From patchwork Thu May 23 09:51:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 10957183 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 403B2924 for ; Thu, 23 May 2019 09:52:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 24E7728448 for ; Thu, 23 May 2019 09:52:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 182A72844E; Thu, 23 May 2019 09:52:06 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 989CE28449 for ; Thu, 23 May 2019 09:52:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727440AbfEWJwE (ORCPT ); Thu, 23 May 2019 05:52:04 -0400 Received: from new1-smtp.messagingengine.com ([66.111.4.221]:39189 "EHLO new1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728277AbfEWJwE (ORCPT ); Thu, 23 May 2019 05:52:04 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailnew.nyi.internal (Postfix) with ESMTP id BCBED3489F; Thu, 23 May 2019 05:52:02 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Thu, 23 May 2019 05:52:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=iuGWWd txzYLyR42j3h191SP4rNqTlpMjuZC7Sjrrods=; b=rQSmMDy7umZX0wkqcWmqnu aKs7oVoTDMgl3amWFudICPrxV+Uimru3gIZRGxPeFEC+pLV9R1fVyr7AkDVOrZof iRdPIYt5lDbEpJYnwWp7PlsDIEge3oX+LmTA3y2x3FTpGn8iw9Fm4JwDDqoVwyhE bi6bt3K7COZVrwb3KiDwfElpUCzXGuX+lJ0fsoKoXj/HAiyWT3AMkRcoSBHXLgXu 4WlkCSaFjgL9Sk1fuycZ0VZZIc4+mxzkIzjjKRnnkbRJaXVaKgj6chiJtqYjPT93 i8o+XEdA7v4CXsvlpDxOdqDjs88g+KO/j0Va4OutNnVdOHoYVG0ZMBocsHWqYXkw == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduuddruddugedgvddvucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucfkphepkeefrdekiedrkeelrd dutdejnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomhen ucevlhhushhtvghrufhiiigvpedt X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 2226A380089; Thu, 23 May 2019 05:51:57 -0400 (EDT) Subject: FAILED: patch "[PATCH] ftrace/x86_64: Emulate call function while updating in" failed to apply to 4.9-stable tree To: peterz@infradead.org, bigeasy@linutronix.de, bp@alien8.de, hpa@zytor.com, jgross@suse.com, jikos@kernel.org, joe.lawrence@redhat.com, jpoimboe@redhat.com, jroedel@suse.de, konrad.wilk@oracle.com, linux-kselftest@vger.kernel.org, luto@kernel.org, mbenes@suse.cz, mhiramat@kernel.org, mingo@redhat.com, nayna@linux.ibm.com, ndesaulniers@google.com, nstange@suse.de, pmladek@suse.com, rostedt@goodmis.org, shuah@kernel.org, tglx@linutronix.de, tim.c.chen@linux.intel.com, x86@kernel.org, yamada.masahiro@socionext.com, zohar@linux.ibm.com Cc: From: Date: Thu, 23 May 2019 11:51:55 +0200 Message-ID: <1558605115220151@kroah.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 9e298e8604088a600d8100a111a532a9d342af09 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 1 May 2019 15:11:17 +0200 Subject: [PATCH] ftrace/x86_64: Emulate call function while updating in breakpoint handler Nicolai Stange discovered[1] that if live kernel patching is enabled, and the function tracer started tracing the same function that was patched, the conversion of the fentry call site during the translation of going from calling the live kernel patch trampoline to the iterator trampoline, would have as slight window where it didn't call anything. As live kernel patching depends on ftrace to always call its code (to prevent the function being traced from being called, as it will redirect it). This small window would allow the old buggy function to be called, and this can cause undesirable results. Nicolai submitted new patches[2] but these were controversial. As this is similar to the static call emulation issues that came up a while ago[3]. But after some debate[4][5] adding a gap in the stack when entering the breakpoint handler allows for pushing the return address onto the stack to easily emulate a call. [1] http://lkml.kernel.org/r/20180726104029.7736-1-nstange@suse.de [2] http://lkml.kernel.org/r/20190427100639.15074-1-nstange@suse.de [3] http://lkml.kernel.org/r/3cf04e113d71c9f8e4be95fb84a510f085aa4afa.1541711457.git.jpoimboe@redhat.com [4] http://lkml.kernel.org/r/CAHk-=wh5OpheSU8Em_Q3Hg8qw_JtoijxOdPtHru6d+5K8TWM=A@mail.gmail.com [5] http://lkml.kernel.org/r/CAHk-=wjvQxY4DvPrJ6haPgAa6b906h=MwZXO6G8OtiTGe=N7_w@mail.gmail.com [ Live kernel patching is not implemented on x86_32, thus the emulate calls are only for x86_64. ] Cc: Andy Lutomirski Cc: Nicolai Stange Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: the arch/x86 maintainers Cc: Josh Poimboeuf Cc: Jiri Kosina Cc: Miroslav Benes Cc: Petr Mladek Cc: Joe Lawrence Cc: Shuah Khan Cc: Konrad Rzeszutek Wilk Cc: Tim Chen Cc: Sebastian Andrzej Siewior Cc: Mimi Zohar Cc: Juergen Gross Cc: Nick Desaulniers Cc: Nayna Jain Cc: Masahiro Yamada Cc: Joerg Roedel Cc: "open list:KERNEL SELFTEST FRAMEWORK" Cc: stable@vger.kernel.org Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching") Tested-by: Nicolai Stange Reviewed-by: Nicolai Stange Reviewed-by: Masami Hiramatsu Signed-off-by: Peter Zijlstra (Intel) [ Changed to only implement emulated calls for x86_64 ] Signed-off-by: Steven Rostedt (VMware) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index ef49517f6bb2..bd553b3af22e 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -29,6 +29,7 @@ #include #include #include +#include #ifdef CONFIG_DYNAMIC_FTRACE @@ -231,6 +232,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, } static unsigned long ftrace_update_func; +static unsigned long ftrace_update_func_call; static int update_ftrace_func(unsigned long ip, void *new) { @@ -259,6 +261,8 @@ int ftrace_update_ftrace_func(ftrace_func_t func) unsigned char *new; int ret; + ftrace_update_func_call = (unsigned long)func; + new = ftrace_call_replace(ip, (unsigned long)func); ret = update_ftrace_func(ip, new); @@ -294,13 +298,28 @@ int ftrace_int3_handler(struct pt_regs *regs) if (WARN_ON_ONCE(!regs)) return 0; - ip = regs->ip - 1; - if (!ftrace_location(ip) && !is_ftrace_caller(ip)) - return 0; + ip = regs->ip - INT3_INSN_SIZE; - regs->ip += MCOUNT_INSN_SIZE - 1; +#ifdef CONFIG_X86_64 + if (ftrace_location(ip)) { + int3_emulate_call(regs, (unsigned long)ftrace_regs_caller); + return 1; + } else if (is_ftrace_caller(ip)) { + if (!ftrace_update_func_call) { + int3_emulate_jmp(regs, ip + CALL_INSN_SIZE); + return 1; + } + int3_emulate_call(regs, ftrace_update_func_call); + return 1; + } +#else + if (ftrace_location(ip) || is_ftrace_caller(ip)) { + int3_emulate_jmp(regs, ip + CALL_INSN_SIZE); + return 1; + } +#endif - return 1; + return 0; } NOKPROBE_SYMBOL(ftrace_int3_handler); @@ -859,6 +878,8 @@ void arch_ftrace_update_trampoline(struct ftrace_ops *ops) func = ftrace_ops_get_func(ops); + ftrace_update_func_call = (unsigned long)func; + /* Do a safe modify in case the trampoline is executing */ new = ftrace_call_replace(ip, (unsigned long)func); ret = update_ftrace_func(ip, new); @@ -960,6 +981,7 @@ static int ftrace_mod_jmp(unsigned long ip, void *func) { unsigned char *new; + ftrace_update_func_call = 0UL; new = ftrace_jmp_replace(ip, (unsigned long)func); return update_ftrace_func(ip, new);