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Message-ID: <20130428172731.GA26169@redhat.com> Date: Sun, 28 Apr 2013 19:27:31 +0200 From: Oleg Nesterov <oleg@...hat.com> To: Frederic Weisbecker <fweisbec@...il.com> Cc: "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Cyrill Gorcunov <gorcunov@...il.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Thomas Gleixner <tglx@...utronix.de>, David Miller <davem@...emloft.net>, "Theodore Ts'o" <tytso@....edu>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, the arch/x86 maintainers <x86@...nel.org>, Network Development <netdev@...r.kernel.org>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org> Subject: Re: [PATCH v2] x86: make DR*_RESERVED unsigned long On 04/28, Frederic Weisbecker wrote: > > On Sat, Apr 27, 2013 at 04:45:37PM +0200, Oleg Nesterov wrote: > > > > -/* 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) I missed this suggestion... Yes, and this allows to kill ifdef too. > If this should stay stable UAPI, I do not know, but I guess it would be safer to keep the old define's. > I really don't mind. Oh, I do not mind too ;) OK, please see v3. ------------------------------------------------------------------------------ Subject: [PATCH v3] x86: make DR*_RESERVED unsigned long DR6_RESERVED and DR_CONTROL_RESERVED are used to clear the unwanted bits in the "unsigned long" data, but "ulong &= ~int" also clears the upper bits that are not specified in mask. This is actually fine, dr6[32:63] are reserved, but this is not clear so it would be better to make them "unsigned long" to cleanup the code. However, depending on sizeof(long), DR6_RESERVED should be either 0xFFFF0FF0 or 0xFFFFFFFF_FFFF0FF0, so this patch redefines them as (~ 32_bit_mask UL) to avoid ifdef's. Reported-by: Linus Torvalds <torvalds@...ux-foundation.org> Suggested-by: H. Peter Anvin <hpa@...or.com> Signed-off-by: Oleg Nesterov <oleg@...hat.com> --- arch/x86/include/uapi/asm/debugreg.h | 8 ++------ 1 files changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/uapi/asm/debugreg.h b/arch/x86/include/uapi/asm/debugreg.h index 3c0874d..4ff5d05 100644 --- a/arch/x86/include/uapi/asm/debugreg.h +++ b/arch/x86/include/uapi/asm/debugreg.h @@ -15,7 +15,7 @@ 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_RESERVED (~0xF00FUL) #define DR_TRAP0 (0x1) /* db0 */ #define DR_TRAP1 (0x2) /* db1 */ @@ -64,11 +64,7 @@ We can slow the instruction pipeline for instructions coming via the gdt or the ldt if we want to. I am not sure why this is an advantage */ -#ifdef __i386__ -#define DR_CONTROL_RESERVED (0xFC00) /* Reserved by Intel */ -#else -#define DR_CONTROL_RESERVED (0xFFFFFFFF0000FC00UL) /* Reserved */ -#endif +#define DR_CONTROL_RESERVED (~0xFFFF03FFUL) /* Reserved by Intel */ #define DR_LOCAL_SLOWDOWN (0x100) /* Local slow the pipeline */ #define DR_GLOBAL_SLOWDOWN (0x200) /* Global slow the pipeline */ -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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