0, [%1] \n"
+ : "+r" (val)
+ : "r"(&(lock->slock))
+ : "memory");
+
+ smp_mb();
+
+ return (val == __ARCH_SPIN_LOCK_UNLOCKED__);
+}
+
+static inline void arch_spin_unlock(arch_spinlock_t *lock)
+{
+ unsigned int val = __ARCH_SPIN_LOCK_UNLOCKED__;
+
+ /*
+ * RELEASE barrier: given the instructions avail on ARCv2, full barrier
+ * is the only option
+ */
+ smp_mb();
+
+ /*
+ * EX is not really required here, a simple STore of 0 suffices.
+ * However this causes tasklist livelocks in SystemC based SMP virtual
+ * platforms where the systemc core scheduler uses EX as a cue for
+ * moving to next core. Do a git log of this file for details
+ */
+ __asm__ __volatile__(
+ " ex %0, [%1] \n"
+ : "+r" (val)
+ : "r"(&(lock->slock))
+ : "memory");
+
+ /*
+ * see pairing version/comment in arch_spin_lock above
+ */
+ smp_mb();
+}
+
+/*
+ * Read-write spinlocks, allowing multiple readers but only one writer.
+ * Unfair locking as Writers could be starved indefinitely by Reader(s)
+ *
+ * The spinlock itself is contained in @counter and access to it is
+ * serialized with @lock_mutex.
+ */
+
+/* 1 - lock taken successfully */
+static inline int arch_read_trylock(arch_rwlock_t *rw)
+{
+ int ret = 0;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ arch_spin_lock(&(rw->lock_mutex));
+
+ /*
+ * zero means writer holds the lock exclusively, deny Reader.
+ * Otherwise grant lock to first/subseq reader
+ */
+ if (rw->counter > 0) {
+ rw->counter--;
+ ret = 1;
+ }
+
+ arch_spin_unlock(&(rw->lock_mutex));
+ local_irq_restore(flags);
+
+ return ret;
+}
+
+/* 1 - lock taken successfully */
+static inline int arch_write_trylock(arch_rwlock_t *rw)
+{
+ int ret = 0;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ arch_spin_lock(&(rw->lock_mutex));
+
+ /*
+ * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
+ * deny writer. Otherwise if unlocked grant to writer
+ * Hence the claim that Linux rwlocks are unfair to writers.
+ * (can be starved for an indefinite time by readers).
+ */
+ if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
+ rw->counter = 0;
+ ret = 1;
+ }
+ arch_spin_unlock(&(rw->lock_mutex));
+ local_irq_restore(flags);
+
+ return ret;
+}
+
+static inline void arch_read_lock(arch_rwlock_t *rw)
+{
+ while (!arch_read_trylock(rw))
+ cpu_relax();
+}
+
+static inline void arch_write_lock(arch_rwlock_t *rw)
+{
+ while (!arch_write_trylock(rw))
+ cpu_relax();
+}
+
+static inline void arch_read_unlock(arch_rwlock_t *rw)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ arch_spin_lock(&(rw->lock_mutex));
+ rw->counter++;
+ arch_spin_unlock(&(rw->lock_mutex));
+ local_irq_restore(flags);
+}
+
+static inline void arch_write_unlock(arch_rwlock_t *rw)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ arch_spin_lock(&(rw->lock_mutex));
+ rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
+ arch_spin_unlock(&(rw->lock_mutex));
+ local_irq_restore(flags);
+}
+
+#endif
+
+#endif /* __ASM_SPINLOCK_H */
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