[PATCH 4.2.y-ckt 79/98] arm64: account for sparsemem section alignment when choosing vmemmap offset

Kamal Mostafa kamal at canonical.com
Tue Mar 15 23:31:13 UTC 2016


4.2.8-ckt6 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Ard Biesheuvel <ard.biesheuvel at linaro.org>

commit 36e5cd6b897e17d03008f81e075625d8e43e52d0 upstream.

Commit dfd55ad85e4a ("arm64: vmemmap: use virtual projection of linear
region") fixed an issue where the struct page array would overflow into the
adjacent virtual memory region if system RAM was placed so high up in
physical memory that its addresses were not representable in the build time
configured virtual address size.

However, the fix failed to take into account that the vmemmap region needs
to be relatively aligned with respect to the sparsemem section size, so that
a sequence of page structs corresponding with a sparsemem section in the
linear region appears naturally aligned in the vmemmap region.

So round up vmemmap to sparsemem section size. Since this essentially moves
the projection of the linear region up in memory, also revert the reduction
of the size of the vmemmap region.

Fixes: dfd55ad85e4a ("arm64: vmemmap: use virtual projection of linear region")
Tested-by: Mark Langsdorf <mlangsdo at redhat.com>
Tested-by: David Daney <david.daney at cavium.com>
Tested-by: Robert Richter <rrichter at cavium.com>
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Signed-off-by: Will Deacon <will.deacon at arm.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/arm64/include/asm/pgtable.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 514fb0c..526a9cb 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -39,12 +39,13 @@
  * VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space,
  *	fixed mappings and modules
  */
-#define VMEMMAP_SIZE		ALIGN((1UL << (VA_BITS - PAGE_SHIFT - 1)) * sizeof(struct page), PUD_SIZE)
+#define VMEMMAP_SIZE		ALIGN((1UL << (VA_BITS - PAGE_SHIFT)) * sizeof(struct page), PUD_SIZE)
 #define VMALLOC_START		(UL(0xffffffffffffffff) << VA_BITS)
 #define VMALLOC_END		(PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
 
 #define VMEMMAP_START		(VMALLOC_END + SZ_64K)
-#define vmemmap			((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
+#define vmemmap			((struct page *)VMEMMAP_START - \
+				 SECTION_ALIGN_DOWN(memstart_addr >> PAGE_SHIFT))
 
 #define FIRST_USER_ADDRESS	0UL
 
-- 
2.7.0





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