On Wed, Feb 11, 2015 at 1:13 PM, Denys Vlasenko <[email protected]> wrote: > On 02/11/2015 09:36 PM, Andy Lutomirski wrote: >> On Wed, Jan 14, 2015 at 1:48 PM, Denys Vlasenko <[email protected]> wrote: >>> RESTORE_EXTRA_REGS + RESTORE_C_REGS looks small, but it's >>> a lot of instructions (fourteen). Let's reuse them. >>> >>> Signed-off-by: Denys Vlasenko <[email protected]> >>> CC: Linus Torvalds <[email protected]> >>> CC: Oleg Nesterov <[email protected]> >>> CC: Borislav Petkov <[email protected]> >>> CC: "H. Peter Anvin" <[email protected]> >>> CC: Andy Lutomirski <[email protected]> >>> CC: Frederic Weisbecker <[email protected]> >>> CC: X86 ML <[email protected]> >>> CC: Alexei Starovoitov <[email protected]> >>> CC: Will Drewry <[email protected]> >>> CC: Kees Cook <[email protected]> >>> CC: [email protected] >>> --- >>> arch/x86/kernel/entry_64.S | 6 ++---- >>> 1 file changed, 2 insertions(+), 4 deletions(-) >>> >>> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S >>> index a21b5b3..f5e815e 100644 >>> --- a/arch/x86/kernel/entry_64.S >>> +++ b/arch/x86/kernel/entry_64.S >>> @@ -1270,12 +1270,10 @@ ENTRY(paranoid_exit) >>> jnz paranoid_restore >>> TRACE_IRQS_IRETQ 0 >>> SWAPGS_UNSAFE_STACK >>> - RESTORE_EXTRA_REGS >>> - RESTORE_C_REGS >>> - REMOVE_PT_GPREGS_FROM_STACK 8 >>> - INTERRUPT_RETURN >>> + jmp paranoid_restore1 >>> paranoid_restore: >>> TRACE_IRQS_IRETQ_DEBUG 0 >>> +paranoid_restore1: >>> RESTORE_EXTRA_REGS >>> RESTORE_C_REGS >>> REMOVE_PT_GPREGS_FROM_STACK 8 >> >> This is sort of a reply to the wrong thread, but wouldn't it be nicer >> if we could pop a bunch of regs instead of using mov followed by add? > > I like this (pop instead of mov) too. > >> (Yes, this could be a followup, but it could be easier to spot now by >> changing macros like RESTORE_XYZ.) > > I don't understand what this means. > "Let's switch to pops now, in this patch"? Or something else?
You're replacing things like SAVE_XYZ with sequences like ALLOC_SPACE_FOR_XYZ, RESTORE_XYZ, and replacing them with POP_XYZ could be done in a single step. That being said, let's not overcomplicate this. I'll review the patch as is, and we can switch to push/pop (or not) later on. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
