On Thu, Mar 19, 2015 at 06:17:48PM +0100, Denys Vlasenko wrote: > FIXUP_TOP_OF_STACK is only necessary because we don't save %r11 > to pt_regs->r11 on SYSCALL64 fast path, but we want ptrace to see > it populated. > > Bite the bullet, add a single additional PUSH insn, and remove > FIXUP_TOP_OF_STACK. > > RESTORE_TOP_OF_STACK is already a nop. Remove it too. > > On SandyBridge CPU, it does not get slower: > measured 54.22 ns per getpid syscall before and after last two changes > on defconfig kernel. > > Signed-off-by: Denys Vlasenko <[email protected]> > CC: Linus Torvalds <[email protected]> > CC: Steven Rostedt <[email protected]> > CC: Ingo Molnar <[email protected]> > CC: Borislav Petkov <[email protected]> > CC: "H. Peter Anvin" <[email protected]> > CC: Andy Lutomirski <[email protected]> > CC: Oleg Nesterov <[email protected]> > CC: Frederic Weisbecker <[email protected]> > CC: Alexei Starovoitov <[email protected]> > CC: Will Drewry <[email protected]> > CC: Kees Cook <[email protected]> > CC: [email protected] > CC: [email protected] > --- > arch/x86/kernel/entry_64.S | 35 ++--------------------------------- > 1 file changed, 2 insertions(+), 33 deletions(-)
Nice diffstat. Acked-by: Borislav Petkov <[email protected]> -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- 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/
