From: David Miller <davem@xxxxxxxxxxxxx> Date: Wed, 18 Aug 2010 17:16:28 -0700 (PDT) > From: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Date: Wed, 18 Aug 2010 19:44:05 -0400 (EDT) > >> They are not: >> 0000000000000000 <atomic_add>: >> 0000000000000028 <atomic_sub>: >> 0000000000000050 <atomic_add_ret>: >> 000000000000007c <atomic_sub_ret>: >> 00000000000000a8 <atomic64_add>: >> 00000000000000d0 <atomic64_sub>: >> 00000000000000f8 <atomic64_add_ret>: >> 0000000000000124 <atomic64_sub_ret>: >> >> (on UP compile without backoff). That dummy backoff code produces jump >> forward and backward. > > That's a bug, it should be just an empty macro expansion. Ok, something like this: 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@xxxxxxxxxxxxx> diff --git a/arch/sparc/include/asm/backoff.h b/arch/sparc/include/asm/backoff.h index fa1fdf6..db3af0d 100644 --- 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 0268210..5da1665 100644 --- 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 %g7, %o0, %g7 sra %g7, 0, %o0 retl @@ -67,7 +67,7 @@ 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 %g7, %o0, %g7 sra %g7, 0, %o0 retl @@ -83,7 +83,7 @@ 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 @@ -98,7 +98,7 @@ 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 @@ -113,7 +113,7 @@ 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) add %g7, %o0, %g7 mov %g7, %o0 retl @@ -129,7 +129,7 @@ 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) sub %g7, %o0, %g7 mov %g7, %o0 retl diff --git a/arch/sparc/lib/bitops.S b/arch/sparc/lib/bitops.S index 2b7228c..3dc61d5 100644 --- 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 -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
