On 7/22/21 1:52 PM, Yu-cheng Yu wrote:
quoted hunk ↗ jump to hunk
+ if (fpregs_state_valid(fpu, smp_processor_id())) {
+ rdmsrl(MSR_IA32_PL3_SSP, ssp);
+ } else {
+ struct cet_user_state *p;
+
+ /*
+ * When !fpregs_state_valid() and get_xsave_addr() returns
+ * null, XFEAUTRE_CET_USER is in init state. Shadow stack
+ * pointer is null in this case, so return zero.
+ */
+ p = get_xsave_addr(&fpu->state.xsave, XFEATURE_CET_USER);
+ if (p)
+ ssp = p->user_ssp;
+ }
+
+ fpregs_unlock();
Why are we even calling into this code if shadow stacks might be
disabled? Seems like we should have just errored out long before
getting here.