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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86@kernel.org, linux-sgx@vger.kernel.org,
	akpm@linux-foundation.org, dave.hansen@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
Subject: Re: [PATCH v19 19/27] x86/sgx: ptrace() support for the SGX driver
Date: Thu, 21 Mar 2019 17:02:15 +0200
Message-ID: <20190321150215.GQ4603@linux.intel.com> (raw)
In-Reply-To: <20190319222201.GK25575@linux.intel.com>

On Tue, Mar 19, 2019 at 03:22:01PM -0700, Sean Christopherson wrote:
> On Sun, Mar 17, 2019 at 11:14:48PM +0200, Jarkko Sakkinen wrote:
> > Add VMA callbacks for ptrace() that can be used with debug enclaves.
> > With debug enclaves data can be read and write the memory word at a time
> > by using ENCLS(EDBGRD) and ENCLS(EDBGWR) leaf instructions.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> >  arch/x86/kernel/cpu/sgx/encl.c | 97 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 97 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> > index 1b8874699dd3..5b5fc933ee19 100644
> > --- a/arch/x86/kernel/cpu/sgx/encl.c
> > +++ b/arch/x86/kernel/cpu/sgx/encl.c
> > @@ -256,10 +256,107 @@ static unsigned int sgx_vma_fault(struct vm_fault *vmf)
> >  	return ret;
> >  }
> >  
> > +static int sgx_edbgrd(struct sgx_encl *encl, struct sgx_encl_page *page,
> > +		      unsigned long addr, void *data)
> > +{
> > +	unsigned long offset;
> > +	int ret;
> > +
> > +	offset = addr & ~PAGE_MASK;
> > +
> > +	if ((page->desc & SGX_ENCL_PAGE_TCS) &&
> > +	    offset > offsetof(struct sgx_tcs, gs_limit))
> > +		return -ECANCELED;
> > +
> > +	ret = __edbgrd(sgx_epc_addr(page->epc_page) + offset, data);
> > +	if (ret)
> > +		return -EIO;
> > +
> > +	return 0;
> > +}
> > +
> > +static int sgx_edbgwr(struct sgx_encl *encl, struct sgx_encl_page *page,
> > +		      unsigned long addr, void *data)
> > +{
> > +	unsigned long offset;
> > +	int ret;
> > +
> > +	offset = addr & ~PAGE_MASK;
> > +
> > +	/* Writing anything else than flags will cause #GP */
> > +	if ((page->desc & SGX_ENCL_PAGE_TCS) &&
> > +	    offset != offsetof(struct sgx_tcs, flags))
> > +		return -ECANCELED;
> > +
> > +	ret = __edbgwr(sgx_epc_addr(page->epc_page) + offset, data);
> > +	if (ret)
> > +		return -EIO;
> > +
> > +	return 0;
> > +}
> > +
> > +static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
> > +			  void *buf, int len, int write)
> > +{
> > +	struct sgx_encl *encl = vma->vm_private_data;
> > +	struct sgx_encl_page *entry = NULL;
> > +	unsigned long align;
> > +	char data[sizeof(unsigned long)];
> > +	int offset;
> > +	int cnt;
> > +	int ret = 0;
> > +	int i;
> > +
> > +	/* If process was forked, VMA is still there but vm_private_data is set
> > +	 * to NULL.
> > +	 */
> > +	if (!encl)
> > +		return -EFAULT;
> > +
> > +	if (!(encl->flags & SGX_ENCL_DEBUG) ||
> > +	    !(encl->flags & SGX_ENCL_INITIALIZED) ||
> > +	    (encl->flags & SGX_ENCL_DEAD))
> > +		return -EFAULT;
> > +
> > +	for (i = 0; i < len; i += cnt) {
> > +		entry = sgx_encl_reserve_page(encl, (addr + i) & PAGE_MASK);
> 
> Taking a lock indirectly via sgx_encl_reserve_page() and releasing it
> directly via mutex_unlock() is a bit difficult to follow, having a helper
> to pair up with sgx_encl_reserve_page() would be more readable.  Open
> coding sgx_encl_reserve_page() would probably be even better since this
> is the only user AFAICT.
> 
> All that being said, I prefer the old approach of marking the page RESERVED
> instead of holding the enclave's lock, even though it was slightly more
> complex.

For me the big rationale is to minimize the amount of state in the
context of this patch set. And this approach should work just fine.

/Jarkko

  reply index

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-17 21:14 [PATCH v19 00/27] Intel SGX1 support Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 01/27] x86/cpufeatures: Add Intel-defined SGX feature bit Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 02/27] x86/cpufeatures: Add SGX sub-features (as Linux-defined bits) Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 03/27] x86/msr: Add IA32_FEATURE_CONTROL.SGX_ENABLE definition Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 04/27] x86/cpufeatures: Add Intel-defined SGX_LC feature bit Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 05/27] x86/msr: Add SGX Launch Control MSR definitions Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 06/27] x86/mm: x86/sgx: Add new 'PF_SGX' page fault error code bit Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 07/27] x86/mm: x86/sgx: Signal SIGSEGV for userspace #PFs w/ PF_SGX Jarkko Sakkinen
2019-03-18 17:15   ` Dave Hansen
2019-03-18 19:53     ` Sean Christopherson
2019-03-17 21:14 ` [PATCH v19 08/27] x86/cpu/intel: Detect SGX support and update caps appropriately Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 09/27] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 10/27] x86/sgx: Add SGX1 and SGX2 architectural data structures Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 11/27] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 12/27] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2019-03-18 19:50   ` Sean Christopherson
2019-03-21 14:40     ` Jarkko Sakkinen
2019-03-21 15:28       ` Sean Christopherson
2019-03-22 10:19         ` Jarkko Sakkinen
2019-03-22 10:50           ` Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 13/27] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2019-03-19 19:59   ` Sean Christopherson
2019-03-21 14:51     ` Jarkko Sakkinen
2019-03-21 15:40       ` Sean Christopherson
2019-03-22 11:00         ` Jarkko Sakkinen
2019-03-22 16:43           ` Sean Christopherson
2019-03-17 21:14 ` [PATCH v19 16/27] x86/sgx: Add the Linux SGX Enclave Driver Jarkko Sakkinen
2019-03-19 21:19   ` Sean Christopherson
2019-03-21 15:51     ` Jarkko Sakkinen
2019-03-21 16:47       ` Sean Christopherson
2019-03-22 11:10         ` Jarkko Sakkinen
2019-03-26 13:26       ` Jarkko Sakkinen
2019-03-26 23:58         ` Sean Christopherson
2019-03-27  5:28           ` Jarkko Sakkinen
2019-03-27 17:57             ` Sean Christopherson
2019-03-27 18:38             ` Jethro Beekman
2019-03-27 20:06               ` Sean Christopherson
2019-03-28  1:21                 ` Jethro Beekman
2019-03-28 13:19                 ` Jarkko Sakkinen
2019-03-28 19:05                   ` Andy Lutomirski
2019-03-29  9:43                     ` Jarkko Sakkinen
2019-03-29 16:20                     ` Sean Christopherson
2019-04-01 10:01                       ` Jarkko Sakkinen
2019-04-01 17:25                         ` Jethro Beekman
2019-04-01 22:57                           ` Jarkko Sakkinen
2019-03-28 13:15               ` Jarkko Sakkinen
2019-03-19 23:00   ` Sean Christopherson
2019-03-21 16:18     ` Jarkko Sakkinen
2019-03-21 17:38       ` Sean Christopherson
2019-03-22 11:17         ` Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 17/27] x86/sgx: Add provisioning Jarkko Sakkinen
2019-03-19 20:09   ` Sean Christopherson
2019-03-21  2:08     ` Huang, Kai
2019-03-21 14:32       ` Jarkko Sakkinen
2019-03-21 21:41         ` Huang, Kai
2019-03-22 11:31           ` Jarkko Sakkinen
2019-03-21 14:30     ` Jarkko Sakkinen
2019-03-21 14:38   ` Nathaniel McCallum
2019-03-22 11:22     ` Jarkko Sakkinen
2019-03-21 16:50   ` Andy Lutomirski
2019-03-22 11:29     ` Jarkko Sakkinen
2019-03-22 11:43       ` Jarkko Sakkinen
2019-03-22 18:20         ` Andy Lutomirski
2019-03-25 14:55           ` Jarkko Sakkinen
2019-03-27  0:14             ` Sean Christopherson
2019-04-05 10:18             ` Jarkko Sakkinen
2019-04-05 13:53               ` Andy Lutomirski
2019-04-05 14:20                 ` Jarkko Sakkinen
2019-04-05 14:34                   ` Greg KH
2019-04-09 13:37                     ` Jarkko Sakkinen
2019-04-05 14:21                 ` Greg KH
2019-03-17 21:14 ` [PATCH v19 19/27] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2019-03-19 22:22   ` Sean Christopherson
2019-03-21 15:02     ` Jarkko Sakkinen [this message]
2019-03-17 21:14 ` [PATCH v19 20/27] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 21/27] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 22/27] x86/fault: Attempt to fixup unhandled #PF in vDSO before signaling Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 23/27] x86/traps: Attempt to fixup exceptions " Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 25/27] x86/sgx: SGX documentation Jarkko Sakkinen
2019-03-20 17:14   ` Sean Christopherson
2019-03-21 16:24     ` Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 26/27] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2019-03-17 21:14 ` [PATCH v19 27/27] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2019-03-19 17:12   ` Sean Christopherson
2019-03-21 14:42     ` Jarkko Sakkinen
     [not found] ` <20190317211456.13927-19-jarkko.sakkinen@linux.intel.com>
2019-03-19 22:09   ` [PATCH v19 18/27] x86/sgx: Add swapping code to the core and SGX driver Sean Christopherson
2019-03-21 14:59     ` Jarkko Sakkinen
2019-03-19 23:41 ` [PATCH v19 00/27] Intel SGX1 support Sean Christopherson
2019-03-19 23:52   ` Jethro Beekman
2019-03-20  0:22     ` Sean Christopherson
2019-03-21 16:20     ` Jarkko Sakkinen
2019-03-21 16:00   ` Jarkko Sakkinen

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