LoongArch: Linux Syscall Interface

1 files changed, 96 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/loongarch/clone.S b/sysdeps/unix/sysv/linux/loongarch/clone.S
new file mode 100644
index 0000000000..c73245be82
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/clone.S
@@ -0,0 +1,96 @@
+/* The clone syscall wrapper.
+   Copyright (C) 2022 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
+   <https://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 <sys/asm.h>
+#include <sysdep.h>
+#define _ERRNO_H  1
+#include <bits/errno.h>
+#include <tls.h>
+#include "tcb-offsets.h"
+
+/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
+   void *parent_tidptr, void *tls, void *child_tidptr) */
+
+ENTRY (__clone)
+
+	/* Align stack to 16.  */
+	BSTRINS		a1, zero, 3, 0
+
+	/* Sanity check arguments.  */
+	beqz		a0, L (invalid) /* No NULL function pointers.  */
+	beqz		a1, L (invalid) /* No NULL stack pointers.  */
+
+	ADDI 		a1, a1, -16 /* Reserve argument save space.  */
+	REG_S		a0, a1, 0   /* Save function pointer.  */
+	REG_S		a3, a1, SZREG   /* Save argument pointer.  */
+
+	/* The syscall expects the args to be in different slots.  */
+	or		a0, a2, zero
+	or		a2, a4, zero
+	or		a3, a6, zero
+	or		a4, a5, zero
+
+	/* Do the system call.  */
+	LI		a7,__NR_clone
+	syscall		0
+
+	blt		a0, zero ,L (error)
+	beqz		a0,L (thread_start)
+
+	/* Successful return from the parent.  */
+	ret
+
+L (invalid):
+	LI		a0, -EINVAL
+
+	/* Something bad happened -- no child created.  */
+L (error):
+	b		__syscall_error
+
+END (__clone)
+
+/* Load up the arguments to the function.  Put this block of code in
+   its own function so that we can terminate the stack trace with our
+   debug info.  */
+ENTRY (__thread_start)
+L (thread_start):
+
+/* Terminate call stack by noting ra is undefined.  Use a dummy
+   .cfi_label to force starting the FDE.  */
+	.cfi_label .Ldummy
+	cfi_undefined (1)
+
+	/* Restore the arg for user's function.  */
+	REG_L		a1, sp, 0   /* Function pointer.  */
+	REG_L		a0, sp, SZREG   /* Argument pointer.  */
+
+	/* Call the user's function.  */
+	jirl		ra, a1, 0
+
+	/* Call exit with the function's return value.  */
+	LI		a7, __NR_exit
+	syscall		0
+
+	END (__thread_start)
+
+libc_hidden_def (__clone)
+weak_alias (__clone, clone)