[PATCH] LoongArch: Add Syscall Assembly Implementation

[caiyinyu <caiyinyu@loongson.cn>]

---
 sysdeps/unix/sysv/linux/loongarch/syscall.S | 48 +++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/loongarch/syscall.S

diff --git a/sysdeps/unix/sysv/linux/loongarch/syscall.S b/sysdeps/unix/sysv/linux/loongarch/syscall.S
new file mode 100644
index 0000000000..de2d5e9fb8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/syscall.S
@@ -0,0 +1,48 @@
+/* Copyright (C) 2023 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/>.  */
+
+#include <sysdep.h>
+
+/* syscall (int nr, ...)
+
+   LoongArch system calls take between 0 and 7 arguments. On entry here nr
+   is in a0 and any other system call arguments are in register a1..a7.
+
+   For kernel entry we need to move the system call nr to a7 then
+   load the remaining arguments to register.  */
+
+ ENTRY (syscall)
+        move	t0, a7
+        move	a7, a0		/* Syscall number -> a0.  */
+        move	a0, a1		/* shift arg1 - arg6.  */
+        move	a1, a2
+        move	a2, a3
+        move	a3, a4
+        move	a4, a5
+        move	a5, a6
+        move	a6, t0		/* arg7 is saved in t0.  */
+        syscall 0		/* Do the system call.  */
+
+	lu12i.w	t0, -1
+        bltu	t0, a0, L (error)
+        ret                     /* Return to caller.  */
+
+L (error):
+        b	__syscall_error
+
+PSEUDO_END (syscall)
-- 
2.31.1