Re: [PATCH 2/5] perf, x86: AMD implementation for hardwarebreakpoint address mask

From: Oleg Nesterov
Date: Sun Apr 21 2013 - 13:22:46 EST


Not a comment, but the question...

On 04/09, Jacob Shin wrote:
>
> --- a/arch/x86/include/asm/hw_breakpoint.h
> +++ b/arch/x86/include/asm/hw_breakpoint.h
> @@ -14,6 +14,7 @@ struct arch_hw_breakpoint {
> unsigned long address;
> u8 len;
> u8 type;
> + u32 mask;
> };
...
> @@ -254,6 +258,7 @@ static int arch_build_bp_info(struct perf_event *bp)
> struct arch_hw_breakpoint *info = counter_arch_bp(bp);
>
> info->address = bp->attr.bp_addr;
> + info->mask = bp->attr.bp_addr_mask;

OK, this matches the usage of info->address so I think this change
is right.

But otoh, why do we need info->address (or mask added by this patch)?
we could use bp->attr.bp_addr instead. arch_hw_breakpoint could have
a single filed = "type | len" for encode_dr7().

Yes, off-topic, sorry for noise.

Oleg.

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