cosmopolitan/libc/crt/crt.S
2023-08-11 04:39:19 -07:00

148 lines
4.6 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
#if SupportsXnu() && defined(__x86_64__)
// XNU AMD64 Entrypoint
//
// @note Rosetta barely implements MAC_LC_UNIXTHREAD
// @note Rosetta sets many registers to weird values
_apple: mov $_HOSTXNU,%cl
jmp 1f
.endfn _apple,weak,hidden
#endif
// 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:
#ifdef __x86_64__
#if SupportsFreebsd()
// detect free besiyata dishmaya
test %rdi,%rdi
cmovnz %rdi,%rsp
jz 0f
movb $_HOSTFREEBSD,%cl
0:
#endif
// set operating system when already detected
1: 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)
// setup a stack frame
// align stack to GetStackSize() so GetStackAddr() is fast
.weak ape_stack_memsz
mov $ape_stack_memsz,%r9d
mov $16,%r8d
test %r9d,%r9d
cmovnz %r9,%r8
neg %r8
and %r8,%rsp
xor %ebp,%ebp
// bofram 9f
#if SupportsWindows()
// make win32 imps noop
.weak ape_idata_iat
.weak ape_idata_iatend
ezlea __win32_oops,ax
ezlea ape_idata_iat,di
ezlea ape_idata_iatend,cx
sub %rdi,%rcx
shr $3,%ecx
rep stosq
#endif
// 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
////////////////////////////////////////////////////////////////////////////////
#elif defined(__aarch64__)
// save original stack pointer
// this is the first argument to cosmo() below
mov x0,sp
// align stack to GetStackSize() so GetStackAddr() is fast
mov x1,sp
.weak ape_stack_memsz
ldr x2,=ape_stack_memsz
neg x2,x2
and x1,x2,x1
mov sp,x1
// setup backtraces
mov x29,#0
// second arg shall be struct Syslib passed by ape-m1.c
// used to talk to apple's authoritarian libraries
// should be set to zero on other platforms
mov x1,x15
// switch to c code
bl cosmo
.unreachable
////////////////////////////////////////////////////////////////////////////////
#else
#error "architecture unsupported"
#endif /* __x86_64__ */
.endfn _start,weak,hidden