[Bug runtime/23068] New: need to get section-list for dynamically loaded kernel module

[me at serhei dot io]

https://sourceware.org/bugzilla/show_bug.cgi?id=23068

            Bug ID: 23068
           Summary: need to get section-list for dynamically loaded kernel
                    module
           Product: systemtap
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: runtime
          Assignee: systemtap at sourceware dot org
          Reporter: me at serhei dot io
                CC: smakarov at redhat dot com
  Target Milestone: ---

The only available section-list information for kernel modules is what's
collected and passed by staprun at stap module startup. If a new module is
loaded during the lifetime of a stap module, the new module's section-list info
cannot be accessed from the stap module itself. This prevents e.g. build-id
checking for dynamically loaded modules. 

- on more recent kernels, could the section-list be accessed directly?
- failing that, could staprun be asked to re-run its section-list information
gathering and pass updated info to the module?

Steps to repro:
$ modprobe igb
$ stap -DDEBUG_SYMBOLS=3 -ve 'probe module("igb").function("igb_*_module") {
printf("%s: %s.\n", ctime(gettimeofday_s()), ppfunc()); }'
... observe that section-list for igb is loaded ...
^C
$ rmmod igb
$ stap -DDEBUG_SYMBOLS=3 -ve 'probe module("igb").function("igb_*_module") {
printf("%s: %s.\n", ctime(gettimeofday_s()), ppfunc()); }'
...
$ modprobe igb # while the stap module is running
... observe that section-list for igb is not loaded, build-id check is not
performed, and so forth ...

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