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authorLinus Torvalds <torvalds@linux-foundation.org>2024-11-27 11:19:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2024-11-27 11:19:09 -0800
commit91dbbe6c9ffe5eded9a3e75d773ff92da8d2bc57 (patch)
tree30c98b08c3906a35d34327eff7725618c9045588 /include/asm-generic/spinlock.h
parentc94696977527f69cbb41aa6a9af9d1991895d002 (diff)
parent8d4f1e05ff821a5d59116ab8c3a30fcae81d8597 (diff)
Merge tag 'riscv-for-linus-6.13-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-v updates from Palmer Dabbelt: - Support for pointer masking in userspace - Support for probing vector misaligned access performance - Support for qspinlock on systems with Zacas and Zabha * tag 'riscv-for-linus-6.13-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (38 commits) RISC-V: Remove unnecessary include from compat.h riscv: Fix default misaligned access trap riscv: Add qspinlock support dt-bindings: riscv: Add Ziccrse ISA extension description riscv: Add ISA extension parsing for Ziccrse asm-generic: ticket-lock: Add separate ticket-lock.h asm-generic: ticket-lock: Reuse arch_spinlock_t of qspinlock riscv: Implement xchg8/16() using Zabha riscv: Implement arch_cmpxchg128() using Zacas riscv: Improve zacas fully-ordered cmpxchg() riscv: Implement cmpxchg8/16() using Zabha dt-bindings: riscv: Add Zabha ISA extension description riscv: Implement cmpxchg32/64() using Zacas riscv: Do not fail to build on byte/halfword operations with Zawrs riscv: Move cpufeature.h macros into their own header KVM: riscv: selftests: Add Smnpm and Ssnpm to get-reg-list test RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests riscv: hwprobe: Export the Supm ISA extension riscv: selftests: Add a pointer masking test riscv: Allow ptrace control of the tagged address ABI ...
Diffstat (limited to 'include/asm-generic/spinlock.h')
-rw-r--r--include/asm-generic/spinlock.h87
1 files changed, 1 insertions, 86 deletions
diff --git a/include/asm-generic/spinlock.h b/include/asm-generic/spinlock.h
index 90803a826ba0..970590baf61b 100644
--- a/include/asm-generic/spinlock.h
+++ b/include/asm-generic/spinlock.h
@@ -1,94 +1,9 @@
/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * 'Generic' ticket-lock implementation.
- *
- * It relies on atomic_fetch_add() having well defined forward progress
- * guarantees under contention. If your architecture cannot provide this, stick
- * to a test-and-set lock.
- *
- * It also relies on atomic_fetch_add() being safe vs smp_store_release() on a
- * sub-word of the value. This is generally true for anything LL/SC although
- * you'd be hard pressed to find anything useful in architecture specifications
- * about this. If your architecture cannot do this you might be better off with
- * a test-and-set.
- *
- * It further assumes atomic_*_release() + atomic_*_acquire() is RCpc and hence
- * uses atomic_fetch_add() which is RCsc to create an RCsc hot path, along with
- * a full fence after the spin to upgrade the otherwise-RCpc
- * atomic_cond_read_acquire().
- *
- * The implementation uses smp_cond_load_acquire() to spin, so if the
- * architecture has WFE like instructions to sleep instead of poll for word
- * modifications be sure to implement that (see ARM64 for example).
- *
- */
-
#ifndef __ASM_GENERIC_SPINLOCK_H
#define __ASM_GENERIC_SPINLOCK_H
-#include <linux/atomic.h>
-#include <asm-generic/spinlock_types.h>
-
-static __always_inline void arch_spin_lock(arch_spinlock_t *lock)
-{
- u32 val = atomic_fetch_add(1<<16, lock);
- u16 ticket = val >> 16;
-
- if (ticket == (u16)val)
- return;
-
- /*
- * atomic_cond_read_acquire() is RCpc, but rather than defining a
- * custom cond_read_rcsc() here we just emit a full fence. We only
- * need the prior reads before subsequent writes ordering from
- * smb_mb(), but as atomic_cond_read_acquire() just emits reads and we
- * have no outstanding writes due to the atomic_fetch_add() the extra
- * orderings are free.
- */
- atomic_cond_read_acquire(lock, ticket == (u16)VAL);
- smp_mb();
-}
-
-static __always_inline bool arch_spin_trylock(arch_spinlock_t *lock)
-{
- u32 old = atomic_read(lock);
-
- if ((old >> 16) != (old & 0xffff))
- return false;
-
- return atomic_try_cmpxchg(lock, &old, old + (1<<16)); /* SC, for RCsc */
-}
-
-static __always_inline void arch_spin_unlock(arch_spinlock_t *lock)
-{
- u16 *ptr = (u16 *)lock + IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
- u32 val = atomic_read(lock);
-
- smp_store_release(ptr, (u16)val + 1);
-}
-
-static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
-{
- u32 val = lock.counter;
-
- return ((val >> 16) == (val & 0xffff));
-}
-
-static __always_inline int arch_spin_is_locked(arch_spinlock_t *lock)
-{
- arch_spinlock_t val = READ_ONCE(*lock);
-
- return !arch_spin_value_unlocked(val);
-}
-
-static __always_inline int arch_spin_is_contended(arch_spinlock_t *lock)
-{
- u32 val = atomic_read(lock);
-
- return (s16)((val >> 16) - (val & 0xffff)) > 1;
-}
-
+#include <asm-generic/ticket_spinlock.h>
#include <asm/qrwlock.h>
#endif /* __ASM_GENERIC_SPINLOCK_H */