Kernel: Implement a simple process time profiler

The kernel now supports basic profiling of all the threads in a process
by calling profiling_enable(pid_t). You finish the profiling by calling
profiling_disable(pid_t).

This all works by recording thread stacks when the timer interrupt
fires and the current thread is in a process being profiled.
Note that symbolication is deferred until profiling_disable() to avoid
adding more noise than necessary to the profile.

A simple "/bin/profile" command is included here that can be used to
start/stop profiling like so:

    $ profile 10 on
    ... wait ...
    $ profile 10 off

After a profile has been recorded, it can be fetched in /proc/profile

There are various limits (or "bugs") on this mechanism at the moment:

- Only one process can be profiled at a time.
- We allocate 8MB for the samples, if you use more space, things will
  not work, and probably break a bit.
- Things will probably fall apart if the profiled process dies during
  profiling, or while extracing /proc/profile

1 files changed, 1 insertions, 0 deletions

diff --git a/Kernel/Makefile b/Kernel/Makefile
index 932bcfef42..987a9a14db 100644
--- a/Kernel/Makefile
+++ b/Kernel/Makefile
@@ -76,6 +76,7 @@ CXX_OBJS = \
     PCI.o \
     Process.o \
     ProcessTracer.o \
+    Profiling.o \
     RTC.o \
     Scheduler.o \
     SharedBuffer.o \