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-rw-r--r--libc/sysdeps/linux/xtensa/clone.S103
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diff --git a/libc/sysdeps/linux/xtensa/clone.S b/libc/sysdeps/linux/xtensa/clone.S
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+++ b/libc/sysdeps/linux/xtensa/clone.S
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+/* Copyright (C) 2001, 2005, 2007 Free Software Foundation, Inc.
+
+ 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., 51 Franklin Street - Fifth Floor,
+ Boston, MA 02110-1301, USA. */
+
+/* clone is even more special than fork as it mucks with stacks
+ and invokes a function in the right context after it's all over. */
+
+#include "sysdep.h"
+#include <sys/syscall.h>
+#define _ERRNO_H 1
+#include <bits/errno.h>
+
+/* int clone (a2 = int (*fn)(void *arg),
+ a3 = void *child_stack,
+ a4 = int flags,
+ a5 = void *arg,
+ a6 = pid_t *ptid,
+ a7 = struct user_desc *tls,
+ 16(sp) = pid_t *ctid) */
+
+ .text
+ENTRY (__clone)
+
+ /* Sanity check arguments. */
+ beqz a2, .Leinval /* no NULL function pointers */
+ beqz a3, .Leinval /* no NULL stack pointers */
+
+ /* a2 and a3 are candidates for destruction by system-call return
+ parameters. We don't need the stack pointer after the system
+ call. We trust that the kernel will preserve a7, a9, and a6. */
+
+ mov a9, a5 /* save function argument */
+ mov a5, a7
+ mov a7, a2 /* save function pointer */
+ mov a8, a6 /* use a8 as a temp */
+ mov a6, a4
+ mov a4, a8
+ l32i a8, a1, 16 /* child_tid */
+ movi a2, SYS_ify (clone)
+
+ /* syscall (a2 = NR_clone,
+ a6 = clone_flags,
+ a3 = usp,
+ a4 = parent_tid,
+ a5 = child_tls,
+ a8 = child_tid) */
+ syscall
+ bltz a2, SYSCALL_ERROR_LABEL
+ beqz a2, .Lthread_start
+
+ /* Fall through for parent. */
+.Lpseudo_end:
+ retw
+
+.Leinval:
+ movi a2, -EINVAL
+ j SYSCALL_ERROR_LABEL
+
+.Lthread_start:
+ /* Start child thread. */
+ movi a0, 0 /* terminate the stack frame */
+
+#ifdef RESET_PID
+ /* Check and see if we need to reset the PID. */
+ bbsi.l a6, 16, 1f /* CLONE_THREAD = 0x00010000 */
+ movi a2, -1
+ bbsi.l a6, 8, 2f /* CLONE_VM = 0x00000100 */
+ movi a2, SYS_ify (getpid)
+ syscall
+2: rur a3, THREADPTR
+ movi a4, PID_OFFSET
+ add a4, a4, a3
+ s32i a2, a4, 0
+ movi a4, TID_OFFSET
+ add a4, a4, a3
+ s32i a2, a3, 0
+1:
+#endif /* RESET_PID */
+
+ mov a6, a9 /* load up the 'arg' parameter */
+ callx4 a7 /* call the user's function */
+
+ /* Call _exit. Note that any return parameter from the user's
+ function in a6 is seen as inputs to _exit. */
+ movi a2, JUMPTARGET(_exit)
+ callx4 a2
+
+PSEUDO_END (__clone)
+
+weak_alias (__clone, clone)