Implement CLONE_INTO_CGROUP feature, allowing to put a child in a
specified cgroup in a clean and simple way. Note that the feature only
works for cgroup v2, and requires Linux kernel 5.7 or newer.
Using the feature requires a new syscall, clone3. Currently this is the
only reason to use clone3, but the code is structured in a way so that
other cases may be easily added in the future.
Add a test case.
While at it, try to simplify the syscall calling code in
forkAndExecInChild1, which became complicated over time because:
1. It was using either rawVforkSyscall or RawSyscall6 depending on
whether CLONE_NEWUSER was set.
2. On Linux/s390, the first two arguments to clone(2) system call are
swapped (which deserved a mention in Linux ABI hall of shame). It
was worked around in rawVforkSyscall on s390, but had to be
implemented via a switch/case when using RawSyscall6, making the code
less clear.
Let's
- modify rawVforkSyscall to have two arguments (which is also required
for clone3);
- remove the arguments workaround from s390 asm, instead implementing
arguments swap in the caller (which still looks ugly but at least
it's done once and is clearly documented now);
- use rawVforkSyscall for all cases (since it is essentially similar to
RawSyscall6, except for having less parameters, not returning r2, and
saving/restoring the return address before/after syscall on 386 and
amd64).
Updates #51246.
Change-Id: Ifcd418ebead9257177338ffbcccd0bdecb94474e
Reviewed-on: https://go-review.googlesource.com/c/go/+/417695
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Kirill Kolyshkin <kolyshkin@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
The constants for these were auto-generated from the C includes
into zerrors_linux* files quite some time ago. The generator is
currently broken, but some new flags need to be added nevertheless.
As the flags won't change and the values are the same for all
architectures, we can just define them statically (as it's already
done in the runtime package):
- remove the CLONE_* constants from zerrors_linux_*.go;
- patch mkerrors.sh to not generate CLONE_ constants
(in case it will be fixed and used in the future);
- add the constants and some comments about them to exec_linux.go,
using Linux v5.17 include/uapi/sched.h as the ultimate source.
This adds the following new flags:
- CLONE_CLEAR_SIGHAND
- CLONE_INTO_CGROUP
- CLONE_NEWCGROUP
- CLONE_NEWTIME
- CLONE_PIDFD
For #51246.
Change-Id: I0c635723926218bd403d37e113ee4d62194463a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/407574
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Joedian Reid <joedian@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
