[PATCH v1 0/9] uretprobes: Return uprobes implementation

[Anton Arapov <anton@redhat.com>]

Hello All!

Uretprobes' core implementation. Enables a function's return probes in uprobe-
based event tracing.

Patchset introduce additional handler (ret_handler) in uprobe consumer that
defines uretprobe.

There is a regular uprobe with return probe handler behind every uretprobe.
Once hit the uprobe that has ret_handler set, we hijack the return address of
the probed function and replace it with the address of trampoline. Trampoline
is a preallocated page in probed task's xol area that filled with breakpoint
opcode. In turn, when the return breakpoint is hit, we invoke the ret_handler.

The patchset shouldn't be difficult to read and hopefully the comments to
commits will help. Please, review.

patchset in git:
  http://github.com/arapov/linux-aa/commits/uretprobes_v1

previous versions:
  v0: https://lkml.org/lkml/2013/3/22/218

RFC reviews:
  RFCv4: https://lkml.org/lkml/2013/3/4/246
  RFCv3: https://lkml.org/lkml/2013/2/28/148
  RFCv2: https://lkml.org/lkml/2013/1/9/157
  RFCv1: https://lkml.org/lkml/2012/12/21/133

thanks,
Anton.

Anton Arapov (9):
  uretprobes: Introduce uprobe_consumer->ret_handler()
  uretprobes: Reserve the first slot in xol_vma for trampoline
  uretprobes/x86: Hijack return address
  uretprobes/ppc: Hijack return address
  uretprobes: Return probe entry, prepare_uretprobe()
  uretprobes: Return probe exit, invoke handlers
  uretprobes: Limit the depth of return probe nestedness
  uretprobes: Remove -ENOSYS as return probes implemented
  uretprobes: Documentation update
 
 Documentation/trace/uprobetracer.txt | 126 +++++++++++++---------
 arch/powerpc/include/asm/uprobes.h   |   1 +
 arch/powerpc/kernel/uprobes.c        |  13 +++
 arch/x86/include/asm/uprobes.h       |   1 +
 arch/x86/kernel/uprobes.c            |  29 +++++
 include/linux/uprobes.h              |   7 ++
 kernel/events/uprobes.c              | 202 +++++++++++++++++++++++++++++++++--
 7 files changed, 320 insertions(+), 59 deletions(-)

-- 
1.8.1.4