From: Sean Christopherson <sean.j.christopherson@intel.com> To: Dave Hansen <dave.hansen@intel.com> Cc: Andy Lutomirski <luto@amacapital.net>, Andrew Lutomirski <luto@kernel.org>, Jann Horn <jannh@google.com>, Linus Torvalds <torvalds@linux-foundation.org>, Rich Felker <dalias@libc.org>, Dave Hansen <dave.hansen@linux.intel.com>, Jethro Beekman <jethro@fortanix.com>, "Jarkko Sakkinen" <jarkko.sakkinen@linux.intel.com>, Florian Weimer <fweimer@redhat.com>, Linux API <linux-api@vger.kernel.org>, X86 ML <x86@kernel.org>, linux-arch <linux-arch@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, <nhorman@redhat.com>, <npmccallum@redhat.com>, "Ayoun, Serge" <serge.ayoun@intel.com>, <shay.katz-zamir@intel.com>, <linux-sgx@vger.kernel.org>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, "Carlos O'Donell" <carlos@redhat.com>, <adhemerval.zanella@linaro.org> Subject: Re: RFC: userspace exception fixups Date: Thu, 8 Nov 2018 13:16:00 -0800 [thread overview] Message-ID: <20181108211600.GA17167@linux.intel.com> (raw) In-Reply-To: <7027c3dc-addb-1b96-027e-a57fccf1f812@intel.com> On Thu, Nov 08, 2018 at 12:10:30PM -0800, Dave Hansen wrote: > On 11/8/18 12:05 PM, Andy Lutomirski wrote: > > Hmm. The idea being that the SDK preserves RBP but not RSP. That's > > not the most terrible thing in the world. But could the SDK live with > > something more like my suggestion where the vDSO supplies a normal > > function that takes a struct containing registers that are visible to > > the enclave? This would make it extremely awkward for the enclave to > > use the untrusted stack per se, but it would make it quite easy (I > > think) for the untrusted part of the SDK to allocate some extra memory > > and just tell the enclave that *that* memory is the stack. > > I really think the enclave should keep its grubby mitts off the > untrusted stack. There are lots of ways to get memory, even with > stack-like semantics, that don't involve mucking with the stack itself. > > I have not heard a good, hard argument for why there is an absolute > *need* to store things on the actual untrusted stack. Convenience and performance are the only arguments I've heard, e.g. so that allocating memory doesn't require an extra EEXIT->EENTER round trip. > We could quite easily have the untrusted code just promise to allocate a > stack-sized virtual area (even derived from the stack rlimit size) and > pass that into the enclave for parameter use. I agree more and more the further I dig. AFAIK there is no need to for the enclave to actually load %rsp. The initial EENTER can pass in the base/top of the pseudo-stack and from there the enclave can manage it purely in software.
WARNING: multiple messages have this Message-ID (diff)
From: Sean Christopherson <sean.j.christopherson@intel.com> To: Dave Hansen <dave.hansen@intel.com> Cc: Andy Lutomirski <luto@amacapital.net>, Andrew Lutomirski <luto@kernel.org>, Jann Horn <jannh@google.com>, Linus Torvalds <torvalds@linux-foundation.org>, Rich Felker <dalias@libc.org>, Dave Hansen <dave.hansen@linux.intel.com>, Jethro Beekman <jethro@fortanix.com>, Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, Florian Weimer <fweimer@redhat.com>, Linux API <linux-api@vger.kernel.org>, X86 ML <x86@kernel.org>, linux-arch <linux-arch@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, nhorman@redhat.com, npmccallum@redhat.com, "Ayoun, Serge" <serge.ayoun@intel.com>, shay.katz-zamir@intel.com, linux-sgx@vger.kernel.org, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Carlos O'Donell <carlos@redhat.com>, adhemerval.zanella@linaro.org Subject: Re: RFC: userspace exception fixups Date: Thu, 8 Nov 2018 13:16:00 -0800 [thread overview] Message-ID: <20181108211600.GA17167@linux.intel.com> (raw) Message-ID: <20181108211600.MH9dKZtGoKuzS9OMBQiGsHoLzb07YndIV99k-Nav3xY@z> (raw) In-Reply-To: <7027c3dc-addb-1b96-027e-a57fccf1f812@intel.com> On Thu, Nov 08, 2018 at 12:10:30PM -0800, Dave Hansen wrote: > On 11/8/18 12:05 PM, Andy Lutomirski wrote: > > Hmm. The idea being that the SDK preserves RBP but not RSP. That's > > not the most terrible thing in the world. But could the SDK live with > > something more like my suggestion where the vDSO supplies a normal > > function that takes a struct containing registers that are visible to > > the enclave? This would make it extremely awkward for the enclave to > > use the untrusted stack per se, but it would make it quite easy (I > > think) for the untrusted part of the SDK to allocate some extra memory > > and just tell the enclave that *that* memory is the stack. > > I really think the enclave should keep its grubby mitts off the > untrusted stack. There are lots of ways to get memory, even with > stack-like semantics, that don't involve mucking with the stack itself. > > I have not heard a good, hard argument for why there is an absolute > *need* to store things on the actual untrusted stack. Convenience and performance are the only arguments I've heard, e.g. so that allocating memory doesn't require an extra EEXIT->EENTER round trip. > We could quite easily have the untrusted code just promise to allocate a > stack-sized virtual area (even derived from the stack rlimit size) and > pass that into the enclave for parameter use. I agree more and more the further I dig. AFAIK there is no need to for the enclave to actually load %rsp. The initial EENTER can pass in the base/top of the pseudo-stack and from there the enclave can manage it purely in software.
next prev parent reply other threads:[~2018-11-08 21:16 UTC|newest] Thread overview: 163+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-01 17:53 RFC: userspace exception fixups Andy Lutomirski 2018-11-01 17:53 ` Andy Lutomirski 2018-11-01 18:09 ` Florian Weimer 2018-11-01 18:09 ` Florian Weimer 2018-11-01 18:30 ` Rich Felker 2018-11-01 18:30 ` Rich Felker 2018-11-01 19:00 ` Jarkko Sakkinen 2018-11-01 19:00 ` Jarkko Sakkinen 2018-11-01 18:27 ` Rich Felker 2018-11-01 18:27 ` Rich Felker 2018-11-01 18:33 ` Jann Horn 2018-11-01 18:33 ` Jann Horn 2018-11-01 18:52 ` Rich Felker 2018-11-01 18:52 ` Rich Felker 2018-11-01 19:10 ` Linus Torvalds 2018-11-01 19:10 ` Linus Torvalds 2018-11-01 19:31 ` Rich Felker 2018-11-01 19:31 ` Rich Felker 2018-11-01 21:24 ` Linus Torvalds 2018-11-01 21:24 ` Linus Torvalds 2018-11-01 23:22 ` Andy Lutomirski 2018-11-01 23:22 ` Andy Lutomirski 2018-11-02 16:30 ` Sean Christopherson 2018-11-02 16:30 ` Sean Christopherson 2018-11-02 16:37 ` Jethro Beekman 2018-11-02 16:37 ` Jethro Beekman 2018-11-02 16:52 ` Sean Christopherson 2018-11-02 16:52 ` Sean Christopherson 2018-11-02 16:56 ` Jethro Beekman 2018-11-02 16:56 ` Jethro Beekman 2018-11-02 17:01 ` Andy Lutomirski 2018-11-02 17:01 ` Andy Lutomirski 2018-11-02 17:05 ` Jethro Beekman 2018-11-02 17:05 ` Jethro Beekman 2018-11-02 17:16 ` Andy Lutomirski 2018-11-02 17:16 ` Andy Lutomirski 2018-11-02 17:32 ` Rich Felker 2018-11-02 17:32 ` Rich Felker 2018-11-02 17:12 ` Sean Christopherson 2018-11-02 17:12 ` Sean Christopherson 2018-11-02 22:42 ` Jarkko Sakkinen 2018-11-02 22:42 ` Jarkko Sakkinen 2018-11-02 16:56 ` Dave Hansen 2018-11-02 16:56 ` Dave Hansen 2018-11-02 17:06 ` Sean Christopherson 2018-11-02 17:06 ` Sean Christopherson 2018-11-02 17:13 ` Dave Hansen 2018-11-02 17:13 ` Dave Hansen 2018-11-02 17:33 ` Sean Christopherson 2018-11-02 17:33 ` Sean Christopherson 2018-11-02 17:48 ` Andy Lutomirski 2018-11-02 17:48 ` Andy Lutomirski 2018-11-02 18:27 ` Sean Christopherson 2018-11-02 18:27 ` Sean Christopherson 2018-11-02 19:02 ` Jann Horn 2018-11-02 19:02 ` Jann Horn 2018-11-02 22:04 ` Sean Christopherson 2018-11-02 22:04 ` Sean Christopherson 2018-11-02 23:27 ` Jann Horn 2018-11-02 23:27 ` Jann Horn 2018-11-02 23:32 ` Andy Lutomirski 2018-11-02 23:32 ` Andy Lutomirski 2018-11-02 23:36 ` Jann Horn 2018-11-02 23:36 ` Jann Horn 2018-11-06 15:37 ` Sean Christopherson 2018-11-06 15:37 ` Sean Christopherson 2018-11-06 16:57 ` Andy Lutomirski 2018-11-06 16:57 ` Andy Lutomirski 2018-11-06 17:03 ` Dave Hansen 2018-11-06 17:03 ` Dave Hansen 2018-11-06 17:19 ` Sean Christopherson 2018-11-06 17:19 ` Sean Christopherson 2018-11-06 18:20 ` Andy Lutomirski 2018-11-06 18:20 ` Andy Lutomirski 2018-11-06 18:41 ` Dave Hansen 2018-11-06 18:41 ` Dave Hansen 2018-11-06 19:02 ` Andy Lutomirski 2018-11-06 19:02 ` Andy Lutomirski 2018-11-06 19:22 ` Dave Hansen 2018-11-06 19:22 ` Dave Hansen 2018-11-06 20:12 ` Andy Lutomirski 2018-11-06 20:12 ` Andy Lutomirski 2018-11-06 21:00 ` Dave Hansen 2018-11-06 21:00 ` Dave Hansen 2018-11-06 21:07 ` Andy Lutomirski 2018-11-06 21:07 ` Andy Lutomirski 2018-11-06 21:41 ` Andy Lutomirski 2018-11-06 21:41 ` Andy Lutomirski 2018-11-06 21:59 ` Sean Christopherson 2018-11-06 21:59 ` Sean Christopherson 2018-11-06 23:00 ` Andy Lutomirski 2018-11-06 23:00 ` Andy Lutomirski 2018-11-06 23:35 ` Sean Christopherson 2018-11-06 23:35 ` Sean Christopherson 2018-11-06 23:39 ` Andy Lutomirski 2018-11-06 23:39 ` Andy Lutomirski 2018-11-07 0:02 ` Sean Christopherson 2018-11-07 0:02 ` Sean Christopherson 2018-11-07 1:17 ` Andy Lutomirski 2018-11-07 1:17 ` Andy Lutomirski 2018-11-07 6:47 ` Jethro Beekman 2018-11-07 6:47 ` Jethro Beekman 2018-11-07 15:34 ` Sean Christopherson 2018-11-07 15:34 ` Sean Christopherson 2018-11-07 19:01 ` Sean Christopherson 2018-11-07 19:01 ` Sean Christopherson 2018-11-07 20:56 ` Dave Hansen 2018-11-07 20:56 ` Dave Hansen 2018-11-08 15:04 ` Jarkko Sakkinen 2018-11-08 15:04 ` Jarkko Sakkinen 2018-11-08 19:54 ` Sean Christopherson 2018-11-08 19:54 ` Sean Christopherson 2018-11-08 20:05 ` Andy Lutomirski 2018-11-08 20:05 ` Andy Lutomirski 2018-11-08 20:10 ` Dave Hansen 2018-11-08 20:10 ` Dave Hansen 2018-11-08 21:16 ` Sean Christopherson [this message] 2018-11-08 21:16 ` Sean Christopherson 2018-11-08 21:50 ` Dave Hansen 2018-11-08 21:50 ` Dave Hansen 2018-11-08 22:04 ` Sean Christopherson 2018-11-08 22:04 ` Sean Christopherson 2018-11-09 7:12 ` Christoph Hellwig 2018-11-09 7:12 ` Christoph Hellwig 2018-11-06 23:17 ` Rich Felker 2018-11-06 23:17 ` Rich Felker 2018-11-06 23:26 ` Sean Christopherson 2018-11-06 23:26 ` Sean Christopherson 2018-11-07 21:27 ` Rich Felker 2018-11-07 21:27 ` Rich Felker 2018-11-07 21:33 ` Andy Lutomirski 2018-11-07 21:33 ` Andy Lutomirski 2018-11-07 21:40 ` Sean Christopherson 2018-11-07 21:40 ` Sean Christopherson 2018-11-08 15:11 ` Jarkko Sakkinen 2018-11-08 15:11 ` Jarkko Sakkinen 2018-11-06 17:00 ` Dave Hansen 2018-11-06 17:00 ` Dave Hansen 2018-11-02 22:37 ` Jarkko Sakkinen 2018-11-02 22:37 ` Jarkko Sakkinen 2018-11-01 19:06 ` Linus Torvalds 2018-11-01 19:06 ` Linus Torvalds 2018-11-02 22:07 ` Jarkko Sakkinen 2018-11-02 22:07 ` Jarkko Sakkinen 2018-11-18 7:15 ` Jarkko Sakkinen 2018-11-18 7:18 ` Jarkko Sakkinen 2018-11-18 13:02 ` Jarkko Sakkinen 2018-11-19 5:17 ` Jethro Beekman 2018-11-19 14:05 ` Jarkko Sakkinen 2018-11-19 14:59 ` Jarkko Sakkinen 2018-11-19 15:29 ` Andy Lutomirski 2018-11-19 16:02 ` Jarkko Sakkinen 2018-11-19 17:00 ` Andy Lutomirski 2018-11-20 10:11 ` Jarkko Sakkinen 2018-11-20 15:19 ` Andy Lutomirski 2018-11-20 22:55 ` Jarkko Sakkinen 2018-11-21 5:17 ` Jethro Beekman 2018-11-21 15:17 ` Jarkko Sakkinen 2018-11-24 17:07 ` Jarkko Sakkinen 2018-11-26 14:35 ` Sean Christopherson 2018-11-26 22:06 ` Jarkko Sakkinen 2018-11-20 18:09 ` Sean Christopherson 2018-11-20 22:46 ` Jarkko Sakkinen
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