[PATCH] UBUNTU: SAUCE: dove: avoid page table overwrite when

Eric Miao eric.miao at canonical.com
Fri Apr 23 07:16:17 BST 2010


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>
---

It was posted weeks ago, thought it was merged but not. This is an updated
version addressing the previous comments to make it cleaner.

 arch/arm/mach-dove/Makefile |    2 ++
 arch/arm/mach-dove/swsusp.S |    8 ++++++++
 2 files changed, 10 insertions(+), 0 deletions(-)

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..9b752a0 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 +210,15 @@ FUNC(swsusp_arch_suspend)

 FUNC_END(swsusp_arch_suspend)

+#define KERNEL_RAM_PADDR	(PHYS_OFFSET + TEXT_OFFSET)
+#define SWAPPER_PG_DIR		(KERNEL_RAM_PADDR - 0x4000)
+
 FUNC(swsusp_arch_resume)
 	/* set page table if needed */
+	ldr	r0, =SWAPPER_PG_DIR
+	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
-- 
1.7.0.4



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