On Sat, Apr 27, 2013 at 04:45:37PM +0200, Oleg Nesterov wrote: > On 04/26, Oleg Nesterov wrote: > > > On 04/26, H. Peter Anvin wrote: > > > > > > On 04/26/2013 09:38 AM, Oleg Nesterov wrote: > > > > > > > > - do_debug: > > > > > > > > dr6 &= ~DR6_RESERVED; > > > > > > > > this also wrongly clears 32-63 bits. Fortunately these > > > > bits are reserved and must be zero. > > > > > > I don't think this is wrongly at all. > > > > OK, I meant that it also clears the bits that are not specified in > > DR6_RESERVED mask. > > > > > The whole point is to mask out > > > the bits that the handler doesn't want to deal with, so masking out the > > > reserved bits [63:32] seems reasonable to me. > > > > Then we should do > > > > - #define DR6_RESERVED 0xFFFF0FF0 > > + #define DR6_RESERVED 0xFFFFFFFFFFFF0FF0 > > > > ? > > > > or what? (just in case, I will happily agree with "do nothing" ;) > > Or we can do the s/reserved/mask/ change and avoid any "unexpected" > effect of "long &= ~int". This allso allows to kill ifdef(__i386__). > > But this is include/uapi, I do not know if I can simply remove the > old define's. > > In short: whatever you prefer, including "leave it alone". > > Oleg. > > diff --git a/arch/x86/include/uapi/asm/debugreg.h > b/arch/x86/include/uapi/asm/debugreg.h > index 3c0874d..2678b23 100644 > --- a/arch/x86/include/uapi/asm/debugreg.h > +++ b/arch/x86/include/uapi/asm/debugreg.h > @@ -14,8 +14,7 @@ > which debugging register was responsible for the trap. The other bits > are either reserved or not of interest to us. */ > > -/* Define reserved bits in DR6 which are always set to 1 */ > -#define DR6_RESERVED (0xFFFF0FF0) > +#define DR6_MASK (0xF00FU) /* Everything else is reserved */
I'm personally fine either with that or with Peter's suggestion to do: -#define DR6_RESERVED (0xFFFF0FF0) +#define DR6_RESERVED (~0xF00FUL) If this should stay stable UAPI, we probably want Peter's solution. Otherwise I really don't mind. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
