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sparc64: Make lock backoff really a NOP on UP builds. 

As noticed by Mikulas Patocka, the backoff macros don't
completely nop out for UP builds, we still get a
branch always and a delay slot nop.

Fix this by making the branch to the backoff spin loop
selective, then we can nop out the spin loop completely.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2010-08-18 22:53:26 -07:00
parent 6ec274750c
commit 0f58189d4a
3 changed files with 22 additions and 17 deletions
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11
arch/sparc/include/asm/backoff.h
View File

@ -8,6 +8,9 @@
#define BACKOFF_SETUP(reg) \
mov 1, reg
#define BACKOFF_LABEL(spin_label, continue_label) \
spin_label
#define BACKOFF_SPIN(reg, tmp, label) \
mov reg, tmp; \
88: brnz,pt tmp, 88b; \
@ -22,9 +25,11 @@
#else
#define BACKOFF_SETUP(reg)
#define BACKOFF_SPIN(reg, tmp, label) \
ba,pt %xcc, label; \
nop;
#define BACKOFF_LABEL(spin_label, continue_label) \
continue_label
#define BACKOFF_SPIN(reg, tmp, label)
#endif

16
arch/sparc/lib/atomic_64.S
View File

@ -21,7 +21,7 @@ atomic_add: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -36,7 +36,7 @@ atomic_sub: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -51,7 +51,7 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
add %g1, %o0, %g1
retl
sra %g1, 0, %o0
@ -66,7 +66,7 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
bne,pn %icc, BACKOFF_LABEL(2f, 1b)
sub %g1, %o0, %g1
retl
sra %g1, 0, %o0
@ -81,7 +81,7 @@ atomic64_add: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -96,7 +96,7 @@ atomic64_sub: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -111,7 +111,7 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
add %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
add %g1, %o0, %o0
@ -126,7 +126,7 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
sub %g1, %o0, %g7
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
sub %g1, %o0, %o0

12
arch/sparc/lib/bitops.S
View File

@ -22,7 +22,7 @@ test_and_set_bit: /* %o0=nr, %o1=addr */
or %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
and %g7, %o2, %g2
clr %o0
movrne %g2, 1, %o0
@ -45,7 +45,7 @@ test_and_clear_bit: /* %o0=nr, %o1=addr */
andn %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
and %g7, %o2, %g2
clr %o0
movrne %g2, 1, %o0
@ -68,7 +68,7 @@ test_and_change_bit: /* %o0=nr, %o1=addr */
xor %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
and %g7, %o2, %g2
clr %o0
movrne %g2, 1, %o0
@ -91,7 +91,7 @@ set_bit: /* %o0=nr, %o1=addr */
or %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -112,7 +112,7 @@ clear_bit: /* %o0=nr, %o1=addr */
andn %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop
@ -133,7 +133,7 @@ change_bit: /* %o0=nr, %o1=addr */
xor %g7, %o2, %g1
casx [%o1], %g7, %g1
cmp %g7, %g1
bne,pn %xcc, 2f
bne,pn %xcc, BACKOFF_LABEL(2f, 1b)
nop
retl
nop