ref: 690ab7aa8e6c56a4ae8a2bd5bce58d1df681234e
dir: /rt/start-osx.s/
.data
/* sys.__cenvp : byte## */
.globl _sys$__cenvp
_sys$__cenvp:
.quad 0
.globl thread$__tls
thread$__tls:
.fill 104 /* sizeof(tlshdr) + (8 * sizeof(void#)) = 40 + 64 */
.text
/*
* The entry point for the whole program.
* This is called by the OS. In order, it:
* - Sets up all argc entries as slices
* - Converts argc/argv to a slice
* - Stashes a raw envp copy in __cenvp (for syscalls to use)
* - Sets up thread local storage for the main thread
* - Calls main()
*/
.globl start
start:
movq %rsp,%rbp
andq $-16,%rsp /* align the stack pointer */
/* load argc, argv, envp from stack */
movq (%rbp),%rax /* argc */
leaq 8(%rbp),%rbx /* argv */
leaq 16(%rbp,%rax,8),%rcx /* envp = argv + 8*argc + 8 */
/* store envp for some syscalls to use without converting */
movq %rcx,_sys$__cenvp(%rip)
/* stack allocate sizeof(byte[:])*argc */
imulq $16,%rax,%rdx
subq %rdx,%rsp
movq %rsp,%rcx /* args[:] */
/* convert argc, argv to byte[:][:] for args. */
pushq %rax
pushq %rcx
call cvt
/* set up the intial tls region for the main thread */
movq $0x3000003,%rax /* undocumented setgsbase syscall */
leaq thread$__tls(%rip),%rdi
movq %rdi,0x20(%rdi) /* also store a copy in __tls.self */
syscall
xorq %rbp,%rbp
call ___init__
call _main
call ___fini__
/* exit */
xorq %rdi,%rdi
movq $0x2000001,%rax
syscall