cosmopolitan/libc/crt/crt.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

93 lines
3.4 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 2020 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/dce.h"
#include "libc/macros.internal.h"
#include "libc/notice.inc"
#include "libc/runtime/internal.h"
.section .start,"ax",@progbits
// System Five userspace program entrypoint.
//
// @param rsp is [n,argv₀..argvₙ₋₁,0,envp₀..,0,auxv₀..,0,..]
// @note FreeBSD is special (see freebsd/lib/csu/amd64/...)
// @note NetBSD will only zero the call-clobbered registers
// @note ape.S and ape-loader both set RCX to XNU on Darwin
// @noreturn
_start:
#if SupportsFreebsd()
// detect free besiyata dishmaya
test %rdi,%rdi
cmovnz %rdi,%rsp
jz 0f
movb $FREEBSD,%cl
0:
#endif
// set operating system when already detected
mov %cl,__hostos(%rip)
// get startup timestamp as early as possible
// its used by --strace flag and kprintf() %T
rdtsc
ezlea kStartTsc,bx
mov %eax,(%rbx)
mov %edx,4(%rbx)
// translates arguments from old stack abi
mov (%rsp),%ebx # argc
lea 8(%rsp),%rsi # argv
lea 16(%rsp,%rbx,8),%rdx # envp
mov %rsp,__oldstack(%rip)
and $-16,%rsp
xor %ebp,%ebp
// bofram 9f
// make win32 imps noop
.weak ape_idata_iat
.weak ape_idata_iatend
ezlea missingno,ax
ezlea ape_idata_iat,di
ezlea ape_idata_iatend,cx
sub %rdi,%rcx
shr $3,%ecx
rep stosq
// scan through environment varis
// find start of auxiliary values
xor %eax,%eax
or $-1,%ecx
mov %rdx,%rdi
repnz scasq
mov %rdi,%rcx # auxv
#if SupportsXnu()
// xnu doesn't have auxiliary values
testb IsXnu()
jz 1f # polyfill xnu auxv
push $0 # auxv[1][1]=0
push $0 # auxv[1][0]=0
mov %rsp,%rcx # auxv
#endif
// enter cosmopolitan runtime
1: mov %ebx,%edi
call cosmo
9: .unreachable
.endfn _start,weak,hidden