Using this helper allows us to avoid the in-kernel calls to the sys_read() 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_read(). 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@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> --- arch/s390/kernel/compat_linux.c | 2 +- fs/read_write.c | 7 ++++++- include/linux/syscalls.h | 1 + init/do_mounts.c | 2 +- init/do_mounts_rd.c | 10 +++++----- 5 files changed, 14 insertions(+), 8 deletions(-) diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c index 9c5e975f71a6..af0469f204fd 100644 --- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -460,7 +460,7 @@ COMPAT_SYSCALL_DEFINE3(s390_read, unsigned int, fd, char __user *, buf, compat_s if ((compat_ssize_t) count < 0) return -EINVAL; - return sys_read(fd, buf, count); + return ksys_read(fd, buf, count); } COMPAT_SYSCALL_DEFINE3(s390_write, unsigned int, fd, const char __user *, buf, compat_size_t, count) diff --git a/fs/read_write.c b/fs/read_write.c index b38b008a078e..fc441e1ac683 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -568,7 +568,7 @@ static inline void file_pos_write(struct file *file, loff_t pos) file->f_pos = pos; } -SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) +ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count) { struct fd f = fdget_pos(fd); ssize_t ret = -EBADF; @@ -583,6 +583,11 @@ SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) return ret; } +SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count) +{ + return ksys_read(fd, buf, count); +} + ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count) { struct fd f = fdget_pos(fd); diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 0f24e5334569..3a2e90842ff8 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -959,6 +959,7 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent, unsigned int count); int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg); off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence); +ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count); /* * The following kernel syscall equivalents are just wrappers to fs-internal diff --git a/init/do_mounts.c b/init/do_mounts.c index b17e0095eb4e..2c71dabe5626 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -500,7 +500,7 @@ void __init change_floppy(char *fmt, ...) ksys_ioctl(fd, TCGETS, (long)&termios); termios.c_lflag &= ~ICANON; ksys_ioctl(fd, TCSETSF, (long)&termios); - sys_read(fd, &c, 1); + ksys_read(fd, &c, 1); termios.c_lflag |= ICANON; ksys_ioctl(fd, TCSETSF, (long)&termios); ksys_close(fd); diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c index 13e54148c0e0..12c159824c7b 100644 --- a/init/do_mounts_rd.c +++ b/init/do_mounts_rd.c @@ -91,7 +91,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor) * Read block 0 to test for compressed kernel */ ksys_lseek(fd, start_block * BLOCK_SIZE, 0); - sys_read(fd, buf, size); + ksys_read(fd, buf, size); *decompressor = decompress_method(buf, size, &compress_name); if (compress_name) { @@ -137,7 +137,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor) * Read 512 bytes further to check if cramfs is padded */ ksys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0); - sys_read(fd, buf, size); + ksys_read(fd, buf, size); if (cramfsb->magic == CRAMFS_MAGIC) { printk(KERN_NOTICE @@ -151,7 +151,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor) * Read block 1 to test for minix and ext2 superblock */ ksys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0); - sys_read(fd, buf, size); + ksys_read(fd, buf, size); /* Try minix */ if (minixsb->s_magic == MINIX_SUPER_MAGIC || @@ -269,7 +269,7 @@ int __init rd_load_image(char *from) } printk("Loading disk #%d... ", disk); } - sys_read(in_fd, buf, BLOCK_SIZE); + ksys_read(in_fd, buf, BLOCK_SIZE); ksys_write(out_fd, buf, BLOCK_SIZE); #if !defined(CONFIG_S390) if (!(i % 16)) { @@ -307,7 +307,7 @@ static int crd_infd, crd_outfd; static long __init compr_fill(void *buf, unsigned long len) { - long r = sys_read(crd_infd, buf, len); + long r = ksys_read(crd_infd, buf, len); if (r < 0) printk(KERN_ERR "RAMDISK: error while reading compressed data"); else if (r == 0) -- 2.16.3
