First things first, this RFC is not intended to address whether or not vDSO is the appropriate method for supporting SGX enclaves, but rather its purpose is to hammer out the vDSO implementation *if* we decide it is the best approach.
Though the code technically stands alone, the intent is to roll it into the main SGX series once it has been beat on for a bit. For that reason there are no dependencies on CONFIG_SGX (which doesn't exist) or any other bits that one might expect. The quick and dirty is that for all intents and purposes, the SGX architecture requires userspace to gracefully handle exceptions. The vast majority of enclaves are expected to leverage a library to handle much of the plumbing. Unfortunately for us (them?), putting two and two together means SGX libraries would need to handle most signals on behalf of the enclave's application, which is far from ideal. One proposed solution for supporting SGX without requiring signals is to wrap enclave transitions in a vDSO function so that SGX exceptions can be intercepted via exception fixup and returned inline to the caller. This RFC series adds exception fixup and SGX support to the vDSO. Sean Christopherson (4): x86/vdso: Add support for exception fixup in vDSO functions x86/fault: Attempt to fixup unhandled #PF in vDSO before signaling x86/traps: Attempt to fixup exceptions in vDSO before signaling x86/vdso: Add __vdso_sgx_eenter() to wrap SGX enclave transitions arch/x86/entry/vdso/Makefile | 5 +- arch/x86/entry/vdso/extable.c | 37 +++++++++ arch/x86/entry/vdso/extable.h | 17 ++++ arch/x86/entry/vdso/vdso-layout.lds.S | 9 ++- arch/x86/entry/vdso/vdso.lds.S | 1 + arch/x86/entry/vdso/vdso2c.h | 58 ++++++++++++-- arch/x86/entry/vdso/vsgx_eenter.c | 108 ++++++++++++++++++++++++++ arch/x86/include/asm/vdso.h | 5 ++ arch/x86/kernel/traps.c | 11 +++ arch/x86/mm/fault.c | 7 ++ 10 files changed, 247 insertions(+), 11 deletions(-) create mode 100644 arch/x86/entry/vdso/extable.c create mode 100644 arch/x86/entry/vdso/extable.h create mode 100644 arch/x86/entry/vdso/vsgx_eenter.c -- 2.19.2
