linux-kernel - Re: [patch V3 05/11] x86/mm/cpa: Add debug mechanism

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Date:   Sat, 10 Nov 2018 15:01:43 +0000
From:   Jordan Glover <Golden_Miller83@...tonmail.ch>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Bin Yang <bin.yang@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Mark Gross <mark.gross@...el.com>
Subject: Re: [patch V3 05/11] x86/mm/cpa: Add debug mechanism

Hello,

The patch  "x86/mm/cpa: Add debug mechanism" (https://lore.kernel.org/lkml/20180917143546.078998733@linutronix.de/) caused a thousands of messages during boot on my machine.

They look like below:

kernel: CPA  protect    Text RO: 0xffffffff8affc000 - 0xffffffff8affcfff PFN 12cffc req 0000000000000063 prevent 0000000000000002
kernel: CPA  protect    Text RO: 0xffffffff8affd000 - 0xffffffff8affdfff PFN 12cffd req 0000000000000063 prevent 0000000000000002
kernel: CPA  protect    Text RO: 0xffffffff8affe000 - 0xffffffff8affefff PFN 12cffe req 0000000000000063 prevent 0000000000000002
kernel: CPA  protect    Text RO: 0xffffffff8afff000 - 0xffffffff8affffff PFN 12cfff req 0000000000000063 prevent 0000000000000002
kernel: CPA conflict  Rodata RO: 0xffffa2fbece00000 - 0xffffa2fbecffffff PFN 12ce00 req 80000000000000e3 prevent 0000000000000002
kernel: CPA  protect  Rodata RO: 0xffffa2fbece00000 - 0xffffa2fbece00fff PFN 12ce00 req 8000000000000063 prevent 0000000000000002
kernel: CPA  protect  Rodata RO: 0xffffa2fbece01000 - 0xffffa2fbece01fff PFN 12ce01 req 8000000000000063 prevent 0000000000000002
kernel: CPA  protect  Rodata RO: 0xffffa2fbece02000 - 0xffffa2fbece02fff PFN 12ce02 req 8000000000000063 prevent 0000000000000002


The exact reason for those may be related to some out-of-tree patches which I use:

https://github.com/anthraxx/linux-hardened/commit/c492687efa253c32972115a5e110e51614af445e#diff-e1f7e9a10ed7feb8c32493438cff8456

https://github.com/anthraxx/linux-hardened/commit/266d16fc47257b2548e6fcbfafebcc5d84d46389#diff-e1f7e9a10ed7feb8c32493438cff8456

but I wonder if those messages shouldn't be rate-limited or hidden behind 'CONFIG_CPA_DEBUG' in general as there may be a chance that someone will trigger something like that with vanillia kernel.

Jordan