Implementation of a memory paging management. More...

Classes
struct	page_iterator_s
	Structure for iterating page directory entries. More...

struct	pg_iter_entry_s
	Structure for iterating page table entries. More...

Macros
#define	__DEBUG_HEADER__ "[PAGING]"
	Change header.

#define	__DEBUG_LEVEL__ LOGLEVEL_NOTICE
	Set log level.

#define	ERR_PRESENT 0x01
	Page not present.

#define	ERR_RW 0x02
	Page is read only.

#define	ERR_USER 0x04
	Page is privileged.

#define	ERR_RESERVED 0x08
	Overwrote reserved bit.

#define	ERR_INST 0x10
	Instruction fetch.

Typedefs
typedef struct page_iterator_s	page_iterator_t
	Structure for iterating page directory entries.

typedef struct pg_iter_entry_s	pg_iter_entry_t
	Structure for iterating page table entries.

Functions
page_directory_t *	paging_get_main_directory (void)
	Provide access to the main page directory. More...

int	is_current_pgd (page_directory_t *pgd)
	Checks if the given page directory is the current one. More...

int	paging_switch_directory_va (page_directory_t *dir)
	Switches paging directory, the pointer can be a lowmem address. More...

void	paging_flush_tlb_single (unsigned long addr)
	Invalidate a single tlb page (the one that maps the specified virtual address) More...

vm_area_struct_t *	create_vm_area (mm_struct_t *mm, uint32_t vm_start, size_t size, uint32_t pgflags, uint32_t gfpflags)
	Create a virtual memory area. More...

uint32_t	clone_vm_area (mm_struct_t mm, vm_area_struct_t area, int cow, uint32_t gfpflags)
	Clone a virtual memory area, using copy on write if specified. More...

int	destroy_vm_area (mm_struct_t mm, vm_area_struct_t area)
	Destroys a virtual memory area. More...

vm_area_struct_t *	find_vm_area (mm_struct_t *mm, uint32_t vm_start)
	Searches for the virtual memory area at the given address. More...

int	is_valid_vm_area (mm_struct_t *mm, uintptr_t vm_start, uintptr_t vm_end)
	Checks if the given virtual memory area range is valid. More...

int	find_free_vm_area (mm_struct_t mm, size_t length, uintptr_t vm_start)
	Searches for an empty spot for a new virtual memory area. More...

static void	__init_pagedir (page_directory_t *pdir)
	Initializes the page directory. More...

static void	__init_pagetable (page_table_t *ptable)
	Initializes the page table. More...

int	paging_init (boot_info_t *info)
	Initializes the paging system, sets up memory caches, page directories, and maps important memory regions. More...

static void	__set_pg_table_flags (page_table_entry_t *table, uint32_t flags)
	Sets the given page table flags. More...

static void	__page_fault_panic (pt_regs *f, uint32_t addr)
	Prints stack frame data and calls kernel_panic. More...

static int	__page_handle_cow (page_table_entry_t *entry)
	Handles the Copy-On-Write (COW) mechanism for a page table entry. If the page is marked as COW, it allocates a new page and updates the entry. More...

static page_table_t *	__mem_pg_entry_alloc (page_dir_entry_t *entry, uint32_t flags)
	Allocates memory for a page table entry. More...

static int	__set_pg_entry_frame (page_dir_entry_t entry, page_table_t table)
	Sets the frame attribute of a page directory entry based on the page table's physical address. More...

void	page_fault_handler (pt_regs *f)
	Handles a page fault. More...

static int	__pg_iter_init (page_iterator_t iter, page_directory_t pgd, uint32_t addr_start, uint32_t size, uint32_t flags)
	Initialize a page iterator. More...

static int	__pg_iter_has_next (page_iterator_t *iter)
	Checks if the iterator has a next entry. More...

static pg_iter_entry_t	__pg_iter_next (page_iterator_t *iter)
	Moves the iterator to the next entry. More...

page_t *	mem_virtual_to_page (page_directory_t pgd, uint32_t virt_start, size_t size)
	Maps a virtual address to a corresponding physical page. More...

int	mem_upd_vm_area (page_directory_t *pgd, uint32_t virt_start, uint32_t phy_start, size_t size, uint32_t flags)
	Updates the virtual memory area in a page directory. More...

int	mem_clone_vm_area (page_directory_t src_pgd, page_directory_t dst_pgd, uint32_t src_start, uint32_t dst_start, size_t size, uint32_t flags)
	Clones a range of pages between two distinct page tables. More...

mm_struct_t *	create_blank_process_image (size_t stack_size)
	Creates the main memory descriptor. More...

mm_struct_t *	clone_process_image (mm_struct_t *mmp)
	Create a Memory Descriptor. More...

int	destroy_process_image (mm_struct_t *mm)
	Free Memory Descriptor with all the memory segment contained. More...

void *	sys_mmap (void *addr, size_t length, int prot, int flags, int fd, off_t offset)

int	sys_munmap (void *addr, size_t length)

Variables
kmem_cache_t *	mm_cache
	Cache for storing mm_struct.

kmem_cache_t *	vm_area_cache
	Cache for storing vm_area_struct.

kmem_cache_t *	pgdir_cache
	Cache for storing page directories.

kmem_cache_t *	pgtbl_cache
	Cache for storing page tables. More...

static mm_struct_t *	main_mm
	The mm_struct of the kernel.

Detailed Description

Implementation of a memory paging management.

Copyright: (c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Function Documentation

◆ __init_pagedir()

static void __init_pagedir ( page_directory_t * pdir )

static

Initializes the page directory.

Parameters

pdir	the page directory to initialize.

◆ __init_pagetable()

static void __init_pagetable ( page_table_t * ptable )

static

Initializes the page table.

Parameters

ptable the page table to initialize.

◆ __mem_pg_entry_alloc()

static page_table_t* __mem_pg_entry_alloc	(	page_dir_entry_t *	entry,
		uint32_t	flags
	)

static

Allocates memory for a page table entry.

If the page table is not present, allocates a new one and sets flags accordingly.

Parameters

entry	The page directory entry for which memory is being allocated.
flags	The flags that control the allocation, such as permissions and attributes.

Returns: A pointer to the allocated page table, or NULL if allocation fails.

◆ __page_fault_panic()

static void __page_fault_panic	(	pt_regs *	f,
		uint32_t	addr
	)

static

Prints stack frame data and calls kernel_panic.

Parameters

f	The interrupt stack frame.
addr	The faulting address.

◆ __page_handle_cow()

static int __page_handle_cow ( page_table_entry_t * entry )

static

Handles the Copy-On-Write (COW) mechanism for a page table entry. If the page is marked as COW, it allocates a new page and updates the entry.

Parameters

entry The page table entry to manage.

Returns: 0 on success, 1 on error.

◆ __pg_iter_has_next()

static int __pg_iter_has_next ( page_iterator_t * iter )

static

Checks if the iterator has a next entry.

Parameters

iter	The iterator to check.

Returns: Returns 1 if the iterator can continue the iteration; otherwise, returns 0.

◆ __pg_iter_init()

static int __pg_iter_init	(	page_iterator_t *	iter,
		page_directory_t *	pgd,
		uint32_t	addr_start,
		uint32_t	size,
		uint32_t	flags
	)

static

Initialize a page iterator.

Parameters

iter	The iterator to initialize.
pgd	The page directory to iterate.
addr_start	The starting address.
size	The total amount we want to iterate.
flags	Allocation flags.

Returns: 0 on success, -1 on error.

◆ __pg_iter_next()

static pg_iter_entry_t __pg_iter_next ( page_iterator_t * iter )

static

Moves the iterator to the next entry.

Parameters

iter	The iterator to advance.

Returns: The current entry after moving to the next entry.

◆ __set_pg_entry_frame()

static int __set_pg_entry_frame	(	page_dir_entry_t *	entry,
		page_table_t *	table
	)

inlinestatic

Sets the frame attribute of a page directory entry based on the page table's physical address.

Parameters

entry	The page directory entry to modify.
table	The page table whose frame is being set in the directory entry.

Returns: 0 on success, -1 on failure.

◆ __set_pg_table_flags()

static void __set_pg_table_flags	(	page_table_entry_t *	table,
		uint32_t	flags
	)

inlinestatic

Sets the given page table flags.

Parameters

table	the page table.
flags	the flags to set.

◆ clone_process_image()

mm_struct_t* clone_process_image ( mm_struct_t * mmp )

Create a Memory Descriptor.

Parameters

mmp	The memory map to clone

Returns: The Memory Descriptor created.

◆ clone_vm_area()

uint32_t clone_vm_area	(	mm_struct_t *	mm,
		vm_area_struct_t *	area,
		int	cow,
		uint32_t	gfpflags
	)

Clone a virtual memory area, using copy on write if specified.

Parameters

mm	the memory descriptor which will contain the new segment.
area	the area to clone
cow	whether to use copy-on-write or just copy everything.
gfpflags	the Get Free Pages flags.

Returns: Zero on success.

◆ create_blank_process_image()

mm_struct_t* create_blank_process_image ( size_t stack_size )

Creates the main memory descriptor.

Parameters

stack_size The size of the stack in byte.

Returns: The Memory Descriptor created.

◆ create_vm_area()

vm_area_struct_t* create_vm_area	(	mm_struct_t *	mm,
		uint32_t	virt_start,
		size_t	size,
		uint32_t	pgflags,
		uint32_t	gfpflags
	)

Create a virtual memory area.

Parameters

mm	The memory descriptor which will contain the new segment.
virt_start	The virtual address to map to.
size	The size of the segment.
pgflags	The flags for the new memory area.
gfpflags	The Get Free Pages flags.

Returns: The newly created virtual memory area descriptor.

◆ destroy_process_image()

int destroy_process_image ( mm_struct_t * mm )

Free Memory Descriptor with all the memory segment contained.

Parameters

mm	The Memory Descriptor to free.

Returns: Returns -1 on error, otherwise 0.

◆ destroy_vm_area()

int destroy_vm_area	(	mm_struct_t *	mm,
		vm_area_struct_t *	area
	)

Destroys a virtual memory area.

Parameters

mm	the memory descriptor from which we will destroy the area.
area	the are we want to destroy.

Returns: 0 if the area was destroyed, or -1 if the operation failed.

◆ find_free_vm_area()

int find_free_vm_area	(	mm_struct_t *	mm,
		size_t	length,
		uintptr_t *	vm_start
	)

Searches for an empty spot for a new virtual memory area.

Parameters

mm	the memory descriptor which should contain the new area.
length	the size of the empty spot.
vm_start	where we save the starting address for the new area.

Returns: 0 on success, -1 on error, or 1 if no free area is found.

◆ find_vm_area()

vm_area_struct_t* find_vm_area	(	mm_struct_t *	mm,
		uint32_t	vm_start
	)

Searches for the virtual memory area at the given address.

Parameters

mm	the memory descriptor which should contain the area.
vm_start	the starting address of the area we are looking for.

Returns: a pointer to the area if we found it, NULL otherwise.

◆ is_current_pgd()

int is_current_pgd ( page_directory_t * pgd )

Checks if the given page directory is the current one.

Parameters

pgd	A pointer to the page directory to check.

Returns: 1 if the given page directory is the current one, 0 otherwise.

◆ is_valid_vm_area()

int is_valid_vm_area	(	mm_struct_t *	mm,
		uintptr_t	vm_start,
		uintptr_t	vm_end
	)

Checks if the given virtual memory area range is valid.

Parameters

mm	the memory descriptor which we use to check the range.
vm_start	the starting address of the area.
vm_end	the ending address of the area.

Returns: 1 if it's valid, 0 if it's occupied, -1 if it's outside the memory.

◆ mem_clone_vm_area()

int mem_clone_vm_area	(	page_directory_t *	src_pgd,
		page_directory_t *	dst_pgd,
		uint32_t	src_start,
		uint32_t	dst_start,
		size_t	size,
		uint32_t	flags
	)

Clones a range of pages between two distinct page tables.

Parameters

src_pgd	The source page directory.
dst_pgd	The dest page directory.
src_start	The source virtual address for the clone.
dst_start	The destination virtual address for the clone.
size	The size of the segment.
flags	The flags for the new dst memory range.

Returns: 0 on success, -1 on failure.

◆ mem_upd_vm_area()

int mem_upd_vm_area	(	page_directory_t *	pgd,
		uint32_t	virt_start,
		uint32_t	phy_start,
		size_t	size,
		uint32_t	flags
	)

Updates the virtual memory area in a page directory.

Parameters

pgd	The page directory to update.
virt_start	The starting virtual address to update.
phy_start	The starting physical address to map to the virtual addresses.
size	The size of the memory area to update.
flags	Flags to set for the page table entries.

Returns: 0 on success, or -1 on failure.

◆ mem_virtual_to_page()

page_t* mem_virtual_to_page	(	page_directory_t *	pgdir,
		uint32_t	virt_start,
		size_t *	size
	)

Maps a virtual address to a corresponding physical page.

Parameters

pgdir	The page directory.
virt_start	The starting virtual address to map.
size	Pointer to a size_t variable to store the size of the mapped memory.

Returns: A pointer to the physical page corresponding to the virtual address, or NULL on error.

◆ page_fault_handler()

void page_fault_handler ( pt_regs * f )

Handles a page fault.

Parameters

f	The interrupt stack frame.

◆ paging_flush_tlb_single()

void paging_flush_tlb_single ( unsigned long addr )

Invalidate a single tlb page (the one that maps the specified virtual address)

Parameters

addr	The address of the page table.

◆ paging_get_main_directory()

page_directory_t* paging_get_main_directory ( void )

Provide access to the main page directory.

Returns: A pointer to the main page directory, or NULL if main_mm is not initialized.

◆ paging_init()

int paging_init ( boot_info_t * info )

Initializes the paging system, sets up memory caches, page directories, and maps important memory regions.

Parameters

info	Pointer to the boot information structure, containing kernel addresses and other details.

Returns: 0 on success, -1 on error.

◆ paging_switch_directory_va()

int paging_switch_directory_va ( page_directory_t * dir )

Switches paging directory, the pointer can be a lowmem address.

Parameters

dir	A pointer to the new page directory.

Returns: Returns 0 on success, or -1 if an error occurs.

Variable Documentation

◆ pgtbl_cache

kmem_cache_t* pgtbl_cache

Cache for storing page tables.

Cache used to store page tables.

Classes

Macros

Typedefs

Functions

Variables

Detailed Description

Function Documentation

◆ __init_pagedir()

◆ __init_pagetable()

◆ __mem_pg_entry_alloc()

◆ __page_fault_panic()

◆ __page_handle_cow()

◆ __pg_iter_has_next()

◆ __pg_iter_init()

◆ __pg_iter_next()

◆ __set_pg_entry_frame()

◆ __set_pg_table_flags()

◆ clone_process_image()

◆ clone_vm_area()

◆ create_blank_process_image()

◆ create_vm_area()

◆ destroy_process_image()

◆ destroy_vm_area()

◆ find_free_vm_area()

◆ find_vm_area()

◆ is_current_pgd()

◆ is_valid_vm_area()

◆ mem_clone_vm_area()

◆ mem_upd_vm_area()

◆ mem_virtual_to_page()

◆ page_fault_handler()

◆ paging_flush_tlb_single()

◆ paging_get_main_directory()

◆ paging_init()

◆ paging_switch_directory_va()

Variable Documentation

◆ pgtbl_cache