linux-kernel - Re: [PATCH v4 1/4] x86/ibt: factor out cfi and fineibt offset

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Message-ID: <20250304094220.GC11590@noisy.programming.kicks-ass.net>
Date: Tue, 4 Mar 2025 10:42:20 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Menglong Dong <menglong8.dong@...il.com>
Cc: rostedt@...dmis.org, mark.rutland@....com, alexei.starovoitov@...il.com,
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Subject: Re: [PATCH v4 1/4] x86/ibt: factor out cfi and fineibt offset

On Tue, Mar 04, 2025 at 03:47:45PM +0800, Menglong Dong wrote:
> We don't have to select FUNCTION_ALIGNMENT_32B, so the
> worst case is to increase ~2.2%.
> 
> What do you think?

Well, since I don't understand what you need this for at all, I'm firmly
on the side of not doing this.

What actual problem is being solved with this meta data nonsense? Why is
it worth blowing up our I$ footprint over.

Also note, that if you're going to be explaining this, start from
scratch, as I have absolutely 0 clues about BPF and such.