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/* 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 throught 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
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