ref: fbd0a767de45e5c5d9dfe6dc4a86c95a328bd22b
dir: /rt/start-openbsd.s/
.section ".note.openbsd.ident", "a"
.p2align 2
.long 8
.long 4
.long 1
.ascii "OpenBSD\0"
.long 0
.p2align 2
.data
/* sys.__cenvp : byte## */
.globl sys$__cenvp
sys$__cenvp:
.quad 0
.globl thread$__tls
thread$__tls:
.fill 88 /* sizeof(tlshdr) + (8 * sizeof(void#)) = 24 + 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 $329,%rax /* Sys__set_tcb */
leaq thread$__tls(%rip),%rdi
syscall
xorq %rbp,%rbp
/*
we're done startup, and we kind of want
to call kbind here, but this breaks
when we dynamically link in libc.
*/
call __init__
call main
call __fini__
/* exit(0) */
xorq %rdi,%rdi
movq $1,%rax
syscall
/*
* provide __guard_local for if we are
* linking against libc
*/
.section ".openbsd.randomdata", "aw"
.global __guard_local
.hidden __guard_local
.type __guard_local, "object"
.p2align 3
__guard_local:
.quad 0
.size __guard_local, 8
.section ".note.openbsd.ident", "a"
.p2align 2
.long 8
.long 4
.long 1
.ascii "OpenBSD\0"
.long 0
.p2align 2