[PATCH ftrace/core v3 0/3] ftrace, kprobes: Introduce IPMODIFY flag for ftrace_ops to detect conflicts

From: Masami Hiramatsu
Date: Tue Jul 15 2014 - 02:00:28 EST


Here is the 3rd version of the series of patches which introduces
IPMODIFY flag for ftrace_ops to detect conflicts of ftrace users
who can modify regs->ip in their handler.
This version is basically an update of previous version, however
I've descided to split the kprobe/x86 side fix to an independent
patch (which is [1/3])

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

Here we talked on github.

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.

The 3rd patch adds a special reservation of IPMODIFY on the
jprobed address, since it is the only user who will change
the regs->ip. Other kprobes do not change it anymore.

For testing, see the testcase in the previous version.

Thank you,


Masami Hiramatsu (3):
[BUGFIX]kprobes/ftrace: Recover original IP if pre_handler doesn't change it
ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict
kprobes: Set IPMODIFY flag only if the probe can change regs->ip

Documentation/kprobes.txt | 12 +--
Documentation/trace/ftrace.txt | 5 +
arch/x86/kernel/kprobes/ftrace.c | 9 ++-
include/linux/ftrace.h | 15 ++++
kernel/kprobes.c | 122 +++++++++++++++++++++++++++++++----
kernel/trace/ftrace.c | 132 +++++++++++++++++++++++++++++++++++++-
6 files changed, 266 insertions(+), 29 deletions(-)


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