744cfd3720
Currently, we use sentinels (starting with -1 and ending with 0) in
preinit_array/init_array/fini_array in executables. But after using LTO,
the sentinels can be reordered by LLD and no longer work. So make below
changes to not rely on them:
1. In crtbegin.c, use symbols (like __init_array_start) inserted by the
linker.
2. Add array_count fields in structors_array_t.
3. In static libc, use array_count fields to decide array lengths.
4. To make new dynamic executables work with old libc.so, create a fake
fini_array with sentinels, and pass it to __libc_init. The fake
fini_array contains a function to call functions in real fini_array.
5. To make old dynamic executables work with new libc.so, libc.so
still uses sentinels to decide the length of fini_array.
Bug: 295944813
Bug: https://github.com/android/ndk/issues/1461
Test: run bionic-unit-tests-static
Test: test static executables manually
Test: boot cf_gwear_x86-trunk_staging-userdebug
Change-Id: I1ce31f07bcfe0e99b4237984898a8fc9e98ff426
131 lines
4.8 KiB
C
131 lines
4.8 KiB
C
/*
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* Copyright (C) 2012 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "../../bionic/libc_init_common.h"
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#include <stddef.h>
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#include <stdint.h>
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extern init_func_t* __preinit_array_start[];
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extern init_func_t* __preinit_array_end[];
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extern init_func_t* __init_array_start[];
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extern init_func_t* __init_array_end[];
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extern fini_func_t* __fini_array_start[];
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extern fini_func_t* __fini_array_end[];
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#if !defined(CRTBEGIN_STATIC)
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/* This function will be called during normal program termination
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* to run the destructors that are listed in the .fini_array section
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* of the executable, if any.
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*
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* 'fini_array' points to a list of function addresses.
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*/
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static void call_fini_array() {
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fini_func_t** array = __fini_array_start;
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size_t count = __fini_array_end - __fini_array_start;
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// Call fini functions in reverse order.
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while (count-- > 0) {
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fini_func_t* function = array[count];
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(*function)();
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}
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}
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// libc.so needs fini_array with sentinels. So create a fake fini_array with sentinels.
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// It contains a function to call functions in real fini_array.
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static fini_func_t* fini_array_with_sentinels[] = {
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(fini_func_t*)-1,
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&call_fini_array,
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(fini_func_t*)0,
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};
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#endif // !defined(CRTBEGIN_STATIC)
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__used static void _start_main(void* raw_args) {
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structors_array_t array = {};
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#if defined(CRTBEGIN_STATIC)
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array.preinit_array = __preinit_array_start;
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array.preinit_array_count = __preinit_array_end - __preinit_array_start;
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array.init_array = __init_array_start;
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array.init_array_count = __init_array_end - __init_array_start;
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array.fini_array = __fini_array_start;
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array.fini_array_count = __fini_array_end - __fini_array_start;
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#else
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if (__fini_array_end - __fini_array_start > 0) {
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array.fini_array = fini_array_with_sentinels;
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}
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#endif // !defined(CRTBEGIN_STATIC)
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__libc_init(raw_args, NULL, &main, &array);
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}
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#define PRE ".text; .global _start; .type _start,%function; _start:"
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#define POST "; .size _start, .-_start"
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#if defined(__aarch64__)
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__asm__(PRE "bti j; mov x29,#0; mov x30,#0; mov x0,sp; b _start_main" POST);
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#elif defined(__arm__)
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__asm__(PRE "mov fp,#0; mov lr,#0; mov r0,sp; b _start_main" POST);
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#elif defined(__i386__)
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__asm__(PRE
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"xorl %ebp,%ebp; movl %esp,%eax; andl $~0xf,%esp; subl $12,%esp; pushl %eax;"
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"call _start_main" POST);
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#elif defined(__riscv)
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__asm__(PRE "li fp,0; li ra,0; mv a0,sp; tail _start_main" POST);
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#elif defined(__x86_64__)
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__asm__(PRE "xorl %ebp, %ebp; movq %rsp,%rdi; andq $~0xf,%rsp; callq _start_main" POST);
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#else
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#error unsupported architecture
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#endif
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#undef PRE
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#undef POST
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// On arm32 and arm64, when targeting Q and up, overalign the TLS segment to
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// (8 * sizeof(void*)), which reserves enough space between the thread pointer
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// and the executable's TLS segment for Bionic's TLS slots. It has the side
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// effect of placing a 0-sized TLS segment into Android executables that don't
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// use TLS, but this should be harmless.
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//
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// To ensure that the .tdata input section isn't deleted (e.g. by
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// --gc-sections), the .text input section (which contains _start) has a
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// relocation to the .tdata input section.
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#if __ANDROID_API__ >= 29
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#if defined(__arm__)
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asm(" .section .tdata,\"awT\",%progbits\n"
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" .p2align 5\n"
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" .text\n"
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" .reloc 0, R_ARM_NONE, .tdata\n");
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#elif defined(__aarch64__)
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asm(" .section .tdata,\"awT\",@progbits\n"
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" .p2align 6\n"
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" .text\n"
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" .reloc 0, R_AARCH64_NONE, .tdata\n");
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#endif
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#endif
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#include "__dso_handle.h"
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#include "atexit.h"
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#include "pthread_atfork.h"
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