On Wed, Mar 18, 2015 at 12:47 PM, Denys Vlasenko <[email protected]> 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.
Hallelujah! --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/
