Commit bae217ea authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add ksys_open() wrapper; remove in-kernel calls to sys_open() 

Using this wrapper allows us to avoid the in-kernel calls to the
sys_open() syscall. The ksys_ prefix denotes that this function is meant
as a drop-in replacement for the syscall. In particular, it uses the
same calling convention as sys_open().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net



Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 2ca2a09d

fs/open.c

+1 −1
Original line number Diff line number Diff line
@@ -1151,7 +1151,7 @@ COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, fla 
 */

SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)

{

	return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);

	return ksys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);

}



#endif

include/linux/syscalls.h

+11 −0
Original line number Diff line number Diff line
@@ -1057,4 +1057,15 @@ static inline int ksys_close(unsigned int fd) 
	return __close_fd(current->files, fd);

}



extern long do_sys_open(int dfd, const char __user *filename, int flags,

			umode_t mode);



static inline long ksys_open(const char __user *filename, int flags,

			     umode_t mode)

{

	if (force_o_largefile())

		flags |= O_LARGEFILE;

	return do_sys_open(AT_FDCWD, filename, flags, mode);

}



#endif

init/do_mounts.c

+2 −2
Original line number Diff line number Diff line
@@ -489,13 +489,13 @@ void __init change_floppy(char *fmt, ...) 
	va_start(args, fmt);

	vsprintf(buf, fmt, args);

	va_end(args);

	fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);

	fd = ksys_open("/dev/root", O_RDWR | O_NDELAY, 0);

	if (fd >= 0) {

		sys_ioctl(fd, FDEJECT, 0);

		ksys_close(fd);

	}

	printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);

	fd = sys_open("/dev/console", O_RDWR, 0);

	fd = ksys_open("/dev/console", O_RDWR, 0);

	if (fd >= 0) {

		sys_ioctl(fd, TCGETS, (long)&termios);

		termios.c_lflag &= ~ICANON;

init/do_mounts_initrd.c

+2 −2
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ static int init_linuxrc(struct subprocess_info *info, struct cred *new) 
{

	sys_unshare(CLONE_FS | CLONE_FILES);

	/* stdin/stdout/stderr for /linuxrc */

	sys_open("/dev/console", O_RDWR, 0);

	ksys_open("/dev/console", O_RDWR, 0);

	ksys_dup(0);

	ksys_dup(0);

	/* move initrd over / and chdir/chroot in initrd root */
@@ -99,7 +99,7 @@ static void __init handle_initrd(void) 
	if (!error)

		printk("okay\n");

	else {

		int fd = sys_open("/dev/root.old", O_RDWR, 0);

		int fd = ksys_open("/dev/root.old", O_RDWR, 0);

		if (error == -ENOENT)

			printk("/initrd does not exist. Ignored.\n");

		else

init/do_mounts_md.c

+3 −3
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ static void __init md_setup_drive(void) 
			partitioned ? "_d" : "", minor,

			md_setup_args[ent].device_names);



		fd = sys_open(name, 0, 0);

		fd = ksys_open(name, 0, 0);

		if (fd < 0) {

			printk(KERN_ERR "md: open failed - cannot start "

					"array %s\n", name);
@@ -244,7 +244,7 @@ static void __init md_setup_drive(void) 
			 * array without it

			 */

			ksys_close(fd);

			fd = sys_open(name, 0, 0);

			fd = ksys_open(name, 0, 0);

			sys_ioctl(fd, BLKRRPART, 0);

		}

		ksys_close(fd);
@@ -294,7 +294,7 @@ static void __init autodetect_raid(void) 


	wait_for_device_probe();



	fd = sys_open("/dev/md0", 0, 0);

	fd = ksys_open("/dev/md0", 0, 0);

	if (fd >= 0) {

		sys_ioctl(fd, RAID_AUTORUN, raid_autopart);

		ksys_close(fd);

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