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/processor.h>
#include <asm/user32.h>
#include <asm/unistd.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;
typedef u32		compat_uptr_t;

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_flags;
	int		f_spare[4];
};

#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;

typedef union compat_sigval {
	compat_int_t	sival_int;
	compat_uptr_t	sival_ptr;
} compat_sigval_t;

typedef struct compat_siginfo {
	int si_signo;
	int si_errno;
	int si_code;

	union {
		int _pad[128/sizeof(int) - 3];

		/* kill() */
		struct {
			unsigned int _pid;	/* sender's pid */
			unsigned int _uid;	/* sender's uid */
		} _kill;

		/* POSIX.1b timers */
		struct {
			compat_timer_t _tid;	/* timer id */
			int _overrun;		/* overrun count */
			compat_sigval_t _sigval;	/* same as below */
			int _sys_private;	/* not to be passed to user */
			int _overrun_incr;	/* amount to add to overrun */
		} _timer;

		/* POSIX.1b signals */
		struct {
			unsigned int _pid;	/* sender's pid */
			unsigned int _uid;	/* sender's uid */
			compat_sigval_t _sigval;
		} _rt;

		/* SIGCHLD */
		struct {
			unsigned int _pid;	/* which child */
			unsigned int _uid;	/* sender's uid */
			int _status;		/* exit code */
			compat_clock_t _utime;
			compat_clock_t _stime;
		} _sigchld;

		/* SIGCHLD (x32 version) */
		struct {
			unsigned int _pid;	/* which child */
			unsigned int _uid;	/* sender's uid */
			int _status;		/* exit code */
			compat_s64 _utime;
			compat_s64 _stime;
		} _sigchld_x32;

		/* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
		struct {
			unsigned int _addr;	/* faulting insn/memory ref. */
		} _sigfault;

		/* SIGPOLL */
		struct {
			int _band;	/* POLL_IN, POLL_OUT, POLL_MSG */
			int _fd;
		} _sigpoll;

		struct {
			unsigned int _call_addr; /* calling insn */
			int _syscall;	/* triggering system call number */
			unsigned int _arch;	/* AUDIT_ARCH_* of syscall */
		} _sigsys;
	} _sifields;
} compat_siginfo_t;

#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.
 */
#ifdef CONFIG_X86_X32_ABI
typedef struct user_regs_struct compat_elf_gregset_t;

#define PR_REG_SIZE(S) (test_thread_flag(TIF_IA32) ? 68 : 216)
#define PRSTATUS_SIZE(S) (test_thread_flag(TIF_IA32) ? 144 : 296)
#define SET_PR_FPVALID(S,V) \
  do { *(int *) (((void *) &((S)->pr_reg)) + PR_REG_SIZE(0)) = (V); } \
  while (0)

#define COMPAT_USE_64BIT_TIME \
	(!!(task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT))
#else
typedef struct user_regs_struct32 compat_elf_gregset_t;
#endif

/*
 * 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.
 */

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)
{
	compat_uptr_t sp;

	if (test_thread_flag(TIF_IA32)) {
		sp = task_pt_regs(current)->sp;
	} else {
		/* -128 for the x32 ABI redzone */
		sp = task_pt_regs(current)->sp - 128;
	}

	return (void __user *)round_down(sp - len, 16);
}

static inline bool is_x32_task(void)
{
#ifdef CONFIG_X86_X32_ABI
	if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
		return true;
#endif
	return false;
}

static inline bool is_compat_task(void)
{
	return is_ia32_task() || is_x32_task();
}

#endif /* _ASM_X86_COMPAT_H */