Review request: 7003789 PTRACE_GETREGS problems with SA on Linux.

Kevin Walls kevin.walls at oracle.com
Fri Dec 3 02:48:35 PST 2010 

>If PTRACE_GETREGS is undefined and PT_GETREGS is defined, PTRACE_GETREGS_REQ will be defined
>by undefined value.

Yes, that was worrying me as well, as it's what I see on my fedora 13 x86_x64 system.

And yes to your second message - we need to leave in the sparcv9 parts.

I'm convinced PTRACE_GETREGS64 only exists on 64-bit sparcv9, and PowerPC were we don't build. If it became defined on a platform that is not 64-bit we will only use it if we are doing a 64-bit build, so that looks good.  Further searching finds this thread...

So here it is as a webrev. Builds and tests OK on x86 and x64.

http://cr.openjdk.java.net/~kevinw/7003789/webrev.01/

Regards
Kevin



On 03/12/2010 06:47, Yasumasa Suenaga wrote:
> Sorry...
>
>> BTW, this modification is for "agent/src/os/linux/ps_proc.c".
>> I guess that this source affects for Linux ONLY.
>> If my guess is correct, we can delete the statement about SPARC from this source code.
>>
>> -------
>> #if defined(sparc) || defined(sparcv9)
>> #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)
>> #else
>> #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
>> #endif
>> -------
>>
>> and
>>
>> -------
>> #ifdef PTRACE_GETREGS64
>> #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>> -------
> This sentence concerns CPU... not OS.
> I don't have Linux on SPARC. So, I can't confirm that Linux (glibc) ptrace() systemcall on SPARC
> can handle PTRACE_GETREGS64.
> If ptrace() interface is different from x86 and SPARC (Linux on SPARC defines PTRACE_GETREGS64),
> my guess is incorrect...
>
> (2010/12/03 15:21), Yasumasa Suenaga wrote:
>> Hi David, Kevin,
>>
>>>    #if defined(PTRACE_GETREGS) || defined(PT_GETREGS)
>>>      #define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>    #endif
>> If PTRACE_GETREGS is undefined and PT_GETREGS is defined, PTRACE_GETREGS_REQ will be defined
>> by undefined value. (PTRACE_GETREGS: 1? decided by preprocessor... does that case exist?)
>>
>> In Linux manpage PTRACE(2) in Fedora14, PTRACE_GETREGS is described, PTRACE_GETREGS64 and
>> PT_GETREGS is NOT described.
>> > My system(Fedora14 x86_64) defines PTRACE_GETREGS and PT_GETREGS, PTRACE_GETREGS64 does NOT define.
>>
>> So, how about this?
>>
>> -------
>> #if defined(_LP64)&&  defined(PTRACE_GETREGS64) /* for SPARCV9(and others?) */
>> #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>> #elif defined(PTRACE_GETREGS) /* for Linux */
>> #define PTRACE_GETREGS_REQ PTRACE_GETREGS
>> #elif defined(PT_GETREGS) /* last resort */
>> #define PTRACE_GETREGS_REQ PT_GETREGS
>> #endif /* _LP64 */
>> -------
>>
>> BTW, this modification is for "agent/src/os/linux/ps_proc.c".
>> I guess that this source affects for Linux ONLY.
>> If my guess is correct, we can delete the statement about SPARC from this source code.
>>
>> -------
>> #if defined(sparc) || defined(sparcv9)
>> #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, addr, data)
>> #else
>> #define ptrace_getregs(request, pid, addr, data) ptrace(request, pid, data, addr)
>> #endif
>> -------
>>
>> and
>>
>> -------
>> #ifdef PTRACE_GETREGS64
>> #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>> -------
>>
>>
>> Thanks.
>> Yasumasa
>>
>>
>> (2010/12/03 12:23), David Holmes wrote:
>>> Kevin Walls said the following on 12/03/10 06:03:
>>>> Thanks both for pointing out that I didn't notice I was smashing the
>>>> 32-bit case. 8-)
>>>>
>>>> I can now build and test 32 and 64-bit OK with...
>>>>
>>>> #ifdef _LP64
>>>>     #ifdef PTRACE_GETREGS64
>>>>       #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>>>>     #elif defined(PTRACE_GETREGS)
>>>>       #define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>>     #elif defined(PT_GETREGS)
>>>>       #define PTRACE_GETREGS_REQ PT_GETREGS
>>>>     #endif
>>>> #else
>>>>     #if defined(PTRACE_GETREGS) || defined(PT_GETREGS)
>>>>       #define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>>     #endif
>>>> #endif /* _LP64 */
>>>>
>>>> My 64-bit system is Fedora and really needs to use PT_REGS as that's the
>>>> only definition. My 32-bit system is a different RedHat and has
>>>> PTRACE_GETREGS defined so the 32-bit build does work. Am tempted to
>>>> change the 32-bit side of the ifdef to also use PT_GETREGS as a last
>>>> resort...
>>> I'd be tempted to do that too. This seems so inconsistent I wouldn't
>>> trust what you might find on any particular linux.
>>>
>>> If we knew that we'd never find PTRACE_GETREGS64 on a 32-bit system we
>>> could make it somewhat simpler.
>>>
>>> David
>>>
>>>> Thanks
>>>> Kevin
>>>>
>>>>
>>>> On 02/12/2010 02:23, Yasumasa Suenaga wrote:
>>>>> Thank you for the reply.
>>>>>
>>>>> I've read your patch on a webrev.
>>>>> Your patch will work on AMD64 architecture.
>>>>> However, this patch will not work on x86 (32bit) architecture.
>>>>> Preprocessor in GCC for i386 does not define "_LP64" .
>>>>>
>>>>> -----------------
>>>>> [root at RHEL4-4 test]# cat /etc/redhat-release
>>>>> Red Hat Enterprise Linux ES release 4 (Nahant Update 4)
>>>>> [root at RHEL4-4 test]# uname -a
>>>>> Linux RHEL4-4 2.6.9-42.EL #1 Wed Jul 12 23:16:43 EDT 2006 i686 i686 i386 GNU/Linux
>>>>> [root at RHEL4-4 test]# rpm -q glibc
>>>>> glibc-2.3.4-2.25
>>>>> [root at RHEL4-4 test]# rpm -q gcc
>>>>> gcc-3.4.6-3
>>>>> [root at RHEL4-4 test]# touch test.h
>>>>> [root at RHEL4-4 test]# cpp -dM test.h | grep _LP64
>>>>> [root at RHEL4-4 test]#
>>>>> -----------------
>>>>>
>>>>>
>>>>> So, you need to modify the patch as follows:
>>>>>
>>>>> -----------------
>>>>> [root at Fedora13 OpenJDK7]# diff -u b118/openjdk/hotspot/agent/src/os/linux/ps_proc.c trunk/
>>>>> openjdk/hotspot/agent/src/os/linux/ps_proc.c
>>>>> --- a/agent/src/os/linux/ps_proc.c   2010-11-12 05:43:12.000000000 +0900
>>>>> +++ b/agent/src/os/linux/ps_proc.c   2010-12-02 10:45:09.117050388 +0900
>>>>> @@ -124,6 +124,8 @@
>>>>>    #ifdef _LP64
>>>>>    #ifdef PTRACE_GETREGS64
>>>>>    #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>>>>> +#elif defined(PTRACE_GETREGS)
>>>>> +#define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>>>    #endif
>>>>>    #else
>>>>>    #if defined(PTRACE_GETREGS) || defined(PT_GETREGS)
>>>>> -----------------
>>>>>
>>>>>
>>>>> Thanks.
>>>>>
>>>>>
>>>>> (2010/12/02 1:41), Kevin Walls wrote:
>>>>>> Sorry, there was actually a typo in that diff, although it was good
>>>>>> enough to be a solution on my system.
>>>>>>
>>>>>> A webrev also:
>>>>>>
>>>>>> http://cr.openjdk.java.net/~kevinw/7003789/webrev.00/
>>>>>>
>>>>>> Thanks
>>>>>> Kevin
>>>>>>
>>>>>>
>>>>>> On 01/12/2010 16:01, Kevin Walls wrote:
>>>>>>> Hi --
>>>>>>>
>>>>>>> I've just been hitting that as well.... I think it needs to be dealt
>>>>>>> with as a separate bug as there may be a few which are similar - and
>>>>>>> 6359295 is marked fixed in 5.0 long ago...
>>>>>>>
>>>>>>> I just found your message after I'd done some investigating... The patch
>>>>>>> I was working with is to split one of the existing "if defined"
>>>>>>> statements, as currently the bug is: if we have PT_GETREGS defined, we
>>>>>>> use PTRACE_GETREGS to define PTRACE_GETREGS_REQ... We soon realise that
>>>>>>> may NOT be defined and give the "unsupported" message. So I can log and
>>>>>>> bug and get this done if it sounds good:
>>>>>>>
>>>>>>> [kevin at oldbox make]$ hg diff  ../src/os/linux/ps_proc.c
>>>>>>> diff --git a/agent/src/os/linux/ps_proc.c b/agent/src/os/linux/ps_proc.c
>>>>>>> --- a/agent/src/os/linux/ps_proc.c
>>>>>>> +++ b/agent/src/os/linux/ps_proc.c
>>>>>>> @@ -124,9 +124,9 @@
>>>>>>>     #ifdef _LP64
>>>>>>>     #ifdef PTRACE_GETREGS64
>>>>>>>     #define PTRACE_GETREGS_REQ PTRACE_GETREGS64
>>>>>>> -#endif
>>>>>>> -#else
>>>>>>> -#if defined(PTRACE_GETREGS) || defined(PT_GETREGS)
>>>>>>> +#elif defined(PTRACE_GETREGS)
>>>>>>> +#define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>>>>> +#elif defined (PT_GETREGS)
>>>>>>>     #define PTRACE_GETREGS_REQ PTRACE_GETREGS
>>>>>>>     #endif
>>>>>>>     #endif /* _LP64 */
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Regards
>>>>>>> Kevin
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 15/11/2010 06:46, Yasumasa Suenaga wrote:
>>>>>>>> Hi.
>>>>>>>>
>>>>>>>> I and co-worker use jstack for various trouble shooting.
>>>>>>>>
>>>>>>>> We mainly use Java on Linux with AMD64 architecture.
>>>>>>>> However, jstack -F option doesn't work our platform.
>>>>>>>>
>>>>>>>> I ran jstack -F with LIBSAPROC_DEBUG=1 (environment variable),
>>>>>>>> I got following messages:
>>>>>>>>
>>>>>>>>
>>>>>>>> /***************/
>>>>>>>> Thread 31933: (state = BLOCKED)
>>>>>>>> libsaproc DEBUG: ptrace(PTRACE_GETREGS, ...) not supported
>>>>>>>> Error occurred during stack walking:
>>>>>>>> sun.jvm.hotspot.debugger.DebuggerException: sun.jvm.hotspot.debugger.DebuggerException: get_thread_regs failed for a lwp
>>>>>>>> /***************/
>>>>>>>>
>>>>>>>>
>>>>>>>> In order to fix this problem, I made a patch for preprocessor
>>>>>>>> macro in "agent/src/os/linux/ps_proc.c" .
>>>>>>>> The patch that attached this mail works well on Fedora 13 x86_64.
>>>>>>>>
>>>>>>>> Please merge this patch if you don't fix this problem yet.
>>>>>>>>
>>>>>>>>
>>>>>>>> Best regards.
>>>>>>>>
>>>>>>>>
>>
>

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