OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

OpenRISC: Memory management 

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Jonas Bonn 2011-06-04 11:06:11 +03:00
parent 4f246ba30e
commit 61e85e3675
15 changed files with 2279 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
arch/openrisc/include/asm/cache.h Normal file
View File

@ -0,0 +1,29 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_CACHE_H
#define __ASM_OPENRISC_CACHE_H
/* FIXME: How can we replace these with values from the CPU...
* they shouldn't be hard-coded!
*/
#define L1_CACHE_BYTES 16
#define L1_CACHE_SHIFT 4
#endif /* __ASM_OPENRISC_CACHE_H */

87
arch/openrisc/include/asm/fixmap.h Normal file
View File

@ -0,0 +1,87 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_FIXMAP_H
#define __ASM_OPENRISC_FIXMAP_H
/* Why exactly do we need 2 empty pages between the top of the fixed
* addresses and the top of virtual memory? Something is using that
* memory space but not sure what right now... If you find it, leave
* a comment here.
*/
#define FIXADDR_TOP ((unsigned long) (-2*PAGE_SIZE))
#include <linux/kernel.h>
#include <asm/page.h>
/*
* On OpenRISC we use these special fixed_addresses for doing ioremap
* early in the boot process before memory initialization is complete.
* This is used, in particular, by the early serial console code.
*
* It's not really 'fixmap', per se, but fits loosely into the same
* paradigm.
*/
enum fixed_addresses {
/*
* FIX_IOREMAP entries are useful for mapping physical address
* space before ioremap() is useable, e.g. really early in boot
* before kmalloc() is working.
*/
#define FIX_N_IOREMAPS 32
FIX_IOREMAP_BEGIN,
FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
__end_of_fixed_addresses
};
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
/* FIXADDR_BOTTOM might be a better name here... */
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
/*
* 'index to address' translation. If anyone tries to use the idx
* directly without tranlation, we catch the bug with a NULL-deference
* kernel oops. Illegal ranges of incoming indices are caught too.
*/
static __always_inline unsigned long fix_to_virt(const unsigned int idx)
{
/*
* this branch gets completely eliminated after inlining,
* except when someone tries to use fixaddr indices in an
* illegal way. (such as mixing up address types or using
* out-of-range indices).
*
* If it doesn't get removed, the linker will complain
* loudly with a reasonably clear error message..
*/
if (idx >= __end_of_fixed_addresses)
BUG();
return __fix_to_virt(idx);
}
static inline unsigned long virt_to_fix(const unsigned long vaddr)
{
BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
return __virt_to_fix(vaddr);
}
#endif

24
arch/openrisc/include/asm/memblock.h Normal file
View File

@ -0,0 +1,24 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_MEMBLOCK_H
#define __ASM_OPENRISC_MEMBLOCK_H
/* empty */
#endif /* __ASM_OPENRISC_MEMBLOCK_H */

26
arch/openrisc/include/asm/mmu.h Normal file
View File

@ -0,0 +1,26 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_MMU_H
#define __ASM_OPENRISC_MMU_H
#ifndef __ASSEMBLY__
typedef unsigned long mm_context_t;
#endif
#endif

43
arch/openrisc/include/asm/mmu_context.h Normal file
View File

@ -0,0 +1,43 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_MMU_CONTEXT_H
#define __ASM_OPENRISC_MMU_CONTEXT_H
#include <asm-generic/mm_hooks.h>
extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
extern void destroy_context(struct mm_struct *mm);
extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk);
#define deactivate_mm(tsk, mm) do { } while (0)
#define activate_mm(prev, next) switch_mm((prev), (next), NULL)
/* current active pgd - this is similar to other processors pgd
* registers like cr3 on the i386
*/
extern volatile pgd_t *current_pgd; /* defined in arch/openrisc/mm/fault.c */
static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}
#endif

110
arch/openrisc/include/asm/page.h Normal file
View File

@ -0,0 +1,110 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_PAGE_H
#define __ASM_OPENRISC_PAGE_H
/* PAGE_SHIFT determines the page size */
#define PAGE_SHIFT 13
#ifdef __ASSEMBLY__
#define PAGE_SIZE (1 << PAGE_SHIFT)
#else
#define PAGE_SIZE (1UL << PAGE_SHIFT)
#endif
#define PAGE_MASK (~(PAGE_SIZE-1))
#define PAGE_OFFSET 0xc0000000
#define KERNELBASE PAGE_OFFSET
/* This is not necessarily the right place for this, but it's needed by
* drivers/of/fdt.c
*/
#include <asm/setup.h>
#ifndef __ASSEMBLY__
#define get_user_page(vaddr) __get_free_page(GFP_KERNEL)
#define free_user_page(page, addr) free_page(addr)
#define clear_page(page) memset((page), 0, PAGE_SIZE)
#define copy_page(to, from) memcpy((to), (from), PAGE_SIZE)
#define clear_user_page(page, vaddr, pg) clear_page(page)
#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)
/*
* These are used to make use of C type-checking..
*/
typedef struct {
unsigned long pte;
} pte_t;
typedef struct {
unsigned long pgd;
} pgd_t;
typedef struct {
unsigned long pgprot;
} pgprot_t;
typedef struct page *pgtable_t;
#define pte_val(x) ((x).pte)
#define pgd_val(x) ((x).pgd)
#define pgprot_val(x) ((x).pgprot)
#define __pte(x) ((pte_t) { (x) })
#define __pgd(x) ((pgd_t) { (x) })
#define __pgprot(x) ((pgprot_t) { (x) })
extern unsigned long memory_start;
extern unsigned long memory_end;
#endif /* !__ASSEMBLY__ */
#ifndef __ASSEMBLY__
#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET))
#define __pa(x) ((unsigned long) (x) - PAGE_OFFSET)
#define virt_to_pfn(kaddr) (__pa(kaddr) >> PAGE_SHIFT)
#define pfn_to_virt(pfn) __va((pfn) << PAGE_SHIFT)
#define virt_to_page(addr) \
(mem_map + (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT))
#define page_to_virt(page) \
((((page) - mem_map) << PAGE_SHIFT) + PAGE_OFFSET)
#define page_to_phys(page) ((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)
#define pfn_valid(pfn) ((pfn) < max_mapnr)
#define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
((void *)(kaddr) < (void *)memory_end))
#endif /* __ASSEMBLY__ */
#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#include <asm-generic/memory_model.h>
#include <asm-generic/getorder.h>
#endif /* __ASM_OPENRISC_PAGE_H */

102
arch/openrisc/include/asm/pgalloc.h Normal file
View File

@ -0,0 +1,102 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_PGALLOC_H
#define __ASM_OPENRISC_PGALLOC_H
#include <asm/page.h>
#include <linux/threads.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#include <linux/bootmem.h>
extern int mem_init_done;
#define pmd_populate_kernel(mm, pmd, pte) \
set_pmd(pmd, __pmd(_KERNPG_TABLE + __pa(pte)))
static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
struct page *pte)
{
set_pmd(pmd, __pmd(_KERNPG_TABLE +
((unsigned long)page_to_pfn(pte) <<
(unsigned long) PAGE_SHIFT)));
}
/*
* Allocate and free page tables.
*/
static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *ret = (pgd_t *)__get_free_page(GFP_KERNEL);
if (ret) {
memset(ret, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
memcpy(ret + USER_PTRS_PER_PGD,
swapper_pg_dir + USER_PTRS_PER_PGD,
(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
}
return ret;
}
#if 0
/* FIXME: This seems to be the preferred style, but we are using
* current_pgd (from mm->pgd) to load kernel pages so we need it
* initialized. This needs to be looked into.
*/
extern inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
return (pgd_t *)get_zeroed_page(GFP_KERNEL);
}
#endif
static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
free_page((unsigned long)pgd);
}
extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address);
static inline struct page *pte_alloc_one(struct mm_struct *mm,
unsigned long address)
{
struct page *pte;
pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT, 0);
if (pte)
clear_page(page_address(pte));
return pte;
}
static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
{
free_page((unsigned long)pte);
}
static inline void pte_free(struct mm_struct *mm, struct page *pte)
{
__free_page(pte);
}
#define __pte_free_tlb(tlb, pte, addr) tlb_remove_page((tlb), (pte))
#define pmd_pgtable(pmd) pmd_page(pmd)
#define check_pgt_cache() do { } while (0)
#endif

463
arch/openrisc/include/asm/pgtable.h Normal file
View File

@ -0,0 +1,463 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
/* or32 pgtable.h - macros and functions to manipulate page tables
*
* Based on:
* include/asm-cris/pgtable.h
*/
#ifndef __ASM_OPENRISC_PGTABLE_H
#define __ASM_OPENRISC_PGTABLE_H
#include <asm-generic/pgtable-nopmd.h>
#ifndef __ASSEMBLY__
#include <asm/mmu.h>
#include <asm/fixmap.h>
/*
* The Linux memory management assumes a three-level page table setup. On
* or32, we use that, but "fold" the mid level into the top-level page
* table. Since the MMU TLB is software loaded through an interrupt, it
* supports any page table structure, so we could have used a three-level
* setup, but for the amounts of memory we normally use, a two-level is
* probably more efficient.
*
* This file contains the functions and defines necessary to modify and use
* the or32 page table tree.
*/
extern void paging_init(void);
/* Certain architectures need to do special things when pte's
* within a page table are directly modified. Thus, the following
* hook is made available.
*/
#define set_pte(pteptr, pteval) ((*(pteptr)) = (pteval))
#define set_pte_at(mm, addr, ptep, pteval) set_pte(ptep, pteval)
/*
* (pmds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
*/
#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
#define PGDIR_SHIFT (PAGE_SHIFT + (PAGE_SHIFT-2))
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/*
* entries per page directory level: we use a two-level, so
* we don't really have any PMD directory physically.
* pointers are 4 bytes so we can use the page size and
* divide it by 4 (shift by 2).
*/
#define PTRS_PER_PTE (1UL << (PAGE_SHIFT-2))
#define PTRS_PER_PGD (1UL << (PAGE_SHIFT-2))
/* calculate how many PGD entries a user-level program can use
* the first mappable virtual address is 0
* (TASK_SIZE is the maximum virtual address space)
*/
#define USER_PTRS_PER_PGD (TASK_SIZE/PGDIR_SIZE)
#define FIRST_USER_ADDRESS 0
/*
* Kernels own virtual memory area.
*/
/*
* The size and location of the vmalloc area are chosen so that modules
* placed in this area aren't more than a 28-bit signed offset from any
* kernel functions that they may need. This greatly simplifies handling
* of the relocations for l.j and l.jal instructions as we don't need to
* introduce any trampolines for reaching "distant" code.
*
* 64 MB of vmalloc area is comparable to what's available on other arches.
*/
#define VMALLOC_START (PAGE_OFFSET-0x04000000)
#define VMALLOC_END (PAGE_OFFSET)
#define VMALLOC_VMADDR(x) ((unsigned long)(x))
/* Define some higher level generic page attributes.
*
* If you change _PAGE_CI definition be sure to change it in
* io.h for ioremap_nocache() too.
*/
/*
* An OR32 PTE looks like this:
*
* | 31 ... 10 | 9 | 8 ... 6 | 5 | 4 | 3 | 2 | 1 | 0 |
* Phys pg.num L PP Index D A WOM WBC CI CC
*
* L : link
* PPI: Page protection index
* D : Dirty
* A : Accessed
* WOM: Weakly ordered memory
* WBC: Write-back cache
* CI : Cache inhibit
* CC : Cache coherent
*
* The protection bits below should correspond to the layout of the actual
* PTE as per above
*/
#define _PAGE_CC 0x001 /* software: pte contains a translation */
#define _PAGE_CI 0x002 /* cache inhibit */
#define _PAGE_WBC 0x004 /* write back cache */
#define _PAGE_FILE 0x004 /* set: pagecache, unset: swap (when !PRESENT) */
#define _PAGE_WOM 0x008 /* weakly ordered memory */
#define _PAGE_A 0x010 /* accessed */
#define _PAGE_D 0x020 /* dirty */
#define _PAGE_URE 0x040 /* user read enable */
#define _PAGE_UWE 0x080 /* user write enable */
#define _PAGE_SRE 0x100 /* superuser read enable */
#define _PAGE_SWE 0x200 /* superuser write enable */
#define _PAGE_EXEC 0x400 /* software: page is executable */
#define _PAGE_U_SHARED 0x800 /* software: page is shared in user space */
/* 0x001 is cache coherency bit, which should always be set to
* 1 - for SMP (when we support it)
* 0 - otherwise
*
* we just reuse this bit in software for _PAGE_PRESENT and
* force it to 0 when loading it into TLB.
*/
#define _PAGE_PRESENT _PAGE_CC
#define _PAGE_USER _PAGE_URE
#define _PAGE_WRITE (_PAGE_UWE | _PAGE_SWE)
#define _PAGE_DIRTY _PAGE_D
#define _PAGE_ACCESSED _PAGE_A
#define _PAGE_NO_CACHE _PAGE_CI
#define _PAGE_SHARED _PAGE_U_SHARED
#define _PAGE_READ (_PAGE_URE | _PAGE_SRE)
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED)
#define _PAGE_ALL (_PAGE_PRESENT | _PAGE_ACCESSED)
#define _KERNPG_TABLE \
(_PAGE_BASE | _PAGE_SRE | _PAGE_SWE | _PAGE_ACCESSED | _PAGE_DIRTY)
#define PAGE_NONE __pgprot(_PAGE_ALL)
#define PAGE_READONLY __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE)
#define PAGE_READONLY_X __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_EXEC)
#define PAGE_SHARED \
__pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_UWE | _PAGE_SWE \
| _PAGE_SHARED)
#define PAGE_SHARED_X \
__pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_UWE | _PAGE_SWE \
| _PAGE_SHARED | _PAGE_EXEC)
#define PAGE_COPY __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE)
#define PAGE_COPY_X __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_EXEC)
#define PAGE_KERNEL \
__pgprot(_PAGE_ALL | _PAGE_SRE | _PAGE_SWE \
| _PAGE_SHARED | _PAGE_DIRTY | _PAGE_EXEC)
#define PAGE_KERNEL_RO \
__pgprot(_PAGE_ALL | _PAGE_SRE \
| _PAGE_SHARED | _PAGE_DIRTY | _PAGE_EXEC)
#define PAGE_KERNEL_NOCACHE \
__pgprot(_PAGE_ALL | _PAGE_SRE | _PAGE_SWE \
| _PAGE_SHARED | _PAGE_DIRTY | _PAGE_EXEC | _PAGE_CI)
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY_X
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY_X
#define __P100 PAGE_READONLY
#define __P101 PAGE_READONLY_X
#define __P110 PAGE_COPY
#define __P111 PAGE_COPY_X
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY_X
#define __S010 PAGE_SHARED
#define __S011 PAGE_SHARED_X
#define __S100 PAGE_READONLY
#define __S101 PAGE_READONLY_X
#define __S110 PAGE_SHARED
#define __S111 PAGE_SHARED_X
/* zero page used for uninitialized stuff */
extern unsigned long empty_zero_page[2048];
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
/* number of bits that fit into a memory pointer */
#define BITS_PER_PTR (8*sizeof(unsigned long))
/* to align the pointer to a pointer address */
#define PTR_MASK (~(sizeof(void *)-1))
/* sizeof(void*)==1<<SIZEOF_PTR_LOG2 */
/* 64-bit machines, beware! SRB. */
#define SIZEOF_PTR_LOG2 2
/* to find an entry in a page-table */
#define PAGE_PTR(address) \
((unsigned long)(address)>>(PAGE_SHIFT-SIZEOF_PTR_LOG2)&PTR_MASK&~PAGE_MASK)
/* to set the page-dir */
#define SET_PAGE_DIR(tsk, pgdir)
#define pte_none(x) (!pte_val(x))
#define pte_present(x) (pte_val(x) & _PAGE_PRESENT)
#define pte_clear(mm, addr, xp) do { pte_val(*(xp)) = 0; } while (0)
#define pmd_none(x) (!pmd_val(x))
#define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK)) != _KERNPG_TABLE)
#define pmd_present(x) (pmd_val(x) & _PAGE_PRESENT)
#define pmd_clear(xp) do { pmd_val(*(xp)) = 0; } while (0)
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
static inline int pte_read(pte_t pte) { return pte_val(pte) & _PAGE_READ; }
static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_WRITE; }
static inline int pte_exec(pte_t pte) { return pte_val(pte) & _PAGE_EXEC; }
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_mkspecial(pte_t pte) { return pte; }
static inline pte_t pte_wrprotect(pte_t pte)
{
pte_val(pte) &= ~(_PAGE_WRITE);
return pte;
}
static inline pte_t pte_rdprotect(pte_t pte)
{
pte_val(pte) &= ~(_PAGE_READ);
return pte;
}
static inline pte_t pte_exprotect(pte_t pte)
{
pte_val(pte) &= ~(_PAGE_EXEC);
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_WRITE;
return pte;
}
static inline pte_t pte_mkread(pte_t pte)
{
pte_val(pte) |= _PAGE_READ;
return pte;
}
static inline pte_t pte_mkexec(pte_t pte)
{
pte_val(pte) |= _PAGE_EXEC;
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;
}
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
/* What actually goes as arguments to the various functions is less than
* obvious, but a rule of thumb is that struct page's goes as struct page *,
* really physical DRAM addresses are unsigned long's, and DRAM "virtual"
* addresses (the 0xc0xxxxxx's) goes as void *'s.
*/
static inline pte_t __mk_pte(void *page, pgprot_t pgprot)
{
pte_t pte;
/* the PTE needs a physical address */
pte_val(pte) = __pa(page) | pgprot_val(pgprot);
return pte;
}
#define mk_pte(page, pgprot) __mk_pte(page_address(page), (pgprot))
#define mk_pte_phys(physpage, pgprot) \
({ \
pte_t __pte; \
\
pte_val(__pte) = (physpage) + pgprot_val(pgprot); \
__pte; \
})
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;
}
/*
* pte_val refers to a page in the 0x0xxxxxxx physical DRAM interval
* __pte_page(pte_val) refers to the "virtual" DRAM interval
* pte_pagenr refers to the page-number counted starting from the virtual
* DRAM start
*/
static inline unsigned long __pte_page(pte_t pte)
{
/* the PTE contains a physical address */
return (unsigned long)__va(pte_val(pte) & PAGE_MASK);
}
#define pte_pagenr(pte) ((__pte_page(pte) - PAGE_OFFSET) >> PAGE_SHIFT)
/* permanent address of a page */
#define __page_address(page) (PAGE_OFFSET + (((page) - mem_map) << PAGE_SHIFT))
#define pte_page(pte) (mem_map+pte_pagenr(pte))
/*
* only the pte's themselves need to point to physical DRAM (see above)
* the pagetable links are purely handled within the kernel SW and thus
* don't need the __pa and __va transformations.
*/
static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
{
pmd_val(*pmdp) = _KERNPG_TABLE | (unsigned long) ptep;
}
#define pmd_page(pmd) (pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
#define pmd_page_kernel(pmd) ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
/* to find an entry in a page-table-directory. */
#define pgd_index(address) ((address >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
#define __pgd_offset(address) pgd_index(address)
#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_offset(address) \
(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))
/*
* the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
*
* this macro returns the index of the entry in the pte page which would
* control the given virtual address
*/
#define __pte_offset(address) \
(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, address) \
((pte_t *) pmd_page_kernel(*(dir)) + __pte_offset(address))
#define pte_offset_map(dir, address) \
((pte_t *)page_address(pmd_page(*(dir))) + __pte_offset(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)
#define pte_pfn(x) ((unsigned long)(((x).pte)) >> PAGE_SHIFT)
#define pfn_pte(pfn, prot) __pte((((pfn) << PAGE_SHIFT)) | pgprot_val(prot))
#define pte_ERROR(e) \
printk(KERN_ERR "%s:%d: bad pte %p(%08lx).\n", \
__FILE__, __LINE__, &(e), pte_val(e))
#define pgd_ERROR(e) \
printk(KERN_ERR "%s:%d: bad pgd %p(%08lx).\n", \
__FILE__, __LINE__, &(e), pgd_val(e))
extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; /* defined in head.S */
/*
* or32 doesn't have any external MMU info: the kernel page
* tables contain all the necessary information.
*
* Actually I am not sure on what this could be used for.
*/
static inline void update_mmu_cache(struct vm_area_struct *vma,
unsigned long address, pte_t *pte)
{
}
/* __PHX__ FIXME, SWAP, this probably doesn't work */
/* Encode and de-code a swap entry (must be !pte_none(e) && !pte_present(e)) */
/* Since the PAGE_PRESENT bit is bit 4, we can use the bits above */
#define __swp_type(x) (((x).val >> 5) & 0x7f)
#define __swp_offset(x) ((x).val >> 12)
#define __swp_entry(type, offset) \
((swp_entry_t) { ((type) << 5) | ((offset) << 12) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
/* Encode and decode a nonlinear file mapping entry */
#define PTE_FILE_MAX_BITS 26
#define pte_to_pgoff(x) (pte_val(x) >> 6)
#define pgoff_to_pte(x) __pte(((x) << 6) | _PAGE_FILE)
#define kern_addr_valid(addr) (1)
#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
remap_pfn_range(vma, vaddr, pfn, size, prot)
#include <asm-generic/pgtable.h>
/*
* No page table caches to initialise
*/
#define pgtable_cache_init() do { } while (0)
#define io_remap_page_range remap_page_range
typedef pte_t *pte_addr_t;
#endif /* __ASSEMBLY__ */
#endif /* __ASM_OPENRISC_PGTABLE_H */

34
arch/openrisc/include/asm/tlb.h Normal file
View File

@ -0,0 +1,34 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_TLB_H__
#define __ASM_OPENRISC_TLB_H__
/*
* or32 doesn't need any special per-pte or
* per-vma handling..
*/
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
#include <linux/pagemap.h>
#include <asm-generic/tlb.h>
#endif /* __ASM_OPENRISC_TLB_H__ */

55
arch/openrisc/include/asm/tlbflush.h Normal file
View File

@ -0,0 +1,55 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_TLBFLUSH_H
#define __ASM_OPENRISC_TLBFLUSH_H
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/current.h>
#include <linux/sched.h>
/*
* - flush_tlb() flushes the current mm struct TLBs
* - flush_tlb_all() flushes all processes TLBs
* - flush_tlb_mm(mm) flushes the specified mm context TLB's
* - flush_tlb_page(vma, vmaddr) flushes one page
* - flush_tlb_range(mm, start, end) flushes a range of pages
*/
void flush_tlb_all(void);
void flush_tlb_mm(struct mm_struct *mm);
void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr);
void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start,
unsigned long end);
static inline void flush_tlb(void)
{
flush_tlb_mm(current->mm);
}
static inline void flush_tlb_kernel_range(unsigned long start,
unsigned long end)
{
flush_tlb_range(NULL, start, end);
}
#endif /* __ASM_OPENRISC_TLBFLUSH_H */

355
arch/openrisc/include/asm/uaccess.h Normal file
View File

@ -0,0 +1,355 @@
/*
* OpenRISC Linux
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* OpenRISC implementation:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
* et al.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#ifndef __ASM_OPENRISC_UACCESS_H
#define __ASM_OPENRISC_UACCESS_H
/*
* User space memory access functions
*/
#include <linux/errno.h>
#include <linux/thread_info.h>
#include <linux/prefetch.h>
#include <linux/string.h>
#include <linux/thread_info.h>
#include <asm/page.h>
#define VERIFY_READ 0
#define VERIFY_WRITE 1
/*
* The fs value determines whether argument validity checking should be
* performed or not. If get_fs() == USER_DS, checking is performed, with
* get_fs() == KERNEL_DS, checking is bypassed.
*
* For historical reasons, these macros are grossly misnamed.
*/
/* addr_limit is the maximum accessible address for the task. we misuse
* the KERNEL_DS and USER_DS values to both assign and compare the
* addr_limit values through the equally misnamed get/set_fs macros.
* (see above)
*/
#define KERNEL_DS (~0UL)
#define get_ds() (KERNEL_DS)
#define USER_DS (TASK_SIZE)
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
#define segment_eq(a, b) ((a) == (b))
/* Ensure that the range from addr to addr+size is all within the process'
* address space
*/
#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs()-size))
/* Ensure that addr is below task's addr_limit */
#define __addr_ok(addr) ((unsigned long) addr < get_fs())
#define access_ok(type, addr, size) \
__range_ok((unsigned long)addr, (unsigned long)size)
/*
* The exception table consists of pairs of addresses: the first is the
* address of an instruction that is allowed to fault, and the second is
* the address at which the program should continue. No registers are
* modified, so it is entirely up to the continuation code to figure out
* what to do.
*
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
* we don't even have to jump over them. Further, they do not intrude
* on our cache or tlb entries.
*/
struct exception_table_entry {
unsigned long insn, fixup;
};
/* Returns 0 if exception not found and fixup otherwise. */
extern unsigned long search_exception_table(unsigned long);
extern void sort_exception_table(void);
/*
* These are the main single-value transfer routines. They automatically
* use the right size if we just have the right pointer type.
*
* This gets kind of ugly. We want to return _two_ values in "get_user()"
* and yet we don't want to do any pointers, because that is too much
* of a performance impact. Thus we have a few rather ugly macros here,
* and hide all the uglyness from the user.
*
* The "__xxx" versions of the user access functions are versions that
* do not verify the address space, that must have been done previously
* with a separate "access_ok()" call (this is used when we do multiple
* accesses to the same area of user memory).
*
* As we use the same address space for kernel and user data on the
* PowerPC, we can just do these as direct assignments. (Of course, the
* exception handling means that it's no longer "just"...)
*/
#define get_user(x, ptr) \
__get_user_check((x), (ptr), sizeof(*(ptr)))
#define put_user(x, ptr) \
__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
#define __get_user(x, ptr) \
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
#define __put_user(x, ptr) \
__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
extern long __put_user_bad(void);
#define __put_user_nocheck(x, ptr, size) \
({ \
long __pu_err; \
__put_user_size((x), (ptr), (size), __pu_err); \
__pu_err; \
})
#define __put_user_check(x, ptr, size) \
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) *__pu_addr = (ptr); \
if (access_ok(VERIFY_WRITE, __pu_addr, size)) \
__put_user_size((x), __pu_addr, (size), __pu_err); \
__pu_err; \
})
#define __put_user_size(x, ptr, size, retval) \
do { \
retval = 0; \
switch (size) { \
case 1: __put_user_asm(x, ptr, retval, "l.sb"); break; \
case 2: __put_user_asm(x, ptr, retval, "l.sh"); break; \
case 4: __put_user_asm(x, ptr, retval, "l.sw"); break; \
case 8: __put_user_asm2(x, ptr, retval); break; \
default: __put_user_bad(); \
} \
} while (0)
struct __large_struct {
unsigned long buf[100];
};
#define __m(x) (*(struct __large_struct *)(x))
/*
* We don't tell gcc that we are accessing memory, but this is OK
* because we do not write to any memory gcc knows about, so there
* are no aliasing issues.
*/
#define __put_user_asm(x, addr, err, op) \
__asm__ __volatile__( \
"1: "op" 0(%2),%1\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: l.addi %0,r0,%3\n" \
" l.j 2b\n" \
" l.nop\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 2\n" \
" .long 1b,3b\n" \
".previous" \
: "=r"(err) \
: "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
#define __put_user_asm2(x, addr, err) \
__asm__ __volatile__( \
"1: l.sw 0(%2),%1\n" \
"2: l.sw 4(%2),%H1\n" \
"3:\n" \
".section .fixup,\"ax\"\n" \
"4: l.addi %0,r0,%3\n" \
" l.j 3b\n" \
" l.nop\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 2\n" \
" .long 1b,4b\n" \
" .long 2b,4b\n" \
".previous" \
: "=r"(err) \
: "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
#define __get_user_nocheck(x, ptr, size) \
({ \
long __gu_err, __gu_val; \
__get_user_size(__gu_val, (ptr), (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
#define __get_user_check(x, ptr, size) \
({ \
long __gu_err = -EFAULT, __gu_val = 0; \
const __typeof__(*(ptr)) * __gu_addr = (ptr); \
if (access_ok(VERIFY_READ, __gu_addr, size)) \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
extern long __get_user_bad(void);
#define __get_user_size(x, ptr, size, retval) \
do { \
retval = 0; \
switch (size) { \
case 1: __get_user_asm(x, ptr, retval, "l.lbz"); break; \
case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break; \
case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break; \
case 8: __get_user_asm2(x, ptr, retval); \
default: (x) = __get_user_bad(); \
} \
} while (0)
#define __get_user_asm(x, addr, err, op) \
__asm__ __volatile__( \
"1: "op" %1,0(%2)\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: l.addi %0,r0,%3\n" \
" l.addi %1,r0,0\n" \
" l.j 2b\n" \
" l.nop\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 2\n" \
" .long 1b,3b\n" \
".previous" \
: "=r"(err), "=r"(x) \
: "r"(addr), "i"(-EFAULT), "0"(err))
#define __get_user_asm2(x, addr, err) \
__asm__ __volatile__( \
"1: l.lwz %1,0(%2)\n" \
"2: l.lwz %H1,4(%2)\n" \
"3:\n" \
".section .fixup,\"ax\"\n" \
"4: l.addi %0,r0,%3\n" \
" l.addi %1,r0,0\n" \
" l.addi %H1,r0,0\n" \
" l.j 3b\n" \
" l.nop\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 2\n" \
" .long 1b,4b\n" \
" .long 2b,4b\n" \
".previous" \
: "=r"(err), "=&r"(x) \
: "r"(addr), "i"(-EFAULT), "0"(err))
/* more complex routines */
extern unsigned long __must_check
__copy_tofrom_user(void *to, const void *from, unsigned long size);
#define __copy_from_user(to, from, size) \
__copy_tofrom_user(to, from, size)
#define __copy_to_user(to, from, size) \
__copy_tofrom_user(to, from, size)
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user
static inline unsigned long
copy_from_user(void *to, const void *from, unsigned long n)
{
unsigned long over;
if (access_ok(VERIFY_READ, from, n))
return __copy_tofrom_user(to, from, n);
if ((unsigned long)from < TASK_SIZE) {
over = (unsigned long)from + n - TASK_SIZE;
return __copy_tofrom_user(to, from, n - over) + over;
}
return n;
}
static inline unsigned long
copy_to_user(void *to, const void *from, unsigned long n)
{
unsigned long over;
if (access_ok(VERIFY_WRITE, to, n))
return __copy_tofrom_user(to, from, n);
if ((unsigned long)to < TASK_SIZE) {
over = (unsigned long)to + n - TASK_SIZE;
return __copy_tofrom_user(to, from, n - over) + over;
}
return n;
}
extern unsigned long __clear_user(void *addr, unsigned long size);
static inline __must_check unsigned long
clear_user(void *addr, unsigned long size)
{
if (access_ok(VERIFY_WRITE, addr, size))
return __clear_user(addr, size);
if ((unsigned long)addr < TASK_SIZE) {
unsigned long over = (unsigned long)addr + size - TASK_SIZE;
return __clear_user(addr, size - over) + over;
}
return size;
}
extern int __strncpy_from_user(char *dst, const char *src, long count);
static inline long strncpy_from_user(char *dst, const char *src, long count)
{
if (access_ok(VERIFY_READ, src, 1))
return __strncpy_from_user(dst, src, count);
return -EFAULT;
}
/*
* Return the size of a string (including the ending 0)
*
* Return 0 for error
*/
extern int __strnlen_user(const char *str, long len, unsigned long top);
/*
* Returns the length of the string at str (including the null byte),
* or 0 if we hit a page we can't access,
* or something > len if we didn't find a null byte.
*
* The `top' parameter to __strnlen_user is to make sure that
* we can never overflow from the user area into kernel space.
*/
static inline long strnlen_user(const char __user *str, long len)
{
unsigned long top = (unsigned long)get_fs();
unsigned long res = 0;
if (__addr_ok(str))
res = __strnlen_user(str, len, top);
return res;
}
#define strlen_user(str) strnlen_user(str, TASK_SIZE-1)
#endif /* __ASM_OPENRISC_UACCESS_H */

338
arch/openrisc/mm/fault.c Normal file
View File

@ -0,0 +1,338 @@
/*
* OpenRISC fault.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <asm/siginfo.h>
#include <asm/signal.h>
#define NUM_TLB_ENTRIES 64
#define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))
unsigned long pte_misses; /* updated by do_page_fault() */
unsigned long pte_errors; /* updated by do_page_fault() */
/* __PHX__ :: - check the vmalloc_fault in do_page_fault()
* - also look into include/asm-or32/mmu_context.h
*/
volatile pgd_t *current_pgd;
extern void die(char *, struct pt_regs *, long);
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* If this routine detects a bad access, it returns 1, otherwise it
* returns 0.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long vector, int write_acc)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
siginfo_t info;
int fault;
tsk = current;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*
* NOTE2: This is done so that, when updating the vmalloc
* mappings we don't have to walk all processes pgdirs and
* add the high mappings all at once. Instead we do it as they
* are used. However vmalloc'ed page entries have the PAGE_GLOBAL
* bit set so sometimes the TLB can use a lingering entry.
*
* This verifies that the fault happens in kernel space
* and that the fault was not a protection error.
*/
if (address >= VMALLOC_START &&
(vector != 0x300 && vector != 0x400) &&
!user_mode(regs))
goto vmalloc_fault;
/* If exceptions were enabled, we can reenable them here */
if (user_mode(regs)) {
/* Exception was in userspace: reenable interrupts */
local_irq_enable();
} else {
/* If exception was in a syscall, then IRQ's may have
* been enabled or disabled. If they were enabled,
* reenable them.
*/
if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE))
local_irq_enable();
}
mm = tsk->mm;
info.si_code = SEGV_MAPERR;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (in_interrupt() || !mm)
goto no_context;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (user_mode(regs)) {
/*
* accessing the stack below usp is always a bug.
* we get page-aligned addresses so we can only check
* if we're within a page from usp, but that might be
* enough to catch brutal errors at least.
*/
if (address + PAGE_SIZE < regs->sp)
goto bad_area;
}
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
info.si_code = SEGV_ACCERR;
/* first do some preliminary protection checks */
if (write_acc) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
/* not present */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/* are we trying to execute nonexecutable area */
if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC))
goto bad_area;
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(mm, vma, address, write_acc);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
/*RGD modeled on Cris */
if (fault & VM_FAULT_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
up_read(&mm->mmap_sem);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (user_mode(regs)) {
info.si_signo = SIGSEGV;
info.si_errno = 0;
/* info.si_code has been set above */
info.si_addr = (void *)address;
force_sig_info(SIGSEGV, &info, tsk);
return;
}
no_context:
/* Are we prepared to handle this kernel fault?
*
* (The kernel has valid exception-points in the source
* when it acesses user-memory. When it fails in one
* of those points, we find it in a table and do a jump
* to some fixup code that loads an appropriate error
* code)
*/
{
const struct exception_table_entry *entry;
__asm__ __volatile__("l.nop 42");
if ((entry = search_exception_tables(regs->pc)) != NULL) {
/* Adjust the instruction pointer in the stackframe */
regs->pc = entry->fixup;
return;
}
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if ((unsigned long)(address) < PAGE_SIZE)
printk(KERN_ALERT
"Unable to handle kernel NULL pointer dereference");
else
printk(KERN_ALERT "Unable to handle kernel access");
printk(" at virtual address 0x%08lx\n", address);
die("Oops", regs, write_acc);
do_exit(SIGKILL);
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
__asm__ __volatile__("l.nop 42");
__asm__ __volatile__("l.nop 1");
up_read(&mm->mmap_sem);
printk("VM: killing process %s\n", tsk->comm);
if (user_mode(regs))
do_exit(SIGKILL);
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (void *)address;
force_sig_info(SIGBUS, &info, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
return;
vmalloc_fault:
{
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Use current_pgd instead of tsk->active_mm->pgd
* since the latter might be unavailable if this
* code is executed in a misfortunately run irq
* (like inside schedule() between switch_mm and
* switch_to...).
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
/*
phx_warn("do_page_fault(): vmalloc_fault will not work, "
"since current_pgd assign a proper value somewhere\n"
"anyhow we don't need this at the moment\n");
phx_mmu("vmalloc_fault");
*/
pgd = (pgd_t *)current_pgd + offset;
pgd_k = init_mm.pgd + offset;
/* Since we're two-level, we don't need to do both
* set_pgd and set_pmd (they do the same thing). If
* we go three-level at some point, do the right thing
* with pgd_present and set_pgd here.
*
* Also, since the vmalloc area is global, we don't
* need to copy individual PTE's, it is enough to
* copy the pgd pointer into the pte page of the
* root task. If that is there, we'll find our pte if
* it exists.
*/
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto no_context;
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto bad_area_nosemaphore;
set_pmd(pmd, *pmd_k);
/* Make sure the actual PTE exists as well to
* catch kernel vmalloc-area accesses to non-mapped
* addresses. If we don't do this, this will just
* silently loop forever.
*/
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;
return;
}
}

283
arch/openrisc/mm/init.c Normal file
View File

@ -0,0 +1,283 @@
/*
* OpenRISC idle.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/blkdev.h> /* for initrd_* */
#include <linux/pagemap.h>
#include <linux/memblock.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/dma.h>
#include <asm/io.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/kmap_types.h>
#include <asm/fixmap.h>
#include <asm/tlbflush.h>
int mem_init_done;
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
static void __init zone_sizes_init(void)
{
unsigned long zones_size[MAX_NR_ZONES];
/* Clear the zone sizes */
memset(zones_size, 0, sizeof(zones_size));
/*
* We use only ZONE_NORMAL
*/
zones_size[ZONE_NORMAL] = max_low_pfn;
free_area_init(zones_size);
}
extern const char _s_kernel_ro[], _e_kernel_ro[];
/*
* Map all physical memory into kernel's address space.
*
* This is explicitly coded for two-level page tables, so if you need
* something else then this needs to change.
*/
static void __init map_ram(void)
{
unsigned long v, p, e;
pgprot_t prot;
pgd_t *pge;
pud_t *pue;
pmd_t *pme;
pte_t *pte;
/* These mark extents of read-only kernel pages...
* ...from vmlinux.lds.S
*/
struct memblock_region *region;
v = PAGE_OFFSET;
for_each_memblock(memory, region) {
p = (u32) region->base & PAGE_MASK;
e = p + (u32) region->size;
v = (u32) __va(p);
pge = pgd_offset_k(v);
while (p < e) {
int j;
pue = pud_offset(pge, v);
pme = pmd_offset(pue, v);
if ((u32) pue != (u32) pge || (u32) pme != (u32) pge) {
panic("%s: OR1K kernel hardcoded for "
"two-level page tables",
__func__);
}
/* Alloc one page for holding PTE's... */
pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
set_pmd(pme, __pmd(_KERNPG_TABLE + __pa(pte)));
/* Fill the newly allocated page with PTE'S */
for (j = 0; p < e && j < PTRS_PER_PGD;
v += PAGE_SIZE, p += PAGE_SIZE, j++, pte++) {
if (v >= (u32) _e_kernel_ro ||
v < (u32) _s_kernel_ro)
prot = PAGE_KERNEL;
else
prot = PAGE_KERNEL_RO;
set_pte(pte, mk_pte_phys(p, prot));
}
pge++;
}
printk(KERN_INFO "%s: Memory: 0x%x-0x%x\n", __func__,
region->base, region->base + region->size);
}
}
void __init paging_init(void)
{
extern void tlb_init(void);
unsigned long end;
int i;
printk(KERN_INFO "Setting up paging and PTEs.\n");
/* clear out the init_mm.pgd that will contain the kernel's mappings */
for (i = 0; i < PTRS_PER_PGD; i++)
swapper_pg_dir[i] = __pgd(0);
/* make sure the current pgd table points to something sane
* (even if it is most probably not used until the next
* switch_mm)
*/
current_pgd = init_mm.pgd;
end = (unsigned long)__va(max_low_pfn * PAGE_SIZE);
map_ram();
zone_sizes_init();
/* self modifying code ;) */
/* Since the old TLB miss handler has been running up until now,
* the kernel pages are still all RW, so we can still modify the
* text directly... after this change and a TLB flush, the kernel
* pages will become RO.
*/
{
extern unsigned long dtlb_miss_handler;
extern unsigned long itlb_miss_handler;
unsigned long *dtlb_vector = __va(0x900);
unsigned long *itlb_vector = __va(0xa00);
printk(KERN_INFO "dtlb_miss_handler %p\n", &dtlb_miss_handler);
*dtlb_vector = ((unsigned long)&dtlb_miss_handler -
(unsigned long)dtlb_vector) >> 2;
printk(KERN_INFO "itlb_miss_handler %p\n", &itlb_miss_handler);
*itlb_vector = ((unsigned long)&itlb_miss_handler -
(unsigned long)itlb_vector) >> 2;
}
/* Invalidate instruction caches after code modification */
mtspr(SPR_ICBIR, 0x900);
mtspr(SPR_ICBIR, 0xa00);
/* New TLB miss handlers and kernel page tables are in now place.
* Make sure that page flags get updated for all pages in TLB by
* flushing the TLB and forcing all TLB entries to be recreated
* from their page table flags.
*/
flush_tlb_all();
}
/* References to section boundaries */
extern char _stext, _etext, _edata, __bss_start, _end;
extern char __init_begin, __init_end;
static int __init free_pages_init(void)
{
int reservedpages, pfn;
/* this will put all low memory onto the freelists */
totalram_pages = free_all_bootmem();
reservedpages = 0;
for (pfn = 0; pfn < max_low_pfn; pfn++) {
/*
* Only count reserved RAM pages
*/
if (PageReserved(mem_map + pfn))
reservedpages++;
}
return reservedpages;
}
static void __init set_max_mapnr_init(void)
{
max_mapnr = num_physpages = max_low_pfn;
}
void __init mem_init(void)
{
int codesize, reservedpages, datasize, initsize;
if (!mem_map)
BUG();
set_max_mapnr_init();
high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
/* clear the zero-page */
memset((void *)empty_zero_page, 0, PAGE_SIZE);
reservedpages = free_pages_init();
codesize = (unsigned long)&_etext - (unsigned long)&_stext;
datasize = (unsigned long)&_edata - (unsigned long)&_etext;
initsize = (unsigned long)&__init_end - (unsigned long)&__init_begin;
printk(KERN_INFO
"Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
(unsigned long)nr_free_pages() << (PAGE_SHIFT - 10),
max_mapnr << (PAGE_SHIFT - 10), codesize >> 10,
reservedpages << (PAGE_SHIFT - 10), datasize >> 10,
initsize >> 10, (unsigned long)(0 << (PAGE_SHIFT - 10))
);
printk("mem_init_done ...........................................\n");
mem_init_done = 1;
return;
}
#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
printk(KERN_INFO "Freeing initrd memory: %ldk freed\n",
(end - start) >> 10);
for (; start < end; start += PAGE_SIZE) {
ClearPageReserved(virt_to_page(start));
init_page_count(virt_to_page(start));
free_page(start);
totalram_pages++;
}
}
#endif
void free_initmem(void)
{
unsigned long addr;
addr = (unsigned long)(&__init_begin);
for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
ClearPageReserved(virt_to_page(addr));
init_page_count(virt_to_page(addr));
free_page(addr);
totalram_pages++;
}
printk(KERN_INFO "Freeing unused kernel memory: %luk freed\n",
((unsigned long)&__init_end -
(unsigned long)&__init_begin) >> 10);
}

137
arch/openrisc/mm/ioremap.c Normal file
View File

@ -0,0 +1,137 @@
/*
* OpenRISC ioremap.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/vmalloc.h>
#include <linux/io.h>
#include <asm/pgalloc.h>
#include <asm/kmap_types.h>
#include <asm/fixmap.h>
#include <asm/bug.h>
#include <asm/pgtable.h>
#include <linux/sched.h>
#include <asm/tlbflush.h>
extern int mem_init_done;
static unsigned int fixmaps_used __initdata;
/*
* Remap an arbitrary physical address space into the kernel virtual
* address space. Needed when the kernel wants to access high addresses
* directly.
*
* NOTE! We need to allow non-page-aligned mappings too: we will obviously
* have to convert them into an offset in a page-aligned mapping, but the
* caller shouldn't need to know that small detail.
*/
void __iomem *__init_refok
__ioremap(phys_addr_t addr, unsigned long size, pgprot_t prot)
{
phys_addr_t p;
unsigned long v;
unsigned long offset, last_addr;
struct vm_struct *area = NULL;
/* Don't allow wraparound or zero size */
last_addr = addr + size - 1;
if (!size || last_addr < addr)
return NULL;
/*
* Mappings have to be page-aligned
*/
offset = addr & ~PAGE_MASK;
p = addr & PAGE_MASK;
size = PAGE_ALIGN(last_addr + 1) - p;
if (likely(mem_init_done)) {
area = get_vm_area(size, VM_IOREMAP);
if (!area)
return NULL;
v = (unsigned long)area->addr;
} else {
if ((fixmaps_used + (size >> PAGE_SHIFT)) > FIX_N_IOREMAPS)
return NULL;
v = fix_to_virt(FIX_IOREMAP_BEGIN + fixmaps_used);
fixmaps_used += (size >> PAGE_SHIFT);
}
if (ioremap_page_range(v, v + size, p, prot)) {
if (likely(mem_init_done))
vfree(area->addr);
else
fixmaps_used -= (size >> PAGE_SHIFT);
return NULL;
}
return (void __iomem *)(offset + (char *)v);
}
void iounmap(void *addr)
{
/* If the page is from the fixmap pool then we just clear out
* the fixmap mapping.
*/
if (unlikely((unsigned long)addr > FIXADDR_START)) {
/* This is a bit broken... we don't really know
* how big the area is so it's difficult to know
* how many fixed pages to invalidate...
* just flush tlb and hope for the best...
* consider this a FIXME
*
* Really we should be clearing out one or more page
* table entries for these virtual addresses so that
* future references cause a page fault... for now, we
* rely on two things:
* i) this code never gets called on known boards
* ii) invalid accesses to the freed areas aren't made
*/
flush_tlb_all();
return;
}
return vfree((void *)(PAGE_MASK & (unsigned long)addr));
}
/**
* OK, this one's a bit tricky... ioremap can get called before memory is
* initialized (early serial console does this) and will want to alloc a page
* for its mapping. No userspace pages will ever get allocated before memory
* is initialized so this applies only to kernel pages. In the event that
* this is called before memory is initialized we allocate the page using
* the memblock infrastructure.
*/
pte_t __init_refok *pte_alloc_one_kernel(struct mm_struct *mm,
unsigned long address)
{
pte_t *pte;
if (likely(mem_init_done)) {
pte = (pte_t *) __get_free_page(GFP_KERNEL | __GFP_REPEAT);
} else {
pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
#if 0
/* FIXME: use memblock... */
pte = (pte_t *) __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
#endif
}
if (pte)
clear_page(pte);
return pte;
}

193
arch/openrisc/mm/tlb.c Normal file
View File

@ -0,0 +1,193 @@
/*
* OpenRISC tlb.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Julius Baxter <julius.baxter@orsoc.se>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/spr_defs.h>
#define NO_CONTEXT -1
#define NUM_DTLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
SPR_DMMUCFGR_NTS_OFF))
#define NUM_ITLB_SETS (1 << ((mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_NTS) >> \
SPR_IMMUCFGR_NTS_OFF))
#define DTLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_DTLB_SETS-1))
#define ITLB_OFFSET(addr) (((addr) >> PAGE_SHIFT) & (NUM_ITLB_SETS-1))
/*
* Invalidate all TLB entries.
*
* This comes down to setting the 'valid' bit for all xTLBMR registers to 0.
* Easiest way to accomplish this is to just zero out the xTLBMR register
* completely.
*
*/
void flush_tlb_all(void)
{
int i;
unsigned long num_tlb_sets;
/* Determine number of sets for IMMU. */
/* FIXME: Assumption is I & D nsets equal. */
num_tlb_sets = NUM_ITLB_SETS;
for (i = 0; i < num_tlb_sets; i++) {
mtspr_off(SPR_DTLBMR_BASE(0), i, 0);
mtspr_off(SPR_ITLBMR_BASE(0), i, 0);
}
}
#define have_dtlbeir (mfspr(SPR_DMMUCFGR) & SPR_DMMUCFGR_TEIRI)
#define have_itlbeir (mfspr(SPR_IMMUCFGR) & SPR_IMMUCFGR_TEIRI)
/*
* Invalidate a single page. This is what the xTLBEIR register is for.
*
* There's no point in checking the vma for PAGE_EXEC to determine whether it's
* the data or instruction TLB that should be flushed... that would take more
* than the few instructions that the following compiles down to!
*
* The case where we don't have the xTLBEIR register really only works for
* MMU's with a single way and is hard-coded that way.
*/
#define flush_dtlb_page_eir(addr) mtspr(SPR_DTLBEIR, addr)
#define flush_dtlb_page_no_eir(addr) \
mtspr_off(SPR_DTLBMR_BASE(0), DTLB_OFFSET(addr), 0);
#define flush_itlb_page_eir(addr) mtspr(SPR_ITLBEIR, addr)
#define flush_itlb_page_no_eir(addr) \
mtspr_off(SPR_ITLBMR_BASE(0), ITLB_OFFSET(addr), 0);
void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
if (have_dtlbeir)
flush_dtlb_page_eir(addr);
else
flush_dtlb_page_no_eir(addr);
if (have_itlbeir)
flush_itlb_page_eir(addr);
else
flush_itlb_page_no_eir(addr);
}
void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
int addr;
bool dtlbeir;
bool itlbeir;
dtlbeir = have_dtlbeir;
itlbeir = have_itlbeir;
for (addr = start; addr < end; addr += PAGE_SIZE) {
if (dtlbeir)
flush_dtlb_page_eir(addr);
else
flush_dtlb_page_no_eir(addr);
if (itlbeir)
flush_itlb_page_eir(addr);
else
flush_itlb_page_no_eir(addr);
}
}
/*
* Invalidate the selected mm context only.
*
* FIXME: Due to some bug here, we're flushing everything for now.
* This should be changed to loop over over mm and call flush_tlb_range.
*/
void flush_tlb_mm(struct mm_struct *mm)
{
/* Was seeing bugs with the mm struct passed to us. Scrapped most of
this function. */
/* Several architctures do this */
flush_tlb_all();
}
/* called in schedule() just before actually doing the switch_to */
void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *next_tsk)
{
/* remember the pgd for the fault handlers
* this is similar to the pgd register in some other CPU's.
* we need our own copy of it because current and active_mm
* might be invalid at points where we still need to derefer
* the pgd.
*/
current_pgd = next->pgd;
/* We don't have context support implemented, so flush all
* entries belonging to previous map
*/
if (prev != next)
flush_tlb_mm(prev);
}
/*
* Initialize the context related info for a new mm_struct
* instance.
*/
int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
mm->context = NO_CONTEXT;
return 0;
}
/* called by __exit_mm to destroy the used MMU context if any before
* destroying the mm itself. this is only called when the last user of the mm
* drops it.
*/
void destroy_context(struct mm_struct *mm)
{
flush_tlb_mm(mm);
}
/* called once during VM initialization, from init.c */
void __init tlb_init(void)
{
/* Do nothing... */
/* invalidate the entire TLB */
/* flush_tlb_all(); */
}