x86/entry/common: Protect against instrumentation

x86/entry/common: Protect against instrumentation

Mark the various syscall entries with noinstr to protect them against
instrumentation and add the noinstrumentation_begin()/end() annotations to mark the
parts of the functions which are safe to call out into instrumentable code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134340.520277507@linutronix.de