From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751672AbdGYX6K (ORCPT ); Tue, 25 Jul 2017 19:58:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:56584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751403AbdGYX6J (ORCPT ); Tue, 25 Jul 2017 19:58:09 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EAFB822B69 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, 26 Jul 2017 08:58:04 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Cc: Ingo Molnar , Francis Deslauriers , mathieu.desnoyers@efficios.com, Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S . Miller" , linux-kernel@vger.kernel.org Subject: Re: [PATCH -tip V3] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code Message-Id: <20170726085804.8c723289a56bf171b3e5aa30@kernel.org> In-Reply-To: <150099447887.21894.9704149273177353678.stgit@devbox> References: <150099447887.21894.9704149273177353678.stgit@devbox> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-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, 25 Jul 2017 23:54:49 +0900 Masami Hiramatsu wrote: > Since the kernel segment registers are not prepared at the > entry of irq-entry code, if a kprobe on such code is > jump-optimized, accessing per-cpu variables may cause > kernel panic. > However, if the kprobe is not optimized, it kicks int3 > exception and set segment registers correctly. > > This checks probe-address and if it is in irq-entry code, > it prohibits optimizing such kprobes. This means we can > continuously probing such interrupt handlers by kprobes > but it is not optimized anymore. > > Signed-off-by: Masami Hiramatsu > Reported-by: Francis Deslauriers > Tested-by: Francis Deslauriers > --- > Changes in V3: > - Define __irqentry_text_start/end symbols when CONFIG_OPTPROBES=y. > --- > arch/x86/kernel/kprobes/opt.c | 9 ++++++--- > include/asm-generic/vmlinux.lds.h | 6 ++++-- > include/linux/interrupt.h | 3 ++- > 3 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c > index 69ea0bc..c26e7f9 100644 > --- a/arch/x86/kernel/kprobes/opt.c > +++ b/arch/x86/kernel/kprobes/opt.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr) > > /* > * Do not optimize in the entry code due to the unstable > - * stack handling. > + * stack handling and registers setup. > */ > - if ((paddr >= (unsigned long)__entry_text_start) && > - (paddr < (unsigned long)__entry_text_end)) > + if (((paddr >= (unsigned long)__entry_text_start) && > + (paddr < (unsigned long)__entry_text_end)) || > + ((paddr >= (unsigned long)__irqentry_text_start) && > + (paddr < (unsigned long)__irqentry_text_end))) > return 0; > > /* Check there is enough space for a relative jump. */ > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index da0be9a..3092a1f 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -483,7 +483,8 @@ > *(.entry.text) \ > VMLINUX_SYMBOL(__entry_text_end) = .; > > -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) > +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ > + defined(CONFIG_OPTPROBES) > #define IRQENTRY_TEXT \ > ALIGN_FUNCTION(); \ > VMLINUX_SYMBOL(__irqentry_text_start) = .; \ > @@ -493,7 +494,8 @@ > #define IRQENTRY_TEXT > #endif > > -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) > +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ > + defined(CONFIG_OPTPROBES) > #define SOFTIRQENTRY_TEXT \ > ALIGN_FUNCTION(); \ > VMLINUX_SYMBOL(__softirqentry_text_start) = .; \ > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index a2fdddd..a1b78f4 100644 > --- a/include/linux/interrupt.h > +++ b/include/linux/interrupt.h > @@ -726,7 +726,8 @@ extern int early_irq_init(void); > extern int arch_probe_nr_irqs(void); > extern int arch_early_irq_init(void); > > -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) > +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) || \ > + defined(CONFIG_KPROBES) Oops, this should be CONFIG_OPTPROBES... > /* > * We want to know which function is an entrypoint of a hardirq or a softirq. > */ > -- Masami Hiramatsu