[Pal] Move x86_64 implementation of pal_start to a separate file

Pal/src/host/Linux/Makefile

@@ -33,7 +33,8 @@ objs = \
 	db_sockets.o \
 	db_streams.o \
 	db_threading.o \
-	$(commons_objs)
+	$(commons_objs) \
+	pal_start-$(ARCH).o
 
 graphene_lib = .lib/graphene-lib.a
 

Pal/src/host/Linux/db_main.c

@@ -38,16 +38,6 @@
 #include <elf/elf.h>
 #include <sysdeps/generic/ldsodefs.h>
 
-__asm__ (
-    ".global pal_start\n"
-    "    .type pal_start,@function\n"
-    "pal_start:\n"
-    "    movq %rsp, %rdi\n" /* 1st arg for pal_linux_main: initial RSP */
-    "    movq %rdx, %rsi\n" /* 2nd arg: fini callback */
-    "    xorq %rbp, %rbp\n" /* mark the last stack frame with RBP == 0 (for debuggers) */
-    "    andq $~15, %rsp\n"
-    "    call pal_linux_main\n");
-
 #define RTLD_BOOTSTRAP
 
 /* pal_start is the entry point of libpal.so, which calls pal_main */

Pal/src/host/Linux/pal_start-x86_64.S

@@ -0,0 +1,31 @@
+/*
+   This file is part of Graphene Library OS.
+
+   Graphene Library OS 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 3 of the
+   License, or (at your option) any later version.
+
+   Graphene Library OS 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/*
+ * pal_start-x86_64.S
+ *
+ * This file contains architecture-specific implementation of pal_start.
+ */
+
+#include "sysdep-arch.h"
+
+	.text
+ENTRY(pal_start)
+	movq  %rsp, %rdi /* 1st arg for pal_linux_main: initial RSP */
+	movq  %rdx, %rsi /* 2nd arg: fini callback */
+	xorq  %rbp, %rbp /* mark the last stack frame with RBP == 0 (for debuggers) */
+	andq  $~15, %rsp
+	call  pal_linux_main