On Thu, Mar 19, 2020 at 01:03:41PM -0700, Xing, Cedric wrote: > On 3/18/2020 6:11 PM, Sean Christopherson wrote: > > #endif > > SYM_FUNC_START(__vdso_sgx_enter_enclave) > > /* Prolog */ > >@@ -82,7 +84,9 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) > > .cfi_rel_offset %rbp, 0 > > mov %rsp, %rbp > > .cfi_def_cfa_register %rbp > >+ push %rbx > A CFI directive is needed here: > > .cfi_rel_offset %rbx, -8 Darn, I suspected as much, but wasn't 100% positive. Shouldn't have hedged. :-) Is the rule of thumb for adding directives that one is needed any time there is a new saved value of a register, or if the relative address of the last saved value changes? Are CFI directives only used for non-volatile registers? > >+ mov %ecx, %eax > > .Lenter_enclave: > > /* EENTER <= leaf <= ERESUME */ > > cmp $0x2, %eax > >@@ -108,6 +112,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) > > jne .Linvoke_userspace_handler > > .Lout: > >+ pop %rbx > > leave > > .cfi_def_cfa %rsp, 8 > > ret > >
