From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752352AbdJCPhZ (ORCPT ); Tue, 3 Oct 2017 11:37:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:42320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752056AbdJCPhX (ORCPT ); Tue, 3 Oct 2017 11:37:23 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B27682188D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org Date: Wed, 4 Oct 2017 00:37:20 +0900 From: Masami Hiramatsu To: Josh Poimboeuf , Ingo Molnar Cc: Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S . Miller" , linux-kernel@vger.kernel.org, x86@kernel.org, Richard Weinberger Subject: Re: [PATCH] x86/kprobes: Set up frame pointer in kprobe trampoline Message-Id: <20171004003720.ee20bc25823c76cda8d63ef7@kernel.org> In-Reply-To: <7aef2f8ecd75c2f505ef9b80490412262cf4a44c.1507038547.git.jpoimboe@redhat.com> References: <7aef2f8ecd75c2f505ef9b80490412262cf4a44c.1507038547.git.jpoimboe@redhat.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 3 Oct 2017 08:51:43 -0500 Josh Poimboeuf wrote: > Richard Weinberger saw an unwinder warning when running bcc's opensnoop: > > WARNING: kernel stack frame pointer at ffff99ef4076bea0 in opensnoop:2008 has bad value 0000000000000008 > unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0 > ... > ffff99ef4076be88: ffff99ef4076bea0 (0xffff99ef4076bea0) > ffff99ef4076be90: ffffffffac442721 (optimized_callback +0x81/0x90) > ... > > A lockdep stack trace was initiated from inside a kprobe handler, when > the unwinder noticed a bad frame pointer on the stack. The bad frame > pointer is related to the fact that the kprobe optprobe trampoline > doesn't save the frame pointer before calling into optimized_callback(). OK, this looks good to me :) Acked-by: Masami Hiramatsu Thanks! > > Reported-and-tested-by: Richard Weinberger > Signed-off-by: Josh Poimboeuf > --- > arch/x86/kernel/kprobes/common.h | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/kprobes/common.h b/arch/x86/kernel/kprobes/common.h > index e2c2a1970869..595b56b37d27 100644 > --- a/arch/x86/kernel/kprobes/common.h > +++ b/arch/x86/kernel/kprobes/common.h > @@ -3,6 +3,15 @@ > > /* Kprobes and Optprobes common header */ > > +#include > + > +#ifdef CONFIG_FRAME_POINTER > +# define SAVE_RBP_STRING " push %" _ASM_BP "\n" \ > + " mov %" _ASM_SP ", %" _ASM_BP "\n" > +#else > +# define SAVE_RBP_STRING " push %" _ASM_BP "\n" > +#endif > + > #ifdef CONFIG_X86_64 > #define SAVE_REGS_STRING \ > /* Skip cs, ip, orig_ax. */ \ > @@ -17,7 +26,7 @@ > " pushq %r10\n" \ > " pushq %r11\n" \ > " pushq %rbx\n" \ > - " pushq %rbp\n" \ > + SAVE_RBP_STRING \ > " pushq %r12\n" \ > " pushq %r13\n" \ > " pushq %r14\n" \ > @@ -48,7 +57,7 @@ > " pushl %es\n" \ > " pushl %ds\n" \ > " pushl %eax\n" \ > - " pushl %ebp\n" \ > + SAVE_RBP_STRING \ > " pushl %edi\n" \ > " pushl %esi\n" \ > " pushl %edx\n" \ > -- > 2.13.6 > -- Masami Hiramatsu