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 <[email protected]> Suggested-by: H. Peter Anvin <[email protected]> Signed-off-by: Oleg Nesterov <[email protected]> --- 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-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/
