[SPARC64]: Optimized TSB table initialization.

We only need to write an invalid tag every 16 bytes,
so taking advantage of this can save many instructions
compared to the simple memset() call we make now.

A prefetching implementation is implemented for sun4u
and a block-init store version if implemented for Niagara.

The next trick is to be able to perform an init and
a copy_tsb() in parallel when growing a TSB table.

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 72 insertions, 1 deletions

diff --git a/arch/sparc64/kernel/tsb.S b/arch/sparc64/kernel/tsb.S
index 1b154c8636..118baea44f 100644
--- a/arch/sparc64/kernel/tsb.S
+++ b/arch/sparc64/kernel/tsb.S
@@ -371,3 +371,72 @@ copy_tsb:		/* %o0=old_tsb_base, %o1=old_tsb_size
         retl
          TSB_MEMBAR
         .size           copy_tsb, .-copy_tsb
+
+        /* Set the invalid bit in all TSB entries.  */
+        .align          32
+        .globl          tsb_init
+        .type           tsb_init,#function
+tsb_init:               /* %o0 = TSB vaddr, %o1 = size in bytes */
+        prefetch        [%o0 + 0x000], #n_writes
+        mov             1, %g1
+        prefetch        [%o0 + 0x040], #n_writes
+        sllx            %g1, TSB_TAG_INVALID_BIT, %g1
+        prefetch        [%o0 + 0x080], #n_writes
+1:      prefetch        [%o0 + 0x0c0], #n_writes
+        stx             %g1, [%o0 + 0x00]
+        stx             %g1, [%o0 + 0x10]
+        stx             %g1, [%o0 + 0x20]
+        stx             %g1, [%o0 + 0x30]
+        prefetch        [%o0 + 0x100], #n_writes
+        stx             %g1, [%o0 + 0x40]
+        stx             %g1, [%o0 + 0x50]
+        stx             %g1, [%o0 + 0x60]
+        stx             %g1, [%o0 + 0x70]
+        prefetch        [%o0 + 0x140], #n_writes
+        stx             %g1, [%o0 + 0x80]
+        stx             %g1, [%o0 + 0x90]
+        stx             %g1, [%o0 + 0xa0]
+        stx             %g1, [%o0 + 0xb0]
+        prefetch        [%o0 + 0x180], #n_writes
+        stx             %g1, [%o0 + 0xc0]
+        stx             %g1, [%o0 + 0xd0]
+        stx             %g1, [%o0 + 0xe0]
+        stx             %g1, [%o0 + 0xf0]
+        subcc           %o1, 0x100, %o1
+        bne,pt          %xcc, 1b
+         add            %o0, 0x100, %o0
+        retl
+         nop
+        nop
+        nop
+        .size           tsb_init, .-tsb_init
+
+        .globl          NGtsb_init
+        .type           NGtsb_init,#function
+NGtsb_init:
+        rd              %asi, %g2
+        mov             1, %g1
+        wr              %g0, ASI_BLK_INIT_QUAD_LDD_P, %asi
+        sllx            %g1, TSB_TAG_INVALID_BIT, %g1
+1:      stxa            %g1, [%o0 + 0x00] %asi
+        stxa            %g1, [%o0 + 0x10] %asi
+        stxa            %g1, [%o0 + 0x20] %asi
+        stxa            %g1, [%o0 + 0x30] %asi
+        stxa            %g1, [%o0 + 0x40] %asi
+        stxa            %g1, [%o0 + 0x50] %asi
+        stxa            %g1, [%o0 + 0x60] %asi
+        stxa            %g1, [%o0 + 0x70] %asi
+        stxa            %g1, [%o0 + 0x80] %asi
+        stxa            %g1, [%o0 + 0x90] %asi
+        stxa            %g1, [%o0 + 0xa0] %asi
+        stxa            %g1, [%o0 + 0xb0] %asi
+        stxa            %g1, [%o0 + 0xc0] %asi
+        stxa            %g1, [%o0 + 0xd0] %asi
+        stxa            %g1, [%o0 + 0xe0] %asi
+        stxa            %g1, [%o0 + 0xf0] %asi
+        subcc           %o1, 0x100, %o1
+        bne,pt          %xcc, 1b
+         add            %o0, 0x100, %o0
+        retl
+         wr             %g2, 0x0, %asi
+        .size           NGtsb_init, .-NGtsb_init
diff --git a/arch/sparc64/lib/NGbzero.S b/arch/sparc64/lib/NGbzero.S
index fef584f745..e86baece5c 100644
--- a/arch/sparc64/lib/NGbzero.S
+++ b/arch/sparc64/lib/NGbzero.S
@@ -157,6 +157,7 @@ niagara_patch_bzero:
         NG_DO_PATCH(memset, NGmemset)
         NG_DO_PATCH(__bzero, NGbzero)
         NG_DO_PATCH(__clear_user, NGclear_user)
+        NG_DO_PATCH(tsb_init, NGtsb_init)
         retl
          nop
         .size   niagara_patch_bzero,.-niagara_patch_bzero
diff --git a/arch/sparc64/mm/tsb.c b/arch/sparc64/mm/tsb.c
index 1af797a0a0..b2064e2a44 100644
--- a/arch/sparc64/mm/tsb.c
+++ b/arch/sparc64/mm/tsb.c
@@ -313,7 +313,7 @@ retry_tsb_alloc:
         }
 
         /* Mark all tags as invalid.  */
-        memset(new_tsb, 0x40, new_size);
+        tsb_init(new_tsb, new_size);
 
         /* Ok, we are about to commit the changes.  If we are
          * growing an existing TSB the locking is very tricky,
diff --git a/include/asm-sparc64/mmu.h b/include/asm-sparc64/mmu.h
index da14a9bf0e..230ba678d3 100644
--- a/include/asm-sparc64/mmu.h
+++ b/include/asm-sparc64/mmu.h
@@ -88,6 +88,7 @@ struct tsb {
 
 extern void __tsb_insert(unsigned long ent, unsigned long tag, unsigned long pte);
 extern void tsb_flush(unsigned long ent, unsigned long tag);
+extern void tsb_init(struct tsb *tsb, unsigned long size);
 
 typedef struct {
         spinlock_t              lock;