platform_bionic/libc/arch-common/bionic/crtbegin.c
Ryan Prichard a0d177d010 crtbegin: Correctly align ESP to 16 for __i386__
The (lowest) address of the argument area (aka ESP immediately prior to
the call instruction) must be aligned to 0 mod 16. Here, it is aligned to
12 mod 16.

From the SysV ABI doc (2.2.2 The Stack Frame)

"""The end of the input argument area shall be aligned on a 16 (32, if
__m256 is passed on stack) byte boundary. In other words, the value
(%esp + 4) is always a multiple of 16 (32) when control is transferred to
the function entry point."""

Test: extract code into a separate C file and verify stack alignment in a
  "start_main" function
Test: use the upcoming NDK r17-beta1 (with new Bionic crtbegin*.o files)
  with an M-23 x86 system image, check alignment in main (compiled with
  Clang not GCC, compiled w/o -mstackrealign)
Bug: b/73140672

Change-Id: Ia8d93fe5668d0a514a9fd22c40bf8362805111e6
2018-02-08 20:55:57 -08:00

71 lines
2.7 KiB
C

/*
* 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.
*/
#include "../../bionic/libc_init_common.h"
#include <stddef.h>
#include <stdint.h>
#define SECTION(name) __attribute__((__section__(name)))
SECTION(".preinit_array") void (*__PREINIT_ARRAY__)(void) = (void (*)(void)) -1;
SECTION(".init_array") void (*__INIT_ARRAY__)(void) = (void (*)(void)) -1;
SECTION(".fini_array") void (*__FINI_ARRAY__)(void) = (void (*)(void)) -1;
#undef SECTION
__used static void _start_main(void* raw_args) {
structors_array_t array;
array.preinit_array = &__PREINIT_ARRAY__;
array.init_array = &__INIT_ARRAY__;
array.fini_array = &__FINI_ARRAY__;
__libc_init(raw_args, NULL, &main, &array);
}
#define PRE ".text; .global _start; .type _start,%function; _start:"
#define POST "; .size _start, .-_start"
#if defined(__aarch64__)
__asm__(PRE "mov x0,sp; b _start_main" POST);
#elif defined(__arm__)
__asm__(PRE "mov r0,sp; b _start_main" POST);
#elif defined(__i386__)
__asm__(PRE "movl %esp,%eax; andl $~0xf,%esp; subl $12,%esp; pushl %eax; calll _start_main" POST);
#elif defined(__x86_64__)
__asm__(PRE "movq %rsp,%rdi; andq $~0xf,%rsp; callq _start_main" POST);
#else
#error unsupported architecture
#endif
#undef PRE
#undef POST
#include "__dso_handle.h"
#include "atexit.h"
#include "pthread_atfork.h"
#ifdef __i386__
# include "../../arch-x86/bionic/__stack_chk_fail_local.h"
#endif