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121 lines
4.0 KiB
ArmAsm
121 lines
4.0 KiB
ArmAsm
/* Startup code compliant to the ELF m68k ABI.
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Copyright (C) 1996-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file with other
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programs, and to distribute those programs without any restriction
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coming from the use of this file. (The GNU Lesser General Public
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License restrictions do apply in other respects; for example, they
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cover modification of the file, and distribution when not linked
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into another program.)
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Note that people who make modified versions of this file are not
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obligated to grant this special exception for their modified
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versions; it is their choice whether to do so. The GNU Lesser
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General Public License gives permission to release a modified
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version without this exception; this exception also makes it
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possible to release a modified version which carries forward this
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exception.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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/* This is the canonical entry point, usually the first thing in the text
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segment. The SVR4/m68k ABI says that when the entry point runs,
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most registers' values are unspecified, except for:
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%a1 Contains a function pointer to be registered with `atexit'.
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This is how the dynamic linker arranges to have DT_FINI
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functions called for shared libraries that have been loaded
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before this code runs.
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%sp The stack contains the arguments and environment:
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0(%sp) argc
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4(%sp) argv[0]
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...
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(4*argc)(%sp) NULL
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(4*(argc+1))(%sp) envp[0]
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...
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NULL
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*/
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#include <sysdep.h>
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.text
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.globl _start
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.type _start,@function
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_start:
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/* Clear the frame pointer. The ABI suggests this be done, to mark
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the outermost frame obviously. */
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sub.l %fp, %fp
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/* Extract the arguments as encoded on the stack and set up the
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arguments for `main': argc, argv. envp will be determined
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later in __libc_start_main. */
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move.l (%sp)+, %d0 /* Pop the argument count. */
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move.l %sp, %a0 /* The argument vector starts just at the
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current stack top. */
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/* Provide the highest stack address to the user code (for stacks
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which grow downward). */
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pea (%sp)
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pea (%a1) /* Push address of the shared library
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termination function. */
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#ifdef PIC
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/* Load PIC register. */
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LOAD_GOT (%a5)
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/* Push the address of our own entry points to `.fini' and
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`.init'. */
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move.l __libc_csu_fini@GOT(%a5), -(%sp)
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move.l __libc_csu_init@GOT(%a5), -(%sp)
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pea (%a0) /* Push second argument: argv. */
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move.l %d0, -(%sp) /* Push first argument: argc. */
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move.l main@GOT(%a5), -(%sp)
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/* Call the user's main function, and exit with its value. But
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let the libc call main. */
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jbsr __libc_start_main@PLTPC
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#else
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/* Push the address of our own entry points to `.fini' and
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`.init'. */
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pea __libc_csu_fini
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pea __libc_csu_init
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pea (%a0) /* Push second argument: argv. */
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move.l %d0, -(%sp) /* Push first argument: argc. */
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pea main
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/* Call the user's main function, and exit with its value. But
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let the libc call main. */
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jbsr __libc_start_main
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#endif
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illegal /* Crash if somehow `exit' does return. */
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/* Define a symbol for the first piece of initialized data. */
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.data
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.globl __data_start
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__data_start:
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.long 0
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.weak data_start
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data_start = __data_start
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