[Bug general/4389] New: ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[Bug general/4389] New: ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

Here is a trace of TestBreakpoints under a merged ptrace/event-loop:


FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
notifyCodeBreakpoint(134,514,608)

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceTaskState$Running handleSignaledEvent
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
handleSignaledEvent, signal: 5

17-Apr-07 5:36:20 PM frysk.proc.Task notifySignaled
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
notifySignaled(int)

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceTask sendContinue
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
sendContinue

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceWaitBuilder getTask
FINE: {TaskId,1569} stopped

17-Apr-07 5:36:20 PM frysk.proc.Host get
FINE: {frysk.proc.LinuxPtraceHost@17f990,state=running} get TaskId

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceTaskState$Running handleSignaledEvent
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
handleSignaledEvent, signal: 11

17-Apr-07 5:36:20 PM frysk.proc.Task notifySignaled
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
notifySignaled(int)

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceTask sendContinue
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1569,tid=1569,state=running}
sendContinue

17-Apr-07 5:36:20 PM frysk.proc.LinuxPtraceWaitBuilder getTask
FINE: {TaskId,1569} exitEvent


and here is the same trace, when the ptrace server is being used:


FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1563,tid=1563,state=running}
notifyCodeBreakpoint(134,514,608)

17-Apr-07 5:36:11 PM frysk.proc.LinuxPtraceTaskState$Running handleSignaledEvent
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1563,tid=1563,state=running}
handleSignaledEvent, signal: 5

17-Apr-07 5:36:11 PM frysk.proc.Task notifySignaled
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1563,tid=1563,state=running}
notifySignaled(int)

17-Apr-07 5:36:11 PM frysk.proc.LinuxPtraceTask sendContinue
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1563,tid=1563,state=running}
sendContinue

17-Apr-07 5:36:11 PM frysk.proc.LinuxPtraceWaitBuilder getTask
FINE: {TaskId,1563} stopped

17-Apr-07 5:36:11 PM frysk.proc.Host get
FINE: {frysk.proc.LinuxPtraceHost@17f990,state=running} get TaskId

17-Apr-07 5:36:11 PM frysk.proc.LinuxPtraceTaskState$Running handleTrappedEvent
FINE: {frysk.proc.LinuxPtraceTask@37eee0,pid=1563,tid=1563,state=running}
handleTrappedEvent


Notice how, in the first trace, after the breakpoint has been processed the next
thing back is a signal 11 - sigsegv, while, for the second case, another
breakpoint is seen.

-- 
           Summary: ptrace in event-loop causes TestBreakpoints inferior to
                    sig-seg-v
           Product: frysk
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: general
        AssignedTo: frysk-bugzilla at sourceware dot org
        ReportedBy: cagney at redhat dot com
OtherBugsDependingO 1522
             nThis:


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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

------- Additional Comments From cagney at redhat dot com  2007-04-17 23:34 -------
Dropped the tag cagney-20070413-pt-segv-branch.

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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

------- Additional Comments From cagney at redhat dot com  2007-04-17 23:46 -------
Here are the dieing moments of the trace; pt=7 is PT_CONTINUE:

poke space=frysk.sys.Ptrace$AddressSpace@3c7970:USR pid=3664 index=114 value=f0
ptrace: pt=3 pid=3664 addr=0x114 data=0x0 -> 0xffff0ff0
ptrace: pt=6 pid=3664 addr=0x114 data=0xffff0ff0 -> 0x0
poke space=frysk.sys.Ptrace$AddressSpace@3c7970:USR pid=3664 index=115 value=f
ptrace: pt=3 pid=3664 addr=0x114 data=0x0 -> 0xffff0ff0
ptrace: pt=6 pid=3664 addr=0x114 data=0xffff0ff0 -> 0x0
poke space=frysk.sys.Ptrace$AddressSpace@3c7970:USR pid=3664 index=116 value=ff
ptrace: pt=3 pid=3664 addr=0x114 data=0x0 -> 0xffff0ff0
ptrace: pt=6 pid=3664 addr=0x114 data=0xffff0ff0 -> 0x0
poke space=frysk.sys.Ptrace$AddressSpace@3c7970:USR pid=3664 index=117 value=ff
ptrace: pt=3 pid=3664 addr=0x114 data=0x0 -> 0xffff0ff0
ptrace: pt=6 pid=3664 addr=0x114 data=0xffff0ff0 -> 0x0
ptrace: pt=12 pid=3664 addr=0x0 data=0x3c2378 -> 0x0
ptrace: pt=7 pid=3664 addr=0x0 data=0x5 -> 0x0
ptrace: pt=7 pid=3664 addr=0x0 data=0xb -> 0x0
ptrace: pt=16897 pid=3664 addr=0x0 data=0xbfb16ad8 -> 0x0
ptrace: pt=7 pid=3664 addr=0x0 data=0xb -> 0x0

and it's sending PT_CONT of signal 5/SIGTRAP to the process.  Per other
discussion, if in a signal handler this can kill the inferior.

-- 


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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[mark at klomp dot org]

------- Additional Comments From mark at klomp dot org  2007-04-18 12:34 -------
(In reply to comment #2)
> and it's sending PT_CONT of signal 5/SIGTRAP to the process.  Per other
> discussion, if in a signal handler this can kill the inferior.

Not in this case since the funit-breakpoints uses the SA_NODEFER workaround. The
test does check that SIGTRAP and segfaults not caused by frysk itself are
propagated correctly. See bug #3997 for a discussion about this.

I'll checkout the branch and test first against the simpler unit tests first.
TestTaskObserverCode which only does a set breakpoint, run, check that it got
hit (maybe expand it to then continue running again), the
TestTaskObserverInstruction test, the TestTaskObserverInstructionSigReturn and
the combined TestTaskObserverInstructionAndCode tests. If those work then we can
proceed with the all singing and dancing TestBreakpoints which is really a
combination of all those tests.

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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[mark at klomp dot org]

------- Additional Comments From mark at klomp dot org  2007-04-18 13:10 -------
On cagney-20070413-pt-segv-branch 9FC6 x86_64, kernel 2.6.20-1.2944:

testCode(frysk.proc.TestTaskObserverCode)
testInstruction(frysk.proc.TestTaskObserverInstruction)
both PASS

testStepSigReturn(frysk.proc.TestTaskObserverInstructionSigReturn)
testInstructionAndCode(frysk.proc.TestTaskObserverInstructionAndCode)
both FAIL

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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

------- Additional Comments From cagney at redhat dot com  2007-04-18 18:58 -------
Found one issue:

2007-04-18  Andrew Cagney  <cagney@redhat.com>

        * RegisterSetByteBuffer.java (GetRegs.execute): Call
        registerSet.set, not get.



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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[mark at klomp dot org]

------- Additional Comments From mark at klomp dot org  2007-04-19 13:55 -------
That issue seems to have been it.

frysk.proc.TestTaskObserverCode
frysk.proc.TestTaskObserverInstruction
frysk.proc.TestTaskObserverInstructionSigReturn
frysk.proc.TestTaskObserverInstructionAndCode
frysk.proc.TestBreakpoints

All PASS for me now.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=4389

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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

------- Additional Comments From cagney at redhat dot com  2007-04-19 15:21 -------
We're missing a testcase for this root-cause failure.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |


http://sourceware.org/bugzilla/show_bug.cgi?id=4389

------- You are receiving this mail because: -------
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[Bug general/4389] ptrace in event-loop causes TestBreakpoints inferior to sig-seg-v

[cagney at redhat dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|frysk-bugzilla at sourceware|cagney at redhat dot com
                   |dot org                     |
             Status|REOPENED                    |ASSIGNED


http://sourceware.org/bugzilla/show_bug.cgi?id=4389

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