[PATCH ftrace/for-next v5 0/5] ftrace, kprobes: Introduce IPMODIFY flag for ftrace_ops to detect conflicts

From: Masami Hiramatsu
Date: Thu Oct 09 2014 - 09:01:23 EST


Hi,

Here is the 5th 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.

The previous version is here;
https://lkml.org/lkml/2014/7/28/13

This version is basically an update of previous version to the
latest ftrace tree, and adding a test code to selftest.

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.
The ftrace_ops with IPMODIFY flag requires at least one
entry for filter hash, and its notrace_hash must be empty,
because the IPMODIFY action is very address sensitve and
user must consider the ip address.

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.

Thank you,

---

Masami Hiramatsu (5):
kprobes/ftrace: Recover original IP if pre_handler doesn't change it
ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict
kprobes: Add IPMODIFY flag to kprobe_ftrace_ops
kprobes: Set IPMODIFY flag only if the probe can change regs->ip
kselftest,ftrace: Add ftrace IPMODIFY flag test


Documentation/kprobes.txt | 12 +
Documentation/trace/ftrace.txt | 5 +
arch/x86/kernel/kprobes/ftrace.c | 9 +
include/linux/ftrace.h | 16 ++
kernel/kprobes.c | 123 +++++++++++++--
kernel/trace/ftrace.c | 142 +++++++++++++++++
tools/testing/selftests/ftrace/Makefile | 11 +
tools/testing/selftests/ftrace/ipmodify/Makefile | 15 ++
tools/testing/selftests/ftrace/ipmodify/ipmodify.c | 168 ++++++++++++++++++++
.../selftests/ftrace/ipmodify/run_ipmodify.sh | 6 +
10 files changed, 478 insertions(+), 29 deletions(-)
create mode 100644 tools/testing/selftests/ftrace/ipmodify/Makefile
create mode 100644 tools/testing/selftests/ftrace/ipmodify/ipmodify.c
create mode 100644 tools/testing/selftests/ftrace/ipmodify/run_ipmodify.sh

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