From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A04EC433E0 for ; Fri, 10 Jul 2020 22:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 777332065F for ; Fri, 10 Jul 2020 22:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726336AbgGJWAS (ORCPT ); Fri, 10 Jul 2020 18:00:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:36328 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726260AbgGJWAR (ORCPT ); Fri, 10 Jul 2020 18:00:17 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9B6F12075D; Fri, 10 Jul 2020 22:00:15 +0000 (UTC) Date: Fri, 10 Jul 2020 18:00:14 -0400 From: Steven Rostedt To: Peter Zijlstra , mhiramat@kernel.org Cc: x86@kernel.org, linux-kernel@vger.kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, pbonzini@redhat.com, mathieu.desnoyers@efficios.com, linux@rasmusvillemoes.dk Subject: Re: [PATCH v6 08/17] static_call: Avoid kprobes on inline static_call()s Message-ID: <20200710180014.08803c91@oasis.local.home> In-Reply-To: <20200710134336.619632370@infradead.org> References: <20200710133831.943894387@infradead.org> <20200710134336.619632370@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 10 Jul 2020 15:38:39 +0200 Peter Zijlstra wrote: > Similar to how we disallow kprobes on any other dynamic text > (ftrace/jump_label) also disallow kprobes on inline static_call()s. > > Signed-off-by: Peter Zijlstra (Intel) I'd like to have Masami review this patch too. > --- > arch/x86/kernel/kprobes/opt.c | 4 +- > include/linux/static_call.h | 11 +++++++ > kernel/kprobes.c | 2 + > kernel/static_call.c | 64 ++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 80 insertions(+), 1 deletion(-) > > --- a/arch/x86/kernel/kprobes/opt.c > +++ b/arch/x86/kernel/kprobes/opt.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -209,7 +210,8 @@ static int copy_optimized_instructions(u > /* Check whether the address range is reserved */ > if (ftrace_text_reserved(src, src + len - 1) || > alternatives_text_reserved(src, src + len - 1) || > - jump_label_text_reserved(src, src + len - 1)) > + jump_label_text_reserved(src, src + len - 1) || > + static_call_text_reserved(src, src + len - 1)) > return -EBUSY; > > return len; > --- a/include/linux/static_call.h > +++ b/include/linux/static_call.h > @@ -110,6 +110,7 @@ struct static_call_key { > > extern void __static_call_update(struct static_call_key *key, void *tramp, void *func); > extern int static_call_mod_init(struct module *mod); > +extern int static_call_text_reserved(void *start, void *end); > > #define DEFINE_STATIC_CALL(name, _func) \ > DECLARE_STATIC_CALL(name, _func); \ > @@ -153,6 +154,11 @@ void __static_call_update(struct static_ > cpus_read_unlock(); > } > > +static inline int static_call_text_reserved(void *start, void *end) > +{ > + return 0; > +} > + > #define EXPORT_STATIC_CALL(name) \ > EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \ > EXPORT_SYMBOL(STATIC_CALL_TRAMP(name)) > @@ -182,6 +188,11 @@ void __static_call_update(struct static_ > WRITE_ONCE(key->func, func); > } > > +static inline int static_call_text_reserved(void *start, void *end) > +{ > + return 0; > +} > + > #define EXPORT_STATIC_CALL(name) EXPORT_SYMBOL(STATIC_CALL_KEY(name)) > #define EXPORT_STATIC_CALL_GPL(name) EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name)) > > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -35,6 +35,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1591,6 +1592,7 @@ static int check_kprobe_address_safe(str > if (!kernel_text_address((unsigned long) p->addr) || > within_kprobe_blacklist((unsigned long) p->addr) || > jump_label_text_reserved(p->addr, p->addr) || > + static_call_text_reserved(p->addr, p->addr) || > find_bug((unsigned long)p->addr)) { > ret = -EINVAL; > goto out; > --- a/kernel/static_call.c > +++ b/kernel/static_call.c > @@ -204,8 +204,58 @@ static int __static_call_init(struct mod > return 0; > } > > +static int addr_conflict(struct static_call_site *site, void *start, void *end) > +{ > + unsigned long addr = (unsigned long)static_call_addr(site); > + > + if (addr <= (unsigned long)end && > + addr + CALL_INSN_SIZE > (unsigned long)start) > + return 1; > + > + return 0; > +} > + > +static int __static_call_text_reserved(struct static_call_site *iter_start, > + struct static_call_site *iter_stop, > + void *start, void *end) > +{ > + struct static_call_site *iter = iter_start; > + > + while (iter < iter_stop) { > + if (addr_conflict(iter, start, end)) > + return 1; > + iter++; > + } > + > + return 0; > +} > + > #ifdef CONFIG_MODULES > > +static int __static_call_mod_text_reserved(void *start, void *end) > +{ > + struct module *mod; > + int ret; > + > + preempt_disable(); > + mod = __module_text_address((unsigned long)start); > + WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); > + if (!try_module_get(mod)) > + mod = NULL; > + preempt_enable(); > + > + if (!mod) > + return 0; > + > + ret = __static_call_text_reserved(mod->static_call_sites, > + mod->static_call_sites + mod->num_static_call_sites, > + start, end); > + > + module_put(mod); > + > + return ret; > +} > + > static int static_call_add_module(struct module *mod) > { > return __static_call_init(mod, mod->static_call_sites, > @@ -275,6 +325,20 @@ static struct notifier_block static_call > > #endif /* CONFIG_MODULES */ > > +int static_call_text_reserved(void *start, void *end) > +{ > + int ret = __static_call_text_reserved(__start_static_call_sites, > + __stop_static_call_sites, start, end); > + > + if (ret) > + return ret; > + > +#ifdef CONFIG_MODULES > + ret = __static_call_mod_text_reserved(start, end); > +#endif Nit, but why not have a #else /* !CONFIG_MODULE */ above and just: static inline int __static_call_mod_text_reserve(..) { return 0; } #endif ? Then you don't need the extra #ifdef above, and just end it with: return __static_call_mod_next_reserved(start, end); -- Steve > + return ret; > +} > + > static void __init static_call_init(void) > { > int ret; >