diff options
Diffstat (limited to 'nptl/sysdeps/unix/sysv/linux/i386/createthread.c')
| -rw-r--r-- | nptl/sysdeps/unix/sysv/linux/i386/createthread.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/nptl/sysdeps/unix/sysv/linux/i386/createthread.c b/nptl/sysdeps/unix/sysv/linux/i386/createthread.c new file mode 100644 index 0000000000..3196a8c754 --- /dev/null +++ b/nptl/sysdeps/unix/sysv/linux/i386/createthread.c @@ -0,0 +1,146 @@ +/* Copyright (C) 2002 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <sched.h> +#include <setjmp.h> +#include <signal.h> +#include <stdlib.h> +#include <atomic.h> +#include <ldsodefs.h> +#include <tls.h> + + +#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD) + + +static int +create_thread (struct pthread *pd, STACK_VARIABLES_PARMS) +{ + union user_desc_init desc; + + /* Describe the thread-local storage segment. */ + + /* The 'entry_number' field. The first three bits of the segment + register value select the GDT, ignore them. We get the index + from the value of the %gs register in the current thread. */ + desc.vals[0] = TLS_GET_GS () >> 3; + /* The 'base_addr' field. Pointer to the TCB. */ + desc.vals[1] = (unsigned long int) pd; + /* The 'limit' field. We use 4GB which is 0xfffff pages. */ + desc.vals[2] = 0xfffff; + /* Collapsed value of the bitfield: + .seg_32bit = 1 + .contents = 0 + .read_exec_only = 0 + .limit_in_pages = 1 + .seg_not_present = 0 + .useable = 1 */ + desc.vals[3] = 0x51; + + + assert (pd->header.data.tcb != NULL); + + + if (__builtin_expect (THREAD_GETMEM (THREAD_SELF, report_events), 0)) + { + /* The parent thread is supposed to report events. Check whether + the TD_CREATE event is needed, too. */ + const int _idx = __td_eventword (TD_CREATE); + const uint32_t _mask = __td_eventmask (TD_CREATE); + + if ((_mask & (__nptl_threads_events.event_bits[_idx] + | pd->eventbuf.eventmask.event_bits[_idx])) != 0) + { + /* We have to report the new thread. Make sure the thread + does not run far by forcing it to get a lock. We lock it + here too so that the new thread cannot continue until we + tell it to. */ + lll_lock (pd->lock); + + /* Create the thread. */ + if (__clone (start_thread_debug, STACK_VARIABLES_ARGS, + CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGNAL | + CLONE_SETTLS | CLONE_PARENT_SETTID | + CLONE_CHILD_CLEARTID | CLONE_DETACHED | 0, + pd, &pd->tid, &desc.desc, &pd->tid) == -1) + /* Failed. */ + return errno; + + /* Now fill in the information about the new thread in + the newly created thread's data structure. We cannot let + the new thread do this since we don't know whether it was + already scheduled when we send the event. */ + pd->eventbuf.eventnum = TD_CREATE; + pd->eventbuf.eventdata = pd; + + /* Enqueue the descriptor. */ + do + pd->nextevent = __nptl_last_event; + while (atomic_compare_and_exchange_acq (__nptl_last_event, pd, + pd->nextevent) != 0); + + /* Now call the function which signals the event. */ + __nptl_create_event (); + + /* And finally restart the new thread. */ + lll_unlock (pd->lock); + + return 0; + } + } + + /* We rely heavily on various flags the CLONE function understands: + + CLONE_VM, CLONE_FS, CLONE_FILES + These flags select semantics with shared address space and + file descriptors according to what POSIX requires. + + CLONE_SIGNAL + This flag selects the POSIX signal semantics. + + CLONE_SETTLS + The sixth parameter to CLONE determines the TLS area for the + new thread. + + CLONE_PARENT_SETTID + The kernels writes the thread ID of the newly created thread + into the location pointed to by the fifth parameters to CLONE. + + Note that it would be semantically equivalent to use + CLONE_CHILD_SETTID but it is be more expensive in the kernel. + + CLONE_CHILD_CLEARTID + The kernels clears the thread ID of a thread that has called + sys_exit() - using the same parameter as CLONE_SETTID. + + CLONE_DETACHED + No signal is generated if the thread exists and it is + automatically reaped. + + The termination signal is chosen to be zero which means no signal + is sent. */ + if (__clone (start_thread, STACK_VARIABLES_ARGS, + CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGNAL | + CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | + CLONE_DETACHED | 0, pd, &pd->tid, &desc.desc, &pd->tid) == -1) + /* Failed. */ + return errno; + + return 0; +} |