Can't attach core image through SA tools

[Yasumasa Suenaga]

Hi David,

Thank you for your cooperation.
I couldn't find this CR.
I will vote it.

Thanks,
Yasumasa

On 2012/01/31 19:58, David Holmes wrote:
> Hi,
> 
> A bug was opened for this just a few days ago - 7133122.
> 
> I'll add your patch to the CR.
> 
> David Holmes
> ------------
> 
> On 31/01/2012 8:32 PM, Yasumasa Suenaga wrote:
>> Hi,
>>
>> I've tried attach a corefile with jstack. However, I couldn't.
>>
>> I guess that this problem is caused by incorrect address mapping of libsaproc.so .
>> I've made a patch which is attached this email. And I've been able to get correct thread stack with jstack.
>>
>> So, I'd like to contribute this patch, and I'd like to backport to JDK6/7 .
>> Could you help me?
>>
>>
>> ------ details ------
>>
>> I got these messages then I ran jstack with LIBSAPROC_DEBUG environment variable:
>>
>> /*************************/
>>
>>     :
>>
>> libsaproc DEBUG: reading library /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.1.x86_64/jre/lib/amd64/server/libjvm.so @ 0x7f53b455a000 [ 0x7f53b455a000 ]
>> libsaproc DEBUG: ---- sorted virtual address map ----
>>
>>     :
>>
>> libsaproc DEBUG: base = 0x7f53b455a000  size = 9993772
>> libsaproc DEBUG: base = 0x7f53b455a000  size = 4096
>>
>>     :
>>
>> libsaproc DEBUG: can't locate map_info at 0x7f53b4dbe000
>> libsaproc DEBUG: core read failed for 4096 byte(s) @ 0x7f53b4dbe000 (4096 more bytes)
>>
>>     :
>>
>> /*************************/
>>
>> libsaproc.so tries to read libjvm.so library address, and it is duplicated.
>> I read Linux kernel source code of function of core dump, and I found these comment:
>>
>> source code: kernel-3.2.1-3.fc16.src.rpm (Fedora16 x86_64)
>> in fs/binfmt_elf.c: static unsigned long vma_dump_size(struct vm_area_struct *vma, unsigned long mm_flags)
>> ----------------------
>>           /*
>>            * If this looks like the beginning of a DSO or executable mapping,
>>            * check for an ELF header.  If we find one, dump the first page to
>>            * aid in determining what was mapped here.
>>            */
>> ----------------------
>>
>> In fact, core image has executable load section which size is 1 page(0x1000)
>> ----------------------
>>     LOAD           0x0000000005173000 0x00007f53b455a000 0x0000000000000000
>>                    0x0000000000001000 0x0000000000988000  R E    1000
>> ----------------------
>>
>> So, we must think these case when we attach core image.
>> I modified "read_lib_segments()" in hotspot/agent/src/os/linux/ps_core.c to overwrite
>> correct address in shared library .
>>
>>
>> Please check it.
>>
>> Thanks,
>> Yasumasa
>>