On Mon, Sep 28, 2020 at 8:43 AM Yu, Yu-cheng <yu-cheng.yu@xxxxxxxxx> wrote: > > On 9/25/2020 11:23 AM, Andrew Cooper wrote: > > On 15/09/2020 12:28, Jarkko Sakkinen wrote: > >> diff --git a/arch/x86/entry/vdso/vsgx_enter_enclave.S b/arch/x86/entry/vdso/vsgx_enter_enclave.S > >> new file mode 100644 > >> index 000000000000..adbd59d41517 > >> --- /dev/null > >> +++ b/arch/x86/entry/vdso/vsgx_enter_enclave.S > >> @@ -0,0 +1,157 @@ > >> +SYM_FUNC_START(__vdso_sgx_enter_enclave) > >> <snip> > >> +.Lretpoline: > >> + call 2f > >> +1: pause > >> + lfence > >> + jmp 1b > >> +2: mov %rax, (%rsp) > >> + ret > > > > I hate to throw further spanners in the work, but this is not compatible > > with CET, and the user shadow stack work in progress. > > Hi Jarkko, > > These 1: and 2: targets are reached only from these few lines? If they > are direct call/jmp targets, I think it is OK in terms of CET. If they > are reached from an instruction like "jmp *%rax", then we need to put in > an "endbr64". > This also isn't compatible with shadow stack. -- H.J.
