Messages in this thread | | | Subject | [PATCH ftrace/for-next v5 0/5] ftrace, kprobes: Introduce IPMODIFY flag for ftrace_ops to detect conflicts | From | Masami Hiramatsu <> | Date | Thu, 09 Oct 2014 13:00:59 +0000 |
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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,
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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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