From: Masami Hiramatsu <mhiramat@kernel.org>
To: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S . Miller" <davem@davemloft.net>, X86 ML <x86@kernel.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH -tip 1/3] x86/kprobes: Retrieve correct opcode for group instruction
Date: Wed, 3 Mar 2021 00:25:24 +0900 [thread overview]
Message-ID: <161469872400.49483.18214724458034233166.stgit@devnote2> (raw)
In-Reply-To: <161469871251.49483.9142858308048988638.stgit@devnote2>
Since the opcodes start from 0xff are group5 instruction group which is
not 2 bytes opcode but the extended opcode determined by the MOD/RM byte.
The commit abd82e533d88 ("x86/kprobes: Do not decode opcode in resume_execution()")
used insn->opcode.bytes[1], but that is not correct. We have to refer
the insn->modrm.bytes[1] instead.
Fixes: abd82e533d88 ("x86/kprobes: Do not decode opcode in resume_execution()")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
arch/x86/kernel/kprobes/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index df776cdca327..08674e7a5d7b 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -448,7 +448,11 @@ static void set_resume_flags(struct kprobe *p, struct insn *insn)
break;
#endif
case 0xff:
- opcode = insn->opcode.bytes[1];
+ /*
+ * Since the 0xff is an extended group opcode, the instruction
+ * is determined by the MOD/RM byte.
+ */
+ opcode = insn->modrm.bytes[0];
if ((opcode & 0x30) == 0x10) {
/*
* call absolute, indirect
next prev parent reply other threads:[~2021-03-02 18:08 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 23:24 Why do kprobes and uprobes singlestep? Andy Lutomirski
2021-02-24 1:17 ` Masami Hiramatsu
2021-02-24 19:45 ` Andy Lutomirski
2021-02-25 2:22 ` Masami Hiramatsu
2021-02-25 6:03 ` Andy Lutomirski
2021-02-25 9:11 ` Masami Hiramatsu
2021-03-01 14:08 ` [RFC PATCH 0/1] x86/kprobes: Remoev single-step trap from x86 kprobes Masami Hiramatsu
2021-03-01 14:08 ` [RFC PATCH 1/1] x86/kprobes: Use int3 instead of debug trap for single-step Masami Hiramatsu
2021-03-02 8:06 ` Peter Zijlstra
2021-03-02 8:38 ` Peter Zijlstra
2021-03-02 8:41 ` Peter Zijlstra
2021-03-02 8:54 ` Peter Zijlstra
2021-03-02 12:51 ` Masami Hiramatsu
2021-03-02 13:58 ` Peter Zijlstra
2021-03-02 15:25 ` [PATCH -tip 0/3] x86/kprobes: Remoev single-step trap from x86 kprobes Masami Hiramatsu
2021-03-02 15:25 ` Masami Hiramatsu [this message]
2021-03-23 15:15 ` [tip: x86/core] x86/kprobes: Retrieve correct opcode for group instruction tip-bot2 for Masami Hiramatsu
2021-03-02 15:25 ` [PATCH -tip 2/3] x86/kprobes: Identify far indirect JMP correctly Masami Hiramatsu
2021-03-23 15:15 ` [tip: x86/core] " tip-bot2 for Masami Hiramatsu
2021-03-02 15:25 ` [PATCH -tip 3/3] x86/kprobes: Use int3 instead of debug trap for single-step Masami Hiramatsu
2021-03-23 15:15 ` [tip: x86/core] " tip-bot2 for Masami Hiramatsu
2021-03-17 14:55 ` [PATCH -tip 0/3] x86/kprobes: Remoev single-step trap from x86 kprobes Masami Hiramatsu
2021-03-17 16:26 ` Peter Zijlstra
2021-03-17 17:45 ` Andy Lutomirski
2021-02-25 9:59 ` Why do kprobes and uprobes singlestep? Peter Zijlstra
2021-03-01 16:51 ` Oleg Nesterov
2021-03-02 1:36 ` Andy Lutomirski
2021-03-02 20:24 ` Alexei Starovoitov
2021-03-02 21:02 ` Andy Lutomirski
2021-03-03 1:22 ` Alexei Starovoitov
2021-03-03 1:46 ` Andy Lutomirski
2021-03-03 2:18 ` Alexei Starovoitov
2021-03-03 13:27 ` Oleg Nesterov
2021-03-03 18:11 ` Daniel Xu
2021-03-03 19:14 ` Andy Lutomirski
2021-03-02 20:25 ` Oleg Nesterov
2021-03-02 20:35 ` Andy Lutomirski
2021-03-02 20:28 ` Oleg Nesterov
2021-03-02 2:22 ` Masami Hiramatsu
2021-03-02 2:48 ` Andy Lutomirski
2021-03-02 20:31 ` Oleg Nesterov
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