On Mon, Mar 28, 2022 at 02:49:04PM -0700, Reinette Chatre wrote: > Hi Jarkko, > > On 3/22/2022 12:43 AM, Jarkko Sakkinen wrote: > > Simplify the test_encl_bootstrap.S flow by using rip-relative addressing. > > Compiler does the right thing here, and this removes dependency on where > > TCS entries need to be located in the binary, i.e. allows the binary layout > > changed freely in the future. > > > > Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx> > > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > --- > > tools/testing/selftests/sgx/test_encl_bootstrap.S | 6 +----- > > 1 file changed, 1 insertion(+), 5 deletions(-) > > > > diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S > > index 82fb0dfcbd23..1c1b5c6c4ffe 100644 > > --- a/tools/testing/selftests/sgx/test_encl_bootstrap.S > > +++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S > > @@ -40,11 +40,7 @@ > > .text > > > > encl_entry: > > - # RBX contains the base address for TCS, which is the first address > > - # inside the enclave for TCS #1 and one page into the enclave for > > - # TCS #2. By adding the value of encl_stack to it, we get > > - # the absolute address for the stack. > > - lea (encl_stack)(%rbx), %rax > > + lea (encl_stack)(%rip), %rax > > xchg %rsp, %rax > > push %rax > > > > The goal of the above snippet is to set RSP to ensure that each thread has its own stack. > > Since EENTER computes RIP as EnclaveBase + TCS.OENTRY, by using offset from RIP this > would result in all TCS with OENTRY of encl_entry to use the same stack, no? > > Could you please consider the following as an alternative: > https://lore.kernel.org/lkml/65c137c875bd4da675eaba35316ff43d7cfd52f8.1644274683.git.reinette.chatre@xxxxxxxxx/ > > The idea in that patch is that a new TCS would always need to be accompanied by a > dedicated stack so, at least for testing purposes, the TCS and stack can be dynamically > allocated together with the TCS page following its stack. This seems much simpler > to me and also makes the following patch unnecessary. There's no better alternative than use rip. Compiler will fix it up. So, no, I won't consider that. This a dead obvious change. BR, Jarkko
