From: Mark Rutland <mark.rutland@arm.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>, X86 ML <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86/Kconfig: Disable KASLR on debug builds
Date: Mon, 4 Dec 2023 10:42:15 +0000 [thread overview]
Message-ID: <ZW2tBy_8U5cfEkmk@FVFF77S0Q05N> (raw)
In-Reply-To: <20231130124909.GEZWiExTP4J1pjNxPq@fat_crate.local>
On Thu, Nov 30, 2023 at 01:49:09PM +0100, Borislav Petkov wrote:
> On Thu, Nov 30, 2023 at 01:08:31PM +0100, Peter Zijlstra wrote:
> > Works for me, but I have "nokaslr no_hash_pointers" on all my machines
> > by now. It goes right along with "debug ignore_loglevel
> > sysrq_always_enabled earlyprintk=serial,ttyS0,115200" :-)
>
> Bah, there's cmdline switches. Lemme add them to all my scripts starting
> guests and grub too. Thanks for the hint!
>
> I guess we could still do the Kconfig dependency when we're on new
> machines, without the scripts.
>
> Btw, I'm not the only one who's walked right into this one:
>
> config KCOV
> bool "Code coverage for fuzzing"
>
> ...
>
> If RANDOMIZE_BASE is enabled, PC values will not be stable across
> different machines and across reboots. If you need stable PC values,
> disable RANDOMIZE_BASE.
IIUC that's no longer necessary, and the Kconfig.debug wording is stale.
That wording was introduced in March 2016 as part of the original KCOV support
in commit:
5c9a8750a6409c63 ("kernel: add kcov code coverage")
Later, in December 2016 we made KCOV adjust the address to remove the KASLR
offset in commit:
4983f0ab7ffaad1e ("kcov: make kcov work properly with KASLR enabled")
... so I think that's been stale for ~7 years, and we just forgot to clean up
the Kconfig.debug text.
Mark.
next prev parent reply other threads:[~2023-12-04 10:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-30 12:05 [RFC PATCH] x86/Kconfig: Disable KASLR on debug builds Borislav Petkov
2023-11-30 12:08 ` Peter Zijlstra
2023-11-30 12:49 ` Borislav Petkov
2023-12-04 10:42 ` Mark Rutland [this message]
2023-12-04 15:49 ` Borislav Petkov
2023-12-04 17:20 ` Mark Rutland
2023-11-30 18:10 ` Nathan Chancellor
2023-11-30 19:34 ` Borislav Petkov
2023-12-01 16:16 ` Nathan Chancellor
2023-12-01 16:24 ` Borislav Petkov
2023-12-01 16:58 ` Nathan Chancellor
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