From: Mitch Bradley <wmb@laptop.org>
To: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Andres Salomon <dilinger@queued.net>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Ian Campbell <ian.campbell@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
David Woodhouse <dwmw2@infradead.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Vivek Goyal <vgoyal@in.ibm.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"H. Peter Anvin" <hpa@zytor.com>, Dave Jones <davej@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
techteam@lists.laptop.org, Yinghai Lu <yhlu.kernel@gmail.com>
Subject: Re: [Techteam] [RFC PATCH] x86-32: Start out eflags and cr4 clean
Date: Fri, 18 Jan 2013 21:44:07 -1000 [thread overview]
Message-ID: <50FA4EC7.6060402@laptop.org> (raw)
In-Reply-To: <50FA0661.2060400@linux.intel.com>
On 1/18/2013 4:35 PM, H. Peter Anvin wrote:
> On 01/18/2013 05:05 PM, Mitch Bradley wrote:
>>
>>
>> On 1/18/2013 2:42 PM, H. Peter Anvin wrote:
>>> On 01/18/2013 04:40 PM, Andres Salomon wrote:
>>>> Bad news on this patch; I've been told that it breaks booting on an
>>>> XO-1.5. Does anyone from OLPC know why yet?
>>>
>>> What are the settings of CR0 and CR4 on kernel entry on XO-1.5?
>>
>>
>> CR0 is 0x80000011
>> CR4 is 0x10
>>
>
> OK, that makes sense... the kernel doesn't enable the PSE bit yet and I
> bet that's what you're using for the non-stolen page tables.
Indeed, we are using 4M pages to map the firmware into high virtual
addresses.
>
> Can we simply disable paging before mucking with CR4? The other option
> that I can see is to always enable PSE and PGE, since they are simply
> features opt-ins that don't do any harm if unused. At the same time,
> though, entering the kernel through the default_entry path with paging
> enabled is definitely not anything the kernel expects.
>
> Does this patch work for you? Since we have ditched 386 support, we can
> mimic x86-64 (yay, one more difference gone!) and just use a predefined
> value for %cr0 (the FPU flags need to change if we are on an FPU-less
> chip, but that happens during FPU probing.)
>
> Does this patch work for you?
We will test it and get back to you.
>
> -hpa
>
>
>
next prev parent reply other threads:[~2013-01-19 7:44 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 19:43 [PATCH 00/11] x86: Supervisor Mode Access Prevention H. Peter Anvin
2012-09-21 19:43 ` [PATCH 01/11] x86, cpufeature: Add feature bit for SMAP H. Peter Anvin
2012-09-21 19:43 ` [PATCH 02/11] x86-32, mm: The WP test should be done on a kernel page H. Peter Anvin
2012-09-21 19:58 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 03/11] x86, smap: Add CR4 bit for SMAP H. Peter Anvin
2012-09-21 19:59 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 04/11] x86, alternative: Use .pushsection/.popsection H. Peter Anvin
2012-09-21 20:00 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 05/11] x86, alternative: Add header guards to <asm/alternative-asm.h> H. Peter Anvin
2012-09-21 20:01 ` [tip:x86/smap] x86, alternative: Add header guards to <asm/ alternative-asm.h> tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 06/11] x86, smap: Add a header file with macros for STAC/CLAC H. Peter Anvin
2012-09-21 20:02 ` [tip:x86/smap] x86, smap: Add a header file with macros for STAC/ CLAC tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 07/11] x86, uaccess: Merge prototypes for clear_user/__clear_user H. Peter Anvin
2012-09-21 20:03 ` [tip:x86/smap] x86, uaccess: Merge prototypes for clear_user/ __clear_user tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 08/11] x86, smap: Add STAC and CLAC instructions to control user space access H. Peter Anvin
2012-09-21 20:04 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-22 0:16 ` [tip:x86/smap] x86-32, smap: Add STAC/ CLAC instructions to 32-bit kernel entry tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 09/11] x86, smap: Turn on Supervisor Mode Access Prevention H. Peter Anvin
2012-09-21 20:05 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 10/11] x86, smap: A page fault due to SMAP is an oops H. Peter Anvin
2012-09-21 20:06 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:43 ` [PATCH 11/11] x86, smap: Reduce the SMAP overhead for signal handling H. Peter Anvin
2012-09-21 20:07 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-09-21 19:54 ` [PATCH 00/11] x86: Supervisor Mode Access Prevention Linus Torvalds
2012-09-21 19:57 ` H. Peter Anvin
2012-09-21 20:08 ` Ingo Molnar
2012-09-21 21:03 ` H. Peter Anvin
2012-09-21 21:09 ` Linus Torvalds
2012-09-21 21:12 ` H. Peter Anvin
2012-09-21 22:07 ` Eric W. Biederman
2012-09-21 22:12 ` H. Peter Anvin
2012-09-22 0:41 ` Eric W. Biederman
2012-09-24 23:27 ` [RFC PATCH] x86-32: Start out eflags and cr4 clean H. Peter Anvin
2012-09-25 13:27 ` Konrad Rzeszutek Wilk
2012-09-25 13:48 ` Ian Campbell
2012-09-26 11:29 ` Konrad Rzeszutek Wilk
2012-09-27 6:11 ` [tip:x86/smap] " tip-bot for H. Peter Anvin
2012-11-24 3:49 ` Yuhong Bao
2012-11-24 5:06 ` H. Peter Anvin
2012-09-27 6:11 ` [tip:x86/smap] x86, suspend: On wakeup always initialize cr4 and EFER tip-bot for H. Peter Anvin
2012-10-01 22:04 ` [tip:x86/urgent] x86, suspend: Correct the restore of CR4, EFER; skip computing EFLAGS.ID tip-bot for H. Peter Anvin
2012-10-02 6:52 ` tip-bot for H. Peter Anvin
2012-10-10 19:59 ` [RFC PATCH] x86-32: Start out eflags and cr4 clean Andres Salomon
2013-01-19 0:40 ` Andres Salomon
2013-01-19 0:42 ` H. Peter Anvin
2013-01-19 1:05 ` [Techteam] " Mitch Bradley
2013-01-19 2:35 ` H. Peter Anvin
2013-01-19 7:44 ` Mitch Bradley [this message]
2013-01-19 12:34 ` Daniel Drake
2013-01-19 19:15 ` [tip:x86/urgent] x86-32: Start out cr0 clean, disable paging before modifying cr3/4 tip-bot for H. Peter Anvin
2012-09-21 22:08 ` [PATCH 00/11] x86: Supervisor Mode Access Prevention Dave Jones
2012-09-21 22:10 ` H. Peter Anvin
2012-09-22 11:32 ` Ingo Molnar
2012-09-24 20:31 ` H. Peter Anvin
2012-09-24 20:43 ` Kees Cook
2012-09-24 20:51 ` H. Peter Anvin
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