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