Review request: 7003789 PTRACE_GETREGS problems with SA on Linux.

Yasumasa Suenaga suenaga.yasumasa at oss.ntt.co.jp
Thu Dec 2 22:47:42 PST 2010 

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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