vmem.h File Reference

#include <core/system.h>

Go to the source code of this file.

Data Structures
struct	vmem_seg
	A segment of an arena: a range that is either free or allocated. More...
struct	vmem
	An arena: a range, and its segments. More...

Macros
#define	VMEM_LISTS   (sizeof(size_t) * 8)
#define	VMEM_HASH   256

Functions
int	vmem_init (struct vmem *vm, const char *name, uintptr_t base, size_t size, size_t quantum)
	Sets up an arena: the range [base, base + size), all free.
struct vmem_seg *	vmem_alloc (struct vmem *vm, size_t size)
	Allocates a range from an arena.
struct vmem_seg *	vmem_find (struct vmem *vm, uintptr_t base)
	Finds the allocated segment that starts at an address.
void	vmem_free (struct vmem *vm, struct vmem_seg *seg)
	Frees an allocated segment.

Macro Definition Documentation

VMEM_HASH

#define VMEM_HASH   256

Definition at line 38 of file vmem.h.

Referenced by hash_chain().

VMEM_LISTS

#define VMEM_LISTS   (sizeof(size_t) * 8)

Definition at line 37 of file vmem.h.

Referenced by vmem_alloc().

Function Documentation

vmem_alloc()

struct vmem_seg * vmem_alloc	(	struct vmem *	vm,
		size_t	size )

Allocates a range from an arena.

Parameters

vm	the arena
size	the size wanted, in bytes (rounded up to a multiple of the quantum)

Returns

the allocated segment, or NULL if there is no free range that large, or no memory for the record of what's left

Definition at line 134 of file vmem.c.

References vmem_seg::base, vmem::free, vmem_seg::free, free_list(), hash_chain(), vmem::inuse, kmalloc(), list_insert(), log2_ceil(), log2_floor(), M_ZERO, NULL, vmem::quantum, seg_link(), seg_list_remove(), vmem_seg::size, vmem_alloc(), and VMEM_LISTS.

Referenced by kvmem_alloc(), and vmem_alloc().

vmem_find()

struct vmem_seg * vmem_find	(	struct vmem *	vm,
		uintptr_t	base )

Finds the allocated segment that starts at an address.

Parameters

vm	the arena
base	the address

Returns

the segment, or NULL if no allocated segment starts there

Definition at line 193 of file vmem.c.

References vmem_seg::base, hash_chain(), NULL, and vmem_find().

Referenced by kfree(), and vmem_find().

vmem_free()

void vmem_free	(	struct vmem *	vm,
		struct vmem_seg *	seg )

Frees an allocated segment.

It merges with the free segments next to it, so that the arena doesn't fragment. Freeing a free segment panics.

Parameters

vm	the arena
seg	the segment, which vmem_alloc() gave

Definition at line 223 of file vmem.c.

References free_list(), hash_chain(), vmem::inuse, list_insert(), NULL, panic, seg_list_remove(), seg_merge(), and vmem_free().

Referenced by kfree(), kvmem_alloc(), and vmem_free().

vmem_init()

int vmem_init	(	struct vmem *	vm,
		const char *	name,
		uintptr_t	base,
		size_t	size,
		size_t	quantum )

Sets up an arena: the range [base, base + size), all free.

Parameters

vm	the arena
name	its name, for messages
base	the range's start
size	its size, in bytes (rounded down to a multiple of quantum)
quantum	the unit of allocation: every segment's size is a multiple of it

Returns

0, or -ENOMEM if there was no memory for the first segment

Definition at line 104 of file vmem.c.

References vmem_seg::base, free_list(), kmalloc(), list_insert(), M_ZERO, memset(), vmem::name, NULL, vmem::quantum, seg_link(), vmem::size, vmem_seg::size, and vmem_init().

Referenced by kvmem_setup(), and vmem_init().