mm: add pmd_t initializer __pmd() to work around a GCC bug.

THP migration is added but only supports x86_64 at the moment. For all
other architectures, swp_entry_to_pmd() only returns a zero pmd_t.

Due to a GCC zero initializer bug #53119, the standard (pmd_t){0}
initializer is not accepted by all GCC versions. __pmd() is a feasible
workaround. In addition, sparc32's pmd_t is an array instead of a single
value, so we need (pmd_t){ {0}, } instead of (pmd_t){0}. Thus,
a different __pmd() definition is needed in sparc32.

Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/page_32.h b/arch/sparc/include/asm/page_32.h
index 0efd0583a8c9..6249214148c2 100644
--- a/arch/sparc/include/asm/page_32.h
+++ b/arch/sparc/include/asm/page_32.h
@@ -68,6 +68,7 @@ typedef struct { unsigned long iopgprot; } iopgprot_t;
 #define iopgprot_val(x) ((x).iopgprot)
 
 #define __pte(x)        ((pte_t) { (x) } )
+#define __pmd(x)        ((pmd_t) { { (x) }, })
 #define __iopte(x)      ((iopte_t) { (x) } )
 #define __pgd(x)        ((pgd_t) { (x) } )
 #define __ctxd(x)       ((ctxd_t) { (x) } )
@@ -95,6 +96,7 @@ typedef unsigned long iopgprot_t;
 #define iopgprot_val(x) (x)
 
 #define __pte(x)        (x)
+#define __pmd(x)        ((pmd_t) { { (x) }, })
 #define __iopte(x)      (x)
 #define __pgd(x)        (x)
 #define __ctxd(x)       (x)