[PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction

Add hooks to allow a paravirt implementation to track the lifetime of
an mm.  Paravirtualization requires three hooks, but only two are
needed in common code.  They are:

arch_dup_mmap, which is called when a new mmap is created at fork

arch_exit_mmap, which is called when the last process reference to an
  mm is dropped, which typically happens on exit and exec.

The third hook is activate_mm, which is called from the arch-specific
activate_mm() macro/function, and so doesn't need stub versions for
other architectures.  It's called when an mm is first used.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: linux-arch@vger.kernel.org
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 15 insertions, 2 deletions

diff --git a/include/asm-i386/mmu_context.h b/include/asm-i386/mmu_context.h
index e6aa30f8de5b..8198d1cca1f3 100644
--- a/include/asm-i386/mmu_context.h
+++ b/include/asm-i386/mmu_context.h
@@ -5,6 +5,16 @@
 #include <asm/atomic.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
+#include <asm/paravirt.h>
+#ifndef CONFIG_PARAVIRT
+#include <asm-generic/mm_hooks.h>
+
+static inline void paravirt_activate_mm(struct mm_struct *prev,
+                                        struct mm_struct *next)
+{
+}
+#endif  /* !CONFIG_PARAVIRT */
+
 
 /*
  * Used for LDT copy/destruction.
@@ -65,7 +75,10 @@ static inline void switch_mm(struct mm_struct *prev,
 #define deactivate_mm(tsk, mm)                  \
         asm("movl %0,%%gs": :"r" (0));
 
-#define activate_mm(prev, next) \
-        switch_mm((prev),(next),NULL)
+#define activate_mm(prev, next)                         \
+        do {                                            \
+                paravirt_activate_mm(prev, next);       \
+                switch_mm((prev),(next),NULL);          \
+        } while(0);
 
 #endif