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From: Peter Zijlstra <peterz@infradead.org>
To: Kairui Song <kasong@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, Dave Young <dyoung@redhat.com>
Subject: Re: [RFC PATCH v2] perf/x86: make perf callchain work without CONFIG_FRAME_POINTER
Date: Tue, 16 Apr 2019 19:45:28 +0200	[thread overview]
Message-ID: <20190416174528.GT4038@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CACPcB9f0D4SdJLAtUs4vYwduBiPYDpa-y8r7jracYy=sAJmo5g@mail.gmail.com>

On Wed, Apr 17, 2019 at 01:39:19AM +0800, Kairui Song wrote:
> And I also think the "fake"/"real" reg is fragile, could we abuse
> another eflag (just like PERF_EFLAGS_EXACT) to indicate the regs are
> partially dumped fake registers? 

Sure, the SDM seems to suggest bits 1,3,5,15 are 'available'. We've
already used 3 and 5, and I think we can use !X86_EFLAGS_FIXED to
indicate a fake regs set. Any real regs set will always have that set.

  reply	other threads:[~2019-04-16 17:45 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-08 16:59 [RFC PATCH v2] perf/x86: make perf callchain work without CONFIG_FRAME_POINTER Kairui Song
2019-04-15 12:38 ` Jiri Olsa
2019-04-15 15:36 ` Peter Zijlstra
2019-04-15 16:58   ` Josh Poimboeuf
2019-04-16 11:30     ` Kairui Song
2019-04-16 16:16       ` Alexei Starovoitov
2019-04-16 17:39       ` Kairui Song
2019-04-16 17:45         ` Peter Zijlstra [this message]
2019-04-17 14:41           ` Kairui Song
2019-04-16 20:15         ` Josh Poimboeuf
2019-04-17  7:07           ` Peter Zijlstra
2019-04-18  2:15             ` Josh Poimboeuf
2019-04-17 14:44           ` Kairui Song
2019-04-18  7:54             ` Peter Zijlstra

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