From 84664369520170f48546c55cbc1f3fbde9b1e140 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 13 Nov 2020 00:01:30 +0200 Subject: x86/vdso: Implement a vDSO for Intel SGX enclave call MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Enclaves encounter exceptions for lots of reasons: everything from enclave page faults to NULL pointer dereferences, to system calls that must be “proxied” to the kernel from outside the enclave. In addition to the code contained inside an enclave, there is also supporting code outside the enclave called an “SGX runtime”, which is virtually always implemented inside a shared library. The runtime helps build the enclave and handles things like *re*building the enclave if it got destroyed by something like a suspend/resume cycle. The rebuilding has traditionally been handled in SIGSEGV handlers, registered by the library. But, being process-wide, shared state, signal handling and shared libraries do not mix well. Introduce a vDSO function call that wraps the enclave entry functions (EENTER/ERESUME functions of the ENCLU instruciton) and returns information about any exceptions to the caller in the SGX runtime. Instead of generating a signal, the kernel places exception information in RDI, RSI and RDX. The kernel-provided userspace portion of the vDSO handler will place this information in a user-provided buffer or trigger a user-provided callback at the time of the exception. The vDSO function calling convention uses the standard RDI RSI, RDX, RCX, R8 and R9 registers. This makes it possible to declare the vDSO as a C prototype, but other than that there is no specific support for SystemV ABI. Things like storing XSAVE are the responsibility of the enclave and the runtime. [ bp: Change vsgx.o build dependency to CONFIG_X86_SGX. ] Suggested-by: Andy Lutomirski Signed-off-by: Sean Christopherson Co-developed-by: Cedric Xing Signed-off-by: Cedric Xing Co-developed-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen Signed-off-by: Borislav Petkov Tested-by: Jethro Beekman Link: https://lkml.kernel.org/r/20201112220135.165028-20-jarkko@kernel.org --- arch/x86/include/asm/enclu.h | 9 +++++++++ 1 file changed, 9 insertions(+) create mode 100644 arch/x86/include/asm/enclu.h (limited to 'arch/x86/include/asm/enclu.h') diff --git a/arch/x86/include/asm/enclu.h b/arch/x86/include/asm/enclu.h new file mode 100644 index 000000000000..b1314e41a744 --- /dev/null +++ b/arch/x86/include/asm/enclu.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_ENCLU_H +#define _ASM_X86_ENCLU_H + +#define EENTER 0x02 +#define ERESUME 0x03 +#define EEXIT 0x04 + +#endif /* _ASM_X86_ENCLU_H */ -- cgit v1.2.3