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userspace probe breakage with gcc 4.8 due to inablility to locate semaphore variable


I had a userspace probe (details below) and this worked fine with stap 1.6 and gcc 4.6.  After upgrading to gcc 4.8, this has stopped working. (I believe this to be the only change, everything else on the box is the same)

stap âL detects the probe as follows:

$  stap -L 'process("/tmp/app").provider(âfooâ).mark("*")'

But, stap âg âvvvvv with the following probe fails with failure to find foo_bar_semaphore

probe process("/tmp/app").provider("foo").mark("bar")

dwarf_builder::build for /tmp/app
pattern '/tmp/app' matches module '/tmp/app'
focused on module '/tmp/app' = [0x0x400000, -0x0x6bc09d8, bias 0x0 file /tmp/app ELF machine |x86_64 (code 62)
focused on module '/tmp/app'
pattern 'bar' matches function 'bar'
pattern 'foo' matches function 'foo'
saw .note.stapsdt ipsendv (provider foo)  @0xf515bb
matched probe_name bar probe type uprobe3 at 0xf515bb
probe_type == uprobe3, use statement addr: 0xf515bb
pattern '/tmp/tcp_app' matches module '/tmp/app'
focused on module '/tmp/app' = [0x0x400000, -0x0x6bc09d8, bias 0x0 file /tmp/app ELF machine |x86_64 (code 62)
focused on module '/tmp/app'
query_addr 0xf515bb
looking for semaphore symbol foo_bar_semaphore , not found
looking for semaphore symbol foo_bar , not found
semantic error: no match while resolving probe point process("/tmp/app").provider("foo").mark("bar")
deleting module_cache
Pass 2: analyzed script: 1 probe(s), 10 function(s), 1 embed(s), 0 global(s) using 345860virt/73640res/19472shr kb, in 550usr/20sys/567real ms.
Pass 2: analysis failed.  Try again with another '--vp 01' option.

Any help in resolving the above is greatly appreciated.


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