linux-kernel - [PATCH -tip v2 0/2] x86: kprobes: Prohibit kprobes on Xen/KVM emulate prefixes

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Message-Id: <156773100816.29031.12557431294039450779.stgit@devnote2>
Date:   Fri,  6 Sep 2019 09:50:08 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Subject: [PATCH -tip v2 0/2] x86: kprobes: Prohibit kprobes on Xen/KVM emulate prefixes

Hi,

Here is the 2nd version of patches to handle Xen/KVM emulate
prefix by x86 instruction decoder.

These patches allow x86 instruction decoder to decode
Xen and KVM emulate prefix correctly, and prohibit kprobes to
probe on it.

Josh reported that the objtool can not decode such special
prefixed instructions, and I found that we also have to
prohibit kprobes to probe on such instruction.

This series can be applied on -tip master branch which
has merged Josh's objtool/perf sharing common x86 insn
decoder series.

In this version, I added KVM emulate prefix support and generalized
the interface. (insn_has_xen_prefix -> insn_has_emulate_prefix)
Also, I added insn.emulate_prefix_size for those prefixes because
that prefix is NOT an x86 instruction prefix, and the next instruction
of those emulate prefixes can have x86 instruction prefix. So we
can not use insn.prefix for it.

Thank you,

---

Masami Hiramatsu (2):
      x86: xen: insn: Decode Xen and KVM emulate-prefix signature
      x86: kprobes: Prohibit probing on instruction which has emulate prefix

 arch/x86/include/asm/insn.h             |    6 +++++
 arch/x86/include/asm/xen/interface.h    |    7 ++++--
 arch/x86/include/asm/xen/prefix.h       |   10 +++++++++
 arch/x86/kernel/kprobes/core.c          |    4 +++
 arch/x86/lib/insn.c                     |   36 +++++++++++++++++++++++++++++++
 tools/arch/x86/include/asm/insn.h       |    6 +++++
 tools/arch/x86/include/asm/xen/prefix.h |   10 +++++++++
 tools/arch/x86/lib/insn.c               |   36 +++++++++++++++++++++++++++++++
 tools/objtool/sync-check.sh             |    3 ++-
 9 files changed, 115 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86/include/asm/xen/prefix.h
 create mode 100644 tools/arch/x86/include/asm/xen/prefix.h

--
Masami Hiramatsu (Linaro) <mhiramat@...nel.org>