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186 lines
5.4 KiB
ArmAsm
186 lines
5.4 KiB
ArmAsm
/* Startup code compliant to the ELF Mips ABI.
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Copyright (C) 1995-2016 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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<http://www.gnu.org/licenses/>. */
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#define __ASSEMBLY__ 1
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#include <entry.h>
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#include <sgidefs.h>
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#include <sys/asm.h>
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#ifndef ENTRY_POINT
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#error ENTRY_POINT needs to be defined for start.S on MIPS/ELF.
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#endif
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/* This is the canonical entry point, usually the first thing in the text
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segment. The SVR4/Mips ABI (pages 3-31, 3-32) says that when the entry
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point runs, most registers' values are unspecified, except for:
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v0 ($2) 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 ($29) The stack contains the arguments and environment:
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0(%esp) argc
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4(%esp) argv[0]
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...
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(4*argc)(%esp) NULL
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(4*(argc+1))(%esp) envp[0]
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...
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NULL
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ra ($31) The return address register is set to zero so that programs
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that search backword through stack frames recognize the last
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stack frame.
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*/
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/* We need to call:
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__libc_start_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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.text
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.globl ENTRY_POINT
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.type ENTRY_POINT,@function
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#ifndef __mips16
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ENTRY_POINT:
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# ifdef __PIC__
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SETUP_GPX($0)
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SETUP_GPX64($25,$0)
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# else
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PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */
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move $31, $0
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# endif
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PTR_LA $4, main /* main */
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PTR_L $5, 0($29) /* argc */
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PTR_ADDIU $6, $29, PTRSIZE /* argv */
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/* Allocate space on the stack for seven arguments (o32 only)
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and make sure the stack is aligned to double words (8 bytes)
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on o32 and quad words (16 bytes) on n32 and n64. */
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and $29, -2 * SZREG
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# if _MIPS_SIM == _ABIO32
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PTR_SUBIU $29, 32
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# endif
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PTR_LA $7, __libc_csu_init /* init */
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PTR_LA $8, __libc_csu_fini
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# if _MIPS_SIM == _ABIO32
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PTR_S $8, 16($29) /* fini */
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PTR_S $2, 20($29) /* rtld_fini */
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PTR_S $29, 24($29) /* stack_end */
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# else
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move $9, $2 /* rtld_fini */
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move $10, $29 /* stack_end */
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# endif
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PTR_LA $25, __libc_start_main
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jalr $25
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hlt: b hlt /* Crash if somehow it does return. */
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#elif _MIPS_SIM == _ABIO32 /* __mips16 */
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/* MIPS16 entry point. */
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.set mips16
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ENTRY_POINT:
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# ifdef __PIC__
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li $3, %hi(_gp_disp)
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addiu $4, $pc, %lo(_gp_disp)
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sll $3, 16
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addu $3, $4
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move $gp, $3
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# else
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li $3, %hi(_gp)
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sll $3, 16
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addiu $3, %lo(_gp)
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move $gp, $3
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# endif
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/* Tie end of stack frames. */
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li $4, 0
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move $31, $4
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/* Create new SP value in $7, including alignment. */
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li $4, 2 * SZREG
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neg $4, $4
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move $7, $sp
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and $7, $4
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addiu $7, -32
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/* Load arguments with original SP. */
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lw $5, 0($sp)
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addiu $6, $sp, PTRSIZE
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/* Update SP. */
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move $sp, $7
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/* Lay out last arguments, and call __libc_start_main(). */
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# ifdef __PIC__
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sw $7, 24($sp) /* stack_end */
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lw $4, %got(__libc_csu_fini)($3)
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lw $7, %got(__libc_csu_init)($3) /* init */
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sw $4, 16($sp) /* fini */
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lw $4, %got(main)($3) /* main */
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lw $3, %call16(__libc_start_main)($3)
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sw $2, 20($sp) /* rtld_fini */
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move $25, $3
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jalr $3
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# else
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lw $4, 1f
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sw $7, 24($sp) /* stack_end */
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lw $7, 2f /* init */
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sw $4, 16($sp) /* fini */
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lw $4, 3f /* main */
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sw $2, 20($sp) /* rtld_fini */
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/* Load and call __libc_start_main(). */
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lw $3, 4f
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jalr $3
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# endif
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hlt: b hlt /* Crash if somehow it does return. */
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# ifndef __PIC__
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.align 2
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1: .word __libc_csu_fini
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2: .word __libc_csu_init
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3: .word main
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4: .word __libc_start_main
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# endif
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#else /* __mips16 && _MIPS_SIM != _ABIO32 */
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# error "MIPS16 support for N32/N64 not implemented"
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#endif /* __mips16 */
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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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