alpha: Implement Hardware Performance Events

The following patches implement hardware performance events for the Alpha EV67 and later CPUs. I have had this running on a Compaq XP1000 (EV67, single CPU) for a few days now. Pretty cool -- discovered that the glibc exp2() library routine uses on average 985 cycles to execute 777 CPU instructions whereas Compaq's CPML library version of exp2() uses on average 32 cycles to execute 47 CPU instructions to achieve the same thing!

Michael Cree (3):
alpha: Add performance monitor interrupt counter.
alpha: Add wrperfmon.h header file to aid use of wrperfmon PALcall.
alpha: Implement HW performance events on the EV67 and later CPUs.

 arch/alpha/include/asm/hw_irq.h     |    1 +
 arch/alpha/include/asm/perf_event.h |    8 +-
 arch/alpha/include/asm/wrperfmon.h  |   93 ++++
 arch/alpha/kernel/Makefile          |    1 +
 arch/alpha/kernel/irq.c             |    7 +-
 arch/alpha/kernel/irq_alpha.c       |    3 +
 arch/alpha/kernel/perf_event.c      |  836 +++++++++++++++++++++++++++++++++++
 7 files changed, 946 insertions(+), 3 deletions(-)
 create mode 100644 arch/alpha/include/asm/wrperfmon.h
 create mode 100644 arch/alpha/kernel/perf_event.c