ref: bfc9204963426bf0e8121b416458550b8f2616ad
dir: /rt/start-netbsd.s/
.section .note.netbsd.ident
.long 7
.long 4
.long 1
.ascii "NetBSD\0"
.p2align 2
.long 200000000
.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 */
subq $0x10,%rsp
movq $165,%rax /* sysarch */
movq $15,%rdi /* X8664setfsbase */
leaq thread$__tls(%rip),%rsi
movq %rsi,(%rsp)
movq %rsp,%rsi
syscall
addq $0x10,%rsp
xorq %rbp,%rbp
/* call pre-main initializers */
call __init__
/* enter the main program */
call main
/* exit(0) */
xorq %rdi,%rdi
movq $1,%rax
syscall