[PATCH] powerpc/e6500: add locking to hugetlb

[PATCH] powerpc/e6500: add locking to hugetlb

[Scott Wood]

e6500 has threads but does not have TLB write conditional.  Thus,
the hugetlb code needs to take the same lock that the normal TLB miss
handlers take, to ensure that the tlbsx and tlbwe are atomic.

Signed-off-by: Scott Wood <scottwood@freescale.com>
---
 arch/powerpc/mm/hugetlbpage-book3e.c | 46 ++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/arch/powerpc/mm/hugetlbpage-book3e.c b/arch/powerpc/mm/hugetlbpage-book3e.c
index ba47aaf..180707e 100644
--- a/arch/powerpc/mm/hugetlbpage-book3e.c
+++ b/arch/powerpc/mm/hugetlbpage-book3e.c
@@ -51,6 +51,48 @@ static inline int mmu_get_tsize(int psize)
 	return mmu_psize_defs[psize].enc;
 }
 
+#if defined(CONFIG_PPC_FSL_BOOK3E) && defined(CONFIG_PPC64)
+#include <asm/paca.h>
+
+static inline void book3e_tlb_lock(void)
+{
+	struct paca_struct *paca = get_paca();
+	unsigned long tmp;
+	int token = smp_processor_id() + 1;
+
+	asm volatile("1: lbarx %0, 0, %1;"
+		     "cmpwi %0, 0;"
+		     "bne 2f;"
+		     "stbcx. %2, 0, %1;"
+		     "bne 1b;"
+		     "b 3f;"
+		     "2: lbzx %0, 0, %1;"
+		     "cmpwi %0, 0;"
+		     "bne 2b;"
+		     "b 1b;"
+		     "3:" 
+		     : "=&r" (tmp)
+		     : "r" (&paca->tcd_ptr->lock), "r" (token)
+		     : "memory");
+}
+
+static inline void book3e_tlb_unlock(void)
+{
+	struct paca_struct *paca = get_paca();
+
+	isync();
+	paca->tcd_ptr->lock = 0;
+}
+#else
+static inline void book3e_tlb_lock(void)
+{
+}
+
+static inline void book3e_tlb_unlock(void)
+{
+}
+#endif
+
 static inline int book3e_tlb_exists(unsigned long ea, unsigned long pid)
 {
 	int found = 0;
@@ -109,7 +151,10 @@ void book3e_hugetlb_preload(struct vm_area_struct *vma, unsigned long ea,
 	 */
 	local_irq_save(flags);
 
+	book3e_tlb_lock();
+
 	if (unlikely(book3e_tlb_exists(ea, mm->context.id))) {
+		book3e_tlb_unlock();
 		local_irq_restore(flags);
 		return;
 	}
@@ -141,6 +186,7 @@ void book3e_hugetlb_preload(struct vm_area_struct *vma, unsigned long ea,
 
 	asm volatile ("tlbwe");
 
+	book3e_tlb_unlock();
 	local_irq_restore(flags);
 }
 
-- 
2.5.0