hello, at , I read something about 'Sigtramp separation' within the W^X transition. I only know that this sigtramp-page (?) is used to jump back into the kernel when a signal arrives.
My question is, what exactly is this signal trampoline? Why do I need it? Why was it on the Stack (first page of the virtual memory)? And why must it be executable / what does the code? Thank you for your help.  http://www.openbsd.org/papers/ru13-deraadt/mgp00012.html