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[v8,0/3] Add an internal wrapper for clone, clone2 and clone3

Message ID 20210601145516.3553627-1-hjl.tools@gmail.com
Headers show
Series Add an internal wrapper for clone, clone2 and clone3 | expand

Message

H.J. Lu June 1, 2021, 2:55 p.m. UTC 
The clone3 system call provides a superset of the functionality of clone
and clone2.  It also provides a number of API improvements, including
the ability to specify the size of the child's stack area which can be
used by kernel to compute the shadow stack size when allocating the
shadow stack.  Add:

extern int __clone_internal (struct clone_args *__cl_args,
			     int (*__func) (void *__arg), void *__arg);

to provide an abstract interface for clone, clone2 and clone3.

1. Simplify stack management for thread creation by passing both stack
base and size to create_thread.
2. Consolidate clone vs clone2 differences into a single file.
3. Call __clone3 if HAVE_CLONE3_WAPPER is defined.  If __clone3 returns
-1 with ENOSYS, fall back to clone or clone2.
4. Use only __clone_internal to clone a thread.  Since the stack size
argument for create_thread is now unconditional, always pass stack size
to create_thread.
5. Enable the public clone3 wrapper in the future after it has been
added to all targets.

NB: Sandbox should return ENOSYS on clone3 if it is rejected:

https://bugs.chromium.org/p/chromium/issues/detail?id=1213452#c5

H.J. Lu (3):
  Add an internal wrapper for clone, clone2 and clone3
  x86-64: Add the clone3 wrapper
  Add static tests for __clone_internal

 include/clone_internal.h                      |  16 ++
 nptl/allocatestack.c                          |  59 +-------
 nptl/pthread_create.c                         |  38 +++--
 sysdeps/unix/sysv/linux/Makefile              |  11 +-
 sysdeps/unix/sysv/linux/clone-internal.c      |  91 ++++++++++++
 sysdeps/unix/sysv/linux/clone3.c              |   1 +
 sysdeps/unix/sysv/linux/clone3.h              |  60 ++++++++
 sysdeps/unix/sysv/linux/spawni.c              |  26 ++--
 .../sysv/linux/tst-align-clone-internal.c     |  87 +++++++++++
 sysdeps/unix/sysv/linux/tst-clone2-internal.c | 137 ++++++++++++++++++
 sysdeps/unix/sysv/linux/tst-clone3-internal.c |  99 +++++++++++++
 .../unix/sysv/linux/tst-getpid1-internal.c    | 133 +++++++++++++++++
 .../sysv/linux/tst-misalign-clone-internal.c  |  86 +++++++++++
 sysdeps/unix/sysv/linux/x86_64/clone3.S       |  92 ++++++++++++
 sysdeps/unix/sysv/linux/x86_64/sysdep.h       |   2 +
 15 files changed, 850 insertions(+), 88 deletions(-)
 create mode 100644 include/clone_internal.h
 create mode 100644 sysdeps/unix/sysv/linux/clone-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/clone3.c
 create mode 100644 sysdeps/unix/sysv/linux/clone3.h
 create mode 100644 sysdeps/unix/sysv/linux/tst-align-clone-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-clone2-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-clone3-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-getpid1-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/tst-misalign-clone-internal.c
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/clone3.S