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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_IA64_MMU_CONTEXT_H
#define _ASM_IA64_MMU_CONTEXT_H
/*
* Copyright (C) 1998-2002 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
*/
/*
* Routines to manage the allocation of task context numbers. Task context
* numbers are used to reduce or eliminate the need to perform TLB flushes
* due to context switches. Context numbers are implemented using ia-64
* region ids. Since the IA-64 TLB does not consider the region number when
* performing a TLB lookup, we need to assign a unique region id to each
* region in a process. We use the least significant three bits in aregion
* id for this purpose.
*/
#define IA64_REGION_ID_KERNEL 0 /* the kernel's region id (tlb.c depends on this being 0) */
#define ia64_rid(ctx,addr) (((ctx) << 3) | (addr >> 61))
# include <asm/page.h>
# ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/spinlock.h>
#include <asm/processor.h>
#include <asm-generic/mm_hooks.h>
struct ia64_ctx {
spinlock_t lock;
unsigned int next; /* next context number to use */
unsigned int limit; /* available free range */
unsigned int max_ctx; /* max. context value supported by all CPUs */
/* call wrap_mmu_context when next >= max */
unsigned long *bitmap; /* bitmap size is max_ctx+1 */
unsigned long *flushmap;/* pending rid to be flushed */
};
extern struct ia64_ctx ia64_ctx;
DECLARE_PER_CPU(u8, ia64_need_tlb_flush);
extern void mmu_context_init (void);
extern void wrap_mmu_context (struct mm_struct *mm);
/*
* When the context counter wraps around all TLBs need to be flushed because
* an old context number might have been reused. This is signalled by the
* ia64_need_tlb_flush per-CPU variable, which is checked in the routine
* below. Called by activate_mm(). <efocht@ess.nec.de>
*/
static inline void
delayed_tlb_flush (void)
{
extern void local_flush_tlb_all (void);
unsigned long flags;
if (unlikely(__ia64_per_cpu_var(ia64_need_tlb_flush))) {
spin_lock_irqsave(&ia64_ctx.lock, flags);
if (__ia64_per_cpu_var(ia64_need_tlb_flush)) {
local_flush_tlb_all();
__ia64_per_cpu_var(ia64_need_tlb_flush) = 0;
}
spin_unlock_irqrestore(&ia64_ctx.lock, flags);
}
}
static inline nv_mm_context_t
get_mmu_context (struct mm_struct *mm)
{
unsigned long flags;
nv_mm_context_t context = mm->context;
if (likely(context))
goto out;
spin_lock_irqsave(&ia64_ctx.lock, flags);
/* re-check, now that we've got the lock: */
context = mm->context;
if (context == 0) {
cpumask_clear(mm_cpumask(mm));
if (ia64_ctx.next >= ia64_ctx.limit) {
ia64_ctx.next = find_next_zero_bit(ia64_ctx.bitmap,
ia64_ctx.max_ctx, ia64_ctx.next);
ia64_ctx.limit = find_next_bit(ia64_ctx.bitmap,
ia64_ctx.max_ctx, ia64_ctx.next);
if (ia64_ctx.next >= ia64_ctx.max_ctx)
wrap_mmu_context(mm);
}
mm->context = context = ia64_ctx.next++;
__set_bit(context, ia64_ctx.bitmap);
}
spin_unlock_irqrestore(&ia64_ctx.lock, flags);
out:
/*
* Ensure we're not starting to use "context" before any old
* uses of it are gone from our TLB.
*/
delayed_tlb_flush();
return context;
}
/*
* Initialize context number to some sane value. MM is guaranteed to be a
* brand-new address-space, so no TLB flushing is needed, ever.
*/
#define init_new_context init_new_context
static inline int
init_new_context (struct task_struct *p, struct mm_struct *mm)
{
mm->context = 0;
return 0;
}
static inline void
reload_context (nv_mm_context_t context)
{
unsigned long rid;
unsigned long rid_incr = 0;
unsigned long rr0, rr1, rr2, rr3, rr4, old_rr4;
old_rr4 = ia64_get_rr(RGN_BASE(RGN_HPAGE));
rid = context << 3; /* make space for encoding the region number */
rid_incr = 1 << 8;
/* encode the region id, preferred page size, and VHPT enable bit: */
rr0 = (rid << 8) | (PAGE_SHIFT << 2) | 1;
rr1 = rr0 + 1*rid_incr;
rr2 = rr0 + 2*rid_incr;
rr3 = rr0 + 3*rid_incr;
rr4 = rr0 + 4*rid_incr;
#ifdef CONFIG_HUGETLB_PAGE
rr4 = (rr4 & (~(0xfcUL))) | (old_rr4 & 0xfc);
# if RGN_HPAGE != 4
# error "reload_context assumes RGN_HPAGE is 4"
# endif
#endif
ia64_set_rr0_to_rr4(rr0, rr1, rr2, rr3, rr4);
ia64_srlz_i(); /* srlz.i implies srlz.d */
}
/*
* Must be called with preemption off
*/
static inline void
activate_context (struct mm_struct *mm)
{
nv_mm_context_t context;
do {
context = get_mmu_context(mm);
if (!cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm)))
cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
reload_context(context);
/*
* in the unlikely event of a TLB-flush by another thread,
* redo the load.
*/
} while (unlikely(context != mm->context));
}
/*
* Switch from address space PREV to address space NEXT.
*/
#define activate_mm activate_mm
static inline void
activate_mm (struct mm_struct *prev, struct mm_struct *next)
{
/*
* We may get interrupts here, but that's OK because interrupt
* handlers cannot touch user-space.
*/
ia64_set_kr(IA64_KR_PT_BASE, __pa(next->pgd));
activate_context(next);
}
#define switch_mm(prev_mm,next_mm,next_task) activate_mm(prev_mm, next_mm)
#include <asm-generic/mmu_context.h>
# endif /* ! __ASSEMBLY__ */
#endif /* _ASM_IA64_MMU_CONTEXT_H */
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