On Sun, Jan 30, 2022 at 10:22 PM Rick Edgecombe
<rick.p.edgecombe@xxxxxxxxx> wrote:
>
> From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
>
> The single call site of copy_thread() passes stack size in 'arg'. To make
> this clear and in preparation of using this argument for shadow stack
> allocation, change 'arg' to 'stack_size'. No functional changes.
Actually that name is misleading - the single caller copy_process() indeed does:
retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls);
but the member "stack_size" of "struct kernel_clone_args" can actually
also be a pointer argument given to a kthread, see create_io_thread()
and kernel_thread():
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
struct kernel_clone_args args = {
.flags = ((lower_32_bits(flags) | CLONE_VM |
CLONE_UNTRACED) & ~CSIGNAL),
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
.stack = (unsigned long)fn,
.stack_size = (unsigned long)arg,
};
return kernel_clone(&args);
}
And then in copy_thread(), we have:
kthread_frame_init(frame, sp, arg)
So I'm not sure whether this name change really makes sense, or
whether it just adds to the confusion.
