cregit-Linux how code gets into the kernel

Release 4.14 arch/openrisc/include/asm/pgtable.h

/*
 * 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


#define __ARCH_USE_5LEVEL_HACK
#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 << (32-PGDIR_SHIFT))

/* 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      0UL

/*
 * 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_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; }

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static inline int pte_write(pte_t pte) { return pte_val(pte) & _PAGE_WRITE; }

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static inline int pte_exec(pte_t pte) { return pte_val(pte) & _PAGE_EXEC; }

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static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY; }

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static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED; }

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static inline int pte_special(pte_t pte) { return 0; }

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static inline pte_t pte_mkspecial(pte_t pte) { return pte; }

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static inline pte_t pte_wrprotect(pte_t pte) { pte_val(pte) &= ~(_PAGE_WRITE); return pte; }

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static inline pte_t pte_rdprotect(pte_t pte) { pte_val(pte) &= ~(_PAGE_READ); return pte; }

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static inline pte_t pte_exprotect(pte_t pte) { pte_val(pte) &= ~(_PAGE_EXEC); return pte; }

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static inline pte_t pte_mkclean(pte_t pte) { pte_val(pte) &= ~(_PAGE_DIRTY); return pte; }

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static inline pte_t pte_mkold(pte_t pte) { pte_val(pte) &= ~(_PAGE_ACCESSED); return pte; }

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static inline pte_t pte_mkwrite(pte_t pte) { pte_val(pte) |= _PAGE_WRITE; return pte; }

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static inline pte_t pte_mkread(pte_t pte) { pte_val(pte) |= _PAGE_READ; return pte; }

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static inline pte_t pte_mkexec(pte_t pte) { pte_val(pte) |= _PAGE_EXEC; return pte; }

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static inline pte_t pte_mkdirty(pte_t pte) { pte_val(pte) |= _PAGE_DIRTY; return pte; }

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static inline pte_t pte_mkyoung(pte_t pte) { pte_val(pte) |= _PAGE_ACCESSED; return pte; }

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/* * 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; }

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#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; }

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/* * 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); }

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#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; }

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#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 */ struct vm_area_struct; /* * 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) { }

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/* __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 }) #define kern_addr_valid(addr) (1) #include <asm-generic/pgtable.h> /* * No page table caches to initialise */ #define pgtable_cache_init() do { } while (0) typedef pte_t *pte_addr_t; #endif /* __ASSEMBLY__ */ #endif /* __ASM_OPENRISC_PGTABLE_H */

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