From patchwork Tue Sep 3 14:26:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 11128065 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 82FE81395 for ; Tue, 3 Sep 2019 14:29:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D6C723697 for ; Tue, 3 Sep 2019 14:29:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729596AbfICO3y (ORCPT ); Tue, 3 Sep 2019 10:29:54 -0400 Received: from mga12.intel.com ([192.55.52.136]:46685 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729079AbfICO3x (ORCPT ); Tue, 3 Sep 2019 10:29:53 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 03 Sep 2019 07:29:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,463,1559545200"; d="scan'208";a="189826383" Received: from vkuppusa-mobl2.ger.corp.intel.com (HELO localhost) ([10.252.39.67]) by FMSMGA003.fm.intel.com with ESMTP; 03 Sep 2019 07:29:45 -0700 From: Jarkko Sakkinen To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org Cc: akpm@linux-foundation.org, dave.hansen@intel.com, sean.j.christopherson@intel.com, nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@intel.com, andriy.shevchenko@linux.intel.com, tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de, josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com, Andy Lutomirski , Jarkko Sakkinen , Dave Hansen Subject: [PATCH v22 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Date: Tue, 3 Sep 2019 17:26:49 +0300 Message-Id: <20190903142655.21943-19-jarkko.sakkinen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190903142655.21943-1-jarkko.sakkinen@linux.intel.com> References: <20190903142655.21943-1-jarkko.sakkinen@linux.intel.com> MIME-Version: 1.0 Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org From: Sean Christopherson vDSO functions can now leverage an exception fixup mechanism similar to kernel exception fixup. For vDSO exception fixup, the initial user is Intel's Software Guard Extensions (SGX), which will wrap the low-level transitions to/from the enclave, i.e. EENTER and ERESUME instructions, in a vDSO function and leverage fixup to intercept exceptions that would otherwise generate a signal. This allows the vDSO wrapper to return the fault information directly to its caller, obviating the need for SGX applications and libraries to juggle signal handlers. Attempt to fixup vDSO exceptions immediately prior to populating and sending signal information. Except for the delivery mechanism, an exception in a vDSO function should be treated like any other exception in userspace, e.g. any fault that is successfully handled by the kernel should not be directly visible to userspace. Although it's debatable whether or not all exceptions are of interest to enclaves, defer to the vDSO fixup to decide whether to do fixup or generate a signal. Future users of vDSO fixup, if there ever are any, will undoubtedly have different requirements than SGX enclaves, e.g. the fixup vs. signal logic can be made function specific if/when necessary. Suggested-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Jarkko Sakkinen Cc: Dave Hansen Cc: Josh Triplett Signed-off-by: Sean Christopherson --- arch/x86/kernel/traps.c | 14 ++++++++++++++ arch/x86/mm/fault.c | 7 +++++++ 2 files changed, 21 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 4bb0f8447112..9f06a3441f10 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -61,6 +61,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include @@ -210,6 +211,9 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str, tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; die(str, regs, error_code); + } else { + if (fixup_vdso_exception(regs, trapnr, error_code, 0)) + return 0; } /* @@ -557,6 +561,9 @@ do_general_protection(struct pt_regs *regs, long error_code) return; } + if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0)) + return; + tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; @@ -771,6 +778,10 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code) SIGTRAP) == NOTIFY_STOP) goto exit; + if (user_mode(regs) && + fixup_vdso_exception(regs, X86_TRAP_DB, error_code, 0)) + goto exit; + /* * Let others (NMI) know that the debug stack is in use * as we may switch to the interrupt stack. @@ -851,6 +862,9 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr) if (!si_code) return; + if (fixup_vdso_exception(regs, trapnr, error_code, 0)) + return; + force_sig_fault(SIGFPE, si_code, (void __user *)uprobe_get_trap_addr(regs)); } diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7efaf0269951..936946a5e723 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -29,6 +29,7 @@ #include /* efi_recover_from_page_fault()*/ #include /* store_idt(), ... */ #include /* exception stack */ +#include /* fixup_vdso_exception() */ #define CREATE_TRACE_POINTS #include @@ -901,6 +902,9 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, sanitize_error_code(address, &error_code); + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; + if (likely(show_unhandled_signals)) show_signal_msg(regs, error_code, address, tsk); @@ -1018,6 +1022,9 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, sanitize_error_code(address, &error_code); + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; + set_signal_archinfo(address, error_code); #ifdef CONFIG_MEMORY_FAILURE