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authorDavid Daney <ddaney@caviumnetworks.com>2009-05-20 11:40:59 -0700
committerRalf Baechle <ralf@linux-mips.org>2009-06-17 11:06:26 +0100
commit95affdda9bfba0ac17025d48c622e1f30964e316 (patch)
tree18a3551d8882b07da35922d77d4bee7f3b16365e /arch/mips/mm/tlbex.c
parente6f72d3abafd50984decc2833c706e717f5ba04e (diff)
MIPS: Fold the TLB refill at the vmalloc path if possible.
Try to fold the 64-bit TLB refill handler opportunistically at the beginning of the vmalloc path so as to avoid splitting execution flow in half and wasting cycles for a branch required at that point then. Resort to doing the split if either of the newly created parts would not fit into its designated slot. Original-patch-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: David Daney <ddaney@caviumnetworks.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/mm/tlbex.c')
-rw-r--r--arch/mips/mm/tlbex.c73
1 files changed, 49 insertions, 24 deletions
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 678e6339846..d9a18b2b7f8 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -6,7 +6,7 @@
* Synthesize TLB refill handlers at runtime.
*
* Copyright (C) 2004, 2005, 2006, 2008 Thiemo Seufer
- * Copyright (C) 2005, 2007 Maciej W. Rozycki
+ * Copyright (C) 2005, 2007, 2008, 2009 Maciej W. Rozycki
* Copyright (C) 2006 Ralf Baechle (ralf@linux-mips.org)
*
* ... and the days got worse and worse and now you see
@@ -19,6 +19,7 @@
* (Condolences to Napoleon XIV)
*/
+#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/string.h>
@@ -732,36 +733,60 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
uasm_copy_handler(relocs, labels, tlb_handler, p, f);
final_len = p - tlb_handler;
} else {
- /*
- * Split two instructions before the end. One for the
- * branch and one for the instruction in the delay
- * slot.
- */
- u32 *split = tlb_handler + MIPS64_REFILL_INSNS - 2;
+#ifdef MODULE_START
+ const enum label_id ls = label_module_alloc;
+#else
+ const enum label_id ls = label_vmalloc;
+#endif
+ u32 *split;
+ int ov = 0;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(labels) && labels[i].lab != ls; i++)
+ ;
+ BUG_ON(i == ARRAY_SIZE(labels));
+ split = labels[i].addr;
/*
- * Find the split point. If the branch would fall in
- * a delay slot, we must back up an additional
- * instruction so that it is no longer in a delay
- * slot.
+ * See if we have overflown one way or the other.
*/
- if (uasm_insn_has_bdelay(relocs, split - 1))
- split--;
-
+ if (split > tlb_handler + MIPS64_REFILL_INSNS ||
+ split < p - MIPS64_REFILL_INSNS)
+ ov = 1;
+
+ if (ov) {
+ /*
+ * Split two instructions before the end. One
+ * for the branch and one for the instruction
+ * in the delay slot.
+ */
+ split = tlb_handler + MIPS64_REFILL_INSNS - 2;
+
+ /*
+ * If the branch would fall in a delay slot,
+ * we must back up an additional instruction
+ * so that it is no longer in a delay slot.
+ */
+ if (uasm_insn_has_bdelay(relocs, split - 1))
+ split--;
+ }
/* Copy first part of the handler. */
uasm_copy_handler(relocs, labels, tlb_handler, split, f);
f += split - tlb_handler;
- /* Insert branch. */
- uasm_l_split(&l, final_handler);
- uasm_il_b(&f, &r, label_split);
- if (uasm_insn_has_bdelay(relocs, split))
- uasm_i_nop(&f);
- else {
- uasm_copy_handler(relocs, labels, split, split + 1, f);
- uasm_move_labels(labels, f, f + 1, -1);
- f++;
- split++;
+ if (ov) {
+ /* Insert branch. */
+ uasm_l_split(&l, final_handler);
+ uasm_il_b(&f, &r, label_split);
+ if (uasm_insn_has_bdelay(relocs, split))
+ uasm_i_nop(&f);
+ else {
+ uasm_copy_handler(relocs, labels,
+ split, split + 1, f);
+ uasm_move_labels(labels, f, f + 1, -1);
+ f++;
+ split++;
+ }
}
/* Copy the rest of the handler. */