doc: Tasks RCU must protect instructions before trampoline

Protecting the code in a trampoline can also require protecting a
number of instructions prior to actually entering the trampoline.
For example, these earlier instructions might be computing the address
of the trampoline.  This commit therefore updates RCU's requirements to
record this for posterity.

Link: https://lore.kernel.org/lkml/[email protected]/
Reported-by: Lai Jiangshan <[email protected]>
Reported-by: Steven Rostedt <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
1 file changed