> > > + * "Restore" RSP from RBP, even though IRET has already unwound > > > RSP to > > > + * the correct value. objtool doesn't know the callee will IRET and, > > > + * without the explicit restore, thinks the stack is getting walloped. > > > + * Using an unwind hint is problematic due to x86-64's dynamic > > > alignment. > > > + */ > > > + mov %_ASM_BP, %_ASM_SP > > > + pop %_ASM_BP > > > + RET > > > > For NMI, after this RET instruction, we continue to block NMIs. IRET > instead? > > No, IRET has already been done by the kernel-provided handler, e.g. > asm_exc_nmi_kvm_vmx() > by way of error_return(). That's why the CALL above (that got snipped) is > preceded > by the creation of a synthetic NMI/IRQ stack frame: the target returns from > the CALL > via IRET, not RET. You're right, this assembly makes another call into the asm entry point, which returns here with IRET.
