From: Mark Rutland <mark.rutland@arm.com>
To: "Jin, Yao" <yao.jin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
acme@kernel.org, jolsa@kernel.org, mingo@redhat.com,
alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org,
ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com,
Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is specified
Date: Mon, 22 May 2017 09:45:30 +0100 [thread overview]
Message-ID: <20170522084529.GC1478@leverpostej> (raw)
In-Reply-To: <f67248f7-1ebd-98de-ae13-5ca3920d50e5@linux.intel.com>
On Mon, May 22, 2017 at 10:12:22AM +0800, Jin, Yao wrote:
> Hi Peter,
>
> Maybe it's not very easy to move the skid checking to generic code
> because we don't have a common kernel_ip() available to determine if
> ip is a kernel address.
>
> I was trying to move kernel_ip() from arch/x86/events/perf_event.h
> to generic code, but some difficulties I have:
>
> For example, in new kernel_ip(), we may use many
> conditional-compilation for all arch, for example:
>
> #ifdef CONFIG_X86_32
> return ip > PAGE_OFFSET;
> #endif
>
> #ifdef CONFIG_X86_64
> return (long)ip < 0;
> #endif
>
> #ifdef CONFIG_ARM....
> ......
> #ifdef CONFIG_MIPS....
> ......
>
> But the code is being ugly and hard to maintain. And frankly I don't
> know kernel address space for all arch.
>
> Any idea? Could we just do at x86 side this time?
Can we not check user_mode(regs) for all architectures?
!user_mode(regs) implies a kernel sample.
Thanks,
Mark.
next prev parent reply other threads:[~2017-05-22 8:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 10:19 [PATCH] perf/x86/intel: Drop kernel samples even though :u is specified Jin Yao
2017-05-19 9:29 ` Peter Zijlstra
2017-05-19 9:42 ` Will Deacon
2017-05-19 12:06 ` Jin, Yao
2017-05-19 12:10 ` Peter Zijlstra
2017-05-19 12:24 ` Jin, Yao
2017-05-19 12:36 ` Peter Zijlstra
2017-05-19 13:33 ` Jin, Yao
2017-05-22 2:12 ` Jin, Yao
2017-05-22 8:45 ` Mark Rutland [this message]
2017-05-22 9:26 ` Peter Zijlstra
2017-05-22 12:30 ` Jin, Yao
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