From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28827 invoked by alias); 22 Mar 2014 00:49:25 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 28799 invoked by uid 89); 22 Mar 2014 00:49:24 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.5 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.3.2 X-HELO: cdptpa-oedge-vip.email.rr.com Received: from cdptpa-outbound-snat.email.rr.com (HELO cdptpa-oedge-vip.email.rr.com) (107.14.166.232) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sat, 22 Mar 2014 00:49:23 +0000 Received: from [67.255.60.225] ([67.255.60.225:50150] helo=gandalf.local.home) by cdptpa-oedge03 (envelope-from ) (ecelerity 3.5.0.35861 r(Momo-dev:tip)) with ESMTP id ED/1A-25638-D0EDC235; Sat, 22 Mar 2014 00:49:22 +0000 Date: Sat, 22 Mar 2014 00:49:00 -0000 From: Steven Rostedt To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Jeremy Fitzhardinge , x86@kernel.org, Andi Kleen , Ananth N Mavinakayanahalli , Arnd Bergmann , Peter Zijlstra , Frederic Weisbecker , Rusty Russell , "David S. Miller" , Chris Wright , Sandeepa Prabhu , fche@redhat.com, mingo@redhat.com, Rob Landley , "H. Peter Anvin" , Thomas Gleixner , Alok Kataria , systemtap@sourceware.org Subject: Re: [PATCH -tip v8 04/26] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Message-ID: <20140321204917.636820fa@gandalf.local.home> In-Reply-To: <20140305115911.22766.61140.stgit@ltc230.yrl.intra.hitachi.co.jp> References: <20140305115843.22766.8355.stgit@ltc230.yrl.intra.hitachi.co.jp> <20140305115911.22766.61140.stgit@ltc230.yrl.intra.hitachi.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-SW-Source: 2014-q1/txt/msg00327.txt.bz2 On Wed, 05 Mar 2014 20:59:11 +0900 Masami Hiramatsu wrote: > > diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt > index 0cfb00f..7062631 100644 > --- a/Documentation/kprobes.txt > +++ b/Documentation/kprobes.txt > @@ -22,8 +22,9 @@ Appendix B: The kprobes sysctl interface > > Kprobes enables you to dynamically break into any kernel routine and > collect debugging and performance information non-disruptively. You > -can trap at almost any kernel code address, specifying a handler > +can trap at almost any kernel code address(*), specifying a handler > routine to be invoked when the breakpoint is hit. > +(*: at some part of kernel code can not be trapped, see 1.5 Blacklist) "*: some parts of the kernel code can not be trapped," > > There are currently three types of probes: kprobes, jprobes, and > kretprobes (also called return probes). A kprobe can be inserted > @@ -273,6 +274,19 @@ using one of the following techniques: > or > - Execute 'sysctl -w debug.kprobes_optimization=n' > > +1.5 Blacklist > + > +Kprobes can probe almost of the kernel except itself. This means s/almost/most/ > +that there are some functions where kprobes cannot probe. Probing > +(trapping) such functions can cause recursive trap (e.g. double cause a recursive trap > +fault) or at least the nested probe handler never be called. "or the nested probe handler may never be called." > +Kprobes manages such functions as a blacklist. > +If you want to add a function into the blacklist, you just need > +to (1) include linux/kprobes.h and (2) use NOKPROBE_SYMBOL() macro > +to specify a blacklisted function. > +Kprobes checks given probe address with the blacklist and reject "checks the given probe address against the black list and rejects" > +registering if the given address is in the blacklist. registering it, if > + > 2. Architectures Supported > > Kprobes, jprobes, and return probes are implemented on the following > diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h > index 4582e8e..7730c1c 100644 > --- a/arch/x86/include/asm/asm.h > +++ b/arch/x86/include/asm/asm.h > @@ -57,6 +57,12 @@ > .long (from) - . ; \ > .long (to) - . + 0x7ffffff0 ; \ > .popsection > + > +# define _ASM_NOKPROBE(entry) \ > + .pushsection "_kprobe_blacklist","aw" ; \ > + _ASM_ALIGN ; \ > + _ASM_PTR (entry); \ > + .popsection > #else > # define _ASM_EXTABLE(from,to) \ > " .pushsection \"__ex_table\",\"a\"\n" \ > @@ -71,6 +77,7 @@ > " .long (" #from ") - .\n" \ > " .long (" #to ") - . + 0x7ffffff0\n" \ > " .popsection\n" > +/* For C file, we already have NOKPROBE_SYMBOL macro */ > #endif > > #endif /* _ASM_X86_ASM_H */ > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 1b10af8..4c785fd 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -389,6 +390,9 @@ __visible struct pv_cpu_ops pv_cpu_ops = { > .end_context_switch = paravirt_nop, > }; > > +/* At this point, native_get_debugreg has real function entry */ "has a real" -- Steve > +NOKPROBE_SYMBOL(native_get_debugreg); > + > struct pv_apic_ops pv_apic_ops = { > #ifdef CONFIG_X86_LOCAL_APIC > .startup_ipi_hook = paravirt_nop, > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > index bc2121f..81d07d5 100644 > --- a/include/asm-generic/vmlinux.lds.h