include/linux/mman.h

#ifndef _LINUX_MMAN_H
#define _LINUX_MMAN_H

#include <linux/config.h>
#include <linux/mm.h>

#include <asm/atomic.h>
#include <asm/mman.h>

#define MREMAP_MAYMOVE	1
#define MREMAP_FIXED	2

#define OVERCOMMIT_GUESS		0
#define OVERCOMMIT_ALWAYS		1
#define OVERCOMMIT_NEVER		2
extern int sysctl_overcommit_memory;
extern int sysctl_overcommit_ratio;
extern atomic_t vm_committed_space;

#ifdef CONFIG_SMP
extern void vm_acct_memory(long pages);
#else
static inline void vm_acct_memory(long pages)
{
	atomic_add(pages, &vm_committed_space);
}
#endif

static inline void vm_unacct_memory(long pages)
{
	vm_acct_memory(-pages);
}

/*
 * Optimisation macro.  It is equivalent to:
 *      (x & bit1) ? bit2 : 0
 * but this version is faster.
 * ("bit1" and "bit2" must be single bits)
 */
#define _calc_vm_trans(x, bit1, bit2) \
  ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
   : ((x) & (bit1)) / ((bit1) / (bit2)))

/*
 * Combine the mmap "prot" argument into "vm_flags" used internally.
 */
static inline unsigned long
calc_vm_prot_bits(unsigned long prot)
{
	return _calc_vm_trans(prot, PROT_READ,  VM_READ ) |
	       _calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
	       _calc_vm_trans(prot, PROT_EXEC,  VM_EXEC );
}

/*
 * Combine the mmap "flags" argument into "vm_flags" used internally.
 */
static inline unsigned long
calc_vm_flag_bits(unsigned long flags)
{
	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
	       _calc_vm_trans(flags, MAP_DENYWRITE,  VM_DENYWRITE ) |
	       _calc_vm_trans(flags, MAP_EXECUTABLE, VM_EXECUTABLE) |
	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    );
}

#endif /* _LINUX_MMAN_H */