FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Ubuntu > Ubuntu Kernel Team

 
 
LinkBack Thread Tools
 
Old 04-23-2010, 10:19 PM
Eric Miao
 
Default UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

On Sat, Apr 24, 2010 at 12:40 AM, John Johansen
<john.johansen@canonical.com> wrote:
> On 04/23/2010 07:18 AM, Stefan Bader wrote:
>> Eric Miao wrote:
>>> BTW, this may apply to other ARM variants as well, but the hibernation
>>> feature should really be made common first of all in that sense.
>>>
>>> commit 1f3ebd28c0e8adf7f7a1fc85377a57d8dbc56267
>>> Author: Eric Miao <eric.miao@canonical.com>
>>> Date: * Fri Apr 23 14:16:17 2010 +0800
>>>
>>> * * UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from
>>> hibernation
>>>
>>> * * BugLink: http://bugs.launchpad.net/bugs/509006
>>>
>>> * * Resuming from hibernation is OK if 'resume=/dev/sdaX' is explicitly
>>> * * specified on the kernel command line, but it fails if scripts in
>>> * * initramfs are used to trigger the resume. It turned out to be page
>>> * * table being overwritten when restoring the memory content because
>>> * * it's using a normal user process's page table in the latter case,
>>> * * which is not safe and could be overwritten. Fix this by using the
>>> * * safe swapper_pg_dir during restoring.
>>>
>>> * * Signed-off-by: Eric Miao <eric.miao@canonical.com>
>>>
>>> diff --git a/arch/arm/mach-dove/Makefile b/arch/arm/mach-dove/Makefile
>>> index 0be1e1c..c5c028f 100755
>>> --- a/arch/arm/mach-dove/Makefile
>>> +++ b/arch/arm/mach-dove/Makefile
>>> @@ -1,3 +1,5 @@
>>> +AFLAGS_swsusp.o * * * * * * * * * * := -DTEXT_OFFSET=$(TEXT_OFFSET)
>>> +
>>> *obj-y * * * * * * * * * * * * * * * += clock.o common.o addr-map.o irq.o pcie.o mpp.o
>>> * * * * * * * * * * * * * * *sdhci_cam_mbus.o
>>> *obj-$(CONFIG_MACH_DOVE_RD_AVNG) * * += dove-rd-avng-setup.o
>>> diff --git a/arch/arm/mach-dove/swsusp.S b/arch/arm/mach-dove/swsusp.S
>>> index 4f4a884..8e308d8 100644
>>> --- a/arch/arm/mach-dove/swsusp.S
>>> +++ b/arch/arm/mach-dove/swsusp.S
>>> @@ -28,6 +28,7 @@
>>> * */
>>>
>>> *#include <linux/linkage.h>
>>> +#include <asm/memory.h>
>>> *#include <asm/segment.h>
>>> *#include <asm/page.h>
>>> *#include <asm/asm-offsets.h>
>>> @@ -209,8 +210,14 @@ FUNC(swsusp_arch_suspend)
>>>
>>> *FUNC_END(swsusp_arch_suspend)
>>>
>>> +#define KERNEL_RAM_PADDR * *(PHYS_OFFSET + TEXT_OFFSET)
>>> +
>>> *FUNC(swsusp_arch_resume)
>>> * * */* set page table if needed */
>>> + * *ldr * * r0, =(KERNEL_RAM_PADDR - 0x4000)
>>> + * *mcr * * p15, 0, r0, c2, c0, 0 * * * * * @ load page table pointer
>>> + * *mcr * * p15, 0, r0, c8, c7, 0 * * * * * @ invalidate I,D TLBs
>>> + * *mcr * * p15, 0, r0, c7, c5, 4 * * * * * @ ISB
>>>
>>> * * */*
>>> * * * * retore "nr_copy_pages" pages which are saved and specified
>>>
>> The patch probably is correct, but from the reviewing point of view I do not
>> know how I make the connection between swapper_pg_dir in the comment and the
>> patch itself. Is that only me?
>>
> No, I also would like to see a little more information.
>

Ah, sorry for the confusion. swapper_pg_dir is the initial page table for
ARM kernel, which is physically located at KERNEL_RAM_PADDR - 0x4000.
I should have made it clear by a macro or something. The following code is
excerpted from arch/arm/kernel/head.S:

/*
* swapper_pg_dir is the virtual address of the initial page table.
* We place the page tables 16K below KERNEL_RAM_VADDR. Therefore, we must
* make sure that KERNEL_RAM_VADDR is correctly set. Currently, we expect
* the least significant 16 bits to be 0x8000, but we could probably
* relax this restriction to KERNEL_RAM_VADDR >= PAGE_OFFSET + 0x4000.
*/
#if (KERNEL_RAM_VADDR & 0xffff) != 0x8000
#error KERNEL_RAM_VADDR must start at 0xXXXX8000
#endif

.globl swapper_pg_dir
.equ swapper_pg_dir, KERNEL_RAM_VADDR - 0x4000

.macro pgtbl, rd
ldr
d, =(KERNEL_RAM_PADDR - 0x4000)
.endm

--
kernel-team mailing list
kernel-team@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/kernel-team
 
Old 04-28-2010, 03:00 AM
Eric Miao
 
Default UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

> Hm, wouldn't it then be possible to make the patch actually use the macro name
> instead of the hard coded values?
>

How about the patch below, making thing a little bit clearer?

commit ee5c472440e089eba863689c446adb5f1c0ae05e
Author: Eric Miao <eric.miao@canonical.com>
Date: Fri Apr 23 14:16:17 2010 +0800

UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from
hibernation

BugLink: http://bugs.launchpad.net/bugs/509006

Resuming from hibernation is OK if 'resume=/dev/sdaX' is explicitly
specified on the kernel command line, but it fails if scripts in
initramfs are used to trigger the resume. It turned out to be page
table being overwritten when restoring the memory content because
it's using a normal user process's page table in the latter case,
which is not safe and could be overwritten. Fix this by using the
safe swapper_pg_dir during restoring.

Signed-off-by: Eric Miao <eric.miao@canonical.com>

diff --git a/arch/arm/mach-dove/Makefile b/arch/arm/mach-dove/Makefile
index 0be1e1c..c5c028f 100755
--- a/arch/arm/mach-dove/Makefile
+++ b/arch/arm/mach-dove/Makefile
@@ -1,3 +1,5 @@
+AFLAGS_swsusp.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
+
obj-y += clock.o common.o addr-map.o irq.o pcie.o mpp.o
sdhci_cam_mbus.o
obj-$(CONFIG_MACH_DOVE_RD_AVNG) += dove-rd-avng-setup.o
diff --git a/arch/arm/mach-dove/swsusp.S b/arch/arm/mach-dove/swsusp.S
index 4f4a884..8e308d8 100644
--- a/arch/arm/mach-dove/swsusp.S
+++ b/arch/arm/mach-dove/swsusp.S
@@ -28,6 +28,7 @@
*/

#include <linux/linkage.h>
+#include <asm/memory.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/asm-offsets.h>
@@ -209,8 +210,14 @@ FUNC(swsusp_arch_suspend)

FUNC_END(swsusp_arch_suspend)

+#define KERNEL_RAM_PADDR (PHYS_OFFSET + TEXT_OFFSET)
+
FUNC(swsusp_arch_resume)
/* set page table if needed */
+ ldr r0, =(KERNEL_RAM_PADDR - 0x4000)
+ mcr p15, 0, r0, c2, c0, 0 @ load page table pointer
+ mcr p15, 0, r0, c8, c7, 0 @ invalidate I,D TLBs
+ mcr p15, 0, r0, c7, c5, 4 @ ISB

/*
* retore "nr_copy_pages" pages which are saved and specified

--
kernel-team mailing list
kernel-team@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/kernel-team
 
Old 04-28-2010, 06:12 AM
Eric Miao
 
Default UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

On Wed, Apr 28, 2010 at 1:56 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> On 04/28/2010 11:00 AM, Eric Miao wrote:
>>>
>>> Hm, wouldn't it then be possible to make the patch actually use the macro
>>> name
>>> instead of the hard coded values?
>>>
>>
>> How about the patch below, making thing a little bit clearer?
>>
>> commit ee5c472440e089eba863689c446adb5f1c0ae05e
>> Author: Eric Miao<eric.miao@canonical.com>
>> Date: * Fri Apr 23 14:16:17 2010 +0800
>>
>> * * UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from
>> hibernation
>>
>> * * BugLink: http://bugs.launchpad.net/bugs/509006
>>
>> * * Resuming from hibernation is OK if 'resume=/dev/sdaX' is explicitly
>> * * specified on the kernel command line, but it fails if scripts in
>> * * initramfs are used to trigger the resume. It turned out to be page
>> * * table being overwritten when restoring the memory content because
>> * * it's using a normal user process's page table in the latter case,
>> * * which is not safe and could be overwritten. Fix this by using the
>> * * safe swapper_pg_dir during restoring.
>>
>> * * Signed-off-by: Eric Miao<eric.miao@canonical.com>
>>
>> diff --git a/arch/arm/mach-dove/Makefile b/arch/arm/mach-dove/Makefile
>> index 0be1e1c..c5c028f 100755
>> --- a/arch/arm/mach-dove/Makefile
>> +++ b/arch/arm/mach-dove/Makefile
>> @@ -1,3 +1,5 @@
>> +AFLAGS_swsusp.o * * * * * * * * * * * *:= -DTEXT_OFFSET=$(TEXT_OFFSET)
>> +
>> *obj-y * * * * * * * * * * * * += clock.o common.o addr-map.o irq.o pcie.o
>> mpp.o
>> * * * * * * * * * * * * * * * *sdhci_cam_mbus.o
>> *obj-$(CONFIG_MACH_DOVE_RD_AVNG) * * * += dove-rd-avng-setup.o
>> diff --git a/arch/arm/mach-dove/swsusp.S b/arch/arm/mach-dove/swsusp.S
>> index 4f4a884..8e308d8 100644
>> --- a/arch/arm/mach-dove/swsusp.S
>> +++ b/arch/arm/mach-dove/swsusp.S
>> @@ -28,6 +28,7 @@
>> * */
>>
>> *#include<linux/linkage.h>
>> +#include<asm/memory.h>
>> *#include<asm/segment.h>
>> *#include<asm/page.h>
>> *#include<asm/asm-offsets.h>
>> @@ -209,8 +210,14 @@ FUNC(swsusp_arch_suspend)
>>
>> *FUNC_END(swsusp_arch_suspend)
>>
>> +#define KERNEL_RAM_PADDR * * * (PHYS_OFFSET + TEXT_OFFSET)
>> +
>> *FUNC(swsusp_arch_resume)
>> * * * */* set page table if needed */
>> + * * * ldr * * r0, =(KERNEL_RAM_PADDR - 0x4000)
>
> How about using the pgtbl marco as you posted in previous email?
>
> *+ * * pgtbl * r0 * * * * * * * * * * *@ page table address
>
> I think Stephan was asking for this. But if 'pgtbl' is not available in this
> ASM file, I am OK with this patch.
>

Yeah, that's a better approach and I was originally thinking of that, but it
needs this macro to be declared somewhere in a assembly header.

--
kernel-team mailing list
kernel-team@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/kernel-team
 

Thread Tools




All times are GMT. The time now is 05:46 AM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org