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Diffstat (limited to 'arch/csky/include/asm/asid.h')
-rw-r--r-- | arch/csky/include/asm/asid.h | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/arch/csky/include/asm/asid.h b/arch/csky/include/asm/asid.h new file mode 100644 index 0000000000..6ff205a97a --- /dev/null +++ b/arch/csky/include/asm/asid.h @@ -0,0 +1,78 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_ASM_ASID_H +#define __ASM_ASM_ASID_H + +#include <linux/atomic.h> +#include <linux/compiler.h> +#include <linux/cpumask.h> +#include <linux/percpu.h> +#include <linux/spinlock.h> + +struct asid_info +{ + atomic64_t generation; + unsigned long *map; + atomic64_t __percpu *active; + u64 __percpu *reserved; + u32 bits; + /* Lock protecting the structure */ + raw_spinlock_t lock; + /* Which CPU requires context flush on next call */ + cpumask_t flush_pending; + /* Number of ASID allocated by context (shift value) */ + unsigned int ctxt_shift; + /* Callback to locally flush the context. */ + void (*flush_cpu_ctxt_cb)(void); +}; + +#define NUM_ASIDS(info) (1UL << ((info)->bits)) +#define NUM_CTXT_ASIDS(info) (NUM_ASIDS(info) >> (info)->ctxt_shift) + +#define active_asid(info, cpu) *per_cpu_ptr((info)->active, cpu) + +void asid_new_context(struct asid_info *info, atomic64_t *pasid, + unsigned int cpu, struct mm_struct *mm); + +/* + * Check the ASID is still valid for the context. If not generate a new ASID. + * + * @pasid: Pointer to the current ASID batch + * @cpu: current CPU ID. Must have been acquired through get_cpu() + */ +static inline void asid_check_context(struct asid_info *info, + atomic64_t *pasid, unsigned int cpu, + struct mm_struct *mm) +{ + u64 asid, old_active_asid; + + asid = atomic64_read(pasid); + + /* + * The memory ordering here is subtle. + * If our active_asid is non-zero and the ASID matches the current + * generation, then we update the active_asid entry with a relaxed + * cmpxchg. Racing with a concurrent rollover means that either: + * + * - We get a zero back from the cmpxchg and end up waiting on the + * lock. Taking the lock synchronises with the rollover and so + * we are forced to see the updated generation. + * + * - We get a valid ASID back from the cmpxchg, which means the + * relaxed xchg in flush_context will treat us as reserved + * because atomic RmWs are totally ordered for a given location. + */ + old_active_asid = atomic64_read(&active_asid(info, cpu)); + if (old_active_asid && + !((asid ^ atomic64_read(&info->generation)) >> info->bits) && + atomic64_cmpxchg_relaxed(&active_asid(info, cpu), + old_active_asid, asid)) + return; + + asid_new_context(info, pasid, cpu, mm); +} + +int asid_allocator_init(struct asid_info *info, + u32 bits, unsigned int asid_per_ctxt, + void (*flush_cpu_ctxt_cb)(void)); + +#endif |