x86: use the stack frames to get exact stack-traces for CONFIG_FRAMEPOINTER on x86-64

x86: use the stack frames to get exact stack-traces for CONFIG_FRAMEPOINTER on x86-64

x86 32 bit already has this feature: This patch uses the stack frames with
frame pointer into an exact stack trace, by following the frame pointer.
This only affects kernels built with the CONFIG_FRAME_POINTER config option
enabled, and greatly reduces the amount of noise in oopses.

This code uses the traditional method of doing backtraces, but if it
finds a valid frame pointer chain, will use that to show which parts
of the backtrace are reliable and which parts are not

Due to the fragility and importance of the backtrace code, this needs to
be well reviewed and well tested before merging into mainlne.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>