Merge pull request #544 from cpavlina/aarch64_start

Add _start for aarch64

bfsysroot/bfsupport/crt/src/CMakeLists.txt

@@ -24,10 +24,17 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-stack-protector")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-main")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-return-type")
 
-list(APPEND SOURCES
-    crt.cpp
-    start_x64.asm
-)
+if(${BUILD_TARGET_ARCH} STREQUAL x86_64)
+    list(APPEND SOURCES
+        crt.cpp
+        start_x64.asm
+    )
+elseif(${BUILD_TARGET_ARCH} STREQUAL aarch64)
+    list(APPEND SOURCES
+        crt.cpp
+        start_aarch64.S
+    )
+endif()
 
 add_library(bfcrt STATIC ${SOURCES})
 target_compile_definitions(bfcrt PUBLIC STATIC_CRT)

bfsysroot/bfsupport/crt/src/start_aarch64.S

@@ -0,0 +1,62 @@
+/*
+ * Bareflank Hypervisor
+ *
+ * Copyright (C) 2017 Assured Information Security, Inc.
+ * Author: Chris Pavlina     <pavlinac@ainfosec.com>
+ * Author: Rian Quinn        <quinnr@ainfosec.com>
+ * Author: Brendan Kerrigan  <kerriganb@ainfosec.com>
+ *
+ * This 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.
+ *
+ * This 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+.global _start
+.section .text
+.balign 4
+
+// int64_t _start(uint64_t stack, crt_info_t *crt_info)
+// x29 = fp, x30 = lr
+_start:
+    stp  x29, x30, [sp, #-16]!
+    mov  x29, sp
+
+    mov  sp, x0
+    mov  x0, x1
+
+    adr  x1, canary
+    ldr  x1, [x1]
+    stp  x1, x1, [sp, #-16]!
+
+    bl   _start_c
+
+    adr  x1, canary
+    ldr  x1, [x1]
+    ldr  x2, [sp], #16
+
+    mov  sp, x29
+
+    cmp  x1, x2
+    b.ne stack_overflow
+
+    ldp  x29, x30, [sp], #16
+    ret
+
+stack_overflow:
+    mov  x0, #0x0010
+    movk x0, #0x8000, lsl #48       // x0 = 0x8000000000000010
+    ldp  x29, x30, [sp], #16
+    ret
+
+canary:
+    .word 0xABCDEF12, 0x34567890