arm: rewrite crtbegin* as C files.

Rewrite
 crtbegin.S     -> crtbegin.c
 crtbegin_so.S  -> crtbegin_so.c

This change allows us to generate PIC code without relying
on text relocations.

As a consequence of this rewrite, also rewrite
  __dso_handle.S    -> __dso_handle.c
  __dso_handle_so.S -> __dso_handle_so.c
  atexit.S          -> atexit.c

In crtbegin.c _start, place the __PREINIT_ARRAY__, __INIT_ARRAY__,
__FINI_ARRAY__, and __CTOR_LIST__ variables onto the stack, instead of
passing a pointer to the text section of the binary.

This change appears sorta wonky, as I attempted to preserve,
as much as possible, the structure of the original assembly.
As a result, you have C files including other C files, and other
programming uglyness.

Result: This change reduces the number of files with text-relocations
from 315 to 19 on my Android build.

Before:
  $ scanelf -aR $OUT/system | grep TEXTREL | wc -l
  315

After:
  $ scanelf -aR $OUT/system | grep TEXTREL | wc -l
  19

Change-Id: Ib9f98107c0eeabcb606e1ddc7ed7fc4eba01c9c4

libc/Android.mk

@@ -515,8 +515,8 @@ else
     libc_common_cflags += -DANDROID_SMP=0
 endif
 
-# Needed to access private/__dso_handle.S from
+# Needed to access private/__dso_handle.h from
-# crtbegin_xxx.S and crtend_xxx.S
+# crtbegin_xxx.c and crtend_xxx.c
 #
 libc_crt_target_cflags += -I$(LOCAL_PATH)/private
 
@@ -531,9 +531,8 @@ libc_common_c_includes := \
 		$(LOCAL_PATH)/string  \
 		$(LOCAL_PATH)/stdio
 
-# Needed to access private/__dso_handle.S from
+# Needed to access private/__dso_handle.h from
 # crtbegin_xxx.S and crtend_xxx.S
-# and machine/asm.h
 #
 libc_crt_target_cflags += -I$(LOCAL_PATH)/private -I$(LOCAL_PATH)/arch-$(TARGET_ARCH)/include
 
@@ -555,12 +554,16 @@ ifneq ($(filter arm x86,$(TARGET_ARCH)),)
 #
 
 libc_crt_target_so_cflags := $(libc_crt_target_cflags)
+libc_crt_target_crtstart_file := $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin.c
+libc_crt_target_crtstart_so_file := $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin_so.c
 ifeq ($(TARGET_ARCH),x86)
     # This flag must be added for x86 targets, but not for ARM
     libc_crt_target_so_cflags += -fPIC
+    libc_crt_target_crtstart_file := $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin.S
+    libc_crt_target_crtstart_so_file := $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin_so.S
 endif
 GEN := $(TARGET_OUT_INTERMEDIATE_LIBRARIES)/crtbegin_so.o
-$(GEN): $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin_so.S
+$(GEN): $(libc_crt_target_crtstart_so_file)
 	@mkdir -p $(dir $@)
 	$(TARGET_CC) $(libc_crt_target_so_cflags) -o $@ -c $<
 ALL_GENERATED_SOURCES += $(GEN)
@@ -574,13 +577,13 @@ endif # TARGET_ARCH == x86 || TARGET_ARCH == arm
 
 
 GEN := $(TARGET_OUT_INTERMEDIATE_LIBRARIES)/crtbegin_static.o
-$(GEN): $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin.S
+$(GEN): $(libc_crt_target_crtstart_file)
 	@mkdir -p $(dir $@)
 	$(TARGET_CC) $(libc_crt_target_cflags) -o $@ -c $<
 ALL_GENERATED_SOURCES += $(GEN)
 
 GEN := $(TARGET_OUT_INTERMEDIATE_LIBRARIES)/crtbegin_dynamic.o
-$(GEN): $(LOCAL_PATH)/arch-$(TARGET_ARCH)/bionic/crtbegin.S
+$(GEN): $(libc_crt_target_crtstart_file)
 	@mkdir -p $(dir $@)
 	$(TARGET_CC) $(libc_crt_target_cflags) -o $@ -c $<
 ALL_GENERATED_SOURCES += $(GEN)

libc/arch-arm/bionic/atexit.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2012 The Android Open Source Project
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -25,61 +25,29 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-	.text
-	.align 4
-	.type _start,#function
-	.globl _start
 
-# this is the small startup code that is first run when
+/* CRT_LEGACY_WORKAROUND should only be defined when building
-# any executable that is linked with Bionic runs.
+ * this file as part of the platform's C library.
-#
+ *
-# it's purpose is to call __libc_init with appropriate
+ * The C library already defines a function named 'atexit()'
-# arguments, which are:
+ * for backwards compatibility with older NDK-generated binaries.
-#
+ *
-#    - the address of the raw data block setup by the Linux
+ * For newer ones, 'atexit' is actually embedded in the C
-#      kernel ELF loader
+ * runtime objects that are linked into the final ELF
-#
+ * binary (shared library or executable), and will call
-#    - address of an "onexit" function, not used on any
+ * __cxa_atexit() in order to un-register any atexit()
-#      platform supported by Bionic
+ * handler when a library is unloaded.
-#
+ *
-#    - address of the "main" function of the program.
+ * This function must be global *and* hidden. Only the
-#
+ * code inside the same ELF binary should be able to access it.
-#    - address of the constructor list
+ */
-#
-_start:	
-	mov	r0, sp
-	mov	r1, #0
-	ldr	r2, =main
-	adr	r3, 1f
-	ldr	r4, =__libc_init
-	blx	r4
-	mov	r0, #0
-	bx	r0
 
-1:  .long   __PREINIT_ARRAY__
+#ifndef CRT_LEGACY_WORKAROUND
-    .long   __INIT_ARRAY__
+extern void *__dso_handle;
-    .long   __FINI_ARRAY__
-    .long   __CTOR_LIST__
 
-	.section .preinit_array, "aw"
+__attribute__ ((visibility ("hidden")))
-	.globl __PREINIT_ARRAY__
+int atexit(void (*func)(void))
-__PREINIT_ARRAY__:
+{
-	.long -1
+  return (__cxa_atexit((void (*)(void *))func, (void *)0, &__dso_handle));
-
+}
-	.section .init_array, "aw"
+#endif
-	.globl __INIT_ARRAY__
-__INIT_ARRAY__:
-	.long -1
-
-	.section .fini_array, "aw"
-	.globl __FINI_ARRAY__
-__FINI_ARRAY__:
-	.long -1
-
-	.section .ctors, "aw"
-	.globl __CTOR_LIST__
-__CTOR_LIST__:
-	.long -1
-
-#include "__dso_handle.S"
-#include "atexit.S"

libc/arch-arm/bionic/crtbegin.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+
+typedef struct
+{
+    void (**preinit_array)(void);
+    void (**init_array)(void);
+    void (**fini_array)(void);
+    void (**ctors_array)(void);
+} structors_array_t;
+
+extern int main(int argc, char **argv, char **env);
+
+extern void __libc_init(
+  unsigned int *elfdata,
+  void (*onexit)(void),
+  int (*slingshot)(int, char**, char**),
+  structors_array_t const * const structors
+);
+
+__attribute__ ((section (".preinit_array")))
+void (*__PREINIT_ARRAY__)(void) = (void (*)(void)) -1;
+
+__attribute__ ((section (".init_array")))
+void (*__INIT_ARRAY__)(void) = (void (*)(void)) -1;
+
+__attribute__ ((section (".fini_array")))
+void (*__FINI_ARRAY__)(void) = (void (*)(void)) -1;
+
+__attribute__ ((section (".ctors")))
+void (*__CTOR_LIST__)(void) = (void (*)(void)) -1;
+
+__attribute__((visbility("hidden")))
+void _start() {
+  structors_array_t array;
+  void *elfdata;
+
+  array.preinit_array = &__PREINIT_ARRAY__;
+  array.init_array =    &__INIT_ARRAY__;
+  array.fini_array =    &__FINI_ARRAY__;
+  array.ctors_array =   &__CTOR_LIST__;
+
+  elfdata = __builtin_frame_address(0) + sizeof(void *);
+  __libc_init(elfdata, (void *) 0, &main, &array);
+}
+
+#include "__dso_handle.h"
+#include "atexit.h"

libc/arch-arm/bionic/crtbegin_so.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2012 The Android Open Source Project
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,39 +26,18 @@
  * SUCH DAMAGE.
  */
 
-#include <machine/asm.h>
+extern void __cxa_finalize(void *);
+extern void *__dso_handle;
 
-# Implement static C++ destructors when the shared
+__attribute__((visbility("hidden")))
-# library is unloaded through dlclose().
+void __on_dlclose() {
-#
+  __cxa_finalize(&__dso_handle);
-# A call to this function must be the first entry
+}
-# in the .fini_array. See 3.3.5.3.C of C++ ABI
-# standard.
-#
-ENTRY(__on_dlclose)
-        adr     r0, 0f
-        ldr     r0, [r0]
-        b       __cxa_finalize
-END(__on_dlclose)
-
-0:
-        .long   __dso_handle
-
-	.section .init_array, "aw"
-	.globl __INIT_ARRAY__
-__INIT_ARRAY__:
-	.long -1
-
-        .section .fini_array, "aw"
-        .globl __FINI_ARRAY__
-__FINI_ARRAY__:
-        .long -1
-        .long __on_dlclose
 
 #ifdef CRT_LEGACY_WORKAROUND
-#include "__dso_handle.S"
+#include "__dso_handle.h"
 #else
-#include "__dso_handle_so.S"
+#include "__dso_handle_so.h"
 #endif
 
-#include "atexit.S"
+#include "atexit.h"

libc/private/__dso_handle.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011 The Android Open Source Project
+ * Copyright (C) 2012 The Android Open Source Project
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,37 +26,9 @@
  * SUCH DAMAGE.
  */
 
+
 #ifndef CRT_LEGACY_WORKAROUND
-	.arch armv5te
+__attribute__ ((visibility ("hidden")))
-	.fpu softvfp
-	.eabi_attribute 20, 1
-	.eabi_attribute 21, 1
-	.eabi_attribute 23, 3
-	.eabi_attribute 24, 1
-	.eabi_attribute 25, 1
-	.eabi_attribute 26, 2
-	.eabi_attribute 30, 4
-	.eabi_attribute 18, 4
-	.hidden	atexit
-	.code	16
-	.thumb_func
-ENTRY(atexit)
-.LFB0:
-	.save	{r4, lr}
-	push	{r4, lr}
-.LCFI0:
-	ldr	r3, .L3
-	mov	r1, #0
-	@ sp needed for prologue
-.LPIC0:
-	add	r3, pc
-	ldr	r2, [r3]
-	bl	__cxa_atexit
-	pop	{r4, pc}
-.L4:
-	.align	2
-.L3:
-	.word	__dso_handle-(.LPIC0+4)
-.LFE0:
-END(atexit)
 #endif
+__attribute__ ((section (".bss")))
+void *__dso_handle = (void *) 0;

libc/private/__dso_handle_so.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+
+
+__attribute__ ((visibility ("hidden")))
+__attribute__ ((section (".data")))
+void *__dso_handle;