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>

diff --git a/arch/sparc/include/asm/backoff.h b/arch/sparc/include/asm/backoff.h
index fa1fdf6..db3af0d 100644 (file)
--- a/arch/sparc/include/asm/backoff.h
+++ b/arch/sparc/include/asm/backoff.h
@@ -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
 

diff --git a/arch/sparc/lib/atomic_64.S b/arch/sparc/lib/atomic_64.S
index 703c9c3..59186e0 100644 (file)
--- a/arch/sparc/lib/atomic_64.S
+++ b/arch/sparc/lib/atomic_64.S
@@ -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

diff --git a/arch/sparc/lib/bitops.S b/arch/sparc/lib/bitops.S
index 2b7228c..3dc61d5 100644 (file)
--- a/arch/sparc/lib/bitops.S
+++ b/arch/sparc/lib/bitops.S
@@ -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