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linux/include/asm-xtensa/mmu_context.h

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/*
* include/asm-xtensa/mmu_context.h
*
* Switch an MMU context.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*/
#ifndef _XTENSA_MMU_CONTEXT_H
#define _XTENSA_MMU_CONTEXT_H
#include <linux/config.h>
#include <linux/stringify.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
/*
* Linux was ported to Xtensa assuming all auto-refill ways in set 0
* had the same properties (a very likely assumption). Multiple sets
* of auto-refill ways will still work properly, but not as optimally
* as the Xtensa designer may have assumed.
*
* We make this case a hard #error, killing the kernel build, to alert
* the developer to this condition (which is more likely an error).
* You super-duper clever developers can change it to a warning or
* remove it altogether if you think you know what you're doing. :)
*/
#if (XCHAL_HAVE_TLBS != 1)
# error "Linux must have an MMU!"
#endif
#if ((XCHAL_ITLB_ARF_WAYS == 0) || (XCHAL_DTLB_ARF_WAYS == 0))
# error "MMU must have auto-refill ways"
#endif
#if ((XCHAL_ITLB_ARF_SETS != 1) || (XCHAL_DTLB_ARF_SETS != 1))
# error Linux may not use all auto-refill ways as efficiently as you think
#endif
#if (XCHAL_MMU_MAX_PTE_PAGE_SIZE != XCHAL_MMU_MIN_PTE_PAGE_SIZE)
# error Only one page size allowed!
#endif
extern unsigned long asid_cache;
extern pgd_t *current_pgd;
/*
* Define the number of entries per auto-refill way in set 0 of both I and D
* TLBs. We deal only with set 0 here (an assumption further explained in
* assertions.h). Also, define the total number of ARF entries in both TLBs.
*/
#define ITLB_ENTRIES_PER_ARF_WAY (XCHAL_ITLB_SET(XCHAL_ITLB_ARF_SET0,ENTRIES))
#define DTLB_ENTRIES_PER_ARF_WAY (XCHAL_DTLB_SET(XCHAL_DTLB_ARF_SET0,ENTRIES))
#define ITLB_ENTRIES \
(ITLB_ENTRIES_PER_ARF_WAY * (XCHAL_ITLB_SET(XCHAL_ITLB_ARF_SET0,WAYS)))
#define DTLB_ENTRIES \
(DTLB_ENTRIES_PER_ARF_WAY * (XCHAL_DTLB_SET(XCHAL_DTLB_ARF_SET0,WAYS)))
/*
* SMALLEST_NTLB_ENTRIES is the smaller of ITLB_ENTRIES and DTLB_ENTRIES.
* In practice, they are probably equal. This macro simplifies function
* flush_tlb_range().
*/
#if (DTLB_ENTRIES < ITLB_ENTRIES)
# define SMALLEST_NTLB_ENTRIES DTLB_ENTRIES
#else
# define SMALLEST_NTLB_ENTRIES ITLB_ENTRIES
#endif
/*
* asid_cache tracks only the ASID[USER_RING] field of the RASID special
* register, which is the current user-task asid allocation value.
* mm->context has the same meaning. When it comes time to write the
* asid_cache or mm->context values to the RASID special register, we first
* shift the value left by 8, then insert the value.
* ASID[0] always contains the kernel's asid value, and we reserve three
* other asid values that we never assign to user tasks.
*/
#define ASID_INC 0x1
#define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1)
/*
* XCHAL_MMU_ASID_INVALID is a configurable Xtensa processor constant
* indicating invalid address space. XCHAL_MMU_ASID_KERNEL is a configurable
* Xtensa processor constant indicating the kernel address space. They can
* be arbitrary values.
*
* We identify three more unique, reserved ASID values to use in the unused
* ring positions. No other user process will be assigned these reserved
* ASID values.
*
* For example, given that
*
* XCHAL_MMU_ASID_INVALID == 0
* XCHAL_MMU_ASID_KERNEL == 1
*
* the following maze of #if statements would generate
*
* ASID_RESERVED_1 == 2
* ASID_RESERVED_2 == 3
* ASID_RESERVED_3 == 4
* ASID_FIRST_NONRESERVED == 5
*/
#if (XCHAL_MMU_ASID_INVALID != XCHAL_MMU_ASID_KERNEL + 1)
# define ASID_RESERVED_1 ((XCHAL_MMU_ASID_KERNEL + 1) & ASID_MASK)
#else
# define ASID_RESERVED_1 ((XCHAL_MMU_ASID_KERNEL + 2) & ASID_MASK)
#endif
#if (XCHAL_MMU_ASID_INVALID != ASID_RESERVED_1 + 1)
# define ASID_RESERVED_2 ((ASID_RESERVED_1 + 1) & ASID_MASK)
#else
# define ASID_RESERVED_2 ((ASID_RESERVED_1 + 2) & ASID_MASK)
#endif
#if (XCHAL_MMU_ASID_INVALID != ASID_RESERVED_2 + 1)
# define ASID_RESERVED_3 ((ASID_RESERVED_2 + 1) & ASID_MASK)
#else
# define ASID_RESERVED_3 ((ASID_RESERVED_2 + 2) & ASID_MASK)
#endif
#if (XCHAL_MMU_ASID_INVALID != ASID_RESERVED_3 + 1)
# define ASID_FIRST_NONRESERVED ((ASID_RESERVED_3 + 1) & ASID_MASK)
#else
# define ASID_FIRST_NONRESERVED ((ASID_RESERVED_3 + 2) & ASID_MASK)
#endif
#define ASID_ALL_RESERVED ( ((ASID_RESERVED_1) << 24) + \
((ASID_RESERVED_2) << 16) + \
((ASID_RESERVED_3) << 8) + \
((XCHAL_MMU_ASID_KERNEL)) )
/*
* NO_CONTEXT is the invalid ASID value that we don't ever assign to
* any user or kernel context. NO_CONTEXT is a better mnemonic than
* XCHAL_MMU_ASID_INVALID, so we use it in code instead.
*/
#define NO_CONTEXT XCHAL_MMU_ASID_INVALID
#if (KERNEL_RING != 0)
# error The KERNEL_RING really should be zero.
#endif
#if (USER_RING >= XCHAL_MMU_RINGS)
# error USER_RING cannot be greater than the highest numbered ring.
#endif
#if (USER_RING == KERNEL_RING)
# error The user and kernel rings really should not be equal.
#endif
#if (USER_RING == 1)
#define ASID_INSERT(x) ( ((ASID_RESERVED_1) << 24) + \
((ASID_RESERVED_2) << 16) + \
(((x) & (ASID_MASK)) << 8) + \
((XCHAL_MMU_ASID_KERNEL)) )
#elif (USER_RING == 2)
#define ASID_INSERT(x) ( ((ASID_RESERVED_1) << 24) + \
(((x) & (ASID_MASK)) << 16) + \
((ASID_RESERVED_2) << 8) + \
((XCHAL_MMU_ASID_KERNEL)) )
#elif (USER_RING == 3)
#define ASID_INSERT(x) ( (((x) & (ASID_MASK)) << 24) + \
((ASID_RESERVED_1) << 16) + \
((ASID_RESERVED_2) << 8) + \
((XCHAL_MMU_ASID_KERNEL)) )
#else
#error Goofy value for USER_RING
#endif /* USER_RING == 1 */
/*
* All unused by hardware upper bits will be considered
* as a software asid extension.
*/
#define ASID_VERSION_MASK ((unsigned long)~(ASID_MASK|(ASID_MASK-1)))
#define ASID_FIRST_VERSION \
((unsigned long)(~ASID_VERSION_MASK) + 1 + ASID_FIRST_NONRESERVED)
extern inline void set_rasid_register (unsigned long val)
{
__asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t"
" isync\n" : : "a" (val));
}
extern inline unsigned long get_rasid_register (void)
{
unsigned long tmp;
__asm__ __volatile__ (" rsr %0, "__stringify(RASID)"\n\t" : "=a" (tmp));
return tmp;
}
#if ((XCHAL_MMU_ASID_INVALID == 0) && (XCHAL_MMU_ASID_KERNEL == 1))
extern inline void
get_new_mmu_context(struct mm_struct *mm, unsigned long asid)
{
extern void flush_tlb_all(void);
if (! ((asid += ASID_INC) & ASID_MASK) ) {
flush_tlb_all(); /* start new asid cycle */
if (!asid) /* fix version if needed */
asid = ASID_FIRST_VERSION - ASID_FIRST_NONRESERVED;
asid += ASID_FIRST_NONRESERVED;
}
mm->context = asid_cache = asid;
}
#else
#warning ASID_{INVALID,KERNEL} values impose non-optimal get_new_mmu_context implementation
/* XCHAL_MMU_ASID_INVALID == 0 and XCHAL_MMU_ASID_KERNEL ==1 are
really the best, but if you insist... */
extern inline int validate_asid (unsigned long asid)
{
switch (asid) {
case XCHAL_MMU_ASID_INVALID:
case XCHAL_MMU_ASID_KERNEL:
case ASID_RESERVED_1:
case ASID_RESERVED_2:
case ASID_RESERVED_3:
return 0; /* can't use these values as ASIDs */
}
return 1; /* valid */
}
extern inline void
get_new_mmu_context(struct mm_struct *mm, unsigned long asid)
{
extern void flush_tlb_all(void);
while (1) {
asid += ASID_INC;
if ( ! (asid & ASID_MASK) ) {
flush_tlb_all(); /* start new asid cycle */
if (!asid) /* fix version if needed */
asid = ASID_FIRST_VERSION - ASID_FIRST_NONRESERVED;
asid += ASID_FIRST_NONRESERVED;
break; /* no need to validate here */
}
if (validate_asid (asid & ASID_MASK))
break;
}
mm->context = asid_cache = asid;
}
#endif
/*
* Initialize the context related info for a new mm_struct
* instance.
*/
extern inline int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
mm->context = NO_CONTEXT;
return 0;
}
extern inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
unsigned long asid = asid_cache;
/* Check if our ASID is of an older version and thus invalid */
if ((next->context ^ asid) & ASID_VERSION_MASK)
get_new_mmu_context(next, asid);
set_rasid_register (ASID_INSERT(next->context));
invalidate_page_directory();
}
#define deactivate_mm(tsk, mm) do { } while(0)
/*
* Destroy context related info for an mm_struct that is about
* to be put to rest.
*/
extern inline void destroy_context(struct mm_struct *mm)
{
/* Nothing to do. */
}
/*
* After we have set current->mm to a new value, this activates
* the context for the new mm so we see the new mappings.
*/
extern inline void
activate_mm(struct mm_struct *prev, struct mm_struct *next)
{
/* Unconditionally get a new ASID. */
get_new_mmu_context(next, asid_cache);
set_rasid_register (ASID_INSERT(next->context));
invalidate_page_directory();
}
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
/* Nothing to do. */
}
#endif /* _XTENSA_MMU_CONTEXT_H */
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