Hello,
I have a fortran program and want to monitor entry/return events of a specific
function. No big thing (I thought). The function is called DCNTRL in the source
code. Checking the binary gives:
> nm myprog | grep FUNC | grep -i DCNTRL
[15968] | 6564704| 30193|FUNC |GLOB |0 |12 |dcntrl_
OK, its internal name is dcntrl_. Let's instrument the respective pid
entry/return probes:
> dtrace -n 'pid$target::dcntrl_:entry' -n 'pid$target::dcntrl_:return' -c
> myprog
dtrace: invalid probe specifier pid$target::dcntrl_:return: probe description
pid17186::dcntrl_:return does not match any probes
Huh, DTrace does not find the return probe!? But I'm sure the function exist,
so let's put some pressure on DTrace (-Z):
> dtrace -Z -n 'pid$target::dcntrl_:entry' -n 'pid$target::dcntrl_:return' -c
> myprog
dtrace: description 'pid$target::dcntrl*:entry' matched 1 probe
dtrace: description 'pid$target::dcntrl*:return' matched 0 probes
First question: How comes DTrace can instrument the entry probe, but not the
return probe of that function?
Now let's count events a the instrumented probes:
> dtrace -Z -n 'pid$target::dcntrl_:entry
> {...@f[probefunc,probename]=count()}' -n 'pid$target::dcntrl_:return
> {...@f[probefunc,probename]=count()}' -c myprog
dcntrl_ entry
1
Hm, seems like that function was only called once. Fact is, it was called a
couple of times (verified), but the probe seems only to fire the first time.
I conclude that I'm unable to both instrument and observe the function. Does
anyone have an idea, how I could proceed?
Thanks for your help, Manfred
PS: I explicitly switched inlining off for that function. (-inline=no%dcntrl).
Just for reference, I attach the first and last lines of the function:
> mdb myprog
> dcntrl_::dis
dcntrl_: pushq %rbp
dcntrl_+1: movq %rsp,%rbp
dcntrl_+4: pushq %rbx
dcntrl_+5: pushq %r12
dcntrl_+7: pushq %r13
dcntrl_+9: pushq %r14
dcntrl_+0xb: pushq %r15
[..]
dcntrl_+0x75e6: popq %r15
dcntrl_+0x75e8: popq %r14
dcntrl_+0x75ea: popq %r13
dcntrl_+0x75ec: popq %r12
dcntrl_+0x75ee: popq %rbx
dcntrl_+0x75ef: leave
dcntrl_+0x75f0: ret
--
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