clone

pub fn clone() callconv(.naked) u32

File

Code

pub fn clone() callconv(.naked) u32 {
    // __clone(func, stack, flags, arg, ptid, tls, ctid)
    //           a0,    a1,    a2,  a3,   a4,  a5,   a6
    // sys_clone(flags, stack, ptid, ctid, tls)
    //              a0,    a1,   a2,   a3,  a4
    asm volatile (
        \\ srli.w $a1, $a1, 4
        \\ slli.w $a1, $a1, 4
        \\
        \\ # Save function pointer and argument pointer on new thread stack
        \\ addi.w  $a1, $a1, -16
        \\ st.w    $a0, $a1, 0     # save function pointer
        \\ st.w    $a3, $a1, 4     # save argument pointer
        \\ or      $a0, $a2, $zero
        \\ or      $a2, $a4, $zero
        \\ or      $a3, $a6, $zero
        \\ or      $a4, $a5, $zero
        \\ ori     $a7, $zero, 220 # SYS_clone
        \\ syscall 0
        \\
        \\ beq     $a0, $zero, 1f
        \\ jirl    $zero, $ra, 0
        \\1:
    );
    if (builtin.unwind_tables != .none or !builtin.strip_debug_info) asm volatile (
        \\ .cfi_undefined 1
    );
    asm volatile (
        \\ move    $fp, $zero
        \\ move    $ra, $zero
        \\
        \\ ld.w    $t8, $sp, 0     # function pointer
        \\ ld.w    $a0, $sp, 4     # argument pointer
        \\ jirl    $ra, $t8, 0     # call the user's function
        \\ ori     $a7, $zero, 93  # SYS_exit
        \\ syscall 0               # child process exit
    );
}