kprof did not guess correctly the kernel start
address, nor did take into account that it
should compare addresses using
symboladdress>>3 and not
using profilingaddress<<3, because that might
report the wrong function even if resolution suffices.

It now uses libmach kernel start address instead
of trying to guess it.
the start address for 386 seems to be  wrong in libmach

Reference: /n/sources/patch/applied/kprof
Date: Fri Nov 18 16:52:56 CET 2011
Signed-off-by: nemo@lsub.org

--- /sys/src/cmd/kprof.c	Fri Nov 18 16:52:01 2011
+++ /sys/src/cmd/kprof.c	Fri Nov 18 16:51:58 2011
@@ -94,19 +94,25 @@
 		exits(0);
 	if (!textsym(&s, 0))
 		error(0, "no text symbols");
-	tbase = s.value & ~(mach->pgsize-1);	/* align down to page */
-	print("KTZERO %.8llux\n", tbase);
+
+	tbase = mach->kbase;
+	if(tbase != s.value & ~0xFFF)
+		print("warning: kbase %.8llux != tbase %.8llux\n",
+			tbase, s.value&~0xFFF);
+	print("KTZERO %.8llux PGSIZE %dKb\n", tbase, mach->pgsize/1024);
 	/*
 	 * Accumulate counts for each function
 	 */
 	cp = 0;
 	k = 0;
-	for (i = 0, j = (s.value-tbase)/PCRES+2; j < n; i++) {
+	for (i = 0, j = 2; j < n; i++) {
 		name = s.name;		/* save name */
 		if (!textsym(&s, i))	/* get next symbol */
 			break;
+		s.value -= tbase;
+		s.value /= PCRES;
 		sum = 0;
-		while (j < n && j*PCRES < s.value-tbase)
+		while (j < n && j < s.value)
 			sum += data[j++];
 		if (sum) {
 			cp = realloc(cp, (k+1)*sizeof(struct COUNTER));
--- /sys/src/libmach/8.c	Fri Nov 18 16:52:06 2011
+++ /sys/src/libmach/8.c	Fri Nov 18 16:52:03 2011
@@ -68,7 +68,7 @@
 	"setSB",	/* static base register name (bogus anyways) */
 	0,		/* static base register value */
 	0x1000,		/* page size */
-	0x80100000ULL,	/* kernel base */
+	0xF0100000ULL,	/* kernel base */
 	0xF0000000ULL,	/* kernel text mask */
 	0x7FFFFFFFULL,	/* user stack top */
 	1,		/* quantization of pc */