280 lines
6.3 KiB
ArmAsm
280 lines
6.3 KiB
ArmAsm
/*
|
|
* crt0.S -- startup file for MIPS.
|
|
*
|
|
* Copyright (c) 1995, 1996, 1997, 2001 Cygnus Support
|
|
*
|
|
* The authors hereby grant permission to use, copy, modify, distribute,
|
|
* and license this software and its documentation for any purpose, provided
|
|
* that existing copyright notices are retained in all copies and that this
|
|
* notice is included verbatim in any distributions. No written agreement,
|
|
* license, or royalty fee is required for any of the authorized uses.
|
|
* Modifications to this software may be copyrighted by their authors
|
|
* and need not follow the licensing terms described here, provided that
|
|
* the new terms are clearly indicated on the first page of each file where
|
|
* they apply.
|
|
*/
|
|
|
|
#ifdef __mips16
|
|
/* This file contains 32 bit assembly code. */
|
|
.set nomips16
|
|
#endif
|
|
|
|
#include "regs.S"
|
|
|
|
/*
|
|
* Set up some room for a stack. We just grab a chunk of memory.
|
|
*/
|
|
#define STACK_SIZE 0x4000
|
|
#define GLOBAL_SIZE 0x2000
|
|
|
|
#define STARTUP_STACK_SIZE 0x0100
|
|
|
|
/* This is for referencing addresses that are not in the .sdata or
|
|
.sbss section under embedded-pic, or before we've set up gp. */
|
|
#ifdef __mips_embedded_pic
|
|
# ifdef __mips64
|
|
# define LA(t,x) la t,x-PICBASE ; daddu t,s0,t
|
|
# else
|
|
# define LA(t,x) la t,x-PICBASE ; addu t,s0,t
|
|
# endif
|
|
#else /* __mips_embedded_pic */
|
|
# define LA(t,x) la t,x
|
|
#endif /* __mips_embedded_pic */
|
|
|
|
.comm __memsize, 12
|
|
.comm __lstack, STARTUP_STACK_SIZE
|
|
.comm __stackbase,4
|
|
|
|
.text
|
|
.align 2
|
|
|
|
/* Without the following nop, GDB thinks _start is a data variable.
|
|
* This is probably a bug in GDB in handling a symbol that is at the
|
|
* start of the .text section.
|
|
*/
|
|
nop
|
|
|
|
.globl hardware_hazard_hook .text
|
|
.globl _start
|
|
.ent _start
|
|
_start:
|
|
.set noreorder
|
|
#ifdef __mips_embedded_pic
|
|
#define PICBASE start_PICBASE
|
|
PICBASE = .+8
|
|
bal PICBASE
|
|
nop
|
|
move s0,$31
|
|
#endif
|
|
#if !defined(__mips64) || (__mips_fpr==32)
|
|
#define STATUS_MASK (SR_CU1|SR_PE)
|
|
#else
|
|
# For mips3 or mips4, turn on 64-bit addressing and additional float regs
|
|
#define STATUS_MASK (SR_CU1|SR_PE|SR_FR|SR_KX|SR_SX|SR_UX)
|
|
#endif
|
|
li v0, STATUS_MASK
|
|
mtc0 v0, C0_SR
|
|
mtc0 zero, C0_CAUSE
|
|
nop
|
|
|
|
/* Avoid hazard from FPU enable and other SR changes. */
|
|
LA (t0, hardware_hazard_hook)
|
|
beq t0,zero,1f
|
|
nop
|
|
jal t0
|
|
nop
|
|
1:
|
|
|
|
/* Check for FPU presence. Don't check if we know that soft_float is
|
|
being used. (This also avoids illegal instruction exceptions.) */
|
|
|
|
#ifndef __mips_soft_float
|
|
li t2,0xAAAA5555
|
|
mtc1 t2,fp0 /* write to FPR 0 */
|
|
mtc1 zero,fp1 /* write to FPR 1 */
|
|
mfc1 t0,fp0
|
|
mfc1 t1,fp1
|
|
nop
|
|
bne t0,t2,1f /* check for match */
|
|
nop
|
|
bne t1,zero,1f /* double check */
|
|
nop
|
|
j 2f /* FPU is present. */
|
|
nop
|
|
#endif
|
|
1:
|
|
/* FPU is not present. Set status register to say that. */
|
|
li v0, (STATUS_MASK-(STATUS_MASK & SR_CU1))
|
|
mtc0 v0, C0_SR
|
|
nop
|
|
/* Avoid hazard from FPU disable. */
|
|
LA (t0, hardware_hazard_hook)
|
|
beq t0,zero,2f
|
|
nop
|
|
jal t0
|
|
nop
|
|
2:
|
|
|
|
|
|
/* Fix high bits, if any, of the PC so that exception handling
|
|
doesn't get confused. */
|
|
LA (v0, 3f)
|
|
jr v0
|
|
nop
|
|
3:
|
|
LA (gp, _gp) # set the global data pointer
|
|
.end _start
|
|
|
|
/*
|
|
* zero out the bss section.
|
|
*/
|
|
.globl __memsize
|
|
.globl get_mem_info .text
|
|
.globl __stack
|
|
.globl __global
|
|
.ent zerobss
|
|
zerobss:
|
|
LA (v0, _fbss)
|
|
LA (v1, _end)
|
|
3:
|
|
sw zero,0(v0)
|
|
bltu v0,v1,3b
|
|
addiu v0,v0,4 # executed in delay slot
|
|
|
|
la t0, __lstack # make a small stack so we
|
|
addiu sp, t0, STARTUP_STACK_SIZE # can run some C code
|
|
la a0, __memsize # get the usable memory size
|
|
jal get_mem_info
|
|
nop
|
|
|
|
/* setup the stack pointer */
|
|
LA (t0, __stack) # is __stack set ?
|
|
bne t0,zero,4f
|
|
nop
|
|
|
|
/* NOTE: a0[0] contains the amount of memory available, and
|
|
not the last memory address. */
|
|
lw t0,0(a0) # last address of memory available
|
|
la t1,K0BASE # cached kernel memory
|
|
addu t0,t0,t1 # get the end of memory address
|
|
/* Allocate 32 bytes for the register parameters. Allocate 16
|
|
bytes for a null argv and envp. Round the result up to 64
|
|
bytes to preserve alignment. */
|
|
subu t0,t0,64
|
|
4:
|
|
move sp,t0 # set stack pointer
|
|
sw sp,__stackbase # keep this for future ref
|
|
.end zerobss
|
|
|
|
/*
|
|
* initialize target specific stuff. Only execute these
|
|
* functions it they exist.
|
|
*/
|
|
.globl hardware_init_hook .text
|
|
.globl software_init_hook .text
|
|
.type _fini,@function
|
|
.type _init,@function
|
|
.globl atexit .text
|
|
.globl exit .text
|
|
.ent init
|
|
init:
|
|
LA (t9, hardware_init_hook) # init the hardware if needed
|
|
beq t9,zero,6f
|
|
nop
|
|
jal t9
|
|
nop
|
|
6:
|
|
LA (t9, software_init_hook) # init the hardware if needed
|
|
beq t9,zero,7f
|
|
nop
|
|
jal t9
|
|
nop
|
|
7:
|
|
LA (a0, _fini)
|
|
jal atexit
|
|
nop
|
|
|
|
#ifdef GCRT0
|
|
.globl _ftext
|
|
.globl _extext
|
|
LA (a0, _ftext)
|
|
LA (a1, _etext)
|
|
jal monstartup
|
|
nop
|
|
#endif
|
|
|
|
|
|
jal _init # run global constructors
|
|
nop
|
|
|
|
addiu a1,sp,32 # argv = sp + 32
|
|
addiu a2,sp,40 # envp = sp + 40
|
|
#if __mips64
|
|
sd zero,(a1) # argv[argc] = 0
|
|
sd zero,(a2) # envp[0] = 0
|
|
#else
|
|
sw zero,(a1)
|
|
sw zero,(a2)
|
|
#endif
|
|
jal main # call the program start function
|
|
move a0,zero # set argc to 0
|
|
|
|
# fall through to the "exit" routine
|
|
jal exit # call libc exit to run the G++
|
|
# destructors
|
|
move a0,v0 # pass through the exit code
|
|
.end init
|
|
|
|
|
|
/* Assume the PICBASE set up above is no longer valid below here. */
|
|
#ifdef __mips_embedded_pic
|
|
#undef PICBASE
|
|
#endif
|
|
|
|
/*
|
|
* _exit -- Exit from the application. Normally we cause a user trap
|
|
* to return to the ROM monitor for another run. NOTE: This is
|
|
* the only other routine we provide in the crt0.o object, since
|
|
* it may be tied to the "_start" routine. It also allows
|
|
* executables that contain a complete world to be linked with
|
|
* just the crt0.o object.
|
|
*/
|
|
.globl hardware_exit_hook .text
|
|
.globl _exit
|
|
.ent _exit
|
|
_exit:
|
|
7:
|
|
#ifdef __mips_embedded_pic
|
|
/* Need to reinit PICBASE, since we might be called via exit()
|
|
rather than via a return path which would restore old s0. */
|
|
#define PICBASE exit_PICBASE
|
|
PICBASE = .+8
|
|
bal PICBASE
|
|
nop
|
|
move s0,$31
|
|
#endif
|
|
#ifdef GCRT0
|
|
LA (t0, _mcleanup)
|
|
jal t0
|
|
nop
|
|
#endif
|
|
LA (t0, hardware_exit_hook)
|
|
beq t0,zero,1f
|
|
nop
|
|
jal t0
|
|
nop
|
|
1:
|
|
|
|
# break instruction can cope with 0xfffff, but GAS limits the range:
|
|
break 1023
|
|
b 7b # but loop back just in-case
|
|
nop
|
|
.end _exit
|
|
|
|
/* Assume the PICBASE set up above is no longer valid below here. */
|
|
#ifdef __mips_embedded_pic
|
|
#undef PICBASE
|
|
#endif
|
|
|
|
/* EOF crt0.S */
|