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|
@ Copyright (C) 2023-2026 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/>.
.section .text
.global _start
_start:
@@ mov r7, #162 @ SYS_nanosleep
@@ adr r0, timespec @ req
@@ mov r1, #0 @ rem
@@ swi #0 @ syscall
mov r8, sp @ r8 = sp
ldr r9, [r8], #8 @ r9 = original sp, r8 += 8
mov r14, #-1 @ r14 = secondary fd
next_action:
ldr r11, [r8] @ r11 = action number
and r12, r11, #-17 @ actual action number
cmp r12, #0 @ open file?
beq open_file @ open file.
cmp r12, #3 @ jump?
beq rest_of_exec @ jump to code.
cmp r12, #4 @ anonymous mmap?
beq do_mmap_anon @ anonymous mmap.
do_mmap:
add r6, r8, #4 @ r6 = r8 + 4
ldm r6!, {r0, r5} @ vm_address, file_offset
ldm r6!, {r1, r2} @ protection, length
mov r3, r1 @ swap
lsr r5, #12 @ divide file offset by page size
mov r1, r2 @ swap
mov r2, r3 @ swap
ldm r6!, {r3, r12} @ flags, clear
tst r11, #16 @ primary fd?
mov r4, r10 @ primary fd
beq do_mmap_1
mov r4, r14 @ secondary fd
do_mmap_1:
mov r7, #192 @ SYS_mmap2
swi #0 @ syscall
ldr r2, [r8, #4] @ vm_address
cmp r2, r0 @ rc == vm_address?
bne perror
add r0, r1, r2 @ r0 = length + vm_address
sub r3, r0, r12 @ r3 = r0 - clear
mov r1, #0 @ r1 = 0
align:
cmp r0, r3 @ r0 == r3?
beq continue @ continue
tst r3, #3 @ r3 & 3?
bne fill32 @ fill aligned
strb r1, [r3], #1 @ fill byte
b align @ align again
fill32:
sub r2, r0, r3 @ r2 = r0 - r3
cmp r2, #31 @ r2 >= 32?
ble fillb @ start filling bytes
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
str r1, [r3], #4 @ *r3++ = 0
b fill32
fillb:
cmp r0, r3 @ r0 == r3
beq continue @ done
strb r1, [r3], #1 @ ((char *) r3)++ = 0
b fillb
continue:
add r8, r8, #28 @ next action
b next_action
do_mmap_anon:
add r6, r8, #4 @ r6 = r8 + 4
ldm r6!, {r0, r5} @ vm_address, file_offset
ldm r6!, {r1, r2} @ protection, length
mov r3, r1 @ swap
lsr r5, #12 @ divide file offset by page size
mov r1, r2 @ swap
mov r2, r3 @ swap
ldm r6!, {r3, r12} @ flags, clear
mov r4, #-1 @ fd
b do_mmap_1
open_file:
mov r7, #5 @ SYS_open
add r0, r8, #4 @ file name
mov r1, #0 @ O_RDONLY
mov r2, #0 @ mode
swi #0 @ syscall
cmp r0, #-1 @ r0 <= -1?
ble perror
add r8, r8, #4 @ r8 = start of string
mov r1, r8 @ r1 = r8
nextc:
ldrb r2, [r8], #1 @ b = *r0++
cmp r2, #47 @ dir separator?
bne nextc1 @ not dir separator
mov r1, r8 @ r1 = char past separator
nextc1:
cmp r2, #0 @ b?
bne nextc @ next character
add r8, r8, #3 @ round up r8
and r8, r8, #-4 @ mask for round, set r8
tst r11, #16 @ primary fd?
bne secondary @ secondary fd
mov r10, r0 @ primary fd
mov r7, #172 @ SYS_prctl
mov r0, #15 @ PR_SET_NAME, r1 = name
mov r2, #0 @ arg2
mov r3, #0 @ arg3
mov r4, #0 @ arg4
mov r5, #0 @ arg5
swi #0 @ syscall
b next_action @ next action
secondary:
mov r14, r0 @ secondary fd
b next_action @ next action
perror:
mov r7, #1 @ SYS_exit
mvn r0, r0 @ r0 = ~r0
add r0, r0, #1 @ r0 += 1
swi #0
rest_of_exec: @ r8 points to seven ints + string
mov r7, r9 @ r7 = original SP
ldr r6, [r7], #8 @ argc & terminator
lsl r6, r6, #2 @ argc *= 4
add r7, r7, r6 @ now past argv
ldr r6, [r8, #28] @ length of string
add r6, r6, #1
skip_environ:
1: ldr r1, [r7], #4 @ r1 = *r7++
tst r1, r1 @ r1
bne 1b @ r1
1: ldm r7!, {r0, r1} @ a_type, a_un.a_val
tst r0, r0
bne 1b @ a_type -> 1b
@@ Establish the number of bytes in the argument, environment,
@@ and auxiliary vectors to be moved.
sub r5, r7, r9 @ r5 = bytes in vectors
@@ Expand r7 with sufficient space for the filename and align
@@ it.
sub r4, r7, r5
and r4, r4, #-8 @ r4 = address of AT_EXECFN
sub r3, r4, r5 @ r4 - number of bytes in vectors
and r3, r3, #-16 @ r3 = position of new argc
@@ Reserve an area that is guaranteed not to be clobbered into
@@ which to copy the command and file name.
mov r2, r3
cmp r2, r8
blo 1f
mov r2, r8
1: sub r2, r2, #24 @ space for data
@@ [r2, #0] = entry
@@ [r2, #4] = at_entry
@@ [r2, #8] = at_phent
@@ [r2, #12] = at_phnum
@@ [r2, #16] = at_phdr
@@ [r2, #20] = at_base
add r7, r8, #4 @ &cmd->entry
ldm r7!, {r0, r1}
stm r2!, {r0, r1}
ldm r7!, {r0, r1}
stm r2!, {r0, r1}
ldm r7!, {r0, r1}
stm r2!, {r0, r1}
sub r2, r2, #24
sub r0, r2, r6 @ r0 = copy of AT_EXECFN
add r1, r8, #32 @ src
add r5, r1, r6 @ src end
cmp r1, r5
bcs copy_env_and_args
1: ldrb r7, [r1], #1
strb r7, [r0], #1
cmp r1, r5
blo 1b
copy_env_and_args:
mov r5, r3
1: ldr r0, [r9], #4 @ argc and arguments
str r0, [r5], #4 @ *dst = ...
tst r0, r0
bne 1b
1: ldr r0, [r9], #4 @ environment string
str r0, [r5], #4 @ *dst = ...
tst r0, r0
bne 1b
copy_auxv:
ldm r9!, {r0, r1} @ a_type, a_un.a_val
tst r0, r0 @ AT_NULL
beq 8f
cmp r0, #3 @ AT_PHDR
beq 2f
cmp r0, #4 @ AT_PHENT
beq 3f
cmp r0, #5 @ AT_PHNUM
beq 4f
cmp r0, #9 @ AT_ENTRY
beq 5f
cmp r0, #7 @ AT_BASE
beq 6f
cmp r0, #31 @ AT_EXECFN
beq 7f
1: stm r5!, {r0, r1}
b copy_auxv
2: ldr r1, [r2, #16]
b 1b
3: ldr r1, [r2, #8]
b 1b
4: ldr r1, [r2, #12]
b 1b
5: ldr r1, [r2, #4]
b 1b
6: ldr r1, [r2, #20]
b 1b
7: mov r1, r4
b 1b
8:
stm r5!, {r0, r1}
cleanup:
@@ Copy the filename.
sub r0, r2, r6 @ src
add r1, r0, r6 @ src end
cmp r0, r1
bcs 2f
1: ldrb r5, [r0], #1
strb r5, [r4], #1 @ *dst++
cmp r0, r1
blo 1b
2: mov r9, r3 @ replace original SP
cmp r14, #-1 @ secondary fd set?
beq cleanup1 @ not set
mov r7, #6 @ SYS_close
mov r0, r14 @ secondary fd
swi #0 @ syscall
cleanup1:
mov r7, #6 @ SYS_close
mov r0, r10 @ primary fd
swi #0 @ syscall
enter:
mov sp, r9 @ restore original SP
mov r0, #0 @ clear rtld_fini
ldr r1, [r2] @ branch to code
bx r1
@@ timespec:
@@ .long 10
@@ .long 10
@ Local Variables:
@ asm-comment-char: ?@
@ End:
|
