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@@ -1,148 +1,80 @@
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-/* When we enter this piece of code, the program stack looks like this:
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- argc argument counter (integer)
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- argv[0] program name (pointer)
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- argv[1...N] program args (pointers)
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- argv[argc-1] end of args (integer)
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- NULL
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- env[0...N] environment variables (pointers)
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- NULL
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-
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- For uClinux it looks like this:
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-
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- argc argument counter (integer)
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- argv char *argv[]
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- envp char *envp[]
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- argv[0] program name (pointer)
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- argv[1...N] program args (pointers)
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- argv[argc-1] end of args (integer)
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- NULL
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- env[0...N] environment variables (pointers)
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- NULL
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-
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- When we are done here, we want
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- a1=argc
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- a2=argv[0]
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- a3=argv[argc+1]
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-
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-ARM register quick reference:
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-
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- Name Number ARM Procedure Calling Standard Role
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-
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- a1 r0 argument 1 / integer result / scratch register / argc
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- a2 r1 argument 2 / scratch register / argv
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- a3 r2 argument 3 / scratch register / envp
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- a4 r3 argument 4 / scratch register
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- v1 r4 register variable
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- v2 r5 register variable
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- v3 r6 register variable
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- v4 r7 register variable
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- v5 r8 register variable
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- sb/v6 r9 static base / register variable
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- sl/v7 r10 stack limit / stack chunk handle / reg. variable
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- fp r11 frame pointer
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- ip r12 scratch register / new-sb in inter-link-unit calls
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- sp r13 lower end of current stack frame
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- lr r14 link address / scratch register
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- pc r15 program counter
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+/* Startup code for ARM & ELF
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+ Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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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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+
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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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+
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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, write to the Free
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+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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+ 02111-1307 USA. */
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+
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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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+
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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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+
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+
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+ At this entry point, most registers' values are unspecified, except:
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+
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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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+
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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 <features.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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+ /* Fetch address of fini */
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+ ldr ip, =_fini
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-.text
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- .global _start
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- .type _start,%function
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- .type _init,%function
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- .type _fini,%function
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- .type main,%function
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- .type __uClibc_main,%function
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+ /* Clear the frame pointer since this is the outermost frame. */
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+ mov fp, #0
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+ /* Pop argc off the stack and save a pointer to argv */
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+ ldr a2, [sp], #4
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+ mov a3, sp
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-.text
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-_start:
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- /* Save a copy of rtld_fini before r0 gets nuked */
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- mov r5, r0
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-
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- /* clear the frame pointer */
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- mov fp, #0
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-
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-
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- /* Load register r0 with main */
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-#ifdef __PIC__
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- adr r8, .L_main
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- ldr r0, .L_main
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- add r0, r0, r8
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-#else
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- ldr r0, =main
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-#endif
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-
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-
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-#ifdef __ARCH_HAS_MMU__
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-
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- /* Load register r1 from the stack to its final resting place */
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- ldr r1, [sp], #4
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-
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- /* Copy argv pointer into r2 -- which its final resting place */
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- mov r2, sp
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-#else
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- /*
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- * uClinux stacks look a little different from normal
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- * MMU-full Linux stacks (for no good reason)
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- */
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- /* pull argc and argv off the stack */
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- ldr r1,[sp, #0]
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- ldr r2,[sp, #4]
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-#endif
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-
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- /* Store _init and _fini to r3 and r4 */
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-#ifdef __PIC__
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- adr r8, .L_init
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- ldr r3, .L_init
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- add r3, r3, r8
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-
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- ldr r4, .L_init + 4
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- add r4, r4, r8
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-#else
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- ldr r3, =_init
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- ldr r4, =_fini
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-#endif
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-
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- /* Store _fini(r4), rtld_fini(r5), and stack_end(r2) on the stack */
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- str r2, [sp, #-4]!
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- str r5, [sp, #-4]!
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- str r4, [sp, #-4]!
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-
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-
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- /* We need to call __uClibc_main which should not return.
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- __uClibc_main (int (*main) (int, char **, char **), int argc,
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- char **argv, void (*init) (void), void (*fini) (void),
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- void (*rtld_fini) (void), void *stack_end)
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- */
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- bl __uClibc_main
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+ /* Push stack limit */
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+ str a3, [sp, #-4]!
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- /* Crash if somehow `exit' returns anyways. */
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- bl abort
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+ /* Push rtld_fini */
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+ str a1, [sp, #-4]!
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-#ifdef __PIC__
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-.L_init:
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- .word _init
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- .word _fini
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-.L_main:
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- .word main
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-#endif
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+ /* Set up the other arguments in registers */
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+ ldr a1, =main
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+ ldr a4, =_init
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-/* We need this stuff to make gdb behave itself, otherwise
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- gdb will choke with SIGILL when trying to debug apps.
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-*/
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- .section ".note.ABI-tag", "a"
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- .align 4
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- .long 1f - 0f
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- .long 3f - 2f
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- .long 1
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-0: .asciz "GNU"
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-1: .align 4
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-2: .long 0
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- .long 2,0,0
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-3: .align 4
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+ /* Push fini */
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+ str ip, [sp, #-4]!
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+
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+ /* __uClibc_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
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+
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+ /* Let the libc call main and exit with its return code. */
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+ bl __uClibc_main
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+
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+ /* should never get here....*/
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+ bl abort
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/* Define a symbol for the first piece of initialized data. */
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.data
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@@ -151,4 +83,3 @@ __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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-
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