From: Jarkko Sakkinen <jarkko@kernel.org>
To: x86@kernel.org, linux-sgx@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
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, 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,
mikko.ylinen@intel.com
Subject: [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX
Date: Fri, 13 Nov 2020 00:01:17 +0200 [thread overview]
Message-ID: <20201112220135.165028-7-jarkko@kernel.org> (raw)
In-Reply-To: <20201112220135.165028-1-jarkko@kernel.org>
From: Sean Christopherson <sean.j.christopherson@intel.com>
The x86 architecture has a set of page fault error codes. These indicate
things like whether the fault occurred from a write, or whether it
originated in userspace.
The SGX hardware architecture has its own per-page memory management
metadata (EPCM) [*] and hardware which is separate from the normal x86 MMU.
The architecture has a new page fault error code: PF_SGX. This new error
code bit is set whenever a page fault occurs as the result of the SGX MMU.
These faults occur for a variety of reasons. For instance, an access
attempt to enclave memory from outside the enclave causes a PF_SGX fault.
PF_SGX would also be set for permission conflicts, such as if a write to an
enclave page occurs and the page is marked read-write in the x86 page
tables but is read-only in the EPCM.
These faults do not always indicate errors, though. SGX pages are
encrypted with a key that is destroyed at hardware reset, including
suspend. Throwing a SIGSEGV allows user space software to react and recover
when these events occur.
Include PF_SGX in the PF error codes list and throw SIGSEGV when it is
encountered.
[*] Intel SDM: 36.5.1 Enclave Page Cache Map (EPCM)
Acked-by: Jethro Beekman <jethro@fortanix.com> # v40
# Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
arch/x86/include/asm/trap_pf.h | 1 +
arch/x86/mm/fault.c | 12 ++++++++++++
2 files changed, 13 insertions(+)
diff --git a/arch/x86/include/asm/trap_pf.h b/arch/x86/include/asm/trap_pf.h
index 305bc1214aef..1794777b2a85 100644
--- a/arch/x86/include/asm/trap_pf.h
+++ b/arch/x86/include/asm/trap_pf.h
@@ -19,6 +19,7 @@ enum x86_pf_error_code {
X86_PF_RSVD = 1 << 3,
X86_PF_INSTR = 1 << 4,
X86_PF_PK = 1 << 5,
+ X86_PF_SGX = 1 << 15,
};
#endif /* _ASM_X86_TRAP_PF_H */
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 82bf37a5c9ec..9339fee83784 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1101,6 +1101,18 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
if (error_code & X86_PF_PK)
return 1;
+ /*
+ * SGX hardware blocked the access. This usually happens
+ * when the enclave memory contents have been destroyed, like
+ * after a suspend/resume cycle. In any case, the kernel can't
+ * fix the cause of the fault. Handle the fault as an access
+ * error even in cases where no actual access violation
+ * occurred. This allows userspace to rebuild the enclave in
+ * response to the signal.
+ */
+ if (unlikely(error_code & X86_PF_SGX))
+ return 1;
+
/*
* Make sure to check the VMA so that we do not perform
* faults just to hit a X86_PF_PK as soon as we fill in a
--
2.27.0
next prev parent reply other threads:[~2020-11-12 22:02 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 22:01 [PATCH v41 00/24] Intel SGX foundations Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 01/24] x86/sgx: Add SGX architectural data structures Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 02/24] x86/sgx: Add wrappers for ENCLS functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 03/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 04/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-11-16 22:25 ` [PATCH] x86/sgx: clarify 'laundry_list' locking Dave Hansen
2020-11-17 19:29 ` Jarkko Sakkinen
2020-11-12 22:01 ` Jarkko Sakkinen [this message]
2020-11-12 22:01 ` [PATCH v41 07/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 08/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-11-13 10:25 ` Mel Gorman
2020-11-17 18:16 ` Jarkko Sakkinen
2020-11-15 17:08 ` Dr. Greg
2020-11-15 17:32 ` Matthew Wilcox
2020-11-15 18:36 ` Dave Hansen
2020-11-16 10:09 ` Mel Gorman
2020-11-17 19:15 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
[not found] ` <20201115044044.11040-1-hdanton@sina.com>
2020-11-17 17:35 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 19/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-11-17 13:14 ` Borislav Petkov
2020-11-17 19:41 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-11-16 18:19 ` Shuah Khan
2020-11-17 13:22 ` Borislav Petkov
2020-11-17 19:42 ` Jarkko Sakkinen
2020-11-17 17:26 ` Borislav Petkov
2020-11-17 21:27 ` Jarkko Sakkinen
2020-11-17 21:38 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 21/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 22/24] x86/sgx: Add ptrace() support for the SGX driver Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 23/24] docs: x86/sgx: Document SGX kernel architecture Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-11-16 16:55 ` [PATCH v41 00/24] Intel SGX foundations Borislav Petkov
2020-11-16 17:21 ` Dave Hansen
2020-11-16 17:28 ` Borislav Petkov
2020-11-17 19:20 ` Jarkko Sakkinen
[not found] ` <20201114084211.5284-1-hdanton@sina.com>
2020-11-16 18:33 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Dave Hansen
[not found] ` <20201115040127.7804-1-hdanton@sina.com>
2020-11-16 21:11 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Dave Hansen
[not found] ` <20201114090708.8684-1-hdanton@sina.com>
2020-11-17 18:12 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
[not found] ` <20201114093256.7800-1-hdanton@sina.com>
2020-11-17 18:14 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
[not found] ` <20201115030548.1572-1-hdanton@sina.com>
2020-11-17 18:22 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-12-15 5:38 ` [PATCH v41 00/24] Intel SGX foundations Hui, Chunyang
2020-12-15 5:43 ` Hui, Chunyang
2020-12-15 15:58 ` Jarkko Sakkinen
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