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# Copyright (C) 2023-2024 Free Software Foundation, Inc.
#
# This file is part of GNU Emacs.
#
# GNU Emacs is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation, either version 3 of the License,
# or (at your option) any later version.
#
# GNU Emacs is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
include(`config-mips.m4')
# Make sure not to use t4 through t7, in order to maintain portability
# with N32 ABI systems.
.set noreorder # delay slots managed by hand
.section .text
.global __start
__start:
dnl li $v0, SYSCALL_nanosleep # SYS_nanosleep
dnl la $a0, .timespec # rqtp
dnl li $a1, 0 # rmtp
dnl syscall # syscall
lw $s6, ($sp) # original stack pointer
addi $s0, $sp, 8 # start of load area
addi $sp, -8 # primary fd, secondary fd
li $t0, -1 # secondary fd
sw $t0, 4($sp) # initialize secondary fd
.next_action:
lw $s2, ($s0) # action number
nop # delay slot
andi $t0, $s2, 15 # t0 = s2 & 15
beqz $t0, .open_file # open file?
li $t1, 3 # t1 = 3, delay slot
beq $t0, $t1, .rest_of_exec # jump to code
li $t1, 4 # t1 = 4, delay slot
beq $t0, $t1, .do_mmap_anon # anonymous mmap
.do_mmap:
lw $a0, 4($s0) # vm_address, delay slot
lw $v1, 8($s0) # file_offset
lw $a2, 12($s0) # protection
lw $a1, 16($s0) # length
lw $a3, 20($s0) # flags
lw $v0, ($sp) # primary fd
andi $t1, $s2, 16 # t1 = s2 & 16
beqz $t1, .do_mmap_1 # secondary fd?
nop # delay slot
lw $v0, 4($sp) # secondary fd
nop # delay slot
.do_mmap_1:
SYSCALL(`$v0',`$v1',`$zero',`$zero') # syscall args
li $v0, SYSCALL_mmap # SYS_mmap
syscall # syscall
bne $a3, $zero, .perror # perror
RESTORE() # delay slot, restore sp
lw $s5, 24($s0) # clear
add $t0, $a0, $a1 # t0 = length + vm_address, delay slot
sub $t1, $t0, $s5 # t1 = t0 - clear
.align:
beq $t0, $t1, .continue # already finished?
nop # delay slot
andi $t2, $t1, 3 # t1 & 3?
bnez $t2, .fillw # start filling longs
nop # delay slot
sb $zero, ($t1) # clear byte
addi $t1, $t1, 1 # t1++
j .align # continue
nop # delay slot
.fillw:
sub $t2, $t0, $t1 # t2 = t0 - t1
sltiu $t2, $t2, 32 # r2 < 32?
bne $t2, $zero, .fillb # fill bytes
nop # delay slot
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
sw $zero, ($t1) # zero word
addi $t1, $t1, 4 # next word
j .fillw # fill either word or byte
nop # delay slot
.fillb:
beq $t0, $t1, .continue # already finished?
nop # delay slot
sb $zero, ($t1) # clear byte
addi $t1, $t1, 1 # t1++
.continue:
addi $s0, $s0, 28 # s0 = next action
j .next_action # next action
nop # delay slot
.do_mmap_anon:
lw $v1, 8($s0) # file_offset
lw $a2, 12($s0) # protection
lw $a1, 16($s0) # length
lw $a3, 20($s0) # flags
li $t4, -1 # fd
j .do_mmap_1 # do mmap
nop # delay slot
.open_file:
li $v0, SYSCALL_open # SYS_open
addi $a0, $s0, 4 # start of name
move $a1, $zero # flags = O_RDONLY
move $a2, $zero # mode = 0
syscall # syscall
bne $a3, $zero, .perror # perror
addi $s0, $s0, 4 # start of string, delay slot
move $t3, $s0 # t3 = char past separator
.nextc:
lb $t0, ($s0) # load byte
addi $s0, $s0, 1 # s0++
li $t1, 47 # directory separator `/'
bne $t0, $t1, .nextc1 # is separator char?
nop # delay slot
move $t3, $s0 # t3 = char past separator
.nextc1:
bnez $t0, .nextc # next character?
nop # delay slot
addi $s0, $s0, 3 # adjust for round
li $t2, -4 # t2 = -4
and $s0, $s0, $t2 # mask for round
andi $t0, $s2, 16 # t1 = s2 & 16
beqz $t0, .primary # primary fd?
move $t0, $sp # address of primary fd, delay slot
addi $t0, $t0, 4 # address of secondary fd
j .next_action # next action
.primary:
sw $v0, ($t0) # store fd, delay slot
li $v0, SYSCALL_prctl # SYS_prctl
li $a0, 15 # PR_SET_NAME
move $a1, $t3 # name
move $a2, $zero # arg1
move $a3, $zero # arg2
SYSCALL(`$a2',`$a2',`$a2',`$a2') # syscall args
syscall # syscall
RESTORE() # restore sp
j .next_action # next action
nop # delay slot
.perror:
move $a0, $v0 # errno
li $v0, SYSCALL_exit # SYS_exit
syscall # syscall
.rest_of_exec:
move $s1, $s6 # s1 = original SP
lw $t0, ($s1) # argc
nop # delay slot
sll $t0, $t0, 2 # argc *= 4
addi $t0, $t0, 8 # argc += 8
add $s1, $s1, $t0 # s1 = start of envp
.skipenv:
lw $t0, ($s1) # t0 = *s1
addi $s1, $s1, 4 # s1++
bne $t0, $zero, .skipenv # skip again
nop # delay slot
la $s2, .auxvtab # address of auxv table
.one_auxv:
lw $t0, ($s1) # t0 = auxv type
li $t1, 10 # t1 = 10, delay slot
beqz $t0, .finish # is AT_IGNORE?
sltu $t1, $t0, $t1 # t1 = t0 < num offsets, delay slot
beq $t1, $zero, .next # next auxv
sll $t1, $t0, 2 # t1 = t0 * 4, delay slot
add $t1, $s2, $t1 # t1 = .auxvtab + t1
lw $t2, ($t1) # t2 = *t1
nop # delay slot
beqz $t2, .next # skip auxv
add $t2, $s0, $t2 # t2 = s0 + t2
lw $t2, ($t2) # t2 = *t2
nop # delay slot
sw $t2, 4($s1) # set auxv value
.next:
addi $s1, $s1, 8 # next auxv
j .one_auxv # next auxv
nop # delay slot
.finish:
lw $t0, 4($sp) # secondary fd
lw $s1, ($sp) # primary fd, delay slot, preserved
li $t2, -1 # immediate -1
beq $t0, $t2, .finish1 # secondary fd set?
li $v0, SYSCALL_close # SYS_close, delay slot
move $a0, $t0 # fd
syscall # syscall
li $v0, SYSCALL_close # SYS_close
.finish1:
move $a0, $s1 # primary fd
syscall # syscall
li $v0, SYSCALL_prctl # SYS_prctl
li $a0, 45 # PR_SET_FP_MODE
lw $a1, 28($s0) # fpu_mode
move $a2, $zero # arg3
move $a3, $zero # arg4
SYSCALL(`$a2',`$a2',`$a2',`$a2') # syscall args
syscall # syscall
RESTORE() # restore sp
.jump:
move $v0, $zero # rtld_fini
lw $t0, 4($s0) # entry
move $sp, $s6 # restore stack pointer, delay slot
jr $t0 # enter
nop # delay slot
.auxvtab:
.long 0 # 0
.long 0 # 1
.long 0 # 2
.long 20 # 3 AT_PHDR
.long 12 # 4 AT_PHENT
.long 16 # 5 AT_PHNUM
.long 0 # 6
.long 24 # 7 AT_BASE
.long 0 # 8
.long 8 # 9 AT_ENTRY
.timespec:
.long 10
.long 10
# Local Variables:
# asm-comment-char: ?#
# End:
|
