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/bitops.S | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) (limited to 'arch/sparc64/lib/bitops.S') diff --git a/arch/sparc64/lib/bitops.S b/arch/sparc64/lib/bitops.S index 886dcd2b376..31afbfe6c1e 100644 --- a/arch/sparc64/lib/bitops.S +++ b/arch/sparc64/lib/bitops.S @@ -7,20 +7,26 @@ #include #include + .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 +#define BITOP_POST_BARRIER \ + ba,pt %xcc, 80b; \ + membar #StoreLoad | #StoreStore + +80: retl + nop #else -#define BITOP_PRE_BARRIER nop -#define BITOP_POST_BARRIER nop +#define BITOP_PRE_BARRIER +#define BITOP_POST_BARRIER #endif - .text - .globl test_and_set_bit .type test_and_set_bit,#function test_and_set_bit: /* %o0=nr, %o1=addr */ @@ -37,10 +43,11 @@ test_and_set_bit: /* %o0=nr, %o1=addr */ 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 @@ test_and_clear_bit: /* %o0=nr, %o1=addr */ 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 @@ test_and_change_bit: /* %o0=nr, %o1=addr */ 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 -- cgit v1.2.3