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From: Thomas Gleixner <tglx@linutronix.de>
To: "Maciej W. Rozycki" <macro@orcam.me.uk>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	Kees Cook <keescook@chromium.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] x86: Use `get_random_u8' for kernel stack offset randomization
Date: Mon, 13 Feb 2023 20:03:34 +0100	[thread overview]
Message-ID: <874jrptmk9.ffs@tglx> (raw)
In-Reply-To: <alpine.DEB.2.21.2301302011150.55843@angie.orcam.me.uk>

On Mon, Jan 30 2023 at 21:30, Maciej W. Rozycki wrote:
>
> Therefore switch to our generic entropy source and use `get_random_u8' 
> instead, which according to Jason A. Donenfeld is supposed to be fast 
> enough:
>
> "Generally it's very very fast, as most cases wind up being only a
> memcpy -- in this case, a single byte copy. So by and large it should
> be suitable. It's fast enough now that most networking things are able
> to use it. And lots of other places where you'd want really high
> performance. So I'd expect it's okay to use here too. And if it is too
> slow, we should figure out how to make it faster. But I don't suspect
> it'll be too slow."

Please provide numbers on contemporary hardware.

Up to that point, it's easy enough to just disable that randomization on
32bit.

Thanks,

        tglx

  parent reply	other threads:[~2023-02-13 19:04 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-30 21:30 [PATCH v3] x86: Use `get_random_u8' for kernel stack offset randomization Maciej W. Rozycki
2023-01-31 19:34 ` Jason A. Donenfeld
2023-01-31 20:52 ` H. Peter Anvin
2023-01-31 21:01 ` Miko Larsson
2023-02-12 23:17 ` [PING][PATCH " Maciej W. Rozycki
2023-02-13 19:01   ` Thomas Gleixner
2023-02-14  4:54     ` Maciej W. Rozycki
2023-02-14 20:43       ` H. Peter Anvin
2023-02-22 16:44         ` Jason A. Donenfeld
2023-02-13 19:03 ` Thomas Gleixner [this message]
2023-02-14  5:12   ` [PATCH " Maciej W. Rozycki
2023-02-14 13:39     ` Jason A. Donenfeld
2023-02-22 12:05       ` Maciej W. Rozycki
2023-06-05 15:45         ` Maciej W. Rozycki

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