On Sat, Jun 18, 2016 at 1:56 PM, Brian Gerst <brge...@gmail.com> wrote:
> Instead of setting up a fake pt_regs context, put the kernel thread
> function pointer and arg into the unused callee-restored registers
> of struct fork_frame.
This seems generally okay.
>
> Signed-off-by: Brian Gerst <brge...@gmail.com>
> @@ -146,19 +147,12 @@ int copy_thread_tls(unsigned long clone_flags, unsigned
> long sp,
> if (unlikely(p->flags & PF_KTHREAD)) {
> /* kernel thread */
> memset(childregs, 0, sizeof(struct pt_regs));
> - frame->ret_addr = (unsigned long) ret_from_kernel_thread;
> - task_user_gs(p) = __KERNEL_STACK_CANARY;
> - childregs->ds = __USER_DS;
> - childregs->es = __USER_DS;
> - childregs->fs = __KERNEL_PERCPU;
Is the idea that do_execve promises to initialize all these fields to
something sensible if the kernel thread in question tries to return to
user mode?
--Andy
