linux-kernel - Re: [RFC PATCH 6/6] uprobes/x86: Emulate rip-relative conditional "near" jmp's

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Date:	Mon, 7 Apr 2014 16:28:23 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <aarapov@...hat.com>,
	David Long <dave.long@...aro.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Jim Keniston <jkenisto@...ibm.com>,
	Jonathan Lebon <jlebon@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 6/6] uprobes/x86: Emulate rip-relative conditional
	"near" jmp's

On 04/06, Oleg Nesterov wrote:
>
> But I'll try to cleanup this patch...

See v2 below.

-------------------------------------------------------------------------------
Subject: [RFC PATCH v2 6/6] uprobes/x86: Emulate rip-relative conditional "near" jmp's

It seems that 16bit condi jmp is just 0x0f + short_jump_opc_plus_0x10.

Reported-by: Jonathan Lebon <jlebon@...hat.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 arch/x86/kernel/uprobes.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 3865d8b..dae02f9 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -591,6 +591,10 @@ static int ttt_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
 		auprobe->ttt.opc1 = opc1;
 		break;
 
+	case 0x0f:
+		if (insn->opcode.nbytes != 2)
+			return -ENOSYS;
+		opc1 = OPCODE2(insn) - 0x10;
 	default:
 		if (!is_cond_jmp_opcode(opc1))
 			return -ENOSYS;
-- 
1.5.5.1


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