[DTrace-devel] [PATCH v2 0/6] stapsdt provider: simple system-wide probing

[Alan Maguire]

This series adds wildcard support to stapsdt probes to allow
tracing system-wide; this has caveats due to the way the kernel
implements probe addition.  In essence, probes are added on a
per-inode basis (actually in the VMA associated with the inode)
so it is necessary to identify the file where probes are found.
Probes will fire for existing and new processes (the RFC incorrectly
said they will not work for existing binaries; they in fact do).

Patch 1 describes the approach; to facilitate systemwide tracing
we need to tell DTrace the name of the binary/library via the
module field in the probe specifier; we then use [LD_LIBRARY_]PATH
to resolve the full path.  ELF reading of the file and insertion
of probes then proceeds in a similar manner to per-pid tracing.
Full path specification in module name is not supported since
DTrace does not allow a '/' in a module name.

Patches 2-5 test various aspects of systemwide probes; basic
binary support, library support, listing support and is-enabled
probes support.

Patch 6 updates docs to describe wildcard support.

Changes since RFC:

- update documentation/commit messages to reflect that we also
  catch existing programs/libraries when probes are enabled
- fixup provider name for wildcard probes to be 'provider*'
  rather than using the confusing 'provider-1' since the
  latter is the concatenation of probename and pid (-1 is
  used to connote all pids)
- add test for is-enabled systemwide probes

Alan Maguire (6):
  stapsdt provider: support systemwide probing
  test: add systemwide stapsdt note test
  test: add systemwide stapsdt note test for library
  stapsdt: add test for listing systemwide probes in object
  stapsdt: add systemwide test for is-enabled probes
  documentation: update stapsdt docs to describe wildcard support

 .../reference/dtrace_providers_stapsdt.md     |  45 ++++-
 libdtrace/dt_pid.c                            | 158 ++++++++++++----
 libdtrace/dt_prov_uprobe.c                    |  17 +-
 .../tst.stapsdt-notes-systemwide-isenabled.r  |  13 ++
 .../tst.stapsdt-notes-systemwide-isenabled.sh | 177 ++++++++++++++++++
 .../usdt/tst.stapsdt-notes-systemwide-l.sh    |  48 +++++
 .../usdt/tst.stapsdt-notes-systemwide-lib.r   |  14 ++
 .../usdt/tst.stapsdt-notes-systemwide-lib.sh  | 142 ++++++++++++++
 .../usdt/tst.stapsdt-notes-systemwide-lv.sh   |  48 +++++
 .../usdt/tst.stapsdt-notes-systemwide.r       |   2 +
 .../usdt/tst.stapsdt-notes-systemwide.sh      |  51 +++++
 11 files changed, 672 insertions(+), 43 deletions(-)
 create mode 100644 test/unittest/usdt/tst.stapsdt-notes-systemwide-isenabled.r
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-systemwide-isenabled.sh
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-systemwide-l.sh
 create mode 100644 test/unittest/usdt/tst.stapsdt-notes-systemwide-lib.r
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-systemwide-lib.sh
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-systemwide-lv.sh
 create mode 100644 test/unittest/usdt/tst.stapsdt-notes-systemwide.r
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-systemwide.sh

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2.43.5