author | Shawn Walker-Salas <shawn.walker@oracle.com> |
Thu, 14 Apr 2016 12:48:37 -0700 | |
changeset 5781 | ecbdf40c0a37 |
parent 5331 | 9c955076ffe3 |
permissions | -rw-r--r-- |
5331
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
1 |
From 2a6c7739b5bdb5fbaf743d89a18bd466fb178fe1 Mon Sep 17 00:00:00 2001 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
2 |
From: Austin Clements <[email protected]> |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
3 |
Date: Wed, 18 Nov 2015 13:20:35 -0500 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
4 |
Subject: [PATCH 46/63] [release-branch.go1.5] runtime: handle sigprof in |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
5 |
stackBarrier |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
6 |
|
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
7 |
Currently, if a profiling signal happens in the middle of |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
8 |
stackBarrier, gentraceback may see inconsistencies between stkbar and |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
9 |
the barriers on the stack and it will certainly get the wrong return |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
10 |
PC for stackBarrier. In most cases, the return PC won't be a PC at all |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
11 |
and this will immediately abort the traceback (which is considered |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
12 |
okay for a sigprof), but if it happens to be a valid PC this may sent |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
13 |
gentraceback down a rabbit hole. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
14 |
|
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
15 |
Fix this by detecting when the gentraceback starts in stackBarrier and |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
16 |
simulating the completion of the barrier to get the correct initial |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
17 |
frame. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
18 |
|
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
19 |
Change-Id: Ib11f705ac9194925f63fe5dfbfc84013a38333e6 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
20 |
Reviewed-on: https://go-review.googlesource.com/17035 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
21 |
Reviewed-by: Russ Cox <[email protected]> |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
22 |
Run-TryBot: Austin Clements <[email protected]> |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
23 |
TryBot-Result: Gobot Gobot <[email protected]> |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
24 |
Reviewed-on: https://go-review.googlesource.com/17056 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
25 |
--- |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
26 |
src/runtime/traceback.go | 28 ++++++++++++++++++++++++++++ |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
27 |
1 file changed, 28 insertions(+) |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
28 |
|
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
29 |
diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
30 |
index 2def359..aed6cbd 100644 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
31 |
--- a/src/runtime/traceback.go |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
32 |
+++ b/src/runtime/traceback.go |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
33 |
@@ -188,6 +188,34 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
34 |
} |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
35 |
|
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
36 |
f := findfunc(frame.pc) |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
37 |
+ if f.entry == stackBarrierPC { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
38 |
+ // We got caught in the middle of a stack barrier |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
39 |
+ // (presumably by a signal), so stkbar may be |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
40 |
+ // inconsistent with the barriers on the stack. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
41 |
+ // Simulate the completion of the barrier. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
42 |
+ // |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
43 |
+ // On x86, SP will be exactly one word above |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
44 |
+ // savedLRPtr. On LR machines, SP will be above |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
45 |
+ // savedLRPtr by some frame size. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
46 |
+ var stkbarPos uintptr |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
47 |
+ if len(stkbar) > 0 && stkbar[0].savedLRPtr < sp0 { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
48 |
+ // stackBarrier has not incremented stkbarPos. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
49 |
+ stkbarPos = gp.stkbarPos |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
50 |
+ } else if gp.stkbarPos > 0 && gp.stkbar[gp.stkbarPos-1].savedLRPtr < sp0 { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
51 |
+ // stackBarrier has incremented stkbarPos. |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
52 |
+ stkbarPos = gp.stkbarPos - 1 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
53 |
+ } else { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
54 |
+ printlock() |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
55 |
+ print("runtime: failed to unwind through stackBarrier at SP ", hex(sp0), " index ", gp.stkbarPos, "; ") |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
56 |
+ gcPrintStkbars(gp.stkbar) |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
57 |
+ print("\n") |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
58 |
+ throw("inconsistent state in stackBarrier") |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
59 |
+ } |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
60 |
+ |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
61 |
+ frame.pc = gp.stkbar[stkbarPos].savedLRVal |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
62 |
+ stkbar = gp.stkbar[stkbarPos+1:] |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
63 |
+ f = findfunc(frame.pc) |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
64 |
+ } |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
65 |
if f == nil { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
66 |
if callback != nil { |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
67 |
print("runtime: unknown pc ", hex(frame.pc), "\n") |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
68 |
-- |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
69 |
2.6.1 |
9c955076ffe3
PSARC/2015/203 Google Go version 1.5
Shawn Walker-Salas <shawn.walker@oracle.com>
parents:
diff
changeset
|
70 |