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-rw-r--r--libc/sysdeps/linux/aarch64/clone.S85
1 files changed, 85 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/aarch64/clone.S b/libc/sysdeps/linux/aarch64/clone.S
new file mode 100644
index 000000000..7437eec8d
--- /dev/null
+++ b/libc/sysdeps/linux/aarch64/clone.S
@@ -0,0 +1,85 @@
+/* Copyright (C) 1996-2017 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ 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, see
+ <http://www.gnu.org/licenses/>. */
+
+/* clone() is even more special than fork() as it mucks with stacks
+ and invokes a function in the right context after its all over. */
+
+#include <sysdep.h>
+#define _ERRNO_H 1
+#include <bits/errno.h>
+
+#define CLONE_VM_BIT 8
+#define CLONE_VM (1 << CLONE_VM_BIT)
+
+#define CLONE_THREAD_BIT 16
+#define CLONE_THREAD (1 << CLONE_THREAD_BIT)
+
+/* int clone(int (*fn)(void *arg), x0
+ void *child_stack, x1
+ int flags, x2
+ void *arg, x3
+ pid_t *ptid, x4
+ struct user_desc *tls, x5
+ pid_t *ctid); x6
+ */
+ .text
+ENTRY(__clone)
+ /* Save args for the child. */
+ mov x10, x0
+ mov x11, x2
+ mov x12, x3
+
+ /* Sanity check args. */
+ mov x0, #-EINVAL
+ cbz x10, .Lsyscall_error
+ cbz x1, .Lsyscall_error
+
+ /* Do the system call. */
+ /* X0:flags, x1:newsp, x2:parenttidptr, x3:newtls, x4:childtid. */
+ mov x0, x2 /* flags */
+ /* New sp is already in x1. */
+ mov x2, x4 /* ptid */
+ mov x3, x5 /* tls */
+ mov x4, x6 /* ctid */
+ mov x8, #SYS_ify(clone)
+ svc 0x0
+
+ cmp x0, #0
+ beq thread_start
+ blt .Lsyscall_error
+ RET
+PSEUDO_END (__clone)
+
+ .align 4
+ .type thread_start, %function
+thread_start:
+ cfi_startproc
+ cfi_undefined (x30)
+ mov x29, 0
+
+ /* Pick the function arg and execute. */
+ mov x0, x12
+ blr x10
+
+ /* We are done, pass the return value through x0. */
+ b HIDDEN_JUMPTARGET(_exit)
+ cfi_endproc
+ .size thread_start, .-thread_start
+
+libc_hidden_def (__clone)
+weak_alias (__clone, clone)