From: Pavel Machek <pavel@ucw.cz>
To: Andy Lutomirski <luto@kernel.org>
Cc: X86 ML <x86@kernel.org>, Borislav Petkov <bpetkov@suse.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Zhang Rui <rui.zhang@intel.com>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH urgent 3/3] x86/power: Make restore_processor_context() sane
Date: Thu, 14 Dec 2017 23:32:17 +0100 [thread overview]
Message-ID: <20171214223217.GA10525@amd> (raw)
In-Reply-To: <398ee68e5c0f766425a7b746becfc810840770ff.1513286253.git.luto@kernel.org>
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Hi!
> My previous attempt to fix a couple of bugs in
> __restore_processor_context() introduced yet another bug. Rather
> than trying to come up with a minimal fix, let's try to clean it up
> for real. This patch fixes quite a few things:
>
> - The old code saved a nonsensical subset of segment registers.
> The only registers that need to be saved are those that contain
> userspace state or those that can't be trivially restored without
> percpu access working. (On x86_32, we can restore percpu access
> by writing __KERNEL_PERCPU to %fs. On x86_64, it's easier to
> save and restore the kernel's GSBASE.) With this patch, we
> restore hardcoded values to the kernel state where applicable and
> explicitly restore the user state after fixing all the descriptor
> tables.
>
> - We used to use an unholy mix of inline asm and C helpers for
> segment register access. Let's get rid of the inline asm.
>
> Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Fixes: 5b06bbcfc2c6 ("x86/power: Fix some ordering bugs in __restore_processor_context()")
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
Thanks!
Tested-by: Pavel Machek <pavel@ucw.cz>
Reported-by: Pavel Machek <pavel@ucw.cz>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2017-12-14 22:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-14 21:19 [PATCH urgent 0/3] __restore_processor_state() fixes Andy Lutomirski
2017-12-14 21:19 ` [PATCH urgent 1/3] x86/power/64: Use struct desc_ptr for the IDT in struct saved_context Andy Lutomirski
2017-12-15 14:37 ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2017-12-14 21:19 ` [PATCH urgent 2/3] x86/power/32: Move SYSENTER MSR restoration to fix_processor_context() Andy Lutomirski
2017-12-15 14:38 ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2017-12-14 21:19 ` [PATCH urgent 3/3] x86/power: Make restore_processor_context() sane Andy Lutomirski
2017-12-14 22:32 ` Pavel Machek [this message]
2017-12-15 14:38 ` [tip:x86/urgent] " tip-bot for Andy Lutomirski
2017-12-15 1:28 ` [PATCH urgent 0/3] __restore_processor_state() fixes Rafael J. Wysocki
2017-12-15 1:35 ` Linus Torvalds
2017-12-15 11:21 ` Ingo Molnar
2017-12-15 9:18 ` Jarkko Nikula
2017-12-15 11:31 ` Ingo Molnar
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