cregit-Linux how code gets into the kernel

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

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Macros and functions to manipulate Meta page tables.
 */

#ifndef _METAG_PGTABLE_H

#define _METAG_PGTABLE_H

#include <asm/pgtable-bits.h>

#define __ARCH_USE_5LEVEL_HACK
#include <asm-generic/pgtable-nopmd.h>

/* Invalid regions on Meta: 0x00000000-0x001FFFFF and 0xFFFF0000-0xFFFFFFFF */
#if PAGE_OFFSET >= LINGLOBAL_BASE

#define CONSISTENT_START	0xF7000000

#define CONSISTENT_END		0xF73FFFFF

#define VMALLOC_START		0xF8000000

#define VMALLOC_END		0xFFFEFFFF
#else

#define CONSISTENT_START	0x77000000

#define CONSISTENT_END		0x773FFFFF

#define VMALLOC_START		0x78000000

#define VMALLOC_END		0x7FFFFFFF
#endif

/*
 * The Linux memory management assumes a three-level page table setup. On
 * Meta, we use that, but "fold" the mid level into the top-level page
 * table.
 */

/* PGDIR_SHIFT determines the size of the area a second-level page table can
 * map. This is always 4MB.
 */


#define PGDIR_SHIFT	22

#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. First level tables
 * always map 2Gb (local or global) at a granularity of 4MB, second-level
 * tables map 4MB with a granularity between 4MB and 4kB (between 1 and
 * 1024 entries).
 */

#define PTRS_PER_PTE	(PGDIR_SIZE/PAGE_SIZE)

#define HPTRS_PER_PTE	(PGDIR_SIZE/HPAGE_SIZE)

#define PTRS_PER_PGD	512


#define USER_PTRS_PER_PGD	256

#define FIRST_USER_ADDRESS	META_MEMORY_BASE

#define FIRST_USER_PGD_NR	pgd_index(FIRST_USER_ADDRESS)


#define PAGE_NONE	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
                                 _PAGE_CACHEABLE)


#define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_WRITE | \
                                 _PAGE_ACCESSED | _PAGE_CACHEABLE)

#define PAGE_SHARED_C	PAGE_SHARED

#define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
                                 _PAGE_CACHEABLE)

#define PAGE_COPY_C	PAGE_COPY


#define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
                                 _PAGE_CACHEABLE)

#define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_DIRTY | \
                                 _PAGE_ACCESSED | _PAGE_WRITE | \
                                 _PAGE_CACHEABLE | _PAGE_KERNEL)


#define __P000	PAGE_NONE

#define __P001	PAGE_READONLY

#define __P010	PAGE_COPY

#define __P011	PAGE_COPY

#define __P100	PAGE_READONLY

#define __P101	PAGE_READONLY

#define __P110	PAGE_COPY_C

#define __P111	PAGE_COPY_C


#define __S000	PAGE_NONE

#define __S001	PAGE_READONLY

#define __S010	PAGE_SHARED

#define __S011	PAGE_SHARED

#define __S100	PAGE_READONLY

#define __S101	PAGE_READONLY

#define __S110	PAGE_SHARED_C

#define __S111	PAGE_SHARED_C

#ifndef __ASSEMBLY__

#include <asm/page.h>

/* zero page used for uninitialized stuff */
extern unsigned long empty_zero_page;

#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))

/* 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)


#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)


#define pte_pfn(pte)		(pte_val(pte) >> PAGE_SHIFT)


#define pfn_pte(pfn, prot)	__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))


#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 | _PAGE_SZ_MASK)) \
                                        != (_PAGE_TABLE & ~_PAGE_SZ_MASK))

#define pmd_present(x)		(pmd_val(x) & _PAGE_PRESENT)

#define pmd_clear(xp)		do { pmd_val(*(xp)) = 0; } while (0)


#define pte_page(x)		pfn_to_page(pte_pfn(x))

/*
 * The following only work if pte_present() is true.
 * Undefined behaviour if not..
 */


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

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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_wrprotect(pte_t pte) { pte_val(pte) &= (~_PAGE_WRITE); 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_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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static inline pte_t pte_mkspecial(pte_t pte) { return pte; }

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

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/* * Macro and implementation to make a page protection as uncacheable. */ #define pgprot_writecombine(prot) \ __pgprot(pgprot_val(prot) & ~(_PAGE_CACHE_CTRL1 | _PAGE_CACHE_CTRL0)) #define pgprot_noncached(prot) \ __pgprot(pgprot_val(prot) & ~_PAGE_CACHEABLE) /* * Conversion functions: convert a page and protection to a page entry, * and a page entry and page directory to the page they refer to. */ #define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { pte_val(pte) = (pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot); return pte; }

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static inline unsigned long pmd_page_vaddr(pmd_t pmd) { unsigned long paddr = pmd_val(pmd) & PAGE_MASK; if (!paddr) return 0; return (unsigned long)__va(paddr); }

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#define pmd_page(pmd) (pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)) #define pmd_page_shift(pmd) (12 + ((pmd_val(pmd) & _PAGE_SZ_MASK) \ >> _PAGE_SZ_SHIFT)) #define pmd_num_ptrs(pmd) (PGDIR_SIZE >> pmd_page_shift(pmd)) /* * Each pgd is only 2k, mapping 2Gb (local or global). If we're in global * space drop the top bit before indexing the pgd. */ #if PAGE_OFFSET >= LINGLOBAL_BASE #define pgd_index(address) ((((address) & ~0x80000000) >> PGDIR_SHIFT) \ & (PTRS_PER_PGD-1)) #else #define pgd_index(address) (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1)) #endif #define pgd_offset(mm, address) ((mm)->pgd + pgd_index(address)) #define pgd_offset_k(address) pgd_offset(&init_mm, address) #define pmd_index(address) (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1)) /* Find an entry in the second-level page table.. */ #if !defined(CONFIG_HUGETLB_PAGE) /* all pages are of size (1 << PAGE_SHIFT), so no need to read 1st level pt */ # define pte_index(pmd, address) \ (((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) #else /* some pages are huge, so read 1st level pt to find out */ # define pte_index(pmd, address) \ (((address) >> pmd_page_shift(pmd)) & (pmd_num_ptrs(pmd) - 1)) #endif #define pte_offset_kernel(dir, address) \ ((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(*(dir), address)) #define pte_offset_map(dir, address) pte_offset_kernel(dir, address) #define pte_offset_map_nested(dir, address) pte_offset_kernel(dir, address) #define pte_unmap(pte) do { } while (0) #define pte_unmap_nested(pte) do { } while (0) #define pte_ERROR(e) \ pr_err("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e)) #define pgd_ERROR(e) \ pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e)) /* * Meta doesn't have any external MMU info: the kernel page * tables contain all the necessary information. */
static inline void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *pte) { }

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/* * Encode and decode a swap entry (must be !pte_none(e) && !pte_present(e)) * Since PAGE_PRESENT is bit 1, we can use the bits above that. */ #define __swp_type(x) (((x).val >> 1) & 0xff) #define __swp_offset(x) ((x).val >> 10) #define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 1) | \ ((offset) << 10) }) #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) /* * No page table caches to initialise */ #define pgtable_cache_init() do { } while (0) extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; void paging_init(unsigned long mem_end); #ifdef CONFIG_METAG_META12 /* This is a workaround for an issue in Meta 1 cores. These cores cache * invalid entries in the TLB so we always need to flush whenever we add * a new pte. Unfortunately we can only flush the whole TLB not shoot down * single entries so this is sub-optimal. This implementation ensures that * we will get a flush at the second attempt, so we may still get repeated * faults, we just don't overflow the kernel stack handling them. */ #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS #define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \ ({ \ int __changed = !pte_same(*(__ptep), __entry); \ if (__changed) { \ set_pte_at((__vma)->vm_mm, (__address), __ptep, __entry); \ } \ flush_tlb_page(__vma, __address); \ __changed; \ }) #endif #include <asm-generic/pgtable.h> #endif /* __ASSEMBLY__ */ #endif /* _METAG_PGTABLE_H */

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