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