arch-bare-x86-64/syscall.S: from uClibc

a87d450d · Danilo Sabato · Alessandro Rubini · 7296b17d · a87d450d
Commit a87d450d authored Jan 27, 2013 by Danilo Sabato Committed by Alessandro Rubini Feb 10, 2013
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syscall.S arch-bare-x86-64/syscall.S +45 -0

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--- a/arch-bare-x86-64/syscall.S
+++ b/arch-bare-x86-64/syscall.S
+/* Copied from uClibc::libc/sysdeps/linux/x86_6/syscall.S
+
+/* Copyright (C) 2001, 2003 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+/* Please consult the file sysdeps/unix/sysv/linux/x86-64/sysdep.h for
+   more information about the value -4095 used below.  */
+
+/* Usage: long syscall (syscall_number, arg1, arg2, arg3, arg4, arg5, arg6)
+   We need to do some arg shifting, the syscall_number will be in
+   rax.  */
+
+.text
+.globl syscall
+.type	syscall,%function
+.align 16
+syscall:
+	movq %rdi, %rax		/* Syscall number -> rax.  */
+	movq %rsi, %rdi		/* shift arg1 - arg5.  */
+	movq %rdx, %rsi
+	movq %rcx, %rdx
+	movq %r8, %r10
+	movq %r9, %r8
+	movq 8(%rsp),%r9	/* arg6 is on the stack.  */
+	syscall			/* Do the system call.  */
+	cmpq $-4095, %rax	/* Check %rax for error.  */
+	jae __syscall_error		/* Branch forward if it failed.  */
+	ret			/* Return to caller.  */
+
+.size syscall,.-syscall