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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 D6104C433DB for ; Sat, 20 Mar 2021 10:56:46 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 035D461A40 for ; Sat, 20 Mar 2021 10:56:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 035D461A40 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4F2d4D2kyCz3byS for ; Sat, 20 Mar 2021 21:56:44 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=hUozruWt; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linuxfoundation.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=gregkh@linuxfoundation.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=hUozruWt; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4F2d3k2xg3z304Y for ; Sat, 20 Mar 2021 21:56:16 +1100 (AEDT) Received: by mail.kernel.org (Postfix) with ESMTPSA id C26FD61A3E; Sat, 20 Mar 2021 10:56:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616237772; bh=CnkqKhcc/WPXZ1PJ09rzSteqUjpcjox3r41fvuZuU7s=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=hUozruWtEVxsgUFhjdZS6Qx4izdEvfmE6iw7K+q+A6GJG2rcWfwJo7DXrJOoaedej m9mvcycMxukPCBoipJxad684l3JLmu53Hfcqz+pOUbOJ60Pbt/yapfotMsDyXp8MoT t40fFX/F8CedZcC5QvOD/DWWdm8xlcZqS460cZPA= Subject: Patch "vmlinux.lds.h: Create section for protection against instrumentation" has been added to the 4.19-stable tree To: alexandre.chartre@oracle.com, arnd@arndb.de, benh@kernel.crashing.org, dja@axtens.net, drinkcat@chromium.org, gregkh@linuxfoundation.org, groeck@chromium.org, linuxppc-dev@lists.ozlabs.org, michal.lkml@markovi.net, mpe@ellerman.id.au, naveen.n.rao@linux.vnet.ibm.com, npiggin@gmail.com, paulus@samba.org, peterz@infradead.org, sparse@chrisli.org, tglx@linutronix.de, yamada.masahiro@socionext.com From: Date: Sat, 20 Mar 2021 11:56:01 +0100 In-Reply-To: <20210320121614.for-stable-4.19.v2.1.I222f801866f71be9f7d85e5b10665cd4506d78ec@changeid> Message-ID: <161623776156233@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stable-commits@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" This is a note to let you know that I've just added the patch titled vmlinux.lds.h: Create section for protection against instrumentation to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: vmlinux.lds.h-create-section-for-protection-against-instrumentation.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From foo@baz Sat Mar 20 11:54:47 AM CET 2021 From: Nicolas Boichat Date: Sat, 20 Mar 2021 12:16:25 +0800 Subject: vmlinux.lds.h: Create section for protection against instrumentation To: stable@vger.kernel.org Cc: groeck@chromium.org, Thomas Gleixner , Alexandre Chartre , Peter Zijlstra , Nicolas Boichat , Arnd Bergmann , Benjamin Herrenschmidt , Christopher Li , Daniel Axtens , Greg Kroah-Hartman , Masahiro Yamada , Michael Ellerman , Michal Marek , "Naveen N. Rao" , Nicholas Piggin , Paul Mackerras , linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Message-ID: <20210320121614.for-stable-4.19.v2.1.I222f801866f71be9f7d85e5b10665cd4506d78ec@changeid> From: Nicolas Boichat From: Thomas Gleixner commit 6553896666433e7efec589838b400a2a652b3ffa upstream. Some code pathes, especially the low level entry code, must be protected against instrumentation for various reasons: - Low level entry code can be a fragile beast, especially on x86. - With NO_HZ_FULL RCU state needs to be established before using it. Having a dedicated section for such code allows to validate with tooling that no unsafe functions are invoked. Add the .noinstr.text section and the noinstr attribute to mark functions. noinstr implies notrace. Kprobes will gain a section check later. Provide also a set of markers: instrumentation_begin()/end() These are used to mark code inside a noinstr function which calls into regular instrumentable text section as safe. The instrumentation markers are only active when CONFIG_DEBUG_ENTRY is enabled as the end marker emits a NOP to prevent the compiler from merging the annotation points. This means the objtool verification requires a kernel compiled with this option. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134100.075416272@linutronix.de [Nicolas: Guard noinstr macro in include/linux/compiler_types.h in __KERNEL__ && !__ASSEMBLY__, otherwise noinstr is expanded in the linker script construct. Upstream does not have this problem as many macros were moved by commit 71391bdd2e9a ("include/linux/compiler_types.h: don't pollute userspace with macro definitions"). We take the minimal approach here and just guard the new macro. Minor context conflicts in: arch/powerpc/kernel/vmlinux.lds.S include/asm-generic/vmlinux.lds.h include/linux/compiler.h] Signed-off-by: Nicolas Boichat Signed-off-by: Greg Kroah-Hartman --- Technically guarding with !__ASSEMBLY__ should be enough, but there seems to be no reason to expose this new macro when !__KERNEL__, so let's just match what upstream does. Changes in v2: - Guard noinstr macro by __KERNEL__ && !__ASSEMBLY__ to prevent expansion in linker script and match upstream. arch/powerpc/kernel/vmlinux.lds.S | 1 include/asm-generic/sections.h | 3 ++ include/asm-generic/vmlinux.lds.h | 10 +++++++ include/linux/compiler.h | 54 ++++++++++++++++++++++++++++++++++++++ include/linux/compiler_types.h | 6 ++++ scripts/mod/modpost.c | 2 - 6 files changed, 75 insertions(+), 1 deletion(-) --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -99,6 +99,7 @@ SECTIONS #endif /* careful! __ftr_alt_* sections need to be close to .text */ *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); + NOINSTR_TEXT SCHED_TEXT CPUIDLE_TEXT LOCK_TEXT --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -53,6 +53,9 @@ extern char __ctors_start[], __ctors_end /* Start and end of .opd section - used for function descriptors. */ extern char __start_opd[], __end_opd[]; +/* Start and end of instrumentation protected text section */ +extern char __noinstr_text_start[], __noinstr_text_end[]; + extern __visible const void __nosave_begin, __nosave_end; /* Function descriptor handling (if any). Override in asm/sections.h */ --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -483,6 +483,15 @@ } /* + * Non-instrumentable text section + */ +#define NOINSTR_TEXT \ + ALIGN_FUNCTION(); \ + __noinstr_text_start = .; \ + *(.noinstr.text) \ + __noinstr_text_end = .; + +/* * .text section. Map to function alignment to avoid address changes * during second ld run in second ld pass when generating System.map * @@ -496,6 +505,7 @@ *(TEXT_MAIN .text.fixup) \ *(.text.unlikely .text.unlikely.*) \ *(.text.unknown .text.unknown.*) \ + NOINSTR_TEXT \ *(.text..refcount) \ *(.ref.text) \ MEM_KEEP(init.text*) \ --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -129,11 +129,65 @@ void ftrace_likely_update(struct ftrace_ ".pushsection .discard.unreachable\n\t" \ ".long 999b - .\n\t" \ ".popsection\n\t" + +#ifdef CONFIG_DEBUG_ENTRY +/* Begin/end of an instrumentation safe region */ +#define instrumentation_begin() ({ \ + asm volatile("%c0:\n\t" \ + ".pushsection .discard.instr_begin\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__COUNTER__)); \ +}) + +/* + * Because instrumentation_{begin,end}() can nest, objtool validation considers + * _begin() a +1 and _end() a -1 and computes a sum over the instructions. + * When the value is greater than 0, we consider instrumentation allowed. + * + * There is a problem with code like: + * + * noinstr void foo() + * { + * instrumentation_begin(); + * ... + * if (cond) { + * instrumentation_begin(); + * ... + * instrumentation_end(); + * } + * bar(); + * instrumentation_end(); + * } + * + * If instrumentation_end() would be an empty label, like all the other + * annotations, the inner _end(), which is at the end of a conditional block, + * would land on the instruction after the block. + * + * If we then consider the sum of the !cond path, we'll see that the call to + * bar() is with a 0-value, even though, we meant it to happen with a positive + * value. + * + * To avoid this, have _end() be a NOP instruction, this ensures it will be + * part of the condition block and does not escape. + */ +#define instrumentation_end() ({ \ + asm volatile("%c0: nop\n\t" \ + ".pushsection .discard.instr_end\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__COUNTER__)); \ +}) +#endif /* CONFIG_DEBUG_ENTRY */ + #else #define annotate_reachable() #define annotate_unreachable() #endif +#ifndef instrumentation_begin +#define instrumentation_begin() do { } while(0) +#define instrumentation_end() do { } while(0) +#endif + #ifndef ASM_UNREACHABLE # define ASM_UNREACHABLE #endif --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -234,6 +234,12 @@ struct ftrace_likely_data { #define notrace __attribute__((no_instrument_function)) #endif +#if defined(__KERNEL__) && !defined(__ASSEMBLY__) +/* Section for code which can't be instrumented at all */ +#define noinstr \ + noinline notrace __attribute((__section__(".noinstr.text"))) +#endif + /* * it doesn't make sense on ARM (currently the only user of __naked) * to trace naked functions because then mcount is called without --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -895,7 +895,7 @@ static void check_section(const char *mo #define DATA_SECTIONS ".data", ".data.rel" #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \ - ".kprobes.text", ".cpuidle.text" + ".kprobes.text", ".cpuidle.text", ".noinstr.text" #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \ ".fixup", ".entry.text", ".exception.text", ".text.*", \ ".coldtext" Patches currently in stable-queue which might be from drinkcat@chromium.org are queue-4.19/vmlinux.lds.h-create-section-for-protection-against-instrumentation.patch queue-4.19/lkdtm-don-t-move-ctors-to-.rodata.patch