On Mon, Apr 22, 2019 at 01:42:56PM -0700, Cedric Xing wrote: > The current proposed __vdso_sgx_enter_enclave() requires enclaves to preserve > %rsp, which prohibits enclaves from allocating space on the untrusted stack. > However, there are existing enclaves (e.g. those built with current Intel SGX > SDK libraries) relying on the untrusted stack for passing parameters to > untrusted functions (aka. o-calls), which requires allocating space on the > untrusted stack by enclaves. And given its simplicity and convenience, it > could be desired by future SGX applications as well. > > This patchset introduces a new ABI for __vdso_sgx_enter_enclave() to anchor > its stack frame on %rbp (instead of %rsp), so as to allow enclaves to "push" > onto the untrusted stack by decrementing the untrusted %rsp. Additionally, > this new __vdso_sgx_enter_enclave() will take one more parameter - a callback > function, to be invoked upon all enclave exits (both AEX and normal exits). > The callback function will be given the value of %rsp left off by the > enclave, so that data "pushed" by the enclave (if any) could be > addressed/accessed. Please note that the callback function is optional, and > if not supplied (i.e. null), __vdso_sgx_enter_enclave() will just return > (i.e. behave the same as the current implementation) after the enclave exits > (or AEX due to exceptions). > > The SGX selftest is augmented to test out the new callback interface, and to > serve as a simple example to showcase how to use the callback interface in > practice. Please wrap your emails, or use an editor that will do it for you. 75 chars, plus or minus a few, is generally preferred. > Cedric Xing (3): > selftests/x86: Fixed Makefile for SGX selftest > x86/vdso: Modify __vdso_sgx_enter_enclave() to allow parameter passing > on untrusted stack > selftests/x86: Augment SGX selftest to test new > __vdso_sgx_enter_enclave() and its callback interface > > arch/x86/entry/vdso/vsgx_enter_enclave.S | 156 ++++++++++++--------- > arch/x86/include/uapi/asm/sgx.h | 14 +- > tools/testing/selftests/x86/Makefile | 12 +- > tools/testing/selftests/x86/sgx/Makefile | 45 +++--- > tools/testing/selftests/x86/sgx/main.c | 123 +++++++++++++--- > tools/testing/selftests/x86/sgx/sgx_call.S | 40 +++++- > 6 files changed, 264 insertions(+), 126 deletions(-) > > -- > 2.17.1 >
