Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756433AbaLWQlW (ORCPT ); Tue, 23 Dec 2014 11:41:22 -0500 Received: from mail-ob0-f177.google.com ([209.85.214.177]:61754 "EHLO mail-ob0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756262AbaLWQlV (ORCPT ); Tue, 23 Dec 2014 11:41:21 -0500 MIME-Version: 1.0 In-Reply-To: <20141223155714.GC21816@e104818-lin.cambridge.arm.com> References: <20141223155714.GC21816@e104818-lin.cambridge.arm.com> Date: Wed, 24 Dec 2014 00:41:20 +0800 Message-ID: Subject: Re: [PATCH] arm64: setup return path for el1_undef From: Min-Hua Chen To: Catalin Marinas Cc: Will Deacon , AKASHI Takahiro , Kevin Hilman , Larry Bassel , Laura Abbott , "zhangwm@marvell.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 23, 2014 at 11:57 PM, Catalin Marinas wrote: > On Tue, Dec 23, 2014 at 03:15:10PM +0000, Min-Hua Chen wrote: >> Setup return path for el1_undef since el1_undef may >> be handled by handlers. > > Did you find a real issue or it was just code inspection. Thanks for your reply. It was just a code inspection. Min-Hua > >> asmlinkage void __exception do_undefinstr(struct pt_regs *regs) >> { >> siginfo_t info; >> void __user *pc = (void __user *)instruction_pointer(regs); >> >> /* check for AArch32 breakpoint instructions */ >> if (!aarch32_break_handler(regs)) >> return; >> >> if (call_undef_hook(regs) == 0) >> return; >> >> ... >> } >> Signed-off-by: Min-Hua Chen >> --- >> arch/arm64/kernel/entry.S | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S >> index fd4fa37..86ebec5 100644 >> --- a/arch/arm64/kernel/entry.S >> +++ b/arch/arm64/kernel/entry.S >> @@ -313,7 +313,8 @@ el1_undef: >> */ >> enable_dbg >> mov x0, sp >> - b do_undefinstr >> + bl do_undefinstr >> + kernel_exit 1 >> el1_dbg: >> /* >> * Debug exception handling > > I don't think this is needed. The code is pretty convoluted but for an > EL1 undefined exception we should never return from do_undefinstr(). The > call_undef_hook() function returns 1 if !user_mode(regs) and this should > cause a kernel panic. Basically we do not allow any kind of undefined > instructions in the arm64 kernel. > > -- > Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/