dtrace discuss - Jan 2006 - Dtrace not picking up the symbols for user stack.

Hi,

I was trying to get the user stack from a probe. Like this:

bash-3.00# dtrace -n ''fbt:zfs:zfs_getsecattr:{ustack();
exit(0);}''
dtrace: description ''fbt:zfs:zfs_getsecattr:'' matched 2 probes
CPU     ID                    FUNCTION:NAME
   0  37508             zfs_getsecattr:entry

               0xff31d114
               0xff384da0
               0x13d40
               0x12018
               0x11200

No symbols! The binary is not stripped.

bash-3.00# file /usr/bin/ls
/usr/bin/ls:    ELF 32-bit MSB executable SPARC Version 1, dynamically 
linked, not stripped, no debugging information available

bash-3.00# /usr/ccs/bin/nm /usr/bin/ls | grep main
[142]   |     71488|    3132|FUNC |GLOB |0    |9      |main
[196]   |    155748|       0|FUNC |GLOB |0    |UNDEF  |textdomain

Why is dtrace not picking up the symbols?

I am on snv_30.
bash-3.00# uname -a
SunOS pdruv2 5.11 snv_30 sun4u sparc SUNW,Sun-Fire-V240

Regards,
Manoj

This is because the process that triggered the problem has
itself exited before your dtrace command tried to translate
the addresses into symbols. If you start the triggering
command with a -c argument this may solve your issue.


dtrace -n ''fbt:zfs:zfs_readdir:{ustack(); exit(0);}'' -c
"ls /zfs"
						     ^^^^^^^^^^^^
...
CPU     ID                    FUNCTION:NAME
  0  33305                zfs_readdir:entry 
              libc.so.1`getdents64+0x4
              ls`rddir+0x58
              ls`pdirectory+0xf0
              ls`main+0xaa4
              ls`_start+0x108

-r


Manoj Joseph writes:
 > Hi,
 > 
 > I was trying to get the user stack from a probe. Like this:
 > 
 > bash-3.00# dtrace -n ''fbt:zfs:zfs_getsecattr:{ustack();
exit(0);}''
 > dtrace: description ''fbt:zfs:zfs_getsecattr:'' matched 2
probes
 > CPU     ID                    FUNCTION:NAME
 >    0  37508             zfs_getsecattr:entry
 > 
 >                0xff31d114
 >                0xff384da0
 >                0x13d40
 >                0x12018
 >                0x11200
 > 
 > No symbols! The binary is not stripped.
 > 
 > bash-3.00# file /usr/bin/ls
 > /usr/bin/ls:    ELF 32-bit MSB executable SPARC Version 1, dynamically 
 > linked, not stripped, no debugging information available
 > 
 > bash-3.00# /usr/ccs/bin/nm /usr/bin/ls | grep main
 > [142]   |     71488|    3132|FUNC |GLOB |0    |9      |main
 > [196]   |    155748|       0|FUNC |GLOB |0    |UNDEF  |textdomain
 > 
 > Why is dtrace not picking up the symbols?
 > 
 > I am on snv_30.
 > bash-3.00# uname -a
 > SunOS pdruv2 5.11 snv_30 sun4u sparc SUNW,Sun-Fire-V240
 > 
 > Regards,
 > Manoj
 > 
 > _______________________________________________
 > dtrace-discuss mailing list
 > dtrace-discuss at opensolaris.org

Hi Manoj,

The problem is that while the ustack() action grabs the program counter
stack at probe time, the program counters are resolved to symbols later
when the buffer is snapshotted by the user-land consumer.

In addition to using the -c or -p options as Roch suggested, you can also
use the stop() action to ensure the process doesn''t exit until the
ustack()
has been processed as described toward the end of this page:

  http://docs.sun.com/app/docs/doc/817-6223/6mlkidlmm?a=view

Adam

On Wed, Jan 04, 2006 at 05:16:58PM +0530, Manoj Joseph
wrote:
> Hi,
> 
> I was trying to get the user stack from a probe. Like this:
> 
> bash-3.00# dtrace -n ''fbt:zfs:zfs_getsecattr:{ustack();
exit(0);}''
> dtrace: description ''fbt:zfs:zfs_getsecattr:'' matched 2
probes
> CPU     ID                    FUNCTION:NAME
>   0  37508             zfs_getsecattr:entry
> 
>               0xff31d114
>               0xff384da0
>               0x13d40
>               0x12018
>               0x11200
> 
> No symbols! The binary is not stripped.
> 
> bash-3.00# file /usr/bin/ls
> /usr/bin/ls:    ELF 32-bit MSB executable SPARC Version 1, dynamically 
> linked, not stripped, no debugging information available
> 
> bash-3.00# /usr/ccs/bin/nm /usr/bin/ls | grep main
> [142]   |     71488|    3132|FUNC |GLOB |0    |9      |main
> [196]   |    155748|       0|FUNC |GLOB |0    |UNDEF  |textdomain
> 
> Why is dtrace not picking up the symbols?
> 
> I am on snv_30.
> bash-3.00# uname -a
> SunOS pdruv2 5.11 snv_30 sun4u sparc SUNW,Sun-Fire-V240
> 
> Regards,
> Manoj
> 
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
-- 
Adam Leventhal, Solaris Kernel Development       http://blogs.sun.com/ahl