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linux-next/include/asm-m68k/motorola_pgtable.h
Nick Piggin 7e675137a8 mm: introduce pte_special pte bit 
s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory
model (which is more dynamic than most).  Instead, they had proposed to
implement it with an additional path through vm_normal_page(), using a bit in
the pte to determine whether or not the page should be refcounted:

vm_normal_page()
{
	...
        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
                if (vma->vm_flags & VM_MIXEDMAP) {
#ifdef s390
			if (!mixedmap_refcount_pte(pte))
				return NULL;
#else
                        if (!pfn_valid(pfn))
                                return NULL;
#endif
                        goto out;
                }
	...
}

This is fine, however if we are allowed to use a bit in the pte to determine
refcountedness, we can use that to _completely_ replace all the vma based
schemes.  So instead of adding more cases to the already complex vma-based
scheme, we can have a clearly seperate and simple pte-based scheme (and get
slightly better code generation in the process):

vm_normal_page()
{
#ifdef s390
	if (!mixedmap_refcount_pte(pte))
		return NULL;
	return pte_page(pte);
#else
	...
#endif
}

And finally, we may rather make this concept usable by any architecture rather
than making it s390 only, so implement a new type of pte state for this.
Unfortunately the old vma based code must stay, because some architectures may
not be able to spare pte bits.  This makes vm_normal_page a little bit more
ugly than we would like, but the 2 cases are clearly seperate.

So introduce a pte_special pte state, and use it in mm/memory.c.  It is
currently a noop for all architectures, so this doesn't actually result in any
compiled code changes to mm/memory.o.

BTW:
I haven't put vm_normal_page() into arch code as-per an earlier suggestion.
The reason is that, regardless of where vm_normal_page is actually
implemented, the *abstraction* is still exactly the same. Also, while it
depends on whether the architecture has pte_special or not, that is the
only two possible cases, and it really isn't an arch specific function --
the role of the arch code should be to provide primitive functions and
accessors with which to build the core code; pte_special does that. We do
not want architectures to know or care about vm_normal_page itself, and
we definitely don't want them being able to invent something new there
out of sight of mm/ code. If we made vm_normal_page an arch function, then
we have to make vm_insert_mixed (next patch) an arch function too. So I
don't think moving it to arch code fundamentally improves any abstractions,
while it does practically make the code more difficult to follow, for both
mm and arch developers, and easier to misuse.

[akpm@linux-foundation.org: build fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 08:58:23 -07:00

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#ifndef _MOTOROLA_PGTABLE_H
#define _MOTOROLA_PGTABLE_H
/*
* Definitions for MMU descriptors
*/
#define _PAGE_PRESENT 0x001
#define _PAGE_SHORT 0x002
#define _PAGE_RONLY 0x004
#define _PAGE_ACCESSED 0x008
#define _PAGE_DIRTY 0x010
#define _PAGE_SUPER 0x080 /* 68040 supervisor only */
#define _PAGE_GLOBAL040 0x400 /* 68040 global bit, used for kva descs */
#define _PAGE_NOCACHE030 0x040 /* 68030 no-cache mode */
#define _PAGE_NOCACHE 0x060 /* 68040 cache mode, non-serialized */
#define _PAGE_NOCACHE_S 0x040 /* 68040 no-cache mode, serialized */
#define _PAGE_CACHE040 0x020 /* 68040 cache mode, cachable, copyback */
#define _PAGE_CACHE040W 0x000 /* 68040 cache mode, cachable, write-through */
#define _DESCTYPE_MASK 0x003
#define _CACHEMASK040 (~0x060)
#define _TABLE_MASK (0xfffffe00)
#define _PAGE_TABLE (_PAGE_SHORT)
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_NOCACHE)
#define _PAGE_PROTNONE 0x004
#define _PAGE_FILE 0x008 /* pagecache or swap? */
#ifndef __ASSEMBLY__
/* This is the cache mode to be used for pages containing page descriptors for
* processors >= '040. It is in pte_mknocache(), and the variable is defined
* and initialized in head.S */
extern int m68k_pgtable_cachemode;
/* This is the cache mode for normal pages, for supervisor access on
* processors >= '040. It is used in pte_mkcache(), and the variable is
* defined and initialized in head.S */
#if defined(CPU_M68060_ONLY) && defined(CONFIG_060_WRITETHROUGH)
#define m68k_supervisor_cachemode _PAGE_CACHE040W
#elif defined(CPU_M68040_OR_M68060_ONLY)
#define m68k_supervisor_cachemode _PAGE_CACHE040
#elif defined(CPU_M68020_OR_M68030_ONLY)
#define m68k_supervisor_cachemode 0
#else
extern int m68k_supervisor_cachemode;
#endif
#if defined(CPU_M68040_OR_M68060_ONLY)
#define mm_cachebits _PAGE_CACHE040
#elif defined(CPU_M68020_OR_M68030_ONLY)
#define mm_cachebits 0
#else
extern unsigned long mm_cachebits;
#endif
#define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED | mm_cachebits)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | mm_cachebits)
#define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_RONLY | _PAGE_ACCESSED | mm_cachebits)
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_RONLY | _PAGE_ACCESSED | mm_cachebits)
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_DIRTY | _PAGE_ACCESSED | mm_cachebits)
/* Alternate definitions that are compile time constants, for
initializing protection_map. The cachebits are fixed later. */
#define PAGE_NONE_C __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
#define PAGE_SHARED_C __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
#define PAGE_COPY_C __pgprot(_PAGE_PRESENT | _PAGE_RONLY | _PAGE_ACCESSED)
#define PAGE_READONLY_C __pgprot(_PAGE_PRESENT | _PAGE_RONLY | _PAGE_ACCESSED)
/*
* The m68k can't do page protection for execute, and considers that the same are read.
* Also, write permissions imply read permissions. This is the closest we can get..
*/
#define __P000 PAGE_NONE_C
#define __P001 PAGE_READONLY_C
#define __P010 PAGE_COPY_C
#define __P011 PAGE_COPY_C
#define __P100 PAGE_READONLY_C
#define __P101 PAGE_READONLY_C
#define __P110 PAGE_COPY_C
#define __P111 PAGE_COPY_C
#define __S000 PAGE_NONE_C
#define __S001 PAGE_READONLY_C
#define __S010 PAGE_SHARED_C
#define __S011 PAGE_SHARED_C
#define __S100 PAGE_READONLY_C
#define __S101 PAGE_READONLY_C
#define __S110 PAGE_SHARED_C
#define __S111 PAGE_SHARED_C
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot);
return pte;
}
static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
{
unsigned long ptbl = virt_to_phys(ptep) | _PAGE_TABLE | _PAGE_ACCESSED;
unsigned long *ptr = pmdp->pmd;
short i = 16;
while (--i >= 0) {
*ptr++ = ptbl;
ptbl += (sizeof(pte_t)*PTRS_PER_PTE/16);
}
}
static inline void pgd_set(pgd_t *pgdp, pmd_t *pmdp)
{
pgd_val(*pgdp) = _PAGE_TABLE | _PAGE_ACCESSED | __pa(pmdp);
}
#define __pte_page(pte) ((unsigned long)__va(pte_val(pte) & PAGE_MASK))
#define __pmd_page(pmd) ((unsigned long)__va(pmd_val(pmd) & _TABLE_MASK))
#define __pgd_page(pgd) ((unsigned long)__va(pgd_val(pgd) & _TABLE_MASK))
#define pte_none(pte) (!pte_val(pte))
#define pte_present(pte) (pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROTNONE))
#define pte_clear(mm,addr,ptep) ({ pte_val(*(ptep)) = 0; })
#define pte_page(pte) virt_to_page(__va(pte_val(pte)))
#define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT)
#define pfn_pte(pfn, prot) __pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
#define pmd_none(pmd) (!pmd_val(pmd))
#define pmd_bad(pmd) ((pmd_val(pmd) & _DESCTYPE_MASK) != _PAGE_TABLE)
#define pmd_present(pmd) (pmd_val(pmd) & _PAGE_TABLE)
#define pmd_clear(pmdp) ({ \
unsigned long *__ptr = pmdp->pmd; \
short __i = 16; \
while (--__i >= 0) \
*__ptr++ = 0; \
})
#define pmd_page(pmd) virt_to_page(__va(pmd_val(pmd)))
#define pgd_none(pgd) (!pgd_val(pgd))
#define pgd_bad(pgd) ((pgd_val(pgd) & _DESCTYPE_MASK) != _PAGE_TABLE)
#define pgd_present(pgd) (pgd_val(pgd) & _PAGE_TABLE)
#define pgd_clear(pgdp) ({ pgd_val(*pgdp) = 0; })
#define pgd_page(pgd) (mem_map + ((unsigned long)(__va(pgd_val(pgd)) - PAGE_OFFSET) >> PAGE_SHIFT))
#define pte_ERROR(e) \
printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
#define pmd_ERROR(e) \
printk("%s:%d: bad pmd %08lx.\n", __FILE__, __LINE__, pmd_val(e))
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
static inline int pte_write(pte_t pte) { return !(pte_val(pte) & _PAGE_RONLY); }
static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; }
static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; }
static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE; }
static inline int pte_special(pte_t pte) { return 0; }
static inline pte_t pte_wrprotect(pte_t pte) { pte_val(pte) |= _PAGE_RONLY; return pte; }
static inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= ~_PAGE_DIRTY; return pte; }
static inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte) { pte_val(pte) &= ~_PAGE_RONLY; return pte; }
static inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= _PAGE_DIRTY; return pte; }
static inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= _PAGE_ACCESSED; return pte; }
static inline pte_t pte_mknocache(pte_t pte)
{
pte_val(pte) = (pte_val(pte) & _CACHEMASK040) | m68k_pgtable_cachemode;
return pte;
}
static inline pte_t pte_mkcache(pte_t pte)
{
pte_val(pte) = (pte_val(pte) & _CACHEMASK040) | m68k_supervisor_cachemode;
return pte;
}
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
#define PAGE_DIR_OFFSET(tsk,address) pgd_offset((tsk),(address))
#define pgd_index(address) ((address) >> PGDIR_SHIFT)
/* to find an entry in a page-table-directory */
static inline pgd_t *pgd_offset(const struct mm_struct *mm,
unsigned long address)
{
return mm->pgd + pgd_index(address);
}
#define swapper_pg_dir kernel_pg_dir
extern pgd_t kernel_pg_dir[128];
static inline pgd_t *pgd_offset_k(unsigned long address)
{
return kernel_pg_dir + (address >> PGDIR_SHIFT);
}
/* Find an entry in the second-level page table.. */
static inline pmd_t *pmd_offset(pgd_t *dir, unsigned long address)
{
return (pmd_t *)__pgd_page(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PMD-1));
}
/* Find an entry in the third-level page table.. */
static inline pte_t *pte_offset_kernel(pmd_t *pmdp, unsigned long address)
{
return (pte_t *)__pmd_page(*pmdp) + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
}
#define pte_offset_map(pmdp,address) ((pte_t *)__pmd_page(*pmdp) + (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)))
#define pte_offset_map_nested(pmdp, address) pte_offset_map(pmdp, address)
#define pte_unmap(pte) ((void)0)
#define pte_unmap_nested(pte) ((void)0)
/*
* Allocate and free page tables. The xxx_kernel() versions are
* used to allocate a kernel page table - this turns on ASN bits
* if any.
*/
/* Prior to calling these routines, the page should have been flushed
* from both the cache and ATC, or the CPU might not notice that the
* cache setting for the page has been changed. -jskov
*/
static inline void nocache_page(void *vaddr)
{
unsigned long addr = (unsigned long)vaddr;
if (CPU_IS_040_OR_060) {
pgd_t *dir;
pmd_t *pmdp;
pte_t *ptep;
dir = pgd_offset_k(addr);
pmdp = pmd_offset(dir, addr);
ptep = pte_offset_kernel(pmdp, addr);
*ptep = pte_mknocache(*ptep);
}
}
static inline void cache_page(void *vaddr)
{
unsigned long addr = (unsigned long)vaddr;
if (CPU_IS_040_OR_060) {
pgd_t *dir;
pmd_t *pmdp;
pte_t *ptep;
dir = pgd_offset_k(addr);
pmdp = pmd_offset(dir, addr);
ptep = pte_offset_kernel(pmdp, addr);
*ptep = pte_mkcache(*ptep);
}
}
#define PTE_FILE_MAX_BITS 28
static inline unsigned long pte_to_pgoff(pte_t pte)
{
return pte.pte >> 4;
}
static inline pte_t pgoff_to_pte(unsigned off)
{
pte_t pte = { (off << 4) + _PAGE_FILE };
return pte;
}
/* Encode and de-code a swap entry (must be !pte_none(e) && !pte_present(e)) */
#define __swp_type(x) (((x).val >> 4) & 0xff)
#define __swp_offset(x) ((x).val >> 12)
#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 4) | ((offset) << 12) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#endif /* !__ASSEMBLY__ */
#endif /* _MOTOROLA_PGTABLE_H */
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