1 /* Copyright (C) 1996, 1997, 2000 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by David Huggins-Daines <dhd@debian.org>, 2000.
4 Based on the Alpha version by Richard Henderson <rth@tamu.edu>, 1996.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library. If not, see
18 <http://www.gnu.org/licenses/>. */
20 /* clone() is even more special than fork() as it mucks with stacks
21 and invokes a function in the right context after its all over. */
23 #include <asm/unistd.h>
26 #include <bits/errno.h>
28 /* Non-thread code calls __clone with the following parameters:
29 int clone(int (*fn)(void *arg),
34 NPTL Code will call __clone with the following parameters:
35 int clone(int (*fn)(void *arg),
40 struct user_desc *newtls,
43 The code should not mangle the extra input registers.
44 Syscall expects: Input to __clone:
45 4(r25) - function pointer (r26, arg0)
46 0(r25) - argument (r23, arg3)
47 r26 - clone flags. (r24, arg2)
48 r25+64 - user stack pointer. (r25, arg1)
49 r24 - parent tid pointer. (stack - 52)
50 r23 - struct user_desc newtls pointer. (stack - 56)
51 r22 - child tid pointer. (stack - 60)
52 r20 - clone syscall number (constant)
56 On success the thread ID of the child process is returend in
58 On error return -1, and set errno to the value returned by
71 /* Sanity check arguments. */
72 comib,=,n 0, %arg0, .LerrorSanity /* no NULL function pointers */
73 comib,=,n 0, %arg1, .LerrorSanity /* no NULL stack pointers */
75 /* Save the function pointer, arg, and flags on the new stack. */
79 /* Clone arguments are (int flags, void * child_stack) */
80 copy %r24, %r26 /* flags are first */
81 /* User stack pointer is in the correct register already */
83 /* Load args from stack... */
84 ldw -116(%sp), %r24 /* Load parent_tidptr */
85 ldw -120(%sp), %r23 /* Load newtls */
86 ldw -124(%sp), %r22 /* Load child_tidptr */
88 /* Save the PIC register. */
90 copy %r19, %r4 /* parent */
93 /* Do the system call */
98 comclr,>>= %r1, %ret0, %r0 /* Note: unsigned compare. */
101 /* Restore the PIC register. */
103 copy %r4, %r19 /* parent */
106 comib,=,n 0, %ret0, .LthreadStart
108 /* Successful return from the parent
109 No need to restore the PIC register,
110 since we return immediately. */
117 /* Something bad happened -- no child created */
118 bl __syscall_error, %rp
119 sub %r0, %ret0, %arg0
121 /* Return after setting errno, ret0 is set to -1 by __syscall_error. */
126 /* Sanity checks failed, return -1, and set errno to EINVAL. */
127 bl __syscall_error, %rp
135 # define CLONE_VM_BIT 23 /* 0x00000100 */
136 # define CLONE_THREAD_BIT 15 /* 0x00010000 */
137 /* Load original clone flags.
138 If CLONE_THREAD was passed, don't reset the PID/TID.
139 If CLONE_VM was passed, we need to store -1 to PID/TID.
140 If CLONE_VM and CLONE_THREAD were not set store the result
141 of getpid to PID/TID. */
143 bb,<,n %r26, CLONE_THREAD_BIT, 1f
144 bb,< %r26, CLONE_VM_BIT, 2f
147 ldi __NR_getpid, %r20
150 stw %ret0, PID_THREAD_OFFSET(%r26)
151 stw %ret0, TID_THREAD_OFFSET(%r26)
154 /* Load up the arguments. */
158 /* $$dyncall fixes childs PIC register */
160 /* Call the user's function */
169 /* The call to _exit needs saved r19. */
173 /* We should not return from _exit.
174 We do not restore r4, or the stack state. */
175 iitlbp %r0, (%sr0, %r0)
179 weak_alias (__clone, clone)