From b445e26cbf784cdba10f2b6c3e2cd3ee7bab360a Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 27 Jun 2005 15:42:04 -0700 Subject: [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 --- arch/sparc64/lib/atomic.S | 42 ++++++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 16 deletions(-) (limited to 'arch/sparc64/lib/atomic.S') diff --git a/arch/sparc64/lib/atomic.S b/arch/sparc64/lib/atomic.S index e528b8d1a3e6..faf87c31598b 100644 --- a/arch/sparc64/lib/atomic.S +++ b/arch/sparc64/lib/atomic.S @@ -7,18 +7,6 @@ #include #include - /* On SMP we need to use memory barriers to ensure - * correct memory operation ordering, nop these out - * for uniprocessor. - */ -#ifdef CONFIG_SMP -#define ATOMIC_PRE_BARRIER membar #StoreLoad | #LoadLoad -#define ATOMIC_POST_BARRIER membar #StoreLoad | #StoreStore -#else -#define ATOMIC_PRE_BARRIER nop -#define ATOMIC_POST_BARRIER nop -#endif - .text /* Two versions of the atomic routines, one that @@ -52,6 +40,24 @@ atomic_sub: /* %o0 = decrement, %o1 = atomic_ptr */ nop .size atomic_sub, .-atomic_sub + /* On SMP we need to use memory barriers to ensure + * correct memory operation ordering, nop these out + * for uniprocessor. + */ +#ifdef CONFIG_SMP + +#define ATOMIC_PRE_BARRIER membar #StoreLoad | #LoadLoad; +#define ATOMIC_POST_BARRIER \ + ba,pt %xcc, 80b; \ + membar #StoreLoad | #StoreStore + +80: retl + nop +#else +#define ATOMIC_PRE_BARRIER +#define ATOMIC_POST_BARRIER +#endif + .globl atomic_add_ret .type atomic_add_ret,#function atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */ @@ -62,9 +68,10 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */ cmp %g1, %g7 bne,pn %icc, 1b add %g7, %o0, %g7 + sra %g7, 0, %o0 ATOMIC_POST_BARRIER retl - sra %g7, 0, %o0 + nop .size atomic_add_ret, .-atomic_add_ret .globl atomic_sub_ret @@ -77,9 +84,10 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */ cmp %g1, %g7 bne,pn %icc, 1b sub %g7, %o0, %g7 + sra %g7, 0, %o0 ATOMIC_POST_BARRIER retl - sra %g7, 0, %o0 + nop .size atomic_sub_ret, .-atomic_sub_ret .globl atomic64_add @@ -118,9 +126,10 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */ cmp %g1, %g7 bne,pn %xcc, 1b add %g7, %o0, %g7 + mov %g7, %o0 ATOMIC_POST_BARRIER retl - mov %g7, %o0 + nop .size atomic64_add_ret, .-atomic64_add_ret .globl atomic64_sub_ret @@ -133,7 +142,8 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */ cmp %g1, %g7 bne,pn %xcc, 1b sub %g7, %o0, %g7 + mov %g7, %o0 ATOMIC_POST_BARRIER retl - mov %g7, %o0 + nop .size atomic64_sub_ret, .-atomic64_sub_ret -- cgit v1.2.3