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Old 04-23-2010, 02:18 PM
Stefan Bader
 
Default UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

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?

Stefan

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Old 04-23-2010, 04:40 PM
John Johansen
 
Default UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

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.

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