From: Linus Torvalds <torvalds@linux-foundation.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Zhang Rui <rui.zhang@intel.com>,
Andrew Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: Linux 4.15-rc2: Regression in resume from ACPI S3
Date: Tue, 12 Dec 2017 09:27:13 -0800 [thread overview]
Message-ID: <CA+55aFwMCHd7ppU2aWafXoHdTme=g=HJ1UMmNp5WuQ9pQ7i7Cg@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFwK96Eryb2PMoeaLxPSu4srGQakh=jO646Wqv9advLp0A@mail.gmail.com>
On Sun, Dec 10, 2017 at 1:28 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> That said, this *all* smells wrong. Why is there a special
> fix_processor_context() function at all with different 32-bit and
> 64-bit behavior? This code is all written to be maximally confusing.
Hmm. Looking a bit more at this, I think it should be solved by:
- load the original read-write GDT early, along with the IDT.
We have already saved it off in __save_processor_state(), and it may
have already gotten loaded very early in at least some of the paths,
but it definitely hasn't gotten reloaded in all the paths (think
"suspend/resume testing" etc).
- add the LDT descriptor to the save area too, exactly like we
already have IDT/GDT.
Then, we can do "load_ldt()" early (along with IDT and GDT).
- now we can just load all the segments early, and get the percpu and
stack canary stuff without any special cases
- do NOT use "load_gs_index()", which does that swapgs dance (twice!)
and plays with interrupt state. Just load the segment register, and
then do the wrmsrl() of the {FS,GS,KERNEL_GS}_BASE values. There is no
need for the swapgs dance.
- now that we have a fully working system, then the
"fix_processor_context()" code can do the "fancy" stuff like setting
up the RO fixmap GDT and re-initializing the TLB state. Those want
percpu stuff.
In other words, why not try to organize this so that we do a simple
and fairly mindless restore of the low-level state first? Avoid all
the "system is halfway up" crud.
Would that work for people? Andy?
Linus
next prev parent reply other threads:[~2017-12-12 17:27 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-03 16:22 Linux 4.15-rc2 Linus Torvalds
2017-12-04 22:25 ` Linux 4.15-rc2: Regression in resume from ACPI S3 Rafael J. Wysocki
2017-12-04 22:36 ` Linus Torvalds
2017-12-04 22:38 ` Thomas Gleixner
2017-12-04 22:41 ` Rafael J. Wysocki
2017-12-05 0:25 ` Rafael J. Wysocki
2017-12-09 10:33 ` Pavel Machek
2017-12-09 11:41 ` Pavel Machek
[not found] ` <CA+55aFw8tuoJ2gcXx3K2sKFf2Y9hXX4naMVQNqGOUivnjwhjkg@mail.gmail.com>
2017-12-09 22:01 ` Pavel Machek
[not found] ` <CA+55aFySAdiBZhZ0PSDjH5PuvPPcMsBRXbxCkObfm1eY7gHDbQ@mail.gmail.com>
2017-12-10 16:23 ` Pavel Machek
2017-12-10 16:37 ` Linus Torvalds
2017-12-10 18:56 ` Pavel Machek
2017-12-10 20:30 ` Linus Torvalds
2017-12-10 20:43 ` Pavel Machek
2017-12-10 21:28 ` Linus Torvalds
2017-12-10 21:35 ` Pavel Machek
2017-12-12 17:27 ` Linus Torvalds [this message]
2017-12-12 18:05 ` Andy Lutomirski
2017-12-12 18:36 ` Linus Torvalds
2017-12-12 22:10 ` Andy Lutomirski
2017-12-12 22:33 ` Linus Torvalds
2017-12-12 23:10 ` Andy Lutomirski
2017-12-13 11:16 ` Jarkko Nikula
2017-12-13 12:40 ` Ingo Molnar
2017-12-13 18:50 ` Andy Lutomirski
2017-12-10 21:38 ` [PATCH] Fix resume on x86-32 machines Pavel Machek
2017-12-10 21:58 ` Andy Lutomirski
2017-12-10 22:20 ` Pavel Machek
2017-12-11 9:25 ` Jarkko Nikula
2017-12-11 14:22 ` Rafael J. Wysocki
2017-12-11 14:43 ` Rafael J. Wysocki
2017-12-11 14:59 ` Jarkko Nikula
2017-12-11 18:31 ` Linus Torvalds
2017-12-11 18:41 ` Andy Lutomirski
2017-12-11 19:12 ` Linus Torvalds
2017-12-14 20:38 ` Pavel Machek
2017-12-14 20:47 ` Linus Torvalds
2017-12-14 21:20 ` Andy Lutomirski
2017-12-14 22:22 ` Pavel Machek
2017-12-11 15:13 ` Ingo Molnar
2017-12-11 16:26 ` Andy Lutomirski
2017-12-11 14:09 ` Linux 4.15-rc2: Regression in resume from ACPI S3 Zhang Rui
2017-12-11 16:28 ` Andy Lutomirski
2017-12-12 8:00 ` Pavel Machek
2017-12-06 12:15 ` Michal Hocko
2017-12-06 12:23 ` Thomas Gleixner
2017-12-06 14:04 ` Rafael J. Wysocki
2017-12-06 12:31 ` Maarten Lankhorst
2017-12-06 12:46 ` Thomas Gleixner
2017-12-06 13:09 ` Maarten Lankhorst
2017-12-06 14:15 ` Thomas Gleixner
2017-12-07 13:33 ` Maarten Lankhorst
2017-12-08 10:30 ` Thomas Gleixner
2017-12-13 15:57 ` Thomas Gleixner
2017-12-13 16:23 ` Bjorn Helgaas
2017-12-13 16:41 ` Thomas Gleixner
2017-12-13 17:45 ` Linus Torvalds
2017-12-13 18:19 ` Thomas Gleixner
2017-12-13 20:52 ` Thomas Gleixner
2017-12-13 21:06 ` Thomas Gleixner
2017-12-13 22:48 ` Rafael J. Wysocki
2017-12-14 11:54 ` Thomas Gleixner
2017-12-14 12:12 ` Rafael J. Wysocki
2017-12-14 12:30 ` Thomas Gleixner
2017-12-14 15:30 ` Rafael J. Wysocki
2017-12-14 15:52 ` Thomas Gleixner
2017-12-14 15:54 ` Rafael J. Wysocki
2017-12-14 16:17 ` Maarten Lankhorst
2017-12-15 2:07 ` [PATCH] PCI / PM: Force devices to D0 in pci_pm_thaw_noirq() Rafael J. Wysocki
2017-12-15 14:28 ` Rafael J. Wysocki
2017-12-15 18:30 ` Bjorn Helgaas
2017-12-15 23:44 ` Rafael J. Wysocki
2017-12-14 13:24 ` Linux 4.15-rc2: Regression in resume from ACPI S3 Thomas Gleixner
2017-12-14 19:03 ` Linus Torvalds
2017-12-14 22:36 ` Thomas Gleixner
2017-12-14 22:47 ` Linus Torvalds
2017-12-15 9:05 ` Thomas Gleixner
2017-12-15 0:34 ` Rafael J. Wysocki
2017-12-13 22:39 ` Rafael J. Wysocki
2017-12-13 23:26 ` Rafael J. Wysocki
2017-12-07 7:55 ` Michal Hocko
2017-12-10 20:30 ` Michal Hocko
2018-02-21 18:36 ` Linux 4.15-rc2 Eugene Syromiatnikov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CA+55aFwMCHd7ppU2aWafXoHdTme=g=HJ1UMmNp5WuQ9pQ7i7Cg@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=jarkko.nikula@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pavel@ucw.cz \
--cc=rjw@rjwysocki.net \
--cc=rui.zhang@intel.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).