Merge branch 'master' into dev.garbage

Change-Id: I36274cf72b8e1908efc8e375cab7880d7b0b3f43

1 files changed, 26 insertions, 1 deletions

diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index ea9a69aa1e..0f1a5c1c55 100644
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -123,6 +123,9 @@ const (
 	stackPoisonCopy  = 0 // fill stack that should not be accessed with garbage, to detect bad dereferences during copy
 
 	stackCache = 1
+
+	// check the BP links during traceback.
+	debugCheckBP = false
 )
 
 const (
@@ -598,7 +601,7 @@ func adjustpointers(scanp unsafe.Pointer, cbv *bitvector, adjinfo *adjustinfo, f
 			pp := (*uintptr)(add(scanp, i*sys.PtrSize))
 		retry:
 			p := *pp
-			if f != nil && 0 < p && p < _PageSize && debug.invalidptr != 0 {
+			if f != nil && 0 < p && p < minLegalPointer && debug.invalidptr != 0 {
 				// Looks like a junk value in a pointer slot.
 				// Live analysis wrong?
 				getg().m.traceback = 2
@@ -688,6 +691,16 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 		if stackDebug >= 3 {
 			print("      saved bp\n")
 		}
+		if debugCheckBP {
+			// Frame pointers should always point to the next higher frame on
+			// the Go stack (or be nil, for the top frame on the stack).
+			bp := *(*uintptr)(unsafe.Pointer(frame.varp))
+			if bp != 0 && (bp < adjinfo.old.lo || bp >= adjinfo.old.hi) {
+				println("runtime: found invalid frame pointer")
+				print("bp=", hex(bp), " min=", hex(adjinfo.old.lo), " max=", hex(adjinfo.old.hi), "\n")
+				throw("bad frame pointer")
+			}
+		}
 		adjustpointer(adjinfo, unsafe.Pointer(frame.varp))
 	}
 
@@ -719,6 +732,18 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 
 func adjustctxt(gp *g, adjinfo *adjustinfo) {
 	adjustpointer(adjinfo, unsafe.Pointer(&gp.sched.ctxt))
+	if !framepointer_enabled {
+		return
+	}
+	if debugCheckBP {
+		bp := gp.sched.bp
+		if bp != 0 && (bp < adjinfo.old.lo || bp >= adjinfo.old.hi) {
+			println("runtime: found invalid top frame pointer")
+			print("bp=", hex(bp), " min=", hex(adjinfo.old.lo), " max=", hex(adjinfo.old.hi), "\n")
+			throw("bad top frame pointer")
+		}
+	}
+	adjustpointer(adjinfo, unsafe.Pointer(&gp.sched.bp))
 }
 
 func adjustdefers(gp *g, adjinfo *adjustinfo) {