x86: fix stack overflow for large values of MAX_APICS

physid_mask_of_physid() causes a huge stack (12k) to be created if the
number of APICS is large. Replace physid_mask_of_physid() with a
new function that does not create large stacks. This is a problem only
on large x86_64 systems.

this paves the way to increase MAX_APICS.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Cc: linux-mm@kvack.org
Cc: mingo@elte.hu
Cc: tglx@linutronix.de
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/asm-x86/mpspec.h b/include/asm-x86/mpspec.h
index 57a991b9c053..b69e7ba7bf1d 100644
--- a/include/asm-x86/mpspec.h
+++ b/include/asm-x86/mpspec.h
@@ -101,6 +101,7 @@ typedef struct physid_mask physid_mask_t;
                 __physid_mask;                                          \
         })
 
+/* Note: will create very large stack frames if physid_mask_t is big */
 #define physid_mask_of_physid(physid)                                   \
         ({                                                              \
                 physid_mask_t __physid_mask = PHYSID_MASK_NONE;         \
@@ -108,6 +109,12 @@ typedef struct physid_mask physid_mask_t;
                 __physid_mask;                                          \
         })
 
+static inline void physid_set_mask_of_physid(int physid, physid_mask_t *map)
+{
+        physids_clear(*map);
+        physid_set(physid, *map);
+}
+
 #define PHYSID_MASK_ALL         { {[0 ... PHYSID_ARRAY_SIZE-1] = ~0UL} }
 #define PHYSID_MASK_NONE        { {[0 ... PHYSID_ARRAY_SIZE-1] = 0UL} }