diff options
| -rw-r--r-- | include/asm-generic/mmiowb.h | 63 | ||||
| -rw-r--r-- | include/asm-generic/mmiowb_types.h | 12 | ||||
| -rw-r--r-- | kernel/Kconfig.locks | 7 | ||||
| -rw-r--r-- | kernel/locking/spinlock.c | 7 |
4 files changed, 89 insertions, 0 deletions
diff --git a/include/asm-generic/mmiowb.h b/include/asm-generic/mmiowb.h new file mode 100644 index 000000000000..9439ff037b2d --- /dev/null +++ b/include/asm-generic/mmiowb.h @@ -0,0 +1,63 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_GENERIC_MMIOWB_H +#define __ASM_GENERIC_MMIOWB_H + +/* + * Generic implementation of mmiowb() tracking for spinlocks. + * + * If your architecture doesn't ensure that writes to an I/O peripheral + * within two spinlocked sections on two different CPUs are seen by the + * peripheral in the order corresponding to the lock handover, then you + * need to follow these FIVE easy steps: + * + * 1. Implement mmiowb() (and arch_mmiowb_state() if you're fancy) + * in asm/mmiowb.h, then #include this file + * 2. Ensure your I/O write accessors call mmiowb_set_pending() + * 3. Select ARCH_HAS_MMIOWB + * 4. Untangle the resulting mess of header files + * 5. Complain to your architects + */ +#ifdef CONFIG_MMIOWB + +#include <linux/compiler.h> +#include <asm-generic/mmiowb_types.h> + +#ifndef arch_mmiowb_state +#include <asm/percpu.h> +#include <asm/smp.h> + +DECLARE_PER_CPU(struct mmiowb_state, __mmiowb_state); +#define __mmiowb_state() this_cpu_ptr(&__mmiowb_state) +#else +#define __mmiowb_state() arch_mmiowb_state() +#endif /* arch_mmiowb_state */ + +static inline void mmiowb_set_pending(void) +{ + struct mmiowb_state *ms = __mmiowb_state(); + ms->mmiowb_pending = ms->nesting_count; +} + +static inline void mmiowb_spin_lock(void) +{ + struct mmiowb_state *ms = __mmiowb_state(); + ms->nesting_count++; +} + +static inline void mmiowb_spin_unlock(void) +{ + struct mmiowb_state *ms = __mmiowb_state(); + + if (unlikely(ms->mmiowb_pending)) { + ms->mmiowb_pending = 0; + mmiowb(); + } + + ms->nesting_count--; +} +#else +#define mmiowb_set_pending() do { } while (0) +#define mmiowb_spin_lock() do { } while (0) +#define mmiowb_spin_unlock() do { } while (0) +#endif /* CONFIG_MMIOWB */ +#endif /* __ASM_GENERIC_MMIOWB_H */ diff --git a/include/asm-generic/mmiowb_types.h b/include/asm-generic/mmiowb_types.h new file mode 100644 index 000000000000..8eb0095655e7 --- /dev/null +++ b/include/asm-generic/mmiowb_types.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_GENERIC_MMIOWB_TYPES_H +#define __ASM_GENERIC_MMIOWB_TYPES_H + +#include <linux/types.h> + +struct mmiowb_state { + u16 nesting_count; + u16 mmiowb_pending; +}; + +#endif /* __ASM_GENERIC_MMIOWB_TYPES_H */ diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks index fbba478ae522..6ba2570eddad 100644 --- a/kernel/Kconfig.locks +++ b/kernel/Kconfig.locks @@ -251,3 +251,10 @@ config ARCH_USE_QUEUED_RWLOCKS config QUEUED_RWLOCKS def_bool y if ARCH_USE_QUEUED_RWLOCKS depends on SMP + +config ARCH_HAS_MMIOWB + bool + +config MMIOWB + def_bool y if ARCH_HAS_MMIOWB + depends on SMP diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c index 936f3d14dd6b..0ff08380f531 100644 --- a/kernel/locking/spinlock.c +++ b/kernel/locking/spinlock.c @@ -22,6 +22,13 @@ #include <linux/debug_locks.h> #include <linux/export.h> +#ifdef CONFIG_MMIOWB +#ifndef arch_mmiowb_state +DEFINE_PER_CPU(struct mmiowb_state, __mmiowb_state); +EXPORT_PER_CPU_SYMBOL(__mmiowb_state); +#endif +#endif + /* * If lockdep is enabled then we use the non-preemption spin-ops * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are |