From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> To: x86@kernel.org, linux-sgx@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Sean Christopherson <sean.j.christopherson@intel.com>, Andy Lutomirski <luto@amacapital.net>, Jethro Beekman <jethro@fortanix.com>, Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com, asapek@google.com, bp@alien8.de, cedric.xing@intel.com, chenalexchen@google.com, conradparker@google.com, cyhanish@google.com, dave.hansen@intel.com, haitao.huang@intel.com, josh@joshtriplett.org, kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com, ludloff@google.com, luto@kernel.org, nhorman@redhat.com, npmccallum@redhat.com, puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com Subject: [PATCH v33 17/21] x86/traps: Attempt to fixup exceptions in vDSO before signaling Date: Thu, 18 Jun 2020 01:08:39 +0300 Message-ID: <20200617220844.57423-18-jarkko.sakkinen@linux.intel.com> (raw) In-Reply-To: <20200617220844.57423-1-jarkko.sakkinen@linux.intel.com> From: Sean Christopherson <sean.j.christopherson@intel.com> 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 <luto@amacapital.net> Acked-by: Jethro Beekman <jethro@fortanix.com> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> --- arch/x86/kernel/traps.c | 19 ++++++++++++++++--- arch/x86/mm/fault.c | 8 ++++++++ 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index af75109485c2..d283a216e503 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -59,6 +59,7 @@ #include <asm/umip.h> #include <asm/insn.h> #include <asm/insn-eval.h> +#include <asm/vdso.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -118,6 +119,9 @@ 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; } /* @@ -543,6 +547,9 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; + if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0)) + return; + show_signal(tsk, SIGSEGV, "", desc, regs, error_code); force_sig(SIGSEGV); goto exit; @@ -824,9 +831,12 @@ static void handle_debug(struct pt_regs *regs, unsigned long dr6, bool user) #endif if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, 0, - SIGTRAP) == NOTIFY_STOP) { - return; - } + SIGTRAP) == NOTIFY_STOP) + goto out; + + if (user_mode(regs) && + fixup_vdso_exception(regs, X86_TRAP_DB, 0, 0)) + goto out; /* It's safe to allow irq's after DR6 has been saved */ cond_local_irq_enable(regs); @@ -968,6 +978,9 @@ static void math_error(struct pt_regs *regs, int trapnr) if (!si_code) goto exit; + if (fixup_vdso_exception(regs, trapnr, 0, 0)) + return; + force_sig_fault(SIGFPE, si_code, (void __user *)uprobe_get_trap_addr(regs)); exit: diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 966af17523fb..6e51ec08564f 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -31,6 +31,7 @@ #include <asm/cpu_entry_area.h> /* exception stack */ #include <asm/pgtable_areas.h> /* VMALLOC_START, ... */ #include <asm/kvm_para.h> /* kvm_handle_async_pf */ +#include <asm/vdso.h> /* fixup_vdso_exception() */ #define CREATE_TRACE_POINTS #include <asm/trace/exceptions.h> @@ -776,6 +777,10 @@ __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); @@ -895,6 +900,9 @@ 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 -- 2.25.1
next prev parent reply index Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-17 22:08 [PATCH v33 00/21] Intel SGX foundations Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 01/21] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen 2020-06-22 17:37 ` Borislav Petkov 2020-06-25 1:25 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 02/21] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen 2020-06-24 13:04 ` Borislav Petkov 2020-06-24 14:34 ` Sean Christopherson 2020-06-25 1:28 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 03/21] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen 2020-06-25 8:59 ` Borislav Petkov 2020-06-25 15:34 ` Sean Christopherson 2020-06-25 16:49 ` Borislav Petkov 2020-06-25 20:52 ` Jarkko Sakkinen 2020-06-25 21:11 ` Borislav Petkov 2020-06-26 13:34 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 04/21] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 05/21] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 06/21] x86/cpu/intel: Detect SGX support Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 07/21] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 08/21] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen 2020-06-25 10:14 ` Borislav Petkov 2020-06-25 20:11 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 09/21] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen 2020-06-25 17:06 ` Borislav Petkov 2020-06-25 20:55 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 10/21] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen 2020-06-25 17:14 ` Borislav Petkov 2020-06-25 17:30 ` Matthew Wilcox 2020-06-25 18:06 ` Sean Christopherson 2020-06-25 22:40 ` Jarkko Sakkinen 2020-06-25 22:26 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 11/21] x86/sgx: Linux Enclave Driver Jarkko Sakkinen 2020-06-25 17:23 ` Borislav Petkov 2020-06-25 18:34 ` Sean Christopherson 2020-06-25 18:45 ` Borislav Petkov 2020-06-26 14:19 ` Jarkko Sakkinen 2020-06-25 20:21 ` Jarkko Sakkinen 2020-06-25 20:25 ` Borislav Petkov 2020-06-26 13:40 ` Jarkko Sakkinen 2020-06-25 18:53 ` Borislav Petkov 2020-06-26 14:17 ` Jarkko Sakkinen 2020-06-26 9:14 ` Borislav Petkov 2020-06-26 14:16 ` Sean Christopherson 2020-06-26 14:20 ` Borislav Petkov 2020-07-03 23:04 ` Jarkko Sakkinen 2020-07-03 3:09 ` Jarkko Sakkinen 2020-06-26 15:34 ` Borislav Petkov 2020-07-04 0:13 ` Jarkko Sakkinen 2020-10-26 21:26 ` Dave Hansen 2020-10-27 1:52 ` Jarkko Sakkinen 2020-10-27 10:05 ` Borislav Petkov 2020-10-27 15:20 ` Dave Hansen 2020-10-27 15:37 ` Borislav Petkov 2020-06-27 17:43 ` Borislav Petkov 2020-06-29 15:27 ` Sean Christopherson 2020-06-29 15:37 ` Borislav Petkov 2020-07-04 1:43 ` Jarkko Sakkinen 2020-07-07 1:38 ` Sean Christopherson 2020-07-07 3:29 ` Jarkko Sakkinen 2020-07-04 1:42 ` Jarkko Sakkinen 2020-07-02 3:59 ` Sean Christopherson 2020-07-04 3:31 ` Jarkko Sakkinen 2020-09-02 3:06 ` Haitao Huang 2020-09-02 16:10 ` Sean Christopherson 2020-09-02 18:40 ` Haitao Huang 2020-09-04 12:01 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation Jarkko Sakkinen 2020-06-29 16:02 ` Borislav Petkov 2020-06-29 22:04 ` Sean Christopherson 2020-06-30 8:49 ` Borislav Petkov 2020-06-30 14:20 ` Sean Christopherson 2020-06-30 17:13 ` Andy Lutomirski 2020-07-02 20:47 ` Dr. Greg 2020-07-03 2:43 ` Jarkko Sakkinen 2020-07-03 2:38 ` Jarkko Sakkinen 2020-07-03 2:32 ` Jarkko Sakkinen 2020-07-03 2:55 ` Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 13/21] x86/sgx: Add a page reclaimer Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 14/21] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 15/21] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen 2020-06-29 17:10 ` Borislav Petkov 2020-06-30 6:00 ` Sean Christopherson 2020-06-30 8:41 ` Borislav Petkov 2020-06-30 14:55 ` Sean Christopherson 2020-06-30 16:48 ` Andy Lutomirski 2020-06-30 17:23 ` Sean Christopherson 2020-07-02 12:52 ` Thomas Gleixner 2020-06-17 22:08 ` [PATCH v33 16/21] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen 2020-06-17 22:08 ` Jarkko Sakkinen [this message] 2020-06-17 22:08 ` [PATCH v33 18/21] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 19/21] selftests/x86: Add a selftest for SGX Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 20/21] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen 2020-06-17 22:08 ` [PATCH v33 21/21] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
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