Paging

A platform-independent interface to map/unmap virtual memory to physical memory. More...

Collaboration diagram for Paging:

Enumerations
enum	valloc_flags { VALLOC_DEFAULT = 0 , VALLOC_EXACT = MMAP_EXACT }

Functions
vmap_t *	mm_get_free_vaddr_locked (mm_context_t *mmctx, size_t n_pages, ptr_t base_vaddr, valloc_flags flags)
	Gets npages unmapped free pages from a page table.
void	mm_map_kernel_pages (mm_context_t *mmctx, ptr_t vaddr, pfn_t pfn, size_t npages, vm_flags flags)
	Map a block of virtual memory to a block of physical memory.
vmap_t *	mm_map_user_pages (mm_context_t *mmctx, ptr_t vaddr, pfn_t pfn, size_t npages, vm_flags flags, valloc_flags vaflags, vmap_type_t type, vmap_content_t content)
void	mm_replace_page_locked (mm_context_t *mmctx, ptr_t vaddr, pfn_t pfn, vm_flags flags)
	Replace the mappings of a page with a new physical frame.
vmap_t *	mm_clone_vmap_locked (vmap_t *src_vmap, mm_context_t *dst_ctx)
	Remap a block of virtual memory from one page table to another, i.e. copy the mappings.
bool	mm_get_is_mapped_locked (mm_context_t *mmctx, ptr_t vaddr)
	Get if a virtual address is mapped in a page table.
void	mm_flag_pages_locked (mm_context_t *mmctx, ptr_t vaddr, size_t npages, vm_flags flags)
	Update the flags of a block of virtual memory.
ptr_t	mm_get_phys_addr (mm_context_t *ctx, ptr_t vaddr)

Detailed Description

A platform-independent interface to map/unmap virtual memory to physical memory.

Enumeration Type Documentation

valloc_flags

enum valloc_flags

Enumerator
VALLOC_DEFAULT	Default allocation flags.
VALLOC_EXACT	Allocate pages at the exact address.

Definition at line 19 of file paging.h.

Function Documentation

mm_get_free_vaddr_locked()

vmap_t * mm_get_free_vaddr_locked	(	mm_context_t *	mmctx,
		size_t	n_pages,
		ptr_t	base_vaddr,
		valloc_flags	flags )

Gets npages unmapped free pages from a page table.

Parameters

mmctx	The memory management context to allocate from.
n_pages	The number of pages to allocate.
base_vaddr	The base virtual address to allocate at.
flags	Flags to set on the pages, see valloc_flags.

Returns

ptr_t The virtual address of the block of virtual memory.

Note

This function neither allocates nor maps the pages, it only determines the block of virtual memory that can be used to allocate and map the pages.

The returned vmap_t only contains the virtual address and the number of pages, it does not contain any physical addresses, nor the flags of the pages.

Warning

Should call with mmctx->mm_lock held.

Definition at line 18 of file paging.c.

Referenced by cow_allocate_zeroed_pages(), mm_clone_vmap_locked(), mm_map_user_pages(), and mmap_file().

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mm_map_kernel_pages()

void mm_map_kernel_pages	(	mm_context_t *	mmctx,
		ptr_t	vaddr,
		pfn_t	pfn,
		size_t	npages,
		vm_flags	flags )

Map a block of virtual memory to a block of physical memory.

Parameters

mmctx	The memory management context to map to.
vaddr	The virtual address to map to.
pfn	The physical frame to map from.
npages	The number of pages to map.
flags	Flags to set on the pages, see vm_flags.

This function maps the pages in the block, their reference count will NOT be incremented.

Note

This function is rarely used directly, you don't always know the physical address of the pages you want to map.

Definition at line 82 of file paging.c.

Referenced by mos_start_kernel().

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mm_map_user_pages()

vmap_t * mm_map_user_pages	(	mm_context_t *	mmctx,
		ptr_t	vaddr,
		pfn_t	pfn,
		size_t	npages,
		vm_flags	flags,
		valloc_flags	vaflags,
		vmap_type_t	type,
		vmap_content_t	content )

Definition at line 92 of file paging.c.

Referenced by dmabuf_allocate(), and mos_start_kernel().

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mm_replace_page_locked()

void mm_replace_page_locked	(	mm_context_t *	mmctx,
		ptr_t	vaddr,
		pfn_t	pfn,
		vm_flags	flags )

Replace the mappings of a page with a new physical frame.

Parameters

mmctx	The memory management context to replace in.
vaddr	The virtual address to replace.
pfn	The physical frame to replace to.
flags	The new flags to set on the pages.

Note

The reference count of the physical frame will be incremented, and the reference count of the old physical frame will be decremented.

Definition at line 112 of file paging.c.

Referenced by mm_handle_fault(), and mm_resolve_cow_fault().

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mm_clone_vmap_locked()

vmap_t * mm_clone_vmap_locked	(	vmap_t *	src_vmap,
		mm_context_t *	dst_ctx )

Remap a block of virtual memory from one page table to another, i.e. copy the mappings.

Parameters

src_vmap	The source vmap
dst_ctx	The destination paging context

This function firstly unmaps the pages in the destination page table, then copies the pages mappings, including the flags and physical addresses, the physical page reference count is updated accordingly.

Note

If clear_dest is set to true, then the destination page table is cleared before copying, otherwise the function assumes that there are no existing mappings in the destination page table.

Definition at line 132 of file paging.c.

Referenced by cow_clone_vmap_locked(), and process_do_fork().

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mm_get_is_mapped_locked()

bool mm_get_is_mapped_locked	(	mm_context_t *	mmctx,
		ptr_t	vaddr )

Get if a virtual address is mapped in a page table.

Parameters

mmctx	The memory management context to check in.
vaddr	The virtual address to get the physical address of.

Returns

bool True if the virtual address is mapped, false otherwise.

Definition at line 159 of file paging.c.

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mm_flag_pages_locked()

void mm_flag_pages_locked	(	mm_context_t *	mmctx,
		ptr_t	vaddr,
		size_t	npages,
		vm_flags	flags )

Update the flags of a block of virtual memory.

Parameters

mmctx	The memory management context to update the flags in.
vaddr	The virtual address to update the flags of.
npages	The number of pages to update the flags of.
flags	The flags to set on the pages, see vm_flags.

Definition at line 171 of file paging.c.

Referenced by cow_clone_vmap_locked().

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mm_get_phys_addr()

ptr_t mm_get_phys_addr	(	mm_context_t *	ctx,
		ptr_t	vaddr )

Definition at line 179 of file paging.c.

Referenced by futex_get_key(), and x86_dump_stack_at().

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