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

[Stefan Bader]

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?

Stefan