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#ifndef _ASM_IA64_MMU_CONTEXT_H
#define _ASM_IA64_MMU_CONTEXT_H
/*
* Copyright (C) 1998, 1999 Hewlett-Packard Co
* Copyright (C) 1998, 1999 David Mosberger-Tang <davidm@hpl.hp.com>
*/
#include <linux/config.h>
#include <linux/sched.h>
#include <asm/processor.h>
/*
* 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 ia-64 TLBs do not
* guarantee that the region number is checked 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 a region id
* for this purpose. On processors where the region number is checked
* in TLB lookups, we can get back those two bits by defining
* CONFIG_IA64_TLB_CHECKS_REGION_NUMBER. The macro
* IA64_REGION_ID_BITS gives the number of bits in a region id. The
* architecture manual guarantees this number to be in the range
* 18-24.
*
* A context number has the following format:
*
* +--------------------+---------------------+
* | generation number | region id |
* +--------------------+---------------------+
*
* A context number of 0 is considered "invalid".
*
* The generation number is incremented whenever we end up having used
* up all available region ids. At that point with flush the entire
* TLB and reuse the first region id. The new generation number
* ensures that when we context switch back to an old process, we do
* not inadvertently end up using its possibly reused region id.
* Instead, we simply allocate a new region id for that process.
*
* Copyright (C) 1998 David Mosberger-Tang <davidm@hpl.hp.com>
*/
#define IA64_REGION_ID_KERNEL 0 /* the kernel's region id (tlb.c depends on this being 0) */
#define IA64_REGION_ID_BITS 18
#ifdef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
# define IA64_HW_CONTEXT_BITS IA64_REGION_ID_BITS
#else
# define IA64_HW_CONTEXT_BITS (IA64_REGION_ID_BITS - 3)
#endif
#define IA64_HW_CONTEXT_MASK ((1UL << IA64_HW_CONTEXT_BITS) - 1)
extern unsigned long ia64_next_context;
extern void get_new_mmu_context (struct mm_struct *mm);
static inline void
enter_lazy_tlb (struct mm_struct *mm, struct task_struct *tsk, unsigned cpu)
{
}
extern inline unsigned long
ia64_rid (unsigned long context, unsigned long region_addr)
{
# ifdef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
return context;
# else
return context << 3 | (region_addr >> 61);
# endif
}
extern inline void
get_mmu_context (struct mm_struct *mm)
{
/* check if our ASN is of an older generation and thus invalid: */
if (((mm->context ^ ia64_next_context) & ~IA64_HW_CONTEXT_MASK) != 0) {
get_new_mmu_context(mm);
}
}
extern inline void
init_new_context (struct task_struct *p, struct mm_struct *mm)
{
mm->context = 0;
}
extern inline void
destroy_context (struct mm_struct *mm)
{
/* Nothing to do. */
}
extern inline void
reload_context (struct mm_struct *mm)
{
unsigned long rid;
unsigned long rid_incr = 0;
unsigned long rr0, rr1, rr2, rr3, rr4;
rid = (mm->context & IA64_HW_CONTEXT_MASK);
#ifndef CONFIG_IA64_TLB_CHECKS_REGION_NUMBER
rid <<= 3; /* make space for encoding the region number */
rid_incr = 1 << 8;
#endif
/* 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;
ia64_set_rr(0x0000000000000000, rr0);
ia64_set_rr(0x2000000000000000, rr1);
ia64_set_rr(0x4000000000000000, rr2);
ia64_set_rr(0x6000000000000000, rr3);
ia64_set_rr(0x8000000000000000, rr4);
ia64_insn_group_barrier();
ia64_srlz_i(); /* srlz.i implies srlz.d */
ia64_insn_group_barrier();
}
/*
* Switch from address space PREV to address space NEXT. Note that
* TSK may be NULL.
*/
static inline void
switch_mm (struct mm_struct *prev, struct mm_struct *next, struct task_struct *tsk, unsigned cpu)
{
/*
* We may get interrupts here, but that's OK because interrupt
* handlers cannot touch user-space.
*/
__asm__ __volatile__ ("mov ar.k7=%0" :: "r"(__pa(next->pgd)));
get_mmu_context(next);
reload_context(next);
}
#define activate_mm(prev,next) \
switch_mm((prev), (next), NULL, smp_processor_id())
#endif /* _ASM_IA64_MMU_CONTEXT_H */
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