ref: de496a920339b8285ca2e9225b1abff7af54698a
dir: /rt/start-freebsd.s/
.data .globl sys$__cenvp sys$__cenvp: .quad 0 .text /* * The entry point for the whole program. * This is called by the OS. In order, it: * - Sets up all argc entries as slices * - Sets up all envp entries as slices * - Converts argc/argv to a slice * - Stashes envp in std._environment * - Stashes a raw envp copy in __cenvp (for syscalls to use) * - Calls main() */ .globl _start _start: /* stack allocate sizeof(byte[:])*(argc + len(envp)) */ movq (%rdi),%rax leaq 16(%rdi,%rax,8), %rbx /* argp = argv + 8*argc + 8 */ call count addq %r9,%rax imulq $16,%rax subq %rax,%rsp movq %rsp, %rdx /* saved args[:] */ /* convert envp to byte[:][:] for std._environment */ movq (%rdi),%rax leaq 16(%rdi,%rax,8), %rbx /* envp = argv + 8*argc + 8 */ /* store envp for some syscalls to use without spurious conversion. */ movq %rbx,sys$__cenvp(%rip) /* convert argc, argv to byte[:][:] for args. */ movq %rsp, %rcx movq (%rdi), %rax /* argc */ leaq 8(%rdi), %rbx /* argv */ movq (%rdi), %rsi /* saved argc */ call cvt pushq %rsi pushq %rdx xorq %rbp,%rbp /* call pre-main initializers */ call __init__ /* enter the main program */ call main /* exit(0) */ xorq %rdi,%rdi movq $1,%rax syscall