Merge HEAD from /spare/repo/linux-2.6/.git

1 files changed, 73 insertions, 0 deletions

diff --git a/arch/sparc64/lib/mb.S b/arch/sparc64/lib/mb.S
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+/* mb.S: Out of line memory barriers.
+ *
+ * Copyright (C) 2005 David S. Miller (davem@davemloft.net)
+ */
+
+        /* These are here in an effort to more fully work around
+         * Spitfire Errata #51.  Essentially, if a memory barrier
+         * occurs soon after a mispredicted branch, the chip can stop
+         * executing instructions until a trap occurs.  Therefore, if
+         * interrupts are disabled, the chip can hang forever.
+         *
+         * It used to be believed that the memory barrier had to be
+         * right in the delay slot, but a case has been traced
+         * recently wherein the memory barrier was one instruction
+         * after the branch delay slot and the chip still hung.  The
+         * offending sequence was the following in sym_wakeup_done()
+         * of the sym53c8xx_2 driver:
+         *
+         *      call    sym_ccb_from_dsa, 0
+         *       movge  %icc, 0, %l0
+         *      brz,pn  %o0, .LL1303
+         *       mov    %o0, %l2
+         *      membar  #LoadLoad
+         *
+         * The branch has to be mispredicted for the bug to occur.
+         * Therefore, we put the memory barrier explicitly into a
+         * "branch always, predicted taken" delay slot to avoid the
+         * problem case.
+         */
+
+        .text
+
+99:     retl
+         nop
+
+        .globl  mb
+mb:     ba,pt   %xcc, 99b
+         membar #LoadLoad | #LoadStore | #StoreStore | #StoreLoad
+        .size   mb, .-mb
+
+        .globl  rmb
+rmb:    ba,pt   %xcc, 99b
+         membar #LoadLoad
+        .size   rmb, .-rmb
+
+        .globl  wmb
+wmb:    ba,pt   %xcc, 99b
+         membar #StoreStore
+        .size   wmb, .-wmb
+
+        .globl  membar_storeload
+membar_storeload:
+        ba,pt   %xcc, 99b
+         membar #StoreLoad
+        .size   membar_storeload, .-membar_storeload
+
+        .globl  membar_storeload_storestore
+membar_storeload_storestore:
+        ba,pt   %xcc, 99b
+         membar #StoreLoad | #StoreStore
+        .size   membar_storeload_storestore, .-membar_storeload_storestore
+
+        .globl  membar_storeload_loadload
+membar_storeload_loadload:
+        ba,pt   %xcc, 99b
+         membar #StoreLoad | #LoadLoad
+        .size   membar_storeload_loadload, .-membar_storeload_loadload
+
+        .globl  membar_storestore_loadstore
+membar_storestore_loadstore:
+        ba,pt   %xcc, 99b
+         membar #StoreStore | #LoadStore
+        .size   membar_storestore_loadstore, .-membar_storestore_loadstore