Commit MD parts of a loosely functional AMD64 port. This is based on

a heavily stripped down FreeBSD/i386 (brutally stripped down actually) to
attempt to get a stable base to start from.  There is a lot missing still.
Worth noting:
- The kernel runs at 1GB in order to cheat with the pmap code.  pmap uses
  a variation of the PAE code in order to avoid having to worry about 4
  levels of page tables yet.
- It boots in 64 bit "long mode" with a tiny trampoline embedded in the
  i386 loader.  This simplifies locore.s greatly.
- There are still quite a few fragments of i386-specific code that have
  not been translated yet, and some that I cheated and wrote dumb C
  versions of (bcopy etc).
- It has both int 0x80 for syscalls (but using registers for argument
  passing, as is native on the amd64 ABI), and the 'syscall' instruction
  for syscalls.  int 0x80 preserves all registers, 'syscall' does not.
- I have tried to minimize looking at the NetBSD code, except in a couple
  of places (eg: to find which register they use to replace the trashed
  %rcx register in the syscall instruction).  As a result, there is not a
  lot of similarity.  I did look at NetBSD a few times while debugging to
  get some ideas about what I might have done wrong in my first attempt.

1 files changed, 56 insertions, 0 deletions

diff --git a/sys/amd64/amd64/sigtramp.S b/sys/amd64/amd64/sigtramp.S
new file mode 100644
index 0000000..a05ea85
--- /dev/null
+++ b/sys/amd64/amd64/sigtramp.S
@@ -0,0 +1,56 @@
+/*-
+ * Copyright (c) 2003 Peter Wemm <peter@freeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/syscall.h>
+
+#include <machine/asmacros.h>
+
+#include "assym.s"
+
+	.text
+/**********************************************************************
+ *
+ * Signal trampoline, copied to top of user stack
+ *
+ */
+NON_GPROF_ENTRY(sigcode)
+	call	*SIGF_HANDLER(%rsp)	/* call signal handler */
+	lea	SIGF_UC(%rsp),%rdi	/* get ucontext_t */
+	pushq	$0			/* junk to fake return addr. */
+	movq	$SYS_sigreturn,%rax
+	syscall				/* enter kernel with args */
+0:	hlt				/* trap priviliged instruction */
+	jmp	0b
+
+	ALIGN_TEXT
+esigcode:
+
+	.data
+	.globl	szsigcode
+szsigcode:
+	.long	esigcode-sigcode