powerpc/mm: tracking vDSO remap

Some processes (CRIU) are moving the vDSO area using the mremap system
call.  As a consequence the kernel reference to the vDSO base address is
no more valid and the signal return frame built once the vDSO has been
moved is not pointing to the new sigreturn address.

This patch handles vDSO remapping and unmapping.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/powerpc/include/asm/mm-arch-hooks.h b/arch/powerpc/include/asm/mm-arch-hooks.h
index 63091a1..f2a2da8 100644 (file)
--- a/arch/powerpc/include/asm/mm-arch-hooks.h
+++ b/arch/powerpc/include/asm/mm-arch-hooks.h
@@ -12,4 +12,17 @@
 #ifndef _ASM_POWERPC_MM_ARCH_HOOKS_H
 #define _ASM_POWERPC_MM_ARCH_HOOKS_H
 
+static inline void arch_remap(struct mm_struct *mm,
+                             unsigned long old_start, unsigned long old_end,
+                             unsigned long new_start, unsigned long new_end)
+{
+       /*
+        * mremap() doesn't allow moving multiple vmas so we can limit the
+        * check to old_start == vdso_base.
+        */
+       if (old_start == mm->context.vdso_base)
+               mm->context.vdso_base = new_start;
+}
+#define arch_remap arch_remap
+
 #endif /* _ASM_POWERPC_MM_ARCH_HOOKS_H */

diff --cc arch/powerpc/include/asm/mmu_context.h
Simple merge