From patchwork Thu May 23 19:06:36 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: 10958669 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 CD5496C5 for ; Thu, 23 May 2019 19:33:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B76CB286B9 for ; Thu, 23 May 2019 19:33:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A59D6286C1; Thu, 23 May 2019 19:33:35 +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=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 0CC87286B9 for ; Thu, 23 May 2019 19:33:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391826AbfEWT2z (ORCPT ); Thu, 23 May 2019 15:28:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:41644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391048AbfEWT2x (ORCPT ); Thu, 23 May 2019 15:28:53 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 1F9D321841; Thu, 23 May 2019 19:28:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558639731; bh=plf5khnwnrG7TJd0YaGiq3aILycf1dI/vg/fJhtd+SY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PDKdxX4jOhIsTx0/0N+oWlIWmNgnnmG6T97qEFPvZcPWmhMAKUzhqIS/2l5ikrNZb VuWgkQYDotXTa7+JfYpGFRGrFJ7xuTQ+Yp6p55YrQ1WlbnvGiMp4jE1XCbZJXIPVHm rhyG5uA7rD2j5PbqsbKW14xr8cy3Ryedk5tHlgwc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Nicolai Stange , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , the arch/x86 maintainers , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Konrad Rzeszutek Wilk , Tim Chen , Sebastian Andrzej Siewior , Mimi Zohar , Juergen Gross , Nick Desaulniers , Nayna Jain , Masahiro Yamada , Joerg Roedel , "open list:KERNEL SELFTEST FRAMEWORK" , Masami Hiramatsu , "Peter Zijlstra (Intel)" , "Steven Rostedt (VMware)" Subject: [PATCH 5.1 074/122] x86_64: Allow breakpoints to emulate call instructions Date: Thu, 23 May 2019 21:06:36 +0200 Message-Id: <20190523181714.548131991@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181705.091418060@linuxfoundation.org> References: <20190523181705.091418060@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Peter Zijlstra commit 4b33dadf37666c0860b88f9e52a16d07bf6d0b03 upstream. In order to allow breakpoints to emulate call instructions, they need to push the return address onto the stack. The x86_64 int3 handler adds a small gap to allow the stack to grow some. Use this gap to add the return address to be able to emulate a call instruction at the breakpoint location. These helper functions are added: int3_emulate_jmp(): changes the location of the regs->ip to return there. (The next two are only for x86_64) int3_emulate_push(): to push the address onto the gap in the stack int3_emulate_call(): push the return address and change regs->ip 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) [ Modified to only work for x86_64 and added comment to int3_emulate_push() ] Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/text-patching.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) --- a/arch/x86/include/asm/text-patching.h +++ b/arch/x86/include/asm/text-patching.h @@ -39,4 +39,32 @@ extern int poke_int3_handler(struct pt_r extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler); extern int after_bootmem; +static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip) +{ + regs->ip = ip; +} + +#define INT3_INSN_SIZE 1 +#define CALL_INSN_SIZE 5 + +#ifdef CONFIG_X86_64 +static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val) +{ + /* + * The int3 handler in entry_64.S adds a gap between the + * stack where the break point happened, and the saving of + * pt_regs. We can extend the original stack because of + * this gap. See the idtentry macro's create_gap option. + */ + regs->sp -= sizeof(unsigned long); + *(unsigned long *)regs->sp = val; +} + +static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func) +{ + int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE); + int3_emulate_jmp(regs, func); +} +#endif + #endif /* _ASM_X86_TEXT_PATCHING_H */ From patchwork Thu May 23 19:06:37 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: 10958671 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 4C101924 for ; Thu, 23 May 2019 19:33:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3AE29286B9 for ; Thu, 23 May 2019 19:33:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2DAD5286C1; Thu, 23 May 2019 19:33:37 +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=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 7A98C286B9 for ; Thu, 23 May 2019 19:33:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391408AbfEWTdf (ORCPT ); Thu, 23 May 2019 15:33:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:41756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390656AbfEWT2z (ORCPT ); Thu, 23 May 2019 15:28:55 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 DE2342133D; Thu, 23 May 2019 19:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558639734; bh=f5Q21p3PgP0G8RPBuE9/d/I+5FsmteszRjED1pnXQbQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MuFn6HGQKk7+9MQIGf2aFwL9B9/EzJoFq9xQZC+4Fvu6hFHO1q5D9G97HUMyqFHdq OZvSd32oAH5pvf/rJtIREMyBGGbZ4RLrGiQGxshGsq/JRiFg/8/IDLygqalXR3QDxJ rjcWgqZ83jMZxIwxp2/Xmr02s94gMsYade94QisI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Nicolai Stange , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , the arch/x86 maintainers , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Konrad Rzeszutek Wilk , Tim Chen , Sebastian Andrzej Siewior , Mimi Zohar , Juergen Gross , Nick Desaulniers , Nayna Jain , Masahiro Yamada , Joerg Roedel , "open list:KERNEL SELFTEST FRAMEWORK" , Masami Hiramatsu , "Peter Zijlstra (Intel)" , "Steven Rostedt (VMware)" Subject: [PATCH 5.1 075/122] ftrace/x86_64: Emulate call function while updating in breakpoint handler Date: Thu, 23 May 2019 21:06:37 +0200 Message-Id: <20190523181714.674517884@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181705.091418060@linuxfoundation.org> References: <20190523181705.091418060@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Peter Zijlstra commit 9e298e8604088a600d8100a111a532a9d342af09 upstream. 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) Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/ftrace.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) --- 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 } 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_fun 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 * 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(struc 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 { unsigned char *new; + ftrace_update_func_call = 0UL; new = ftrace_jmp_replace(ip, (unsigned long)func); return update_ftrace_func(ip, new);