kevin/linux
1
Fork 0
Code
92794a5d63
linux/include/asm-arm/page.h
Martin Schwidefsky 2f569afd9c CONFIG_HIGHPTE vs. sub-page page tables. 
Background: I've implemented 1K/2K page tables for s390.  These sub-page
page tables are required to properly support the s390 virtualization
instruction with KVM.  The SIE instruction requires that the page tables
have 256 page table entries (pte) followed by 256 page status table entries
(pgste).  The pgstes are only required if the process is using the SIE
instruction.  The pgstes are updated by the hardware and by the hypervisor
for a number of reasons, one of them is dirty and reference bit tracking.
To avoid wasting memory the standard pte table allocation should return
1K/2K (31/64 bit) and 2K/4K if the process is using SIE.

Problem: Page size on s390 is 4K, page table size is 1K or 2K.  That means
the s390 version for pte_alloc_one cannot return a pointer to a struct
page.  Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one
cannot return a pointer to a pte either, since that would require more than
32 bit for the return value of pte_alloc_one (and the pte * would not be
accessible since its not kmapped).

Solution: The only solution I found to this dilemma is a new typedef: a
pgtable_t.  For s390 pgtable_t will be a (pte *) - to be introduced with a
later patch.  For everybody else it will be a (struct page *).  The
additional problem with the initialization of the ptl lock and the
NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and
a destructor pgtable_page_dtor.  The page table allocation and free
functions need to call these two whenever a page table page is allocated or
freed.  pmd_populate will get a pgtable_t instead of a struct page pointer.
 To get the pgtable_t back from a pmd entry that has been installed with
pmd_populate a new function pmd_pgtable is added.  It replaces the pmd_page
call in free_pte_range and apply_to_pte_range.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:42 -08:00

195 lines
4.2 KiB
C
Raw Blame History

/*
* linux/include/asm-arm/page.h
*
* Copyright (C) 1995-2003 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _ASMARM_PAGE_H
#define _ASMARM_PAGE_H
/* PAGE_SHIFT determines the page size */
#define PAGE_SHIFT 12
#define PAGE_SIZE (1UL << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
#ifndef __ASSEMBLY__
#ifndef CONFIG_MMU
#include "page-nommu.h"
#else
#include <asm/glue.h>
/*
* User Space Model
* ================
*
* This section selects the correct set of functions for dealing with
* page-based copying and clearing for user space for the particular
* processor(s) we're building for.
*
* We have the following to choose from:
* v3 - ARMv3
* v4wt - ARMv4 with writethrough cache, without minicache
* v4wb - ARMv4 with writeback cache, without minicache
* v4_mc - ARMv4 with minicache
* xscale - Xscale
* xsc3 - XScalev3
*/
#undef _USER
#undef MULTI_USER
#ifdef CONFIG_CPU_COPY_V3
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER v3
# endif
#endif
#ifdef CONFIG_CPU_COPY_V4WT
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER v4wt
# endif
#endif
#ifdef CONFIG_CPU_COPY_V4WB
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER v4wb
# endif
#endif
#ifdef CONFIG_CPU_SA1100
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER v4_mc
# endif
#endif
#ifdef CONFIG_CPU_XSCALE
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER xscale_mc
# endif
#endif
#ifdef CONFIG_CPU_XSC3
# ifdef _USER
# define MULTI_USER 1
# else
# define _USER xsc3_mc
# endif
#endif
#ifdef CONFIG_CPU_COPY_V6
# define MULTI_USER 1
#endif
#if !defined(_USER) && !defined(MULTI_USER)
#error Unknown user operations model
#endif
struct cpu_user_fns {
void (*cpu_clear_user_page)(void *p, unsigned long user);
void (*cpu_copy_user_page)(void *to, const void *from,
unsigned long user);
};
#ifdef MULTI_USER
extern struct cpu_user_fns cpu_user;
#define __cpu_clear_user_page cpu_user.cpu_clear_user_page
#define __cpu_copy_user_page cpu_user.cpu_copy_user_page
#else
#define __cpu_clear_user_page __glue(_USER,_clear_user_page)
#define __cpu_copy_user_page __glue(_USER,_copy_user_page)
extern void __cpu_clear_user_page(void *p, unsigned long user);
extern void __cpu_copy_user_page(void *to, const void *from,
unsigned long user);
#endif
#define clear_user_page(addr,vaddr,pg) __cpu_clear_user_page(addr, vaddr)
#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
#define clear_page(page) memzero((void *)(page), PAGE_SIZE)
extern void copy_page(void *to, const void *from);
#undef STRICT_MM_TYPECHECKS
#ifdef STRICT_MM_TYPECHECKS
/*
* These are used to make use of C type-checking..
*/
typedef struct { unsigned long pte; } pte_t;
typedef struct { unsigned long pmd; } pmd_t;
typedef struct { unsigned long pgd[2]; } pgd_t;
typedef struct { unsigned long pgprot; } pgprot_t;
#define pte_val(x) ((x).pte)
#define pmd_val(x) ((x).pmd)
#define pgd_val(x) ((x).pgd[0])
#define pgprot_val(x) ((x).pgprot)
#define __pte(x) ((pte_t) { (x) } )
#define __pmd(x) ((pmd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
#else
/*
* .. while these make it easier on the compiler
*/
typedef unsigned long pte_t;
typedef unsigned long pmd_t;
typedef unsigned long pgd_t[2];
typedef unsigned long pgprot_t;
#define pte_val(x) (x)
#define pmd_val(x) (x)
#define pgd_val(x) ((x)[0])
#define pgprot_val(x) (x)
#define __pte(x) (x)
#define __pmd(x) (x)
#define __pgprot(x) (x)
#endif /* STRICT_MM_TYPECHECKS */
typedef struct page *pgtable_t;
#endif /* CONFIG_MMU */
#include <asm/memory.h>
#endif /* !__ASSEMBLY__ */
#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
/*
* With EABI on ARMv5 and above we must have 64-bit aligned slab pointers.
*/
#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
#define ARCH_SLAB_MINALIGN 8
#endif
#include <asm-generic/page.h>
#endif
View Git Blame Copy Permalink