Add kernel profiling through sampling

* NEWS: Advertise feature.
* configfrac.ac (--enable-kernsample): Add option.
* kern/pc_sample.h (take_pc_sample): Add usermode and pc parameter.
(take_pc_sample_macro): Take usermode and pc parameters, pass as such to
take_pc_sample.
* kern/pc_sample.c (take_pc_sample): Use pc parameter when usermode is 1.
* kern/mach_clock.c (clock_interrupt): Add pc parameter. Pass usermode and
pc to take_pc_sample_macro call.
* i386/i386/hardclock.c (hardclock): Pass regs->eip to clock_interrupt call
on normal interrupts, NULL on interrupt interrupt.
* vm/vm_fault.c (vm_fault_cleanup): Set usermode to 1 and pc to NULL in
take_pc_sample_macro call.

1 files changed, 8 insertions, 2 deletions

diff --git a/kern/pc_sample.c b/kern/pc_sample.c
index fcb9d71b..e9f0b16a 100644
--- a/kern/pc_sample.c
+++ b/kern/pc_sample.c
@@ -46,12 +46,18 @@ typedef sampled_pc_t sampled_pcs[MAX_PC_SAMPLES];
 void take_pc_sample(
     const thread_t t,
     sample_control_t *cp,
-    sampled_pc_flavor_t flavor)
+    sampled_pc_flavor_t flavor,
+    boolean_t usermode,
+    vm_offset_t kern_pc)
 {
     vm_offset_t pc;
     struct sampled_pc *sample;
     
-    pc = interrupted_pc(t);
+    if (usermode)
+	pc = interrupted_pc(t);
+    else
+	pc = kern_pc;
+
     cp->seqno++;
     sample = &((sampled_pc_t *)cp->buffer)[cp->seqno % MAX_PC_SAMPLES];
     sample->id = (vm_offset_t)t;