On Fri, Aug 21, 2020 at 3:21 AM Peter Zijlstra <[email protected]> wrote: > > Get rid of the two variables, avoid computing si_code when not needed > and be consistent about which dr6 value is used. >
> - if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp) > - send_sigtrap(regs, 0, si_code); > + /* > + * If dr6 has no reason to give us about the origin of this trap, > + * then it's very likely the result of an icebp/int01 trap. > + * User wants a sigtrap for that. > + */ > + if (dr6 & (DR_STEP | DR_TRAP_BITS) || !dr6) > + send_sigtrap(regs, 0, get_si_code(dr6)); The old condition was ... || (actual DR6 value) and the new condition was ... || (stupid notifier-modified DR6 value). I think the old code was more correct. The right fix is to get rid of the notifier garbage. Want to pick up these two changes into your series: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry&id=b695a5adfdd661a10eead1eebd4002d08400e7ef https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry&id=40ca016606bd39a465feaf5802a8dc3e937aaa06 And then there is no code left that modifies ->debugreg6 out from under you. --Andy
