linux-kernel - Re: [PATCH 1/3] perf/x86/amd: AMD support for bp_len > HW_BREAKPOINT_LEN

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Date:	Fri, 8 Nov 2013 20:41:24 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	suravee.suthikulpanit@....com
Cc:	mingo@...nel.org, mingo@...hat.com, jacob.w.shin@...il.com,
	oleg@...hat.com, a.p.zijlstra@...llo.nl, acme@...stprotocols.net,
	hpa@...or.com, tgl@...ain.invalid, linux-kernel@...r.kernel.org,
	sherry.hurwitz@....com
Subject: Re: [PATCH 1/3] perf/x86/amd: AMD support for bp_len >
 HW_BREAKPOINT_LEN_8

On Wed, Oct 02, 2013 at 11:11:06AM -0500, suravee.suthikulpanit@....com wrote:
> From: Jacob Shin <jacob.w.shin@...il.com>
> 
> Implement hardware breakpoint address mask for AMD Family 16h and
> above processors. CPUID feature bit indicates hardware support for
> DRn_ADDR_MASK MSRs. These masks further qualify DRn/DR7 hardware
> breakpoint addresses to allow matching of larger addresses ranges.
> 
> Valuable advice and pseudo code from Oleg Nesterov <oleg@...hat.com>
> 
> Signed-off-by: Jacob Shin <jacob.w.shin@...il.com>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
>  arch/x86/include/asm/cpufeature.h     |  2 ++
>  arch/x86/include/asm/debugreg.h       |  5 ++++
>  arch/x86/include/asm/hw_breakpoint.h  |  1 +
>  arch/x86/include/uapi/asm/msr-index.h |  4 +++
>  arch/x86/kernel/cpu/amd.c             | 19 ++++++++++++++
>  arch/x86/kernel/hw_breakpoint.c       | 47 ++++++++++++++---------------------
>  6 files changed, 49 insertions(+), 29 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
> index d3f5c63..26609bb 100644
> --- a/arch/x86/include/asm/cpufeature.h
> +++ b/arch/x86/include/asm/cpufeature.h
> @@ -170,6 +170,7 @@
>  #define X86_FEATURE_TOPOEXT	(6*32+22) /* topology extensions CPUID leafs */
>  #define X86_FEATURE_PERFCTR_CORE (6*32+23) /* core performance counter extensions */
>  #define X86_FEATURE_PERFCTR_NB  (6*32+24) /* NB performance counter extensions */
> +#define X86_FEATURE_BPEXT	(6*32+26) /* data breakpoint extension */

Does this feature only work on data breakpoint or is instruction breakpoint
address range supported as well?
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