1. 根目录:
2. arch
3. x86
4. include
5. asm
6. compat.h

#ifndef _ASM_X86_COMPAT_H
#define _ASM_X86_COMPAT_H

/*
 * Architecture specific compatibility types
 */
#include <linux/types.h>
#include <linux/sched.h>
#include <asm/user32.h>

#define COMPAT_USER_HZ		100
#define COMPAT_UTS_MACHINE	"i686\0\0"

typedef u32		compat_size_t;
typedef s32		compat_ssize_t;
typedef s32		compat_time_t;
typedef s32		compat_clock_t;
typedef s32		compat_pid_t;
typedef u16		__compat_uid_t;
typedef u16		__compat_gid_t;
typedef u32		__compat_uid32_t;
typedef u32		__compat_gid32_t;
typedef u16		compat_mode_t;
typedef u32		compat_ino_t;
typedef u16		compat_dev_t;
typedef s32		compat_off_t;
typedef s64		compat_loff_t;
typedef u16		compat_nlink_t;
typedef u16		compat_ipc_pid_t;
typedef s32		compat_daddr_t;
typedef u32		compat_caddr_t;
typedef __kernel_fsid_t	compat_fsid_t;
typedef s32		compat_timer_t;
typedef s32		compat_key_t;

typedef s32		compat_int_t;
typedef s32		compat_long_t;
typedef s64 __attribute__((aligned(4))) compat_s64;
typedef u32		compat_uint_t;
typedef u32		compat_ulong_t;
typedef u64 __attribute__((aligned(4))) compat_u64;

struct compat_timespec {
	compat_time_t	tv_sec;
	s32		tv_nsec;
};

struct compat_timeval {
	compat_time_t	tv_sec;
	s32		tv_usec;
};

struct compat_stat {
	compat_dev_t	st_dev;
	u16		__pad1;
	compat_ino_t	st_ino;
	compat_mode_t	st_mode;
	compat_nlink_t	st_nlink;
	__compat_uid_t	st_uid;
	__compat_gid_t	st_gid;
	compat_dev_t	st_rdev;
	u16		__pad2;
	u32		st_size;
	u32		st_blksize;
	u32		st_blocks;
	u32		st_atime;
	u32		st_atime_nsec;
	u32		st_mtime;
	u32		st_mtime_nsec;
	u32		st_ctime;
	u32		st_ctime_nsec;
	u32		__unused4;
	u32		__unused5;
};

struct compat_flock {
	short		l_type;
	short		l_whence;
	compat_off_t	l_start;
	compat_off_t	l_len;
	compat_pid_t	l_pid;
};

#define F_GETLK64	12	/*  using 'struct flock64' */
#define F_SETLK64	13
#define F_SETLKW64	14

/*
 * IA32 uses 4 byte alignment for 64 bit quantities,
 * so we need to pack this structure.
 */
struct compat_flock64 {
	short		l_type;
	short		l_whence;
	compat_loff_t	l_start;
	compat_loff_t	l_len;
	compat_pid_t	l_pid;
} __attribute__((packed));

struct compat_statfs {
	int		f_type;
	int		f_bsize;
	int		f_blocks;
	int		f_bfree;
	int		f_bavail;
	int		f_files;
	int		f_ffree;
	compat_fsid_t	f_fsid;
	int		f_namelen;	/* SunOS ignores this field. */
	int		f_frsize;
	int		f_spare[5];
};

#define COMPAT_RLIM_OLD_INFINITY	0x7fffffff
#define COMPAT_RLIM_INFINITY		0xffffffff

typedef u32		compat_old_sigset_t;	/* at least 32 bits */

#define _COMPAT_NSIG		64
#define _COMPAT_NSIG_BPW	32

typedef u32               compat_sigset_word;

#define COMPAT_OFF_T_MAX	0x7fffffff
#define COMPAT_LOFF_T_MAX	0x7fffffffffffffffL

struct compat_ipc64_perm {
	compat_key_t key;
	__compat_uid32_t uid;
	__compat_gid32_t gid;
	__compat_uid32_t cuid;
	__compat_gid32_t cgid;
	unsigned short mode;
	unsigned short __pad1;
	unsigned short seq;
	unsigned short __pad2;
	compat_ulong_t unused1;
	compat_ulong_t unused2;
};

struct compat_semid64_ds {
	struct compat_ipc64_perm sem_perm;
	compat_time_t  sem_otime;
	compat_ulong_t __unused1;
	compat_time_t  sem_ctime;
	compat_ulong_t __unused2;
	compat_ulong_t sem_nsems;
	compat_ulong_t __unused3;
	compat_ulong_t __unused4;
};

struct compat_msqid64_ds {
	struct compat_ipc64_perm msg_perm;
	compat_time_t  msg_stime;
	compat_ulong_t __unused1;
	compat_time_t  msg_rtime;
	compat_ulong_t __unused2;
	compat_time_t  msg_ctime;
	compat_ulong_t __unused3;
	compat_ulong_t msg_cbytes;
	compat_ulong_t msg_qnum;
	compat_ulong_t msg_qbytes;
	compat_pid_t   msg_lspid;
	compat_pid_t   msg_lrpid;
	compat_ulong_t __unused4;
	compat_ulong_t __unused5;
};

struct compat_shmid64_ds {
	struct compat_ipc64_perm shm_perm;
	compat_size_t  shm_segsz;
	compat_time_t  shm_atime;
	compat_ulong_t __unused1;
	compat_time_t  shm_dtime;
	compat_ulong_t __unused2;
	compat_time_t  shm_ctime;
	compat_ulong_t __unused3;
	compat_pid_t   shm_cpid;
	compat_pid_t   shm_lpid;
	compat_ulong_t shm_nattch;
	compat_ulong_t __unused4;
	compat_ulong_t __unused5;
};

/*
 * The type of struct elf_prstatus.pr_reg in compatible core dumps.
 */
typedef struct user_regs_struct32 compat_elf_gregset_t;

/*
 * A pointer passed in from user mode. This should not
 * be used for syscall parameters, just declare them
 * as pointers because the syscall entry code will have
 * appropriately converted them already.
 */
typedef	u32		compat_uptr_t;

static inline void __user *compat_ptr(compat_uptr_t uptr)
{
	return (void __user *)(unsigned long)uptr;
}

static inline compat_uptr_t ptr_to_compat(void __user *uptr)
{
	return (u32)(unsigned long)uptr;
}

static inline void __user *arch_compat_alloc_user_space(long len)
{
	struct pt_regs *regs = task_pt_regs(current);
	return (void __user *)regs->sp - len;
}

static inline int is_compat_task(void)
{
	return current_thread_info()->status & TS_COMPAT;
}

#endif /* _ASM_X86_COMPAT_H */