host_syscall.h

/*
 * Copyright (c) 2022, Netflix, Inc.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Rewritten from the original host_syscall.h Copyright (C) 2014 Nathan Whitehorn
 */

#ifndef _HOST_SYSCALL_H
#define _HOST_SYSCALL_H

#include <stand.h>
#include <assert.h>

long host_syscall(int number, ...);

/*
 * Sizes taken from musl's include/alltypes.h.in and expanded for LP64 hosts
 */
typedef uint64_t host_dev_t;
typedef uint64_t host_ino_t;
typedef unsigned int host_mode_t;
typedef unsigned int host_uid_t;
typedef unsigned int host_gid_t;
typedef int64_t host_off_t;
typedef long host_blksize_t;
typedef int64_t host_blkcnt_t;

#include "stat_arch.h"

/*
 * stat flags
 * These are arch independent and match the values in nolib and uapi headers
 * with HOST_ prepended.
 */
#define	HOST_S_IFMT	0170000
#define	HOST_S_IFIFO	0010000
#define	HOST_S_IFCHR	0020000
#define	HOST_S_IFDIR	0040000
#define	HOST_S_IFBLK	0060000
#define	HOST_S_IFREG	0100000
#define	HOST_S_IFLNK	0120000
#define	HOST_S_IFSOCK	0140000

#define	HOST_S_ISBLK(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFBLK)
#define	HOST_S_ISCHR(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFCHR)
#define	HOST_S_ISDIR(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFDIR)
#define	HOST_S_ISFIFO(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFIFO)
#define	HOST_S_ISLNK(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFLNK)
#define	HOST_S_ISREG(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFREG)
#define	HOST_S_ISSOCK(mode)	(((mode) & HOST_S_IFMT) == HOST_S_IFSOCK)

/*
 * Constants for open, fcntl, etc
 *
 * Note: Some of these are arch dependent on Linux, but are the same for
 * powerpc, x86, arm*, and riscv. We should be futureproof, though, since these
 * are the 'generic' values and only older architectures (no longer supported by
 * FreeBSD) vary.
 *
 * These are from tools/include/uapi/asm-generic/fcntl.h and use the octal
 * notation. Beware, hex is used in other places creating potential confsion.
 */
#define HOST_O_RDONLY		    0
#define HOST_O_WRONLY		    1
#define HOST_O_RDWR		    2
#define HOST_O_CREAT		00100
#define HOST_O_EXCL		00200
#define HOST_O_NOCTTY		00400
#define HOST_O_TRUNC		01000
#define HOST_O_APPEND		02000
#define HOST_O_NONBLOCK		04000

#define HOST_AT_FDCWD		-100            /* Relative to current directory */

/*
 * Data types
 */
struct old_utsname {
	char sysname[65];
	char nodename[65];
	char release[65];
	char version[65];
	char machine[65];
};

struct host_timeval {
	time_t tv_sec;
	long tv_usec;
};

/*
 * Must match Linux's values see linux/tools/include/uapi/asm-generic/mman-common.h
 * and linux/tools/include/linux/mman.h
 *
 * And pre-pend HOST_ here.
 */
#define HOST_PROT_READ	0x1
#define HOST_PROT_WRITE	0x2
#define HOST_PROT_EXEC	0x4

#define HOST_MAP_SHARED		0x01
#define	HOST_MAP_PRIVATE	0x02
#define HOST_MAP_FIXED		0x10
#define HOST_MAP_ANONYMOUS	0x20

#define HOST_MAP_FAILED		((void *)-1)

/* Mount flags from uapi */
#define MS_RELATIME (1 << 21)

#define HOST_REBOOT_MAGIC1	0xfee1dead
#define HOST_REBOOT_MAGIC2	672274793
#define HOST_REBOOT_CMD_KEXEC	0x45584543

/*
 * Values from linux/tools/include/uapi/linux/kexec.h
 */

/*
 * Values match ELF architecture types.
 */
#define HOST_KEXEC_ARCH_X86_64  (62 << 16)
#define HOST_KEXEC_ARCH_PPC64   (21 << 16)
#define HOST_KEXEC_ARCH_ARM     (40 << 16)
#define HOST_KEXEC_ARCH_AARCH64 (183 << 16)
#define HOST_KEXEC_ARCH_RISCV   (243 << 16)

/* Arbitrary cap on segments */
#define HOST_KEXEC_SEGMENT_MAX 16

struct host_kexec_segment {
	void *buf;
	int bufsz;
	void *mem;
	int memsz;
};

struct host_dirent64 {
	uint64_t	d_ino;		/* 64-bit inode number */
	int64_t		d_off;		/* 64-bit offset to next structure */
	unsigned short	d_reclen;	/* Size of this dirent */
	unsigned char	d_type;		/* File type */
	char		d_name[];	/* Filename (null-terminated) */
};

/* d_type values */
#define HOST_DT_UNKNOWN		 0
#define HOST_DT_FIFO		 1
#define HOST_DT_CHR		 2
#define HOST_DT_DIR		 4
#define HOST_DT_BLK		 6
#define HOST_DT_REG		 8
#define HOST_DT_LNK		10
#define HOST_DT_SOCK		12
#define HOST_DT_WHT		14

/*
 * System Calls
 */
int host_close(int fd);
int host_dup(int fd);
int host_exit(int code);
int host_fstat(int fd, struct host_kstat *sb);
int host_getdents64(int fd, void *dirp, int count);
int host_getpid(void);
int host_gettimeofday(struct host_timeval *a, void *b);
int host_ioctl(int fd, unsigned long request, unsigned long arg);
int host_kexec_load(unsigned long entry, unsigned long nsegs, struct host_kexec_segment *segs, unsigned long flags);
ssize_t host_llseek(int fd, int32_t offset_high, int32_t offset_lo, uint64_t *result, int whence);
int host_mkdir(const char *, host_mode_t);
void *host_mmap(void *addr, size_t len, int prot, int flags, int fd, off_t off);
int host_mount(const char *src, const char *target, const char *type,
    unsigned long flags, void *data);
int host_munmap(void *addr, size_t len);
int host_open(const char *path, int flags, int mode);
ssize_t host_read(int fd, void *buf, size_t nbyte);
int host_reboot(int, int, int, uintptr_t);
int host_select(int nfds, long *readfds, long *writefds, long *exceptfds,
    struct host_timeval *timeout);
int host_stat(const char *path, struct host_kstat *sb);
int host_symlink(const char *path1, const char *path2);
int host_uname(struct old_utsname *);
ssize_t host_write(int fd, const void *buf, size_t nbyte);

/*
 * Wrappers / one-liners
 */
#define host_getmem(size) \
	host_mmap(0, size, HOST_PROT_READ | HOST_PROT_WRITE, \
	    HOST_MAP_PRIVATE | HOST_MAP_ANONYMOUS, -1, 0);

/*
 * Since we have to interface with the 'raw' system call, we have to cope with
 * Linux's conventions. To run on the most architectures possible, they don't
 * return errors through some CPU flag, but instead, return a negative value for
 * an error, and a positive one for success. However, there's some issues since
 * addresses have to be returned, some of which are also negative, so Linus
 * declared that no successful result could be -4096 to 0. This implements
 * that quirk so we can check return values easily.
 */
static __inline bool
is_linux_error(long e)
{
	return (e < 0 && e >= -4096);
}

/*
 * Translate Linux errno to FreeBSD errno. The two system have idenitcal errors
 * for 1-34. After that, they differ. Linux also has errno that don't map
 * exactly to FreeBSD's errno, plus the Linux errno are arch dependent >
 * 34. Since we just need to do this for simple cases, use the simple mapping
 * function where -1 to -34 are translated to 1 to 34 and all others are EINVAL.
 * Pass the linux return value, which will be the -errno. Linux returns these
 * values as a 'long' which has to align to CPU register size, so accept that
 * size as the error so the assert can catch more values.
 */
static __inline int
host_to_stand_errno(long e)
{
	assert(is_linux_error(e));

	return((-e) > 34 ? EINVAL : (-e));
}
#endif