Re: [PATCH] m68k: Wire up clone3() syscall

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Kars,

On Tue, Nov 26, 2019 at 4:29 PM Kars de Jong <jongk@linux-m68k.org> wrote:
> Op di 26 nov. 2019 om 15:41 schreef Christian Brauner
> <christian.brauner@ubuntu.com>:
> > On Mon, Nov 25, 2019 at 10:12:25AM +0100, Geert Uytterhoeven wrote:
> > > On Sun, Nov 24, 2019 at 8:52 PM Kars de Jong <jongk@linux-m68k.org> wrote:
> > > > Wire up the clone3() syscall for m68k. The special entry point is done in
> > > > assembler as was done for clone() as well. This is needed because all
> > > > registers need to be saved. The C wrapper then calls the generic
> > > > sys_clone3() with the correct arguments.
> > > >
> > > > Tested on A1200 using the simple test program from:
> > > >
> > > >   https://lore.kernel.org/lkml/20190716130631.tohj4ub54md25dys@brauner.io/
> >
> > Please note that we now have a growing test-suite for the clone3()
> > syscall under
> > tools/testing/selftests/clone3/*
> >
> > You can test on a suitable kernel with
> >
> > make TARGETS=clone3 kselftest
>
> I'm afraid my user space is almost prehistoric. I have a homebrewn
> root filesystem of about 2001 vintage, and another one with Debian
> 3.1.
> So until I have bootstrapped a more recent one, I'll leave that to others ;-)

With Ubuntu's libc6-m68k-cross installed, the selftest binaries cross-build
fine.  Running them on a very old Debian requires some hackery:

  1. Copy ld.so.1, ld-2.27.so, libc.so.6, and libc-2.27.so from
     /usr/m68k-linux-gnu/lib/ to /tmp/lib on the m68k target,
  2. mkdir /tmp/proc && mount proc /tmp/proc -t proc,
  3. chroot /tmp /tmp/<test-binary>.

Unfortunately some tests failed:

atari:~# chroot /tmp /tmp/clone3
# clone3() syscall supported
TAP version 13
1..17
# [825] Trying clone3() with flags 0 (size 0)
# I am the parent (825). My child's pid is 826
# I am the child, my PID is 826
# [825] clone3() with flags says: 0 expected 0
ok 1 [825] Result (0) matches expectation (0)
# [825] Trying clone3() with flags 0x20000000 (size 0)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected 0
not ok 2 [825] Result (-22) is different than expected (0)
# [825] Trying clone3() with flags 0 (size 64)
# I am the parent (825). My child's pid is 827
# I am the child, my PID is 827
# [825] clone3() with flags says: 0 expected 0
ok 3 [825] Result (0) matches expectation (0)
# [825] Trying clone3() with flags 0 (size 56)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 4 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0 (size 88)
# I am the parent (825). My child's pid is 828
# I am the child, my PID is 828
# [825] clone3() with flags says: 0 expected 0
ok 5 [825] Result (0) matches expectation (0)
# [825] Trying clone3() with flags 0 (size 0)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 6 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0 (size 0)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 7 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0 (size 0)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 8 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0 (size 0)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 9 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0 (size 88)
# I am the parent (825). My child's pid is 829
# I am the child, my PID is 829
# [825] clone3() with flags says: 0 expected 0
ok 10 [825] Result (0) matches expectation (0)
# [825] Trying clone3() with flags 0 (size 96)
# Argument list too long - Failed to create new process
# [825] clone3() with flags says: -7 expected -7
ok 11 [825] Result (-7) matches expectation (-7)
# [825] Trying clone3() with flags 0 (size 160)
# Argument list too long - Failed to create new process
# [825] clone3() with flags says: -7 expected -7
ok 12 [825] Result (-7) matches expectation (-7)
# [825] Trying clone3() with flags 0 (size 4104)
# Argument list too long - Failed to create new process
# [825] clone3() with flags says: -7 expected -7
ok 13 [825] Result (-7) matches expectation (-7)
# [825] Trying clone3() with flags 0x20000000 (size 64)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected 0
not ok 14 [825] Result (-22) is different than expected (0)
# [825] Trying clone3() with flags 0x20000000 (size 56)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected -22
ok 15 [825] Result (-22) matches expectation (-22)
# [825] Trying clone3() with flags 0x20000000 (size 88)
# Invalid argument - Failed to create new process
# [825] clone3() with flags says: -22 expected 0
not ok 16 [825] Result (-22) is different than expected (0)
# [825] Trying clone3() with flags 0x20000000 (size 4104)
# Argument list too long - Failed to create new process
# [825] clone3() with flags says: -7 expected -7
ok 17 [825] Result (-7) matches expectation (-7)
Bail out!
# Pass 14 Fail 3 Xfail 0 Xpass 0 Skip 0 Error 0
atari:~# chroot /tmp /tmp/clone3_set_tid
TAP version 13
# clone3() syscall supported
1..29
# /proc/sys/kernel/pid_max 32768
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 1 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 2 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 3 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 4 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 5 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 6 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 7 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 8 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 9 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 10 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 0 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 0 says :-22 - expected -22
ok 11 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 12 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 13 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to -1 and 0x20000000
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID -1 says :-22 - expected -22
ok 14 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 1 and 0x0
# File exists - Failed to create new process
# [830] clone3() with CLONE_SET_TID 1 says :-17 - expected -17
ok 15 [830] Result (-17) matches expectation (-17)
# [830] Trying clone3() with CLONE_SET_TID to 1 and 0x20000000
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 1 says :-22 - expected 0
not ok 16 [830] Result (-22) is different than expected (0)
# [830] Trying clone3() with CLONE_SET_TID to 32768 and 0x0
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 32768 says :-22 - expected -22
ok 17 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 32768 and 0x20000000
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 32768 says :-22 - expected -22
ok 18 [830] Result (-22) matches expectation (-22)
# Child has PID 831
# [830] Trying clone3() with CLONE_SET_TID to 831 and 0x0
# I am the parent (830). My child's pid is 831
# I am the child, my PID is 831 (expected 831)
# [830] clone3() with CLONE_SET_TID 831 says :0 - expected 0
ok 19 [830] Result (0) matches expectation (0)
# [830] Trying clone3() with CLONE_SET_TID to 831 and 0x20000000
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 831 says :-22 - expected -22
ok 20 [830] Result (-22) matches expectation (-22)
# [830] Trying clone3() with CLONE_SET_TID to 1 and 0x20000000
# Invalid argument - Failed to create new process
# [830] clone3() with CLONE_SET_TID 1 says :-22 - expected 0
not ok 21 [830] Result (-22) is different than expected (0)
# unshare PID namespace
Bail out! unshare(CLONE_NEWPID) failed: Invalid argument
# Planned tests != run tests (29 != 21)
# Pass 19 Fail 2 Xfail 0 Xpass 0 Skip 0 Error 0
atari:~# chroot /tmp /tmp/clone3_clear_sighand
TAP version 13
# clone3() syscall supported
1..1
Bail out! Failed to clear signal handler for child process
# Planned tests != run tests (1 != 0)
# Pass 0 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0
atari:~#

So this needs a bit more work?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds