security/selinux/ss/ebitmap.h

Source file repositories/reference/linux-study-clean/security/selinux/ss/ebitmap.h

File Facts

System
Linux kernel
Corpus path
security/selinux/ss/ebitmap.h
Extension
.h
Size
4498 bytes
Lines
157
Domain
Core OS
Bucket
Security And Isolation
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ebitmap_node {
	struct ebitmap_node *next;
	unsigned long maps[EBITMAP_UNIT_NUMS];
	u32 startbit;
};

struct ebitmap {
	struct ebitmap_node *node; /* first node in the bitmap */
	u32 highbit; /* highest position in the total bitmap */
};

#define ebitmap_length(e) ((e)->highbit)

static inline u32 ebitmap_start_positive(const struct ebitmap *e,
					 struct ebitmap_node **n)
{
	u32 ofs;

	for (*n = e->node; *n; *n = (*n)->next) {
		ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
		if (ofs < EBITMAP_SIZE)
			return (*n)->startbit + ofs;
	}
	return ebitmap_length(e);
}

static inline void ebitmap_init(struct ebitmap *e)
{
	memset(e, 0, sizeof(*e));
}

static inline u32 ebitmap_next_positive(const struct ebitmap *e,
					struct ebitmap_node **n, u32 bit)
{
	u32 ofs;

	ofs = find_next_bit((*n)->maps, EBITMAP_SIZE, bit - (*n)->startbit + 1);
	if (ofs < EBITMAP_SIZE)
		return ofs + (*n)->startbit;

	for (*n = (*n)->next; *n; *n = (*n)->next) {
		ofs = find_first_bit((*n)->maps, EBITMAP_SIZE);
		if (ofs < EBITMAP_SIZE)
			return ofs + (*n)->startbit;
	}
	return ebitmap_length(e);
}

#define EBITMAP_NODE_INDEX(node, bit) \
	(((bit) - (node)->startbit) / EBITMAP_UNIT_SIZE)
#define EBITMAP_NODE_OFFSET(node, bit) \
	(((bit) - (node)->startbit) % EBITMAP_UNIT_SIZE)

static inline int ebitmap_node_get_bit(const struct ebitmap_node *n, u32 bit)
{
	u32 index = EBITMAP_NODE_INDEX(n, bit);
	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);

	BUG_ON(index >= EBITMAP_UNIT_NUMS);
	if ((n->maps[index] & (EBITMAP_BIT << ofs)))
		return 1;
	return 0;
}

static inline void ebitmap_node_set_bit(struct ebitmap_node *n, u32 bit)
{
	u32 index = EBITMAP_NODE_INDEX(n, bit);
	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);

	BUG_ON(index >= EBITMAP_UNIT_NUMS);
	n->maps[index] |= (EBITMAP_BIT << ofs);
}

static inline void ebitmap_node_clr_bit(struct ebitmap_node *n, u32 bit)
{
	u32 index = EBITMAP_NODE_INDEX(n, bit);
	u32 ofs = EBITMAP_NODE_OFFSET(n, bit);

	BUG_ON(index >= EBITMAP_UNIT_NUMS);
	n->maps[index] &= ~(EBITMAP_BIT << ofs);
}

#define ebitmap_for_each_positive_bit(e, n, bit)      \
	for ((bit) = ebitmap_start_positive(e, &(n)); \
	     (bit) < ebitmap_length(e);               \
	     (bit) = ebitmap_next_positive(e, &(n), bit))

bool ebitmap_equal(const struct ebitmap *e1, const struct ebitmap *e2);
int ebitmap_cpy(struct ebitmap *dst, const struct ebitmap *src);
int ebitmap_and(struct ebitmap *dst, const struct ebitmap *e1,

Annotation

Implementation Notes