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linux/include/asm-m32r/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 _ASM_M32R_PGTABLE_H
#define _ASM_M32R_PGTABLE_H
#include <asm-generic/4level-fixup.h>
#ifdef __KERNEL__
/*
* The Linux memory management assumes a three-level page table setup. On
* the M32R, we use that, but "fold" the mid level into the top-level page
* table, so that we physically have the same two-level page table as the
* M32R mmu expects.
*
* This file contains the functions and defines necessary to modify and use
* the M32R page table tree.
*/
/* CAUTION!: If you change macro definitions in this file, you might have to
* change arch/m32r/mmu.S manually.
*/
#ifndef __ASSEMBLY__
#include <linux/threads.h>
#include <linux/bitops.h>
#include <asm/processor.h>
#include <asm/addrspace.h>
#include <asm/page.h>
struct mm_struct;
struct vm_area_struct;
extern pgd_t swapper_pg_dir[1024];
extern void paging_init(void);
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
extern unsigned long empty_zero_page[1024];
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
#endif /* !__ASSEMBLY__ */
#ifndef __ASSEMBLY__
#include <asm/pgtable-2level.h>
#endif
#define pgtable_cache_init() do { } while (0)
#define PMD_SIZE (1UL << PMD_SHIFT)
#define PMD_MASK (~(PMD_SIZE - 1))
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
#define USER_PTRS_PER_PGD (TASK_SIZE / PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0
#ifndef __ASSEMBLY__
/* Just any arbitrary offset to the start of the vmalloc VM area: the
* current 8MB value just means that there will be a 8MB "hole" after the
* physical memory until the kernel virtual memory starts. That means that
* any out-of-bounds memory accesses will hopefully be caught.
* The vmalloc() routines leaves a hole of 4kB between each vmalloced
* area for the same reason. ;)
*/
#define VMALLOC_START KSEG2
#define VMALLOC_END KSEG3
/*
* M32R TLB format
*
* [0] [1:19] [20:23] [24:31]
* +-----------------------+----+-------------+
* | VPN |0000| ASID |
* +-----------------------+----+-------------+
* +-+---------------------+----+-+---+-+-+-+-+
* |0 PPN |0000|N|AC |L|G|V| |
* +-+---------------------+----+-+---+-+-+-+-+
* RWX
*/
#define _PAGE_BIT_DIRTY 0 /* software: page changed */
#define _PAGE_BIT_FILE 0 /* when !present: nonlinear file
mapping */
#define _PAGE_BIT_PRESENT 1 /* Valid: page is valid */
#define _PAGE_BIT_GLOBAL 2 /* Global */
#define _PAGE_BIT_LARGE 3 /* Large */
#define _PAGE_BIT_EXEC 4 /* Execute */
#define _PAGE_BIT_WRITE 5 /* Write */
#define _PAGE_BIT_READ 6 /* Read */
#define _PAGE_BIT_NONCACHABLE 7 /* Non cachable */
#define _PAGE_BIT_ACCESSED 8 /* software: page referenced */
#define _PAGE_BIT_PROTNONE 9 /* software: if not present */
#define _PAGE_DIRTY (1UL << _PAGE_BIT_DIRTY)
#define _PAGE_FILE (1UL << _PAGE_BIT_FILE)
#define _PAGE_PRESENT (1UL << _PAGE_BIT_PRESENT)
#define _PAGE_GLOBAL (1UL << _PAGE_BIT_GLOBAL)
#define _PAGE_LARGE (1UL << _PAGE_BIT_LARGE)
#define _PAGE_EXEC (1UL << _PAGE_BIT_EXEC)
#define _PAGE_WRITE (1UL << _PAGE_BIT_WRITE)
#define _PAGE_READ (1UL << _PAGE_BIT_READ)
#define _PAGE_NONCACHABLE (1UL << _PAGE_BIT_NONCACHABLE)
#define _PAGE_ACCESSED (1UL << _PAGE_BIT_ACCESSED)
#define _PAGE_PROTNONE (1UL << _PAGE_BIT_PROTNONE)
#define _PAGE_TABLE \
( _PAGE_PRESENT | _PAGE_WRITE | _PAGE_READ | _PAGE_ACCESSED \
| _PAGE_DIRTY )
#define _KERNPG_TABLE \
( _PAGE_PRESENT | _PAGE_WRITE | _PAGE_READ | _PAGE_ACCESSED \
| _PAGE_DIRTY )
#define _PAGE_CHG_MASK \
( PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY )
#ifdef CONFIG_MMU
#define PAGE_NONE \
__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
#define PAGE_SHARED \
__pgprot(_PAGE_PRESENT | _PAGE_WRITE | _PAGE_READ | _PAGE_ACCESSED)
#define PAGE_SHARED_EXEC \
__pgprot(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_WRITE | _PAGE_READ \
| _PAGE_ACCESSED)
#define PAGE_COPY \
__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_ACCESSED)
#define PAGE_COPY_EXEC \
__pgprot(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_ACCESSED)
#define PAGE_READONLY \
__pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_ACCESSED)
#define PAGE_READONLY_EXEC \
__pgprot(_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_ACCESSED)
#define __PAGE_KERNEL \
( _PAGE_PRESENT | _PAGE_EXEC | _PAGE_WRITE | _PAGE_READ | _PAGE_DIRTY \
| _PAGE_ACCESSED )
#define __PAGE_KERNEL_RO ( __PAGE_KERNEL & ~_PAGE_WRITE )
#define __PAGE_KERNEL_NOCACHE ( __PAGE_KERNEL | _PAGE_NONCACHABLE)
#define MAKE_GLOBAL(x) __pgprot((x) | _PAGE_GLOBAL)
#define PAGE_KERNEL MAKE_GLOBAL(__PAGE_KERNEL)
#define PAGE_KERNEL_RO MAKE_GLOBAL(__PAGE_KERNEL_RO)
#define PAGE_KERNEL_NOCACHE MAKE_GLOBAL(__PAGE_KERNEL_NOCACHE)
#else
#define PAGE_NONE __pgprot(0)
#define PAGE_SHARED __pgprot(0)
#define PAGE_SHARED_EXEC __pgprot(0)
#define PAGE_COPY __pgprot(0)
#define PAGE_COPY_EXEC __pgprot(0)
#define PAGE_READONLY __pgprot(0)
#define PAGE_READONLY_EXEC __pgprot(0)
#define PAGE_KERNEL __pgprot(0)
#define PAGE_KERNEL_RO __pgprot(0)
#define PAGE_KERNEL_NOCACHE __pgprot(0)
#endif /* CONFIG_MMU */
/* xwr */
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY
#define __P100 PAGE_READONLY_EXEC
#define __P101 PAGE_READONLY_EXEC
#define __P110 PAGE_COPY_EXEC
#define __P111 PAGE_COPY_EXEC
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY
#define __S010 PAGE_SHARED
#define __S011 PAGE_SHARED
#define __S100 PAGE_READONLY_EXEC
#define __S101 PAGE_READONLY_EXEC
#define __S110 PAGE_SHARED_EXEC
#define __S111 PAGE_SHARED_EXEC
/* page table for 0-4MB for everybody */
#define pte_present(x) (pte_val(x) & (_PAGE_PRESENT | _PAGE_PROTNONE))
#define pte_clear(mm,addr,xp) do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
#define pmd_none(x) (!pmd_val(x))
#define pmd_present(x) (pmd_val(x) & _PAGE_PRESENT)
#define pmd_clear(xp) do { set_pmd(xp, __pmd(0)); } while (0)
#define pmd_bad(x) ((pmd_val(x) & ~PAGE_MASK) != _KERNPG_TABLE)
#define pages_to_mb(x) ((x) >> (20 - PAGE_SHIFT))
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
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_write(pte_t pte)
{
return pte_val(pte) & _PAGE_WRITE;
}
/*
* The following only works if pte_present() is not true.
*/
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_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_wrprotect(pte_t pte)
{
pte_val(pte) &= ~_PAGE_WRITE;
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_mkwrite(pte_t pte)
{
pte_val(pte) |= _PAGE_WRITE;
return pte;
}
static inline pte_t pte_mkspecial(pte_t pte)
{
return pte;
}
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
return test_and_clear_bit(_PAGE_BIT_ACCESSED, ptep);
}
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
clear_bit(_PAGE_BIT_WRITE, ptep);
}
/*
* Macro and implementation to make a page protection as uncachable.
*/
static inline pgprot_t pgprot_noncached(pgprot_t _prot)
{
unsigned long prot = pgprot_val(_prot);
prot |= _PAGE_NONCACHABLE;
return __pgprot(prot);
}
#define pgprot_writecombine(prot) pgprot_noncached(prot)
/*
* 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)
{
set_pte(&pte, __pte((pte_val(pte) & _PAGE_CHG_MASK) \
| pgprot_val(newprot)));
return pte;
}
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
static inline void pmd_set(pmd_t * pmdp, pte_t * ptep)
{
pmd_val(*pmdp) = (((unsigned long) ptep) & PAGE_MASK);
}
#define pmd_page_vaddr(pmd) \
((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
#ifndef CONFIG_DISCONTIGMEM
#define pmd_page(pmd) (mem_map + ((pmd_val(pmd) >> PAGE_SHIFT) - PFN_BASE))
#endif /* !CONFIG_DISCONTIGMEM */
/* to find an entry in a page-table-directory. */
#define pgd_index(address) \
(((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
#define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address))
/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)
#define pmd_index(address) \
(((address) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
#define pte_index(address) \
(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, address) \
((pte_t *)pmd_page_vaddr(*(dir)) + pte_index(address))
#define pte_offset_map(dir, address) \
((pte_t *)page_address(pmd_page(*(dir))) + pte_index(address))
#define pte_offset_map_nested(dir, address) pte_offset_map(dir, address)
#define pte_unmap(pte) do { } while (0)
#define pte_unmap_nested(pte) do { } while (0)
/* Encode and de-code a swap entry */
#define __swp_type(x) (((x).val >> 2) & 0x1f)
#define __swp_offset(x) ((x).val >> 10)
#define __swp_entry(type, offset) \
((swp_entry_t) { ((type) << 2) | ((offset) << 10) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
#endif /* !__ASSEMBLY__ */
/* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
#define kern_addr_valid(addr) (1)
#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
remap_pfn_range(vma, vaddr, pfn, size, prot)
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
#define __HAVE_ARCH_PTEP_SET_WRPROTECT
#define __HAVE_ARCH_PTE_SAME
#include <asm-generic/pgtable.h>
#endif /* __KERNEL__ */
#endif /* _ASM_M32R_PGTABLE_H */
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