linux-kernel - [RFC PATCH 0/2] kprobes/x86: Handle probing on ex

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Date:   Tue, 28 Feb 2017 01:12:18 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC PATCH 0/2] kprobes/x86: Handle probing on ex_table cases

Hi Peter,

Here, I've tried to handle kprobes on exception expected
instructions which are recorded in __ex_table.

1st patch fixes recover_probed_instruction() to use
probe_kernel_read() instead of memcpy kernel text.
So, if you need to get the original instruction for
checking the cause of #UD, you can use it instead
of probe_kernel_read().

2nd patch adds kprobe_exit_singlestep() right before
fixup_exception(), which fixes regs->ip to point original
address and reset current singlestepping process so that
fixup_exeption() can handle the exception correctly.

There seems some die() still not be fixed up. I'm not
sure we should fix that die() messages too. Would we
better fixup regs->ip in those cases?

Thank you,

---

Masami Hiramatsu (2):
      kprobes/x86: Use probe_kernel_read instead of memcpy
      kprobes/x86: Exit single-stepping before trying fixup_exception

 arch/x86/include/asm/kprobes.h |    1 
 arch/x86/kernel/kprobes/core.c |   90 +++++++++++++++++++++++++---------------
 arch/x86/kernel/kprobes/opt.c  |    5 ++
 arch/x86/kernel/traps.c        |   19 ++++++++
 4 files changed, 80 insertions(+), 35 deletions(-)

--
Masami Hiramatsu