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From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	kan.liang@linux.intel.com, like.xu@linux.intel.com,
	Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH] perf/arch: Remove perf_sample_data::regs_user_copy
Date: Fri, 30 Oct 2020 08:33:58 -0400	[thread overview]
Message-ID: <20201030083358.4c771278@oasis.local.home> (raw)
In-Reply-To: <20201030105917.GI2611@hirez.programming.kicks-ass.net>

On Fri, 30 Oct 2020 11:59:17 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, Oct 30, 2020 at 11:26:01AM +0100, Thomas Gleixner wrote:
> > What's worse is perf_sample_data which is 384 bytes and is 64 bytes aligned.  
> 
> Here; this shrinks it to 192 bytes. Combined with the static dummy this
> should reduce stack usage by 360 bytes.
> 
> ---
> Subject: perf/arch: Remove perf_sample_data::regs_user_copy
> 
> struct perf_sample_data lives on-stack, we should be careful about it's
> size. Furthermore, the pt_regs copy in there is only because x86_64 is a
> trainwreck, solve it differently.
> 
> Halves sizeof(perf_sample_data).
> 
> 


I tested with just this patch and it doesn't crash when running
function tracing and perf simultaneously.

-- Steve

  reply	other threads:[~2020-10-30 12:34 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30  4:27 [BUG] Stack overflow when running perf and function tracer Steven Rostedt
2020-10-30  9:00 ` Peter Zijlstra
2020-10-30 10:26   ` Thomas Gleixner
2020-10-30 10:32     ` Peter Zijlstra
2020-10-30 11:36       ` Thomas Gleixner
2020-10-30 13:42         ` Thomas Gleixner
2020-10-30 10:59     ` [PATCH] perf/arch: Remove perf_sample_data::regs_user_copy Peter Zijlstra
2020-10-30 12:33       ` Steven Rostedt [this message]
2020-10-30 11:19   ` [PATCH] perf/x86: Make dummy_iregs static Peter Zijlstra

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