Hi, 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 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 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. https://lkml.org/lkml/2014/6/17/175 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(-) -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
