Re: [PATCH 0/4 v2] x86: entry_64.S: steps towards simpler iret frame handling

* Denys Vlasenko wrote: > These changes make SYSENTER64 code path save flags and user's > stack pointer in pt_regs->flags and pt_regs->sp, where they belong. > > As a result, we can drop stub_iopl() and thread_struct::usersp. > > Usage of PER_CPU(old_rsp) is reduced to bare minimum. > > FIXUP

[PATCH 0/4 v2] x86: entry_64.S: steps towards simpler iret frame handling

These changes make SYSENTER64 code path save flags and user's stack pointer in pt_regs->flags and pt_regs->sp, where they belong. As a result, we can drop stub_iopl() and thread_struct::usersp. Usage of PER_CPU(old_rsp) is reduced to bare minimum. FIXUP/RESTORE_TOP_OF_STACK macros are on diet to