1 /* Copyright (C) 2011-2018 Free Software Foundation, Inc.
3 The GNU C Library is free software; you can redistribute it and/or
4 modify it under the terms of the GNU Lesser General Public
5 License as published by the Free Software Foundation; either
6 version 2.1 of the License, or (at your option) any later version.
8 The GNU C Library is distributed in the hope that it will be useful,
9 but WITHOUT ANY WARRANTY; without even the implied warranty of
10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 Lesser General Public License for more details.
13 You should have received a copy of the GNU Lesser General Public
14 License along with the GNU C Library. If not, see
15 <http://www.gnu.org/licenses/>. */
17 /* clone() is even more special than fork() as it mucks with stacks
18 and invokes a function in the right context after it's all over. */
22 #include <bits/errno.h>
24 #include <asm/unistd.h>
26 #include <linux/sched.h>
28 /* What we save where in the stack frame; must include all callee-saves. */
29 #define FRAME_NEXT_LR (0 * REGSIZE) /* reserved by ABI; not used here */
30 #define FRAME_SP (1 * REGSIZE)
31 #define FRAME_R30 (2 * REGSIZE)
32 #define FRAME_R31 (3 * REGSIZE)
33 #define FRAME_R32 (4 * REGSIZE)
34 #define FRAME_SIZE (5 * REGSIZE)
36 /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
37 pid_t *ptid, struct user_desc *tls, pid_t *ctid); */
41 /* Create a stack frame so we can pass callee-saves to new task. */
45 ADDI_PTR sp, sp, -FRAME_SIZE
48 cfi_def_cfa_offset (FRAME_SIZE)
49 ADDI_PTR r11, sp, FRAME_SP
52 ADDI_PTR r11, sp, FRAME_R30
56 ADDI_PTR r11, sp, FRAME_R31
58 cfi_offset (r30, FRAME_R30 - FRAME_SIZE)
61 ADDI_PTR r11, sp, FRAME_R32
63 cfi_offset (r31, FRAME_R31 - FRAME_SIZE)
65 cfi_offset (r32, FRAME_R32 - FRAME_SIZE)
67 /* sanity check arguments */
71 /* Make sure child stack is properly aligned, and set up the
72 top frame so that we can call out of it immediately in the
73 child. Setting it up here means we fault in the parent if
74 it's bogus, which is probably cleaner than faulting first
75 thing in the child. */
76 ADDI_PTR r1, r1, -C_ABI_SAVE_AREA_SIZE
77 andi r1, r1, -C_ABI_SAVE_AREA_SIZE
78 ADDI_PTR r9, r1, REGSIZE /* sp of this frame on entry, i.e. zero */
81 /* We need to switch the argument convention around from
95 r1 child_stack [same as libc]
100 Plus the callee-saves as described at .Lthread_start, below. */
115 moveli TREG_SYSCALL_NR_NAME, __NR_clone
118 beqz r0, .Lthread_start /* If in child task. */
121 /* Restore the callee-saved registers and return. */
122 ADDLI_PTR lr, sp, FRAME_SIZE
125 ADDLI_PTR r30, sp, FRAME_R30
129 ADDLI_PTR r31, sp, FRAME_R31
133 ADDLI_PTR r32, sp, FRAME_R32
137 ADDI_PTR sp, sp, FRAME_SIZE
139 cfi_def_cfa_offset (0)
153 /* This function expects to receive:
155 sp: the top of a valid stack area
157 r31: the argument to pass to the user function
158 r32: the user function pointer */
161 cfi_def_cfa_offset (FRAME_SIZE)
164 /* Invoke user function with specified argument. */
168 moveli TREG_SYSCALL_NR_NAME, __NR_exit
172 libc_hidden_def (clone)
173 weak_alias (__clone, clone)