1 files changed, 82 insertions, 103 deletions

diff --git a/arch/sparc64/mm/tsb.c b/arch/sparc64/mm/tsb.c
index f36799b7152c..7fbe1e0cd105 100644
--- a/arch/sparc64/mm/tsb.c
+++ b/arch/sparc64/mm/tsb.c
@@ -48,11 +48,15 @@ void flush_tsb_kernel_range(unsigned long start, unsigned long end)
 void flush_tsb_user(struct mmu_gather *mp)
 {
         struct mm_struct *mm = mp->mm;
-        struct tsb *tsb = mm->context.tsb;
-        unsigned long nentries = mm->context.tsb_nentries;
-        unsigned long base;
+        unsigned long nentries, base, flags;
+        struct tsb *tsb;
         int i;
 
+        spin_lock_irqsave(&mm->context.lock, flags);
+
+        tsb = mm->context.tsb;
+        nentries = mm->context.tsb_nentries;
+
         if (tlb_type == cheetah_plus || tlb_type == hypervisor)
                 base = __pa(tsb);
         else
@@ -70,6 +74,8 @@ void flush_tsb_user(struct mmu_gather *mp)
 
                 tsb_flush(ent, tag);
         }
+
+        spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_bytes)
@@ -201,86 +207,9 @@ static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_bytes)
         }
 }
 
-/* The page tables are locked against modifications while this
- * runs.
- *
- * XXX do some prefetching...
- */
-static void copy_tsb(struct tsb *old_tsb, unsigned long old_size,
-                     struct tsb *new_tsb, unsigned long new_size)
-{
-        unsigned long old_nentries = old_size / sizeof(struct tsb);
-        unsigned long new_nentries = new_size / sizeof(struct tsb);
-        unsigned long i;
-
-        for (i = 0; i < old_nentries; i++) {
-                register unsigned long tag asm("o4");
-                register unsigned long pte asm("o5");
-                unsigned long v, hash;
-
-                if (tlb_type == hypervisor) {
-                        __asm__ __volatile__(
-                                "ldda [%2] %3, %0"
-                                : "=r" (tag), "=r" (pte)
-                                : "r" (__pa(&old_tsb[i])),
-                                  "i" (ASI_QUAD_LDD_PHYS_4V));
-                } else if (tlb_type == cheetah_plus) {
-                        __asm__ __volatile__(
-                                "ldda [%2] %3, %0"
-                                : "=r" (tag), "=r" (pte)
-                                : "r" (__pa(&old_tsb[i])),
-                                  "i" (ASI_QUAD_LDD_PHYS));
-                } else {
-                        __asm__ __volatile__(
-                                "ldda [%2] %3, %0"
-                                : "=r" (tag), "=r" (pte)
-                                : "r" (&old_tsb[i]),
-                                  "i" (ASI_NUCLEUS_QUAD_LDD));
-                }
-
-                if (tag & ((1UL << TSB_TAG_LOCK_BIT) |
-                           (1UL << TSB_TAG_INVALID_BIT)))
-                        continue;
-
-                /* We only put base page size PTEs into the TSB,
-                 * but that might change in the future.  This code
-                 * would need to be changed if we start putting larger
-                 * page size PTEs into there.
-                 */
-                WARN_ON((pte & _PAGE_ALL_SZ_BITS) != _PAGE_SZBITS);
-
-                /* The tag holds bits 22 to 63 of the virtual address
-                 * and the context.  Clear out the context, and shift
-                 * up to make a virtual address.
-                 */
-                v = (tag & ((1UL << 42UL) - 1UL)) << 22UL;
-
-                /* The implied bits of the tag (bits 13 to 21) are
-                 * determined by the TSB entry index, so fill that in.
-                 */
-                v |= (i & (512UL - 1UL)) << 13UL;
-
-                hash = tsb_hash(v, new_nentries);
-                if (tlb_type == cheetah_plus ||
-                    tlb_type == hypervisor) {
-                        __asm__ __volatile__(
-                                "stxa   %0, [%1] %2\n\t"
-                                "stxa   %3, [%4] %2"
-                                : /* no outputs */
-                                : "r" (tag),
-                                  "r" (__pa(&new_tsb[hash].tag)),
-                                  "i" (ASI_PHYS_USE_EC),
-                                  "r" (pte),
-                                  "r" (__pa(&new_tsb[hash].pte)));
-                } else {
-                        new_tsb[hash].tag = tag;
-                        new_tsb[hash].pte = pte;
-                }
-        }
-}
-
 /* When the RSS of an address space exceeds mm->context.tsb_rss_limit,
- * update_mmu_cache() invokes this routine to try and grow the TSB.
+ * do_sparc64_fault() invokes this routine to try and grow the TSB.
+ *
  * When we reach the maximum TSB size supported, we stick ~0UL into
  * mm->context.tsb_rss_limit so the grow checks in update_mmu_cache()
  * will not trigger any longer.
@@ -293,12 +222,12 @@ static void copy_tsb(struct tsb *old_tsb, unsigned long old_size,
  * the number of entries that the current TSB can hold at once.  Currently,
  * we trigger when the RSS hits 3/4 of the TSB capacity.
  */
-void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags)
+void tsb_grow(struct mm_struct *mm, unsigned long rss)
 {
         unsigned long max_tsb_size = 1 * 1024 * 1024;
-        unsigned long size, old_size;
+        unsigned long size, old_size, flags;
         struct page *page;
-        struct tsb *old_tsb;
+        struct tsb *old_tsb, *new_tsb;
 
         if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
                 max_tsb_size = (PAGE_SIZE << MAX_ORDER);
@@ -311,12 +240,51 @@ void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags)
                         break;
         }
 
-        page = alloc_pages(gfp_flags, get_order(size));
+        page = alloc_pages(GFP_KERNEL, get_order(size));
         if (unlikely(!page))
                 return;
 
         /* Mark all tags as invalid.  */
-        memset(page_address(page), 0x40, size);
+        new_tsb = page_address(page);
+        memset(new_tsb, 0x40, size);
+
+        /* Ok, we are about to commit the changes.  If we are
+         * growing an existing TSB the locking is very tricky,
+         * so WATCH OUT!
+         *
+         * We have to hold mm->context.lock while committing to the
+         * new TSB, this synchronizes us with processors in
+         * flush_tsb_user() and switch_mm() for this address space.
+         *
+         * But even with that lock held, processors run asynchronously
+         * accessing the old TSB via TLB miss handling.  This is OK
+         * because those actions are just propagating state from the
+         * Linux page tables into the TSB, page table mappings are not
+         * being changed.  If a real fault occurs, the processor will
+         * synchronize with us when it hits flush_tsb_user(), this is
+         * also true for the case where vmscan is modifying the page
+         * tables.  The only thing we need to be careful with is to
+         * skip any locked TSB entries during copy_tsb().
+         *
+         * When we finish committing to the new TSB, we have to drop
+         * the lock and ask all other cpus running this address space
+         * to run tsb_context_switch() to see the new TSB table.
+         */
+        spin_lock_irqsave(&mm->context.lock, flags);
+
+        old_tsb = mm->context.tsb;
+        old_size = mm->context.tsb_nentries * sizeof(struct tsb);
+
+        /* Handle multiple threads trying to grow the TSB at the same time.
+         * One will get in here first, and bump the size and the RSS limit.
+         * The others will get in here next and hit this check.
+         */
+        if (unlikely(old_tsb && (rss < mm->context.tsb_rss_limit))) {
+                spin_unlock_irqrestore(&mm->context.lock, flags);
+
+                free_pages((unsigned long) new_tsb, get_order(size));
+                return;
+        }
 
         if (size == max_tsb_size)
                 mm->context.tsb_rss_limit = ~0UL;
@@ -324,30 +292,37 @@ void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags)
                 mm->context.tsb_rss_limit =
                         ((size / sizeof(struct tsb)) * 3) / 4;
 
-        old_tsb = mm->context.tsb;
-        old_size = mm->context.tsb_nentries * sizeof(struct tsb);
-
-        if (old_tsb)
-                copy_tsb(old_tsb, old_size, page_address(page), size);
+        if (old_tsb) {
+                extern void copy_tsb(unsigned long old_tsb_base,
+                                     unsigned long old_tsb_size,
+                                     unsigned long new_tsb_base,
+                                     unsigned long new_tsb_size);
+                unsigned long old_tsb_base = (unsigned long) old_tsb;
+                unsigned long new_tsb_base = (unsigned long) new_tsb;
+
+                if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
+                        old_tsb_base = __pa(old_tsb_base);
+                        new_tsb_base = __pa(new_tsb_base);
+                }
+                copy_tsb(old_tsb_base, old_size, new_tsb_base, size);
+        }
 
-        mm->context.tsb = page_address(page);
+        mm->context.tsb = new_tsb;
         setup_tsb_params(mm, size);
 
+        spin_unlock_irqrestore(&mm->context.lock, flags);
+
         /* If old_tsb is NULL, we're being invoked for the first time
          * from init_new_context().
          */
         if (old_tsb) {
-                /* Now force all other processors to reload the new
-                 * TSB state.
-                 */
-                smp_tsb_sync(mm);
-
-                /* Finally reload it on the local cpu.  No further
-                 * references will remain to the old TSB and we can
-                 * thus free it up.
-                 */
+                /* Reload it on the local cpu.  */
                 tsb_context_switch(mm);
 
+                /* Now force other processors to do the same.  */
+                smp_tsb_sync(mm);
+
+                /* Now it is safe to free the old tsb.  */
                 free_pages((unsigned long) old_tsb, get_order(old_size));
         }
 }
@@ -363,7 +338,11 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
          * will be confused and think there is an older TSB to free up.
          */
         mm->context.tsb = NULL;
-        tsb_grow(mm, 0, GFP_KERNEL);
+
+        /* If this is fork, inherit the parent's TSB size.  We would
+         * grow it to that size on the first page fault anyways.
+         */
+        tsb_grow(mm, get_mm_rss(mm));
 
         if (unlikely(!mm->context.tsb))
                 return -ENOMEM;