An IPI to configure event counters.

561179c4 · Silas Boyd-Wickizer · 5606f832 · 561179c4 · 561179c4 · 561179c4
--- a/kernel.h
+++ b/kernel.h
@@ -130,6 +130,7 @@ int             cpunum(void);
 void            lapicstartap(u8, u32 addr);
 void            lapiceoi(void);
 void            lapic_tlbflush(u32);
+void            lapic_sampconf(u32);
 void            lapicpc(char mask);

 // mp.c
@@ -227,6 +228,7 @@ void		rcu_gc_worker(void);
 void            sampstart(void);
 int             sampintr(struct trapframe*);
 void            sampdump(void);
+void            sampconf(void);

 // spinlock.c
 void            acquire(struct spinlock*);

--- a/lapic.c
+++ b/lapic.c
@@ -183,6 +183,12 @@ lapic_tlbflush(u32 cpu)
  lapic_ipi(cpu, T_TLBFLUSH);
 }

+void
+lapic_sampconf(u32 cpu)
+{
+  lapic_ipi(cpu, T_SAMPCONF);
+}
+
 // Start additional processor running bootstrap code at addr.
 // See Appendix B of MultiProcessor Specification.
 void

--- a/sampler.c
+++ b/sampler.c
@@ -8,6 +8,7 @@
 #include "kernel.h"
 #include "bits.h"
 #include "amd64.h"
+#include "cpu.h"

 static const u64 debug_sel = 
  0UL << 32 |
@@ -87,13 +88,25 @@ sampdump(void)
 }

 void
-sampstart(void)
+sampconf(void)
 {
  pushcli();
  pmu.config(0, debug_sel, -debug_cnt);
  popcli();
 }

+void
+sampstart(void)
+{
+  for(struct cpu *c = cpus; c < cpus+ncpu; c++) {
+    if(c == cpus+cpunum())
+      continue;
+    lapic_sampconf(c->id);
+  }
+
+  sampconf();
+}
+
 static int
 samplog(struct trapframe *tf)
 {

--- a/trap.c
+++ b/trap.c
@@ -113,8 +113,10 @@ trap(struct trapframe *tf)
    lapiceoi();
    lcr3(rcr3());
    break;
-   
-  //PAGEBREAK: 13
+  case T_SAMPCONF:
+    lapiceoi();
+    sampconf();  
+    break;
  default:
    if(myproc() == 0 || (tf->cs&3) == 0){
      // In kernel, it must be our mistake.

--- a/traps.h
+++ b/traps.h
@@ -26,6 +26,7 @@
 // processor defined exceptions or interrupt vectors.
 #define T_SYSCALL       64      // system call
 #define T_TLBFLUSH      65      // flush TLB
+#define T_SAMPCONF      66      // configure event counters
 #define T_DEFAULT      500      // catchall

 #define T_IRQ0          32      // IRQ 0 corresponds to int T_IRQ