On Thu, Mar 4, 2021 at 10:40 AM H.J. Lu wrote: > > On Mon, Feb 15, 2021 at 6:56 AM Adhemerval Zanella via Libc-alpha > wrote: > > > > > > > > On 15/02/2021 07:44, Florian Weimer via Libc-alpha wrote: > > > * H. J. Lu via Libc-alpha: > > > > > >> The clone3 system call provides a superset of the functionality of clone > > >> and clone2. It also provides a number of API improve ments, 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, size_t size, > > >> int (*__fn) (void *__arg), void *__arg); > > >> > > >> to provide an abstract interface for clone, clone2 and clone3. > > >> > > >> 1. Simplify stack management for clone by passing stack base and size > > >> to __clone_internal. > > >> 2. Consolidate clone vs clone2 differences into a single file. > > >> 3. Use only __clone_internal to clone a thread. If clone3 returns -1 > > >> with ENOSYS, __clone_internal will fall back to clone or clone2. > > >> 4. Add the x86-64 clone3 wrapper. > > >> 5. Enable the public clone3 wrapper in the future after it has been > > >> added to add targets. > > > > > > What do you think about providing a clone wrapper which reuses the > > > caller's stack? That would be useful for a (v)fork-style clone. This > > > variant could also be exported because the callback inherits a > > > semi-valid TCB in this case. > > I have this one as a TODO to improve the posix_spawn. > > Here is the v2 patch: > > 1. Update the stack size field, instead of the stack field, passed to > clone3. > > OK for master? Really add the patch this time :-). -- H.J.