Re: [PATCH v2 00/36] remove in-kernel syscall invocations (part 1)

["Zhang, Ning A" <ning.a.zhang@intel.com>]

在 2018-03-15四的 20:04 +0100，Dominik Brodowski写道：
> Here is a re-spin of the first set of patches which reduce the number of
> syscall invocations from within the kernel; the RFC may be found at
> 
> The rationale for this change is described in patch 1 as follows:
> 
> 	The syscall entry points to the kernel defined by SYSCALL_DEFINEx()
> 	and COMPAT_SYSCALL_DEFINEx() should only be called from userspace
> 	through kernel entry points, but not from the kernel itself. This
> 	will allow cleanups and optimizations to the entry paths *and* to
> 	the parts of the kernel code which currently need to pretend to be
> 	userspace in order to make use of syscalls.

I think this is really bad to change syscalls one by one, to do_*

why not change SYSCALL_DEFINEx to define kernel wrappers?


> 
The whole series can be found at 
> 
> 	https://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux.git syscalls-next
> 
> and will be submitted for merging for the v4.17-rc1 cycle, probably together
> with another batch of related patches I hope to send out tomorrow as a RFC.
> 
> Changes since the RFC / v1:
> 
> - rebase to v4.15-rc5; sys_ioperm already got its SYSCALL_DEFINE3
> - add ACKs
> - CC: -> Cc: (suggested by Ingo Molnar)
> - update comment in include/linux/syscalls.h (suggested by Ingo Molnar and
> 	Andy Lutomirski)
> - separate declarations from definitions with newlines in
> 	include/linux/syscalls.h; add comment on ksys_close() (suggested by
> 	Ingo Molnar)
> - expand commit messages (suggested by Christoph Hellwig)
> - include patch 36:
> 	fs: add ksys_open() wrapper; remove in-kernel calls to sys_open()
> - do not worry about the following archs, as they are going away:
> 	cris, frv, metag, mn10300, score, tile
> 	(solving conflicts in -next)
> - fix builds with CONFIG_FUTEX=n, CONFIG_ADVISE_SYSCALLS=n (solving issues
> 	found by Stephen Rothwell)
> 
> Thanks,
> 	Dominik
> 
> 
> Dominik Brodowski (36):
>   syscalls: define goal to not call sys_xyzzy() from within the kernel
>   kernel: use kernel_wait4() instead of sys_wait4()
>   mm: use do_futex() instead of sys_futex() in mm_release()
>   kernel: add do_getpgid() helper; remove internal call to sys_getpgid()
>   fs: add do_readlinkat() helper; remove internal call to
>     sys_readlinkat()
>   fs: add do_pipe2() helper; remove internal call to sys_pipe2()
>   fs: add do_renameat2() helper; remove internal call to sys_renameat2()
>   fs: add do_futimesat() helper; remove internal call to sys_futimesat()
>   syscalls: add do_epoll_*() helpers; remove internal calls to
>     sys_epoll_*()
>   fs: add do_signalfd4() helper; remove internal calls to
>     sys_signalfd4()
>   fs: add do_eventfd() helper; remove internal call to sys_eventfd()
>   kernel: open-code sys_rt_sigpending() in sys_sigpending()
>   x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to
>     sys_ioperm()
>   fs: add ksys_mount() helper; remove in-kernel calls to sys_mount()
>   fs: add ksys_umount() helper; remove in-kernel call to sys_umount()
>   fs: add ksys_dup{,3}() helper; remove in-kernel calls to sys_dup{,3}()
>   fs: add ksys_chroot() helper; remove-in kernel calls to sys_chroot()
>   fs: add ksys_write() helper; remove in-kernel calls to sys_write()
>   kernel: add ksys_unshare() helper; remove in-kernel calls to
>     sys_unshare()
>   mm: add ksys_fadvise64_64() helper; remove in-kernel call to
>     sys_fadvise64_64()
>   mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to
>     sys_mmap_pgoff()
>   fs: add ksys_chdir() helper; remove in-kernel calls to sys_chdir()
>   fs: add ksys_sync_file_range helper(); remove in-kernel calls to
>     syscall
>   fs: add ksys_unlink() wrapper; remove in-kernel calls to sys_unlink()
>   hostfs: rename do_rmdir() to hostfs_do_rmdir()
>   fs: add ksys_rmdir() wrapper; remove in-kernel calls to sys_rmdir()
>   fs: add do_mkdirat() helper and ksys_mkdir() wrapper; remove in-kernel
>     calls to syscall
>   fs: add do_symlinkat() helper and ksys_symlink() wrapper; remove
>     in-kernel calls to syscall
>   fs: add do_mknodat() helper and ksys_mknod() wrapper; remove in-kernel
>     calls to syscall
>   fs: add do_linkat() helper and ksys_link() wrapper; remove in-kernel
>     calls to syscall
>   fs: add ksys_fchmod() and do_fchmodat() helpers and ksys_chmod()
>     wrapper; remove in-kernel calls to syscall
>   fs: add do_faccessat() helper and ksys_access() wrapper; remove
>     in-kernel calls to syscall
>   fs: add ksys_ftruncate() wrapper; remove in-kernel calls to
>     sys_ftruncate()
>   fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown()
>     wrappers
>   fs: add ksys_close() wrapper; remove in-kernel calls to sys_close()
>   fs: add ksys_open() wrapper; remove in-kernel calls to sys_open()
> 
>  Documentation/process/adding-syscalls.rst |  14 ---
>  arch/alpha/kernel/osf_sys.c               |   2 +-
>  arch/arm/kernel/sys_arm.c                 |   2 +-
>  arch/arm64/kernel/sys.c                   |   2 +-
>  arch/ia64/kernel/sys_ia64.c               |   4 +-
>  arch/m68k/kernel/sys_m68k.c               |   2 +-
>  arch/microblaze/kernel/sys_microblaze.c   |   6 +-
>  arch/mips/kernel/linux32.c                |  10 +-
>  arch/mips/kernel/syscall.c                |   6 +-
>  arch/parisc/kernel/sys_parisc.c           |  14 +--
>  arch/powerpc/kernel/sys_ppc32.c           |   8 +-
>  arch/powerpc/kernel/syscalls.c            |   6 +-
>  arch/riscv/kernel/sys_riscv.c             |   4 +-
>  arch/s390/kernel/compat_linux.c           |  23 ++---
>  arch/s390/kernel/sys_s390.c               |   2 +-
>  arch/sh/kernel/sys_sh.c                   |   4 +-
>  arch/sh/kernel/sys_sh32.c                 |   8 +-
>  arch/sparc/kernel/sys_sparc32.c           |  14 +--
>  arch/sparc/kernel/sys_sparc_32.c          |   6 +-
>  arch/sparc/kernel/sys_sparc_64.c          |   2 +-
>  arch/um/kernel/syscall.c                  |   2 +-
>  arch/x86/ia32/sys_ia32.c                  |  22 ++---
>  arch/x86/include/asm/syscalls.h           |   1 +
>  arch/x86/kernel/ioport.c                  |   7 +-
>  arch/x86/kernel/sys_x86_64.c              |   2 +-
>  arch/xtensa/kernel/syscall.c              |   2 +-
>  drivers/base/devtmpfs.c                   |  11 ++-
>  drivers/tty/vt/vt_ioctl.c                 |   6 +-
>  fs/autofs4/dev-ioctl.c                    |   2 +-
>  fs/binfmt_misc.c                          |   2 +-
>  fs/eventfd.c                              |   9 +-
>  fs/eventpoll.c                            |  23 +++--
>  fs/file.c                                 |  17 +++-
>  fs/hostfs/hostfs.h                        |   2 +-
>  fs/hostfs/hostfs_kern.c                   |   2 +-
>  fs/hostfs/hostfs_user.c                   |   2 +-
>  fs/internal.h                             |  14 +++
>  fs/namei.c                                |  61 +++++++++----
>  fs/namespace.c                            |  19 +++-
>  fs/open.c                                 |  68 ++++++++++----
>  fs/pipe.c                                 |   9 +-
>  fs/read_write.c                           |   9 +-
>  fs/signalfd.c                             |  14 ++-
>  fs/stat.c                                 |  12 ++-
>  fs/sync.c                                 |  12 ++-
>  fs/utimes.c                               |  13 ++-
>  include/linux/futex.h                     |  13 ++-
>  include/linux/syscalls.h                  | 146 +++++++++++++++++++++++++++++-
>  init/do_mounts.c                          |  16 ++--
>  init/do_mounts.h                          |   4 +-
>  init/do_mounts_initrd.c                   |  38 ++++----
>  init/do_mounts_md.c                       |  14 +--
>  init/do_mounts_rd.c                       |  18 ++--
>  init/initramfs.c                          |  48 +++++-----
>  init/main.c                               |   9 +-
>  init/noinitramfs.c                        |   6 +-
>  kernel/exit.c                             |   2 +-
>  kernel/fork.c                             |  11 ++-
>  kernel/pid_namespace.c                    |   6 +-
>  kernel/signal.c                           |  15 ++-
>  kernel/sys.c                              |   9 +-
>  kernel/uid16.c                            |   6 +-
>  kernel/umh.c                              |   2 +-
>  mm/fadvise.c                              |  10 +-
>  mm/mmap.c                                 |  17 +++-
>  mm/nommu.c                                |  17 +++-
>  66 files changed, 614 insertions(+), 275 deletions(-)
>