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authorDavid S. Miller <davem@davemloft.net>2005-09-08 14:37:53 -0700
committerDavid S. Miller <davem@davemloft.net>2005-09-08 14:37:53 -0700
commit4d803fcdcd97dd346d4b39c3b76e5879cead8a31 (patch)
treef30c8caa998261fc0983121021184f0f6cc555b4 /arch/sparc64/lib
parent1b11d78cf87a7014f96e5b7fa2e1233cc8081a00 (diff)
[SPARC64]: Inline membar()'s again.
Since GCC has to emit a call and a delay slot to the out-of-line "membar" routines in arch/sparc64/lib/mb.S it is much better to just do the necessary predicted branch inline instead as: ba,pt %xcc, 1f membar #whatever 1: instead of the current: call membar_foo dslot because this way GCC is not required to allocate a stack frame if the function can be a leaf function. This also makes this bug fix easier to backport to 2.4.x Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc64/lib')
-rw-r--r--arch/sparc64/lib/Makefile2
-rw-r--r--arch/sparc64/lib/mb.S73
2 files changed, 1 insertions, 74 deletions
diff --git a/arch/sparc64/lib/Makefile b/arch/sparc64/lib/Makefile
index 6201f104098..40dbeec7e5d 100644
--- a/arch/sparc64/lib/Makefile
+++ b/arch/sparc64/lib/Makefile
@@ -12,7 +12,7 @@ lib-y := PeeCeeI.o copy_page.o clear_page.o strlen.o strncmp.o \
U1memcpy.o U1copy_from_user.o U1copy_to_user.o \
U3memcpy.o U3copy_from_user.o U3copy_to_user.o U3patch.o \
copy_in_user.o user_fixup.o memmove.o \
- mcount.o ipcsum.o rwsem.o xor.o find_bit.o delay.o mb.o
+ mcount.o ipcsum.o rwsem.o xor.o find_bit.o delay.o
lib-$(CONFIG_DEBUG_SPINLOCK) += debuglocks.o
lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o
diff --git a/arch/sparc64/lib/mb.S b/arch/sparc64/lib/mb.S
deleted file mode 100644
index 4004f748619..00000000000
--- a/arch/sparc64/lib/mb.S
+++ /dev/null
@@ -1,73 +0,0 @@
-/* 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