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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Borislav Petkov <bp@alien8.de>, Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	xen-devel@lists.xenproject.org
Subject: [PATCH -tip v2 2/2] x86: kprobes: Prohibit probing on instruction which has emulate prefix
Date: Fri,  6 Sep 2019 09:50:29 +0900	[thread overview]
Message-ID: <156773102959.29031.18377408063770100148.stgit@devnote2> (raw)
In-Reply-To: <156773100816.29031.12557431294039450779.stgit@devnote2>

Prohibit probing on instruction which has XEN_EMULATE_PREFIX
or KVM's emulate prefix. Since that prefix is a marker for Xen
and KVM, if we modify the marker by kprobe's int3, that doesn't
work as expected.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/x86/kernel/kprobes/core.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 43fc13c831af..4f13af7cbcdb 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -351,6 +351,10 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
 	kernel_insn_init(insn, dest, MAX_INSN_SIZE);
 	insn_get_length(insn);
 
+	/* We can not probe force emulate prefixed instruction */
+	if (insn_has_emulate_prefix(insn))
+		return 0;
+
 	/* Another subsystem puts a breakpoint, failed to recover */
 	if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
 		return 0;


WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@alien8.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: [Xen-devel] [PATCH -tip v2 2/2] x86: kprobes: Prohibit probing on instruction which has emulate prefix
Date: Fri,  6 Sep 2019 09:50:29 +0900	[thread overview]
Message-ID: <156773102959.29031.18377408063770100148.stgit@devnote2> (raw)
In-Reply-To: <156773100816.29031.12557431294039450779.stgit@devnote2>

Prohibit probing on instruction which has XEN_EMULATE_PREFIX
or KVM's emulate prefix. Since that prefix is a marker for Xen
and KVM, if we modify the marker by kprobe's int3, that doesn't
work as expected.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/x86/kernel/kprobes/core.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 43fc13c831af..4f13af7cbcdb 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -351,6 +351,10 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
 	kernel_insn_init(insn, dest, MAX_INSN_SIZE);
 	insn_get_length(insn);
 
+	/* We can not probe force emulate prefixed instruction */
+	if (insn_has_emulate_prefix(insn))
+		return 0;
+
 	/* Another subsystem puts a breakpoint, failed to recover */
 	if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
 		return 0;


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  parent reply	other threads:[~2019-09-06  0:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06  0:50 [PATCH -tip v2 0/2] x86: kprobes: Prohibit kprobes on Xen/KVM emulate prefixes Masami Hiramatsu
2019-09-06  0:50 ` [Xen-devel] " Masami Hiramatsu
2019-09-06  0:50 ` [PATCH -tip v2 1/2] x86: xen: insn: Decode Xen and KVM emulate-prefix signature Masami Hiramatsu
2019-09-06  0:50   ` [Xen-devel] " Masami Hiramatsu
2019-09-06  1:13   ` Josh Poimboeuf
2019-09-06  1:13     ` [Xen-devel] " Josh Poimboeuf
2019-09-06  1:39     ` Masami Hiramatsu
2019-09-06  1:39       ` [Xen-devel] " Masami Hiramatsu
2019-09-06  0:50 ` Masami Hiramatsu [this message]
2019-09-06  0:50   ` [Xen-devel] [PATCH -tip v2 2/2] x86: kprobes: Prohibit probing on instruction which has emulate prefix Masami Hiramatsu

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