[PATCH ftrace/core 0/2] ftrace, kprobes: Introduce IPMODIFY flag for ftrace_ops to detect conflicts

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

Hi,

Here is a pair of patches which introduces IPMODIFY flag for
ftrace_ops to detect conflicts of ftrace users who can modify
regs->ip in their handler.
Currently, only kprobes can change the regs->ip in the handler,
but recently kpatch is also want to change it. Moreover, since
the ftrace itself exported to modules, it might be considerable
senario.

Here we talked on github.
 https://github.com/dynup/kpatch/issues/47

To protect modified regs-ip from each other, this series
introduces FTRACE_OPS_FL_IPMODIFY flag and ftrace now ensures
the flag can be set on each function entry location. If there
is someone who already reserve regs->ip on target function
entry, ftrace_set_filter_ip or register_ftrace_function will
return -EBUSY. Users must handle that.

At this point, all kprobes will reserve regs->ip, since jprobe
requires it.

Thank you,

---

Masami Hiramatsu (2):
      ftrace: Simplify ftrace_hash_disable/enable path in ftrace_hash_move
      ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict


 Documentation/trace/ftrace.txt |    5 +
 include/linux/ftrace.h         |   10 ++-
 kernel/kprobes.c               |    2 -
 kernel/trace/ftrace.c          |  152 ++++++++++++++++++++++++++++++++++------
 4 files changed, 143 insertions(+), 26 deletions(-)

--