[PATCH lucid] UBUNTU: SAUCE: dove: avoid page table overwrite when resuming from hibernation

[John Johansen]

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 at 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 at 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.