runtime: check explicitly for short unwinding of stacks

Right now we find out implicitly if stack barriers are in place,
or defers. This change makes sure we find out about short
unwinds always.

Change-Id: Ibdde1ba9c79eb792660dcb7aa6f186e4e4d559b3
Reviewed-on: https://go-review.googlesource.com/13966
Reviewed-by: Austin Clements <austin@google.com>

diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go
index a5708162de6bfdefe7e8f84c2d767bc38fc678df..35d9e86e8e8ab18bd8fce3abccbcca12b420ed87 100644 (file)
--- a/src/runtime/proc1.go
+++ b/src/runtime/proc1.go
@@ -988,6 +988,7 @@ func newextram() {
        gp.sched.g = guintptr(unsafe.Pointer(gp))
        gp.syscallpc = gp.sched.pc
        gp.syscallsp = gp.sched.sp
+       gp.stktopsp = gp.sched.sp
        // malg returns status as Gidle, change to Gsyscall before adding to allg
        // where GC will see it.
        casgstatus(gp, _Gidle, _Gsyscall)
@@ -2267,6 +2268,7 @@ func newproc1(fn *funcval, argp *uint8, narg int32, nret int32, callerpc uintptr
 
        memclr(unsafe.Pointer(&newg.sched), unsafe.Sizeof(newg.sched))
        newg.sched.sp = sp
+       newg.stktopsp = sp
        newg.sched.pc = funcPC(goexit) + _PCQuantum // +PCQuantum so that previous instruction is in same function
        newg.sched.g = guintptr(unsafe.Pointer(newg))
        gostartcallfn(&newg.sched, fn)

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index fbd43d21da628a5207cedf8bc085c1ea55f8a1dd..7d3c8f6aa2151ee06cb9f6a019f68bec62344bff 100644 (file)
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -229,6 +229,7 @@ type g struct {
        syscallpc      uintptr        // if status==Gsyscall, syscallpc = sched.pc to use during gc
        stkbar         []stkbar       // stack barriers, from low to high
        stkbarPos      uintptr        // index of lowest stack barrier not hit
+       stktopsp       uintptr        // expected sp at top of stack, to check in traceback
        param          unsafe.Pointer // passed parameter on wakeup
        atomicstatus   uint32
        stackLock      uint32 // sigprof/scang lock; TODO: fold in to atomicstatus

diff --git a/src/runtime/stack1.go b/src/runtime/stack1.go
index 9873bd860b43bdea3480b4b35a7f42abbdae1d64..78d168bb5bfe949a18216281fdae847b05ee7327 100644 (file)
--- a/src/runtime/stack1.go
+++ b/src/runtime/stack1.go
@@ -639,6 +639,7 @@ func copystack(gp *g, newsize uintptr) {
        oldsize := gp.stackAlloc
        gp.stackAlloc = newsize
        gp.stkbar = newstkbar
+       gp.stktopsp += adjinfo.delta
 
        // free old stack
        if stackPoisonCopy != 0 {

diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 48ef6e5e27f699b792996496a5e23ae1850c6f97..1025032aeecded0c2b2681f86004fdb664faa0a3 100644 (file)
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -479,6 +479,12 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
                throw("traceback has leftover stack barriers")
        }
 
+       if callback != nil && n < max && frame.sp != gp.stktopsp {
+               print("runtime: g", gp.goid, ": frame.sp=", hex(frame.sp), " top=", hex(gp.stktopsp), "\n")
+               print("\tstack=[", hex(gp.stack.lo), "-", hex(gp.stack.hi), "] n=", n, " max=", max, "\n")
+               throw("traceback did not unwind completely")
+       }
+
        return n
 }