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From: Peter Zijlstra <peterz@infradead.org>
To: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>,
	Suleiman Souhlal <suleiman@google.com>, bpf <bpf@vger.kernel.org>,
	linux-kernel@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	x86@kernel.org
Subject: Re: [PATCH 1/2] x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK
Date: Wed, 7 Sep 2022 09:06:44 +0200	[thread overview]
Message-ID: <YxhDBAhYrs0Sfqjt@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <166251212072.632004.16078953024905883328.stgit@devnote2>

On Wed, Sep 07, 2022 at 09:55:21AM +0900, Masami Hiramatsu (Google) wrote:

> +/* Return the jump target address or 0 */
> +static inline unsigned long insn_get_branch_addr(struct insn *insn)
> +{
> +	switch (insn->opcode.bytes[0]) {
> +	case 0xe0:	/* loopne */
> +	case 0xe1:	/* loope */
> +	case 0xe2:	/* loop */

Oh cute, objtool doesn't know about those, let me go add them.

> +	case 0xe3:	/* jcxz */
> +	case 0xe9:	/* near relative jump */

 /* JMP.d32 */

> +	case 0xeb:	/* short relative jump */

 /* JMP.d8 */

> +		break;
> +	case 0x0f:
> +		if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */

 /* Jcc.d32 */

Are the GNU AS names for these things.

> +			break;
> +		return 0;

> +	default:
> +		if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */
> +			break;
> +		return 0;

You could write that as:

	case 0x70 ... 0x7f: /* Jcc.d8 */
		break;

	default:
		return 0;

> +	}
> +	return (unsigned long)insn->next_byte + insn->immediate.value;
> +}



  reply	other threads:[~2022-09-07  7:06 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-07  0:55 [PATCH 0/2] x86/kprobes: Fixes for CONFIG_RETHUNK Masami Hiramatsu (Google)
2022-09-07  0:55 ` [PATCH 1/2] x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK Masami Hiramatsu (Google)
2022-09-07  7:06   ` Peter Zijlstra [this message]
2022-09-07  9:01     ` [PATCH] objtool,x86: Teach decode about LOOP* instructions Peter Zijlstra
2022-09-07  9:06       ` David Laight
2022-09-07  9:40         ` Peter Zijlstra
2022-09-07 11:13           ` David Laight
2022-09-15 14:24       ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2022-09-07  9:12     ` [PATCH 1/2] x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK Masami Hiramatsu
2022-09-07  9:38       ` Peter Zijlstra
2022-09-07  9:53         ` Masami Hiramatsu
2022-09-07  8:02   ` Peter Zijlstra
2022-09-07  8:11     ` Peter Zijlstra
2022-09-07  9:49     ` Masami Hiramatsu
2022-09-07 10:19       ` Peter Zijlstra
2022-09-07 11:44         ` Peter Zijlstra
2022-09-07 13:05     ` Peter Zijlstra
2022-09-07 14:14       ` Masami Hiramatsu
2022-09-07 14:27         ` Peter Zijlstra
2022-09-07 15:22           ` Masami Hiramatsu
2022-09-07 12:56   ` Peter Zijlstra
2022-09-07 13:49     ` Masami Hiramatsu
2022-09-07 14:28       ` Peter Zijlstra
2022-09-07 12:59   ` Peter Zijlstra
2022-09-07 13:53     ` Masami Hiramatsu
2022-09-07  0:55 ` [PATCH 2/2] x86/kprobes: Fix optprobe optimization " Masami Hiramatsu (Google)
2022-09-07  6:52 ` [PATCH 0/2] x86/kprobes: Fixes for CONFIG_RETHUNK Peter Zijlstra

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