cosmopolitan/ape/loader-elf.S
Justine Tunney db0d8dd806 Support Linux binfmt_misc and APE loading on Apple
The "no modify self" variant of Actually Portable Executable is now
supported on all platforms. If you use `$(APE_NO_MODIFY_SELF)` then
ld.bfd will embed a 4096 byte ELF binary and a 4096 byte Macho file
which are installed on the fly to ${TMPDIR:-/tmp}, which enables us
launch the executable, without needing to copy the whole executable

To prevent it from copying a tiny executable to your temp directory
you need to install the `ape` command (renamed from ape-loader), to
a system path. For example:

    # FreeBSD / NetBSD / OpenBSD
    make -j8 o//ape/ape
    cp o//ape/ape /usr/bin/ape

    # Mac OS
    # make -j8 o//ape/ape.macho
    curl https://justine.lol/ape.macho >/usr/bin/ape
    chmod +x /usr/bin/ape

On Linux you can get even more performance with the new binfmt_misc
support which makes launching non-modifying APE binaries as fast as
launching ELF executables. Running the following command:

    # Linux
    ape/apeinstall.sh

Will copy APE loader to /usr/bin/ape and register with binfmt_misc
Lastly, this change also fixes a really interesting race condition
with OpenBSD thread joining.
2022-05-21 09:28:25 -07:00

140 lines
4.5 KiB
ArmAsm

/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi
Copyright 2021 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/elf/def.h"
#include "libc/macros.internal.h"
// APE Loader Executable Structure
// Linux, FreeBSD, NetBSD, OpenBSD
.align 8
ehdr: .ascii "\177ELF"
.byte ELFCLASS64
.byte ELFDATA2LSB
.byte 1
.byte ELFOSABI_FREEBSD
.quad 0
.word ET_EXEC # e_type
.word EM_NEXGEN32E # e_machine
.long 1 # e_version
.quad _start # e_entry
.quad phdrs - ehdr # e_phoff
.quad 0 # e_shoff
.long 0 # e_flags
.word 64 # e_ehsize
.word 56 # e_phentsize
.word 4 # e_phnum
.word 0 # e_shentsize
.word 0 # e_shnum
.word 0 # e_shstrndx
.endobj ehdr,globl
// Ape Loader Entrpoint
//
// This is normally called by the operating system. However it may
// be called by the Actually Portable Executables themselves, when
// re-executing a program. Just do this:
//
// memcpy(0x200000, loader)
// xor %eax,%eax
// inc %eax
// jmp 0x200000
//
// @see APE_LOADER_ENTRY
jg47h: .org 0x47
.endobj jg47h
_start: mov %rsp,%rsi
jmp ApeLoader
.endfn _start,globl
// System Call Entrpoint
//
// This function is used by the APE loader to make system calls.
// We also pass a reference to this function to the APE binary's
// _start() function. It's needed because on OpenBSD, msyscall()
// restricts which pages can issue system calls, and it can only
// be called once. Therefore if we want to be load and re-load a
// binary multiple times without calling the system execve(), we
// need to be able to handover the SYSCALL function. We hardcode
// this to a fixed address, but that shouldn't be used, since we
// would ideally want to move it to a random page in the future.
//
// @see APE_LOADER_SYSCALL
sc50h: .org 0x50
.endobj sc50h
__syscall_loader:
clc
syscall
jc 1f
ret
1: neg %rax
ret
.endfn __syscall_loader,globl
.align 8
phdrs: .long PT_LOAD # p_type
.long PF_R|PF_X # p_flags
.quad 0 # p_offset
.quad ehdr # p_vaddr
.quad ehdr # p_paddr
.quad filesz # p_filesz
.quad filesz # p_memsz
.quad PAGESIZE # p_align
.long PT_LOAD # p_type
.long PF_R|PF_W # p_flags
.quad 0 # p_offset
.quad bss # p_vaddr
.quad bss # p_paddr
.quad 0 # p_filesz
.quad bsssize # p_memsz
.quad PAGESIZE # p_align
.long PT_GNU_STACK # p_type
.long PF_R|PF_W # p_flags
.quad 0 # p_offset
.quad 0 # p_vaddr
.quad 0 # p_paddr
.quad 0 # p_filesz
.quad 0 # p_memsz
.quad 16 # p_align
.long PT_NOTE # p_type
.long PF_R # p_flags
.quad note - ehdr # p_offset
.quad note # p_vaddr
.quad note # p_paddr
.quad notesize # p_filesz
.quad notesize # p_memsz
.quad 8 # p_align
.endobj phdrs
note: .long 2f-1f
.long 4f-3f
.long 1
1: .asciz "OpenBSD"
2: .align 4
3: .long 0
4: .long 2f-1f
.long 4f-3f
.long 1
1: .asciz "NetBSD"
2: .align 4
3: .long 901000000
4: .endobj note
notesize = . - note