[SPARC64]: Avoid membar instructions in delay slots.
In particular, avoid membar instructions in the delay
slot of a jmpl instruction.
UltraSPARC-I, II, IIi, and IIe have a bug, documented in
the UltraSPARC-IIi User's Manual, Appendix K, Erratum 51
The long and short of it is that if the IMU unit misses
on a branch or jmpl, and there is a store buffer synchronizing
membar in the delay slot, the chip can stop fetching instructions.
If interrupts are enabled or some other trap is enabled, the
chip will unwedge itself, but performance will suffer.
We already had a workaround for this bug in a few spots, but
it's better to have the entire tree sanitized for this rule.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/lib/bitops.S b/arch/sparc64/lib/bitops.S
index 886dcd2..31afbfe 100644
--- a/arch/sparc64/lib/bitops.S
+++ b/arch/sparc64/lib/bitops.S
@@ -7,19 +7,25 @@
#include <linux/config.h>
#include <asm/asi.h>
+ .text
+
/* On SMP we need to use memory barriers to ensure
* correct memory operation ordering, nop these out
* for uniprocessor.
*/
+
#ifdef CONFIG_SMP
#define BITOP_PRE_BARRIER membar #StoreLoad | #LoadLoad
-#define BITOP_POST_BARRIER membar #StoreLoad | #StoreStore
-#else
-#define BITOP_PRE_BARRIER nop
-#define BITOP_POST_BARRIER nop
-#endif
+#define BITOP_POST_BARRIER \
+ ba,pt %xcc, 80b; \
+ membar #StoreLoad | #StoreStore
- .text
+80: retl
+ nop
+#else
+#define BITOP_PRE_BARRIER
+#define BITOP_POST_BARRIER
+#endif
.globl test_and_set_bit
.type test_and_set_bit,#function
@@ -37,10 +43,11 @@
cmp %g7, %g1
bne,pn %xcc, 1b
and %g7, %o2, %g2
- BITOP_POST_BARRIER
clr %o0
+ movrne %g2, 1, %o0
+ BITOP_POST_BARRIER
retl
- movrne %g2, 1, %o0
+ nop
.size test_and_set_bit, .-test_and_set_bit
.globl test_and_clear_bit
@@ -59,10 +66,11 @@
cmp %g7, %g1
bne,pn %xcc, 1b
and %g7, %o2, %g2
- BITOP_POST_BARRIER
clr %o0
+ movrne %g2, 1, %o0
+ BITOP_POST_BARRIER
retl
- movrne %g2, 1, %o0
+ nop
.size test_and_clear_bit, .-test_and_clear_bit
.globl test_and_change_bit
@@ -81,10 +89,11 @@
cmp %g7, %g1
bne,pn %xcc, 1b
and %g7, %o2, %g2
- BITOP_POST_BARRIER
clr %o0
+ movrne %g2, 1, %o0
+ BITOP_POST_BARRIER
retl
- movrne %g2, 1, %o0
+ nop
.size test_and_change_bit, .-test_and_change_bit
.globl set_bit