bcm64: implement dtracy support

sys/src/9/bcm64/l.s

@@ -658,3 +658,16 @@ TEXT vserr(SB), 1, $-4
 	ORR	$(3<<32), R0	// type
 _vserrpatch:
 	B	_vserrpatch	// branch to vtrapX() patched in
+
+/* fault-proof memcpy */
+TEXT peek(SB), 1, $-4
+	MOV	R0, R1
+	MOV	dst+8(FP), R2
+	MOVWU	len+16(FP), R0
+TEXT _peekinst(SB), 1, $-4
+_peekloop:
+	MOVBU	(R1)1!, R3
+	MOVBU	R3, (R2)1!
+	SUBS	$1, R0
+	BNE	_peekloop
+	RETURN

sys/src/9/bcm64/mkfile

@@ -65,6 +65,7 @@ LIB=\
 	/$objtype/lib/libsec.a\
 	/$objtype/lib/libmp.a\
 	/$objtype/lib/libc.a\
+	/$objtype/lib/libdtracy.a\
 
 9:V: $p$CONF s$p$CONF
 

sys/src/9/bcm64/pi3

@@ -21,6 +21,7 @@ dev
 #	gpio	gpio
 	sd
 	usb
+	dtracy
 
 link
 	loopbackmedium
@@ -43,6 +44,9 @@ misc
 	dma
 	vcore
 
+	dtracysys
+	dtracytimer
+
 port
 	int cpuserver = 0;
 

sys/src/9/bcm64/trap.c

@@ -442,13 +442,22 @@ faultarm64(Ureg *ureg)
 	insyscall = up->insyscall;
 	up->insyscall = 1;
 
-	if(!userureg(ureg) && waserror()){
-		if(up->nerrlab == 0){
-			pprint("suicide: sys: %s\n", up->errstr);
-			pexit(up->errstr, 1);
+	if(!userureg(ureg)){
+		extern void _peekinst(void);
+
+		if(ureg->pc == (uintptr)_peekinst){
+			ureg->pc = ureg->link;
+			goto out;
+		}
+
+		if(waserror()){
+			if(up->nerrlab == 0){
+				pprint("suicide: sys: %s\n", up->errstr);
+				pexit(up->errstr, 1);
+			}
+			up->insyscall = insyscall;
+			nexterror();
 		}
-		up->insyscall = insyscall;
-		nexterror();
 	}
 
 	addr = getfar();
@@ -486,6 +495,7 @@ faultarm64(Ureg *ureg)
 	if(!userureg(ureg))
 		poperror();
 
+out:
 	up->insyscall = insyscall;
 }