7e675137a8
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>
384 lines
12 KiB
C
384 lines
12 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_PGTABLE_H
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#define __ASM_AVR32_PGTABLE_H
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#include <asm/addrspace.h>
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#ifndef __ASSEMBLY__
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#include <linux/sched.h>
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#endif /* !__ASSEMBLY__ */
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/*
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* Use two-level page tables just as the i386 (without PAE)
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*/
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#include <asm/pgtable-2level.h>
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/*
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* The following code might need some cleanup when the values are
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* final...
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*/
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#define PMD_SIZE (1UL << PMD_SHIFT)
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#define PMD_MASK (~(PMD_SIZE-1))
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#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
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#define PGDIR_MASK (~(PGDIR_SIZE-1))
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#define USER_PTRS_PER_PGD (TASK_SIZE / PGDIR_SIZE)
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#define FIRST_USER_ADDRESS 0
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#ifndef __ASSEMBLY__
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extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
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extern void paging_init(void);
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/*
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* ZERO_PAGE is a global shared page that is always zero: used for
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* zero-mapped memory areas etc.
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*/
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extern struct page *empty_zero_page;
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#define ZERO_PAGE(vaddr) (empty_zero_page)
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/*
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* Just any arbitrary offset to the start of the vmalloc VM area: the
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* current 8 MiB value just means that there will be a 8 MiB "hole"
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* after the uncached physical memory (P2 segment) until the vmalloc
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* area starts. That means that any out-of-bounds memory accesses will
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* hopefully be caught; we don't know if the end of the P1/P2 segments
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* are actually used for anything, but it is anyway safer to let the
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* MMU catch these kinds of errors than to rely on the memory bus.
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*
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* A "hole" of the same size is added to the end of the P3 segment as
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* well. It might seem wasteful to use 16 MiB of virtual address space
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* on this, but we do have 512 MiB of it...
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*
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* The vmalloc() routines leave a hole of 4 KiB between each vmalloced
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* area for the same reason.
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*/
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#define VMALLOC_OFFSET (8 * 1024 * 1024)
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#define VMALLOC_START (P3SEG + VMALLOC_OFFSET)
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#define VMALLOC_END (P4SEG - VMALLOC_OFFSET)
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#endif /* !__ASSEMBLY__ */
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/*
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* Page flags. Some of these flags are not directly supported by
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* hardware, so we have to emulate them.
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*/
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#define _TLBEHI_BIT_VALID 9
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#define _TLBEHI_VALID (1 << _TLBEHI_BIT_VALID)
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#define _PAGE_BIT_WT 0 /* W-bit : write-through */
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#define _PAGE_BIT_DIRTY 1 /* D-bit : page changed */
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#define _PAGE_BIT_SZ0 2 /* SZ0-bit : Size of page */
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#define _PAGE_BIT_SZ1 3 /* SZ1-bit : Size of page */
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#define _PAGE_BIT_EXECUTE 4 /* X-bit : execute access allowed */
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#define _PAGE_BIT_RW 5 /* AP0-bit : write access allowed */
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#define _PAGE_BIT_USER 6 /* AP1-bit : user space access allowed */
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#define _PAGE_BIT_BUFFER 7 /* B-bit : bufferable */
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#define _PAGE_BIT_GLOBAL 8 /* G-bit : global (ignore ASID) */
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#define _PAGE_BIT_CACHABLE 9 /* C-bit : cachable */
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/* If we drop support for 1K pages, we get two extra bits */
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#define _PAGE_BIT_PRESENT 10
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#define _PAGE_BIT_ACCESSED 11 /* software: page was accessed */
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/* The following flags are only valid when !PRESENT */
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#define _PAGE_BIT_FILE 0 /* software: pagecache or swap? */
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#define _PAGE_WT (1 << _PAGE_BIT_WT)
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#define _PAGE_DIRTY (1 << _PAGE_BIT_DIRTY)
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#define _PAGE_EXECUTE (1 << _PAGE_BIT_EXECUTE)
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#define _PAGE_RW (1 << _PAGE_BIT_RW)
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#define _PAGE_USER (1 << _PAGE_BIT_USER)
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#define _PAGE_BUFFER (1 << _PAGE_BIT_BUFFER)
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#define _PAGE_GLOBAL (1 << _PAGE_BIT_GLOBAL)
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#define _PAGE_CACHABLE (1 << _PAGE_BIT_CACHABLE)
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/* Software flags */
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#define _PAGE_ACCESSED (1 << _PAGE_BIT_ACCESSED)
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#define _PAGE_PRESENT (1 << _PAGE_BIT_PRESENT)
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#define _PAGE_FILE (1 << _PAGE_BIT_FILE)
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/*
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* Page types, i.e. sizes. _PAGE_TYPE_NONE corresponds to what is
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* usually called _PAGE_PROTNONE on other architectures.
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*
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* XXX: Find out if _PAGE_PROTNONE is equivalent with !_PAGE_USER. If
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* so, we can encode all possible page sizes (although we can't really
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* support 1K pages anyway due to the _PAGE_PRESENT and _PAGE_ACCESSED
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* bits)
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*
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*/
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#define _PAGE_TYPE_MASK ((1 << _PAGE_BIT_SZ0) | (1 << _PAGE_BIT_SZ1))
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#define _PAGE_TYPE_NONE (0 << _PAGE_BIT_SZ0)
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#define _PAGE_TYPE_SMALL (1 << _PAGE_BIT_SZ0)
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#define _PAGE_TYPE_MEDIUM (2 << _PAGE_BIT_SZ0)
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#define _PAGE_TYPE_LARGE (3 << _PAGE_BIT_SZ0)
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/*
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* Mask which drop software flags. We currently can't handle more than
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* 512 MiB of physical memory, so we can use bits 29-31 for other
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* stuff. With a fixed 4K page size, we can use bits 10-11 as well as
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* bits 2-3 (SZ)
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*/
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#define _PAGE_FLAGS_HARDWARE_MASK 0xfffff3ff
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#define _PAGE_FLAGS_CACHE_MASK (_PAGE_CACHABLE | _PAGE_BUFFER | _PAGE_WT)
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/* TODO: Check for saneness */
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/* User-mode page table flags (to be set in a pgd or pmd entry) */
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#define _PAGE_TABLE (_PAGE_PRESENT | _PAGE_TYPE_SMALL | _PAGE_RW \
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| _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
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/* Kernel-mode page table flags */
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#define _KERNPG_TABLE (_PAGE_PRESENT | _PAGE_TYPE_SMALL | _PAGE_RW \
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| _PAGE_ACCESSED | _PAGE_DIRTY)
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/* Flags that may be modified by software */
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#define _PAGE_CHG_MASK (PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY \
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| _PAGE_FLAGS_CACHE_MASK)
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#define _PAGE_FLAGS_READ (_PAGE_CACHABLE | _PAGE_BUFFER)
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#define _PAGE_FLAGS_WRITE (_PAGE_FLAGS_READ | _PAGE_RW | _PAGE_DIRTY)
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#define _PAGE_NORMAL(x) __pgprot((x) | _PAGE_PRESENT | _PAGE_TYPE_SMALL \
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| _PAGE_ACCESSED)
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#define PAGE_NONE (_PAGE_ACCESSED | _PAGE_TYPE_NONE)
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#define PAGE_READ (_PAGE_FLAGS_READ | _PAGE_USER)
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#define PAGE_EXEC (_PAGE_FLAGS_READ | _PAGE_EXECUTE | _PAGE_USER)
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#define PAGE_WRITE (_PAGE_FLAGS_WRITE | _PAGE_USER)
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#define PAGE_KERNEL _PAGE_NORMAL(_PAGE_FLAGS_WRITE | _PAGE_EXECUTE | _PAGE_GLOBAL)
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#define PAGE_KERNEL_RO _PAGE_NORMAL(_PAGE_FLAGS_READ | _PAGE_EXECUTE | _PAGE_GLOBAL)
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#define _PAGE_P(x) _PAGE_NORMAL((x) & ~(_PAGE_RW | _PAGE_DIRTY))
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#define _PAGE_S(x) _PAGE_NORMAL(x)
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#define PAGE_COPY _PAGE_P(PAGE_WRITE | PAGE_READ)
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#define PAGE_SHARED _PAGE_S(PAGE_WRITE | PAGE_READ)
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#ifndef __ASSEMBLY__
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/*
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* The hardware supports flags for write- and execute access. Read is
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* always allowed if the page is loaded into the TLB, so the "-w-",
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* "--x" and "-wx" mappings are implemented as "rw-", "r-x" and "rwx",
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* respectively.
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*
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* The "---" case is handled by software; the page will simply not be
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* loaded into the TLB if the page type is _PAGE_TYPE_NONE.
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*/
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#define __P000 __pgprot(PAGE_NONE)
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#define __P001 _PAGE_P(PAGE_READ)
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#define __P010 _PAGE_P(PAGE_WRITE)
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#define __P011 _PAGE_P(PAGE_WRITE | PAGE_READ)
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#define __P100 _PAGE_P(PAGE_EXEC)
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#define __P101 _PAGE_P(PAGE_EXEC | PAGE_READ)
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#define __P110 _PAGE_P(PAGE_EXEC | PAGE_WRITE)
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#define __P111 _PAGE_P(PAGE_EXEC | PAGE_WRITE | PAGE_READ)
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#define __S000 __pgprot(PAGE_NONE)
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#define __S001 _PAGE_S(PAGE_READ)
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#define __S010 _PAGE_S(PAGE_WRITE)
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#define __S011 _PAGE_S(PAGE_WRITE | PAGE_READ)
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#define __S100 _PAGE_S(PAGE_EXEC)
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#define __S101 _PAGE_S(PAGE_EXEC | PAGE_READ)
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#define __S110 _PAGE_S(PAGE_EXEC | PAGE_WRITE)
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#define __S111 _PAGE_S(PAGE_EXEC | PAGE_WRITE | PAGE_READ)
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#define pte_none(x) (!pte_val(x))
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#define pte_present(x) (pte_val(x) & _PAGE_PRESENT)
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#define pte_clear(mm,addr,xp) \
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do { \
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set_pte_at(mm, addr, xp, __pte(0)); \
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} while (0)
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/*
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* The following only work if pte_present() is true.
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* Undefined behaviour if not..
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*/
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static inline int pte_write(pte_t pte)
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{
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return pte_val(pte) & _PAGE_RW;
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}
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static inline int pte_dirty(pte_t pte)
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{
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return pte_val(pte) & _PAGE_DIRTY;
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}
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static inline int pte_young(pte_t pte)
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{
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return pte_val(pte) & _PAGE_ACCESSED;
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}
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static inline int pte_special(pte_t pte)
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{
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return 0;
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}
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/*
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* The following only work if pte_present() is not true.
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*/
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static inline int pte_file(pte_t pte)
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{
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return pte_val(pte) & _PAGE_FILE;
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}
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/* Mutator functions for PTE bits */
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static inline pte_t pte_wrprotect(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_RW));
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return pte;
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}
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static inline pte_t pte_mkclean(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_DIRTY));
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return pte;
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}
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static inline pte_t pte_mkold(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) & ~_PAGE_ACCESSED));
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return pte;
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}
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static inline pte_t pte_mkwrite(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) | _PAGE_RW));
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return pte;
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}
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static inline pte_t pte_mkdirty(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) | _PAGE_DIRTY));
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return pte;
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}
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static inline pte_t pte_mkyoung(pte_t pte)
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{
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set_pte(&pte, __pte(pte_val(pte) | _PAGE_ACCESSED));
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return pte;
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}
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static inline pte_t pte_mkspecial(pte_t pte)
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{
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return pte;
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}
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#define pmd_none(x) (!pmd_val(x))
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#define pmd_present(x) (pmd_val(x) & _PAGE_PRESENT)
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#define pmd_clear(xp) do { set_pmd(xp, __pmd(0)); } while (0)
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#define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) \
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!= _KERNPG_TABLE)
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/*
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* Permanent address of a page. We don't support highmem, so this is
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* trivial.
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*/
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#define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))
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#define pte_page(x) (pfn_to_page(pte_pfn(x)))
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/*
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* Mark the prot value as uncacheable and unbufferable
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*/
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#define pgprot_noncached(prot) \
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__pgprot(pgprot_val(prot) & ~(_PAGE_BUFFER | _PAGE_CACHABLE))
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/*
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* Mark the prot value as uncacheable but bufferable
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*/
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#define pgprot_writecombine(prot) \
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__pgprot((pgprot_val(prot) & ~_PAGE_CACHABLE) | _PAGE_BUFFER)
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/*
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* Conversion functions: convert a page and protection to a page entry,
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* and a page entry and page directory to the page they refer to.
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*
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* extern pte_t mk_pte(struct page *page, pgprot_t pgprot)
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*/
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#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
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static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
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{
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set_pte(&pte, __pte((pte_val(pte) & _PAGE_CHG_MASK)
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| pgprot_val(newprot)));
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return pte;
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}
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#define page_pte(page) page_pte_prot(page, __pgprot(0))
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#define pmd_page_vaddr(pmd) \
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((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
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#define pmd_page(pmd) (phys_to_page(pmd_val(pmd)))
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/* to find an entry in a page-table-directory. */
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#define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
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#define pgd_offset(mm, address) ((mm)->pgd+pgd_index(address))
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#define pgd_offset_current(address) \
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((pgd_t *)__mfsr(SYSREG_PTBR) + pgd_index(address))
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/* to find an entry in a kernel page-table-directory */
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#define pgd_offset_k(address) pgd_offset(&init_mm, address)
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/* Find an entry in the third-level page table.. */
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#define pte_index(address) \
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((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
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#define pte_offset(dir, address) \
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((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(address))
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#define pte_offset_kernel(dir, address) \
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((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(address))
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#define pte_offset_map(dir, address) pte_offset_kernel(dir, address)
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#define pte_offset_map_nested(dir, address) pte_offset_kernel(dir, address)
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#define pte_unmap(pte) do { } while (0)
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#define pte_unmap_nested(pte) do { } while (0)
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struct vm_area_struct;
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extern void update_mmu_cache(struct vm_area_struct * vma,
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unsigned long address, pte_t pte);
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/*
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* Encode and decode a swap entry
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*
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* Constraints:
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* _PAGE_FILE at bit 0
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* _PAGE_TYPE_* at bits 2-3 (for emulating _PAGE_PROTNONE)
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* _PAGE_PRESENT at bit 10
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*
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* We encode the type into bits 4-9 and offset into bits 11-31. This
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* gives us a 21 bits offset, or 2**21 * 4K = 8G usable swap space per
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* device, and 64 possible types.
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*
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* NOTE: We should set ZEROs at the position of _PAGE_PRESENT
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* and _PAGE_PROTNONE bits
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*/
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#define __swp_type(x) (((x).val >> 4) & 0x3f)
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#define __swp_offset(x) ((x).val >> 11)
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#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 4) | ((offset) << 11) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
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#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
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/*
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* Encode and decode a nonlinear file mapping entry. We have to
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* preserve _PAGE_FILE and _PAGE_PRESENT here. _PAGE_TYPE_* isn't
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* necessary, since _PAGE_FILE implies !_PAGE_PROTNONE (?)
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*/
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#define PTE_FILE_MAX_BITS 30
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#define pte_to_pgoff(pte) (((pte_val(pte) >> 1) & 0x1ff) \
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| ((pte_val(pte) >> 11) << 9))
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#define pgoff_to_pte(off) ((pte_t) { ((((off) & 0x1ff) << 1) \
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| (((off) >> 9) << 11) \
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| _PAGE_FILE) })
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typedef pte_t *pte_addr_t;
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#define kern_addr_valid(addr) (1)
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#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
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remap_pfn_range(vma, vaddr, pfn, size, prot)
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/* No page table caches to initialize (?) */
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#define pgtable_cache_init() do { } while(0)
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#include <asm-generic/pgtable.h>
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#endif /* !__ASSEMBLY__ */
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#endif /* __ASM_AVR32_PGTABLE_H */
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