Move the kernel-specific logic to adjust frompc from MI to MD. For

these two reasons:
1. On ia64 a function pointer does not hold the address of the first
   instruction of a functions implementation. It holds the address
   of a function descriptor. Hence the user(), btrap(), eintr() and
   bintr() prototypes are wrong for getting the actual code address.
2. The logic forces interrupt, trap and exception entry points to
   be layed-out contiguously. This can not be achieved on ia64 and is
   generally just bad programming.

The MCOUNT_FROMPC_USER macro is used to set the frompc argument to
some kernel address which represents any frompc that falls outside
the kernel text range. The macro can expand to ~0U to bail out in
that case.
The MCOUNT_FROMPC_INTR macro is used to set the frompc argument to
some kernel address to represent a call to a trap or interrupt
handler. This to avoid that the trap or interrupt handler appear to
be called from everywhere in the call graph. The macro can expand
to ~0U to prevent adjusting frompc. Note that the argument is selfpc,
not frompc.

This commit defines the macros on all architectures equivalently to
the original code in sys/libkern/mcount.c. People can take it from
here...

Compile-tested on: alpha, amd64, i386, ia64 and sparc64
Boot-tested on: i386

1 files changed, 21 insertions, 33 deletions

diff --git a/sys/libkern/mcount.c b/sys/libkern/mcount.c
index 1a9f8ac..d967fe8 100644
--- a/sys/libkern/mcount.c
+++ b/sys/libkern/mcount.c
@@ -39,10 +39,6 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm.h>
 #include <vm/vm_param.h>
 #include <vm/pmap.h>
-void	bintr(void);
-void	btrap(void);
-void	eintr(void);
-void	user(void);
 #endif
 
 /*
@@ -61,16 +57,16 @@ void	user(void);
  * perform this optimization.
  */
 _MCOUNT_DECL(frompc, selfpc)	/* _mcount; may be static, inline, etc */
-	register uintfptr_t frompc, selfpc;
+	uintfptr_t frompc, selfpc;
 {
 #ifdef GUPROF
 	int delta;
 #endif
-	register fptrdiff_t frompci;
-	register u_short *frompcindex;
-	register struct tostruct *top, *prevtop;
-	register struct gmonparam *p;
-	register long toindex;
+	fptrdiff_t frompci;
+	u_short *frompcindex;
+	struct tostruct *top, *prevtop;
+	struct gmonparam *p;
+	long toindex;
 #ifdef _KERNEL
 	MCOUNT_DECL(s)
 #endif
@@ -89,24 +85,20 @@ _MCOUNT_DECL(frompc, selfpc)	/* _mcount; may be static, inline, etc */
 #else
 	p->state = GMON_PROF_BUSY;
 #endif
-	frompci = frompc - p->lowpc;
 
 #ifdef _KERNEL
 	/*
-	 * When we are called from an exception handler, frompci may be
-	 * for a user address.  Convert such frompci's to the index of
-	 * user() to merge all user counts.
+	 * When we are called from an exception handler, frompc may be
+	 * a user address.  Convert such frompc's to some representation
+	 * in kernel address space.
 	 */
-	if (frompci >= p->textsize) {
-		if (frompci + p->lowpc
-		    >= (uintfptr_t)(VM_MAXUSER_ADDRESS))
-			goto done;
-		frompci = (uintfptr_t)user - p->lowpc;
-		if (frompci >= p->textsize)
-		    goto done;
-	}
+	frompc = MCOUNT_FROMPC_USER(frompc);
 #endif
 
+	frompci = frompc - p->lowpc;
+	if (frompci >= p->textsize)
+		goto done;
+
 #ifdef GUPROF
 	if (p->state == GMON_PROF_HIRES) {
 		/*
@@ -141,18 +133,14 @@ _MCOUNT_DECL(frompc, selfpc)	/* _mcount; may be static, inline, etc */
 	/*
 	 * When we are called from an exception handler, frompc is faked
 	 * to be for where the exception occurred.  We've just solidified
-	 * the count for there.  Now convert frompci to the index of btrap()
-	 * for trap handlers and bintr() for interrupt handlers to make
-	 * exceptions appear in the call graph as calls from btrap() and
-	 * bintr() instead of calls from all over.
+	 * the count for there.  Now convert frompci to an index that
+	 * represents the kind of exception so that interruptions appear
+	 * in the call graph as calls from those index instead of calls
+	 * from all over.
 	 */
-	if ((uintfptr_t)selfpc >= (uintfptr_t)btrap
-	    && (uintfptr_t)selfpc < (uintfptr_t)eintr) {
-		if ((uintfptr_t)selfpc >= (uintfptr_t)bintr)
-			frompci = (uintfptr_t)bintr - p->lowpc;
-		else
-			frompci = (uintfptr_t)btrap - p->lowpc;
-	}
+	frompc = MCOUNT_FROMPC_INTR(selfpc);
+	if ((frompc - p->lowpc) < p->textsize)
+		frompci = frompc - p->lowpc;
 #endif
 
 	/*