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137 lines
3.9 KiB
ArmAsm
137 lines
3.9 KiB
ArmAsm
/* Startup code for ARM & ELF
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Copyright (C) 1995-2024 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.
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Note that the code in the .init section has already been run.
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This includes _init and _libc_init
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At this entry point, most registers' values are unspecified, except:
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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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/* Tag_ABI_align8_preserved: This code preserves 8-byte
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alignment in any callee. */
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.eabi_attribute 25, 1
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/* Tag_ABI_align8_needed: This code may require 8-byte alignment from
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the caller. */
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.eabi_attribute 24, 1
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#if defined(__thumb2__)
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.thumb
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.syntax unified
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#endif
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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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/* Protect against unhandled exceptions. */
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.fnstart
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/* Clear the frame pointer and link register since this is the outermost frame. */
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mov fp, #0
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mov lr, #0
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/* Pop argc off the stack and save a pointer to argv */
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pop { a2 }
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mov a3, sp
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/* Push stack limit */
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push { a3 }
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/* Push rtld_fini */
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push { a1 }
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#ifdef PIC
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ldr sl, .L_GOT
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adr a4, .L_GOT
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add sl, sl, a4
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mov a4, #0 /* Used to be init. */
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push { a4 } /* Used to be fini. */
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ldr a1, .L_GOT+4 /* main */
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ldr a1, [sl, a1]
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/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
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/* Let the libc call main and exit with its return code. */
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bl __libc_start_main(PLT)
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#else
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mov a4, #0 /* Used to init. */
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push { a4 } /* Used to fini. */
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ldr a1, =main
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/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
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/* Let the libc call main and exit with its return code. */
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bl __libc_start_main
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#endif
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/* should never get here....*/
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bl abort
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#ifdef PIC
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.align 2
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.L_GOT:
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.word _GLOBAL_OFFSET_TABLE_ - .L_GOT
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.word main(GOT)
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#endif
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.cantunwind
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.fnend
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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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