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linux-next/include/asm-m68k/sun3_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 _SUN3_PGTABLE_H
#define _SUN3_PGTABLE_H
#include <asm/sun3mmu.h>
#ifndef __ASSEMBLY__
#include <asm/virtconvert.h>
#include <linux/linkage.h>
/*
* This file contains all the things which change drastically for the sun3
* pagetable stuff, to avoid making too much of a mess of the generic m68k
* `pgtable.h'; this should only be included from the generic file. --m
*/
/* For virtual address to physical address conversion */
#define VTOP(addr) __pa(addr)
#define PTOV(addr) __va(addr)
#endif /* !__ASSEMBLY__ */
/* These need to be defined for compatibility although the sun3 doesn't use them */
#define _PAGE_NOCACHE030 0x040
#define _CACHEMASK040 (~0x060)
#define _PAGE_NOCACHE_S 0x040
/* Page protection values within PTE. */
#define SUN3_PAGE_VALID (0x80000000)
#define SUN3_PAGE_WRITEABLE (0x40000000)
#define SUN3_PAGE_SYSTEM (0x20000000)
#define SUN3_PAGE_NOCACHE (0x10000000)
#define SUN3_PAGE_ACCESSED (0x02000000)
#define SUN3_PAGE_MODIFIED (0x01000000)
/* Externally used page protection values. */
#define _PAGE_PRESENT (SUN3_PAGE_VALID)
#define _PAGE_ACCESSED (SUN3_PAGE_ACCESSED)
#define PTE_FILE_MAX_BITS 28
/* Compound page protection values. */
//todo: work out which ones *should* have SUN3_PAGE_NOCACHE and fix...
// is it just PAGE_KERNEL and PAGE_SHARED?
#define PAGE_NONE __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_ACCESSED \
| SUN3_PAGE_NOCACHE)
#define PAGE_SHARED __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_WRITEABLE \
| SUN3_PAGE_ACCESSED \
| SUN3_PAGE_NOCACHE)
#define PAGE_COPY __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_ACCESSED \
| SUN3_PAGE_NOCACHE)
#define PAGE_READONLY __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_ACCESSED \
| SUN3_PAGE_NOCACHE)
#define PAGE_KERNEL __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_WRITEABLE \
| SUN3_PAGE_SYSTEM \
| SUN3_PAGE_NOCACHE \
| SUN3_PAGE_ACCESSED \
| SUN3_PAGE_MODIFIED)
#define PAGE_INIT __pgprot(SUN3_PAGE_VALID \
| SUN3_PAGE_WRITEABLE \
| SUN3_PAGE_SYSTEM \
| SUN3_PAGE_NOCACHE)
/*
* Page protections for initialising protection_map. The sun3 has only two
* protection settings, valid (implying read and execute) and writeable. These
* are as close as we can get...
*/
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY
#define __P100 PAGE_READONLY
#define __P101 PAGE_READONLY
#define __P110 PAGE_COPY
#define __P111 PAGE_COPY
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY
#define __S010 PAGE_SHARED
#define __S011 PAGE_SHARED
#define __S100 PAGE_READONLY
#define __S101 PAGE_READONLY
#define __S110 PAGE_SHARED
#define __S111 PAGE_SHARED
/* Use these fake page-protections on PMDs. */
#define SUN3_PMD_VALID (0x00000001)
#define SUN3_PMD_MASK (0x0000003F)
#define SUN3_PMD_MAGIC (0x0000002B)
#ifndef __ASSEMBLY__
/*
* 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) & SUN3_PAGE_CHG_MASK) | pgprot_val(newprot);
return pte;
}
#define pmd_set(pmdp,ptep) do {} while (0)
static inline void pgd_set(pgd_t *pgdp, pmd_t *pmdp)
{
pgd_val(*pgdp) = virt_to_phys(pmdp);
}
#define __pte_page(pte) \
((unsigned long) __va ((pte_val (pte) & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT))
#define __pmd_page(pmd) \
((unsigned long) __va (pmd_val (pmd) & PAGE_MASK))
static inline int pte_none (pte_t pte) { return !pte_val (pte); }
static inline int pte_present (pte_t pte) { return pte_val (pte) & SUN3_PAGE_VALID; }
static inline void pte_clear (struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
pte_val (*ptep) = 0;
}
#define pte_pfn(pte) (pte_val(pte) & SUN3_PAGE_PGNUM_MASK)
#define pfn_pte(pfn, pgprot) \
({ pte_t __pte; pte_val(__pte) = pfn | pgprot_val(pgprot); __pte; })
#define pte_page(pte) virt_to_page(__pte_page(pte))
#define pmd_page(pmd) virt_to_page(__pmd_page(pmd))
static inline int pmd_none2 (pmd_t *pmd) { return !pmd_val (*pmd); }
#define pmd_none(pmd) pmd_none2(&(pmd))
//static inline int pmd_bad (pmd_t pmd) { return (pmd_val (pmd) & SUN3_PMD_MASK) != SUN3_PMD_MAGIC; }
static inline int pmd_bad2 (pmd_t *pmd) { return 0; }
#define pmd_bad(pmd) pmd_bad2(&(pmd))
static inline int pmd_present2 (pmd_t *pmd) { return pmd_val (*pmd) & SUN3_PMD_VALID; }
/* #define pmd_present(pmd) pmd_present2(&(pmd)) */
#define pmd_present(pmd) (!pmd_none2(&(pmd)))
static inline void pmd_clear (pmd_t *pmdp) { pmd_val (*pmdp) = 0; }
static inline int pgd_none (pgd_t pgd) { return 0; }
static inline int pgd_bad (pgd_t pgd) { return 0; }
static inline int pgd_present (pgd_t pgd) { return 1; }
static inline void pgd_clear (pgd_t *pgdp) {}
#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...
* [we have the full set here even if they don't change from m68k]
*/
static inline int pte_write(pte_t pte) { return pte_val(pte) & SUN3_PAGE_WRITEABLE; }
static inline int pte_dirty(pte_t pte) { return pte_val(pte) & SUN3_PAGE_MODIFIED; }
static inline int pte_young(pte_t pte) { return pte_val(pte) & SUN3_PAGE_ACCESSED; }
static inline int pte_file(pte_t pte) { return pte_val(pte) & SUN3_PAGE_ACCESSED; }
static inline int pte_special(pte_t pte) { return 0; }
static inline pte_t pte_wrprotect(pte_t pte) { pte_val(pte) &= ~SUN3_PAGE_WRITEABLE; return pte; }
static inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= ~SUN3_PAGE_MODIFIED; return pte; }
static inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~SUN3_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mkwrite(pte_t pte) { pte_val(pte) |= SUN3_PAGE_WRITEABLE; return pte; }
static inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= SUN3_PAGE_MODIFIED; return pte; }
static inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= SUN3_PAGE_ACCESSED; return pte; }
static inline pte_t pte_mknocache(pte_t pte) { pte_val(pte) |= SUN3_PAGE_NOCACHE; return pte; }
// use this version when caches work...
//static inline pte_t pte_mkcache(pte_t pte) { pte_val(pte) &= SUN3_PAGE_NOCACHE; return pte; }
// until then, use:
static inline pte_t pte_mkcache(pte_t pte) { return pte; }
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pgd_t kernel_pg_dir[PTRS_PER_PGD];
/* Find an entry in a pagetable directory. */
#define pgd_index(address) ((address) >> PGDIR_SHIFT)
#define pgd_offset(mm, address) \
((mm)->pgd + pgd_index(address))
/* Find an entry in a kernel pagetable directory. */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
/* Find an entry in the second-level pagetable. */
static inline pmd_t *pmd_offset (pgd_t *pgd, unsigned long address)
{
return (pmd_t *) pgd;
}
static inline unsigned long pte_to_pgoff(pte_t pte)
{
return pte.pte & SUN3_PAGE_PGNUM_MASK;
}
static inline pte_t pgoff_to_pte(unsigned off)
{
pte_t pte = { off + SUN3_PAGE_ACCESSED };
return pte;
}
/* Find an entry in the third-level pagetable. */
#define pte_index(address) ((address >> PAGE_SHIFT) & (PTRS_PER_PTE-1))
#define pte_offset_kernel(pmd, address) ((pte_t *) __pmd_page(*pmd) + pte_index(address))
/* FIXME: should we bother with kmap() here? */
#define pte_offset_map(pmd, address) ((pte_t *)kmap(pmd_page(*pmd)) + pte_index(address))
#define pte_offset_map_nested(pmd, address) pte_offset_map(pmd, address)
#define pte_unmap(pte) kunmap(pte)
#define pte_unmap_nested(pte) kunmap(pte)
/* Macros to (de)construct the fake PTEs representing swap pages. */
#define __swp_type(x) ((x).val & 0x7F)
#define __swp_offset(x) (((x).val) >> 7)
#define __swp_entry(type,offset) ((swp_entry_t) { ((type) | ((offset) << 7)) })
#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 /* !_SUN3_PGTABLE_H */
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