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[SPARC64]: Avoid membar instructions in delay slots.

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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 <davem@davemloft.net>
This commit is contained in:
David S. Miller 2005-06-27 15:42:04 -07:00
parent 020f46a39e
commit b445e26cbf
15 changed files with 172 additions and 111 deletions
Download patch file Download diff file Expand all files Collapse all files

3
include/asm-sparc64/rwsem.h
View file

@ -55,8 +55,9 @@ static __inline__ int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
"add %%g1, %1, %%g7\n\t"
"cas [%2], %%g1, %%g7\n\t"
"cmp %%g1, %%g7\n\t"
"membar #StoreLoad | #StoreStore\n\t"
"bne,pn %%icc, 1b\n\t"
" membar #StoreLoad | #StoreStore\n\t"
" nop\n\t"
"mov %%g7, %0\n\t"
: "=&r" (tmp)
: "0" (tmp), "r" (sem)

29
include/asm-sparc64/spinlock.h
View file

@ -52,12 +52,14 @@ static inline void _raw_spin_lock(spinlock_t *lock)
__asm__ __volatile__(
"1: ldstub [%1], %0\n"
" membar #StoreLoad | #StoreStore\n"
" brnz,pn %0, 2f\n"
" membar #StoreLoad | #StoreStore\n"
" nop\n"
" .subsection 2\n"
"2: ldub [%1], %0\n"
" membar #LoadLoad\n"
" brnz,pt %0, 2b\n"
" membar #LoadLoad\n"
" nop\n"
" ba,a,pt %%xcc, 1b\n"
" .previous"
: "=&r" (tmp)
@ -95,16 +97,18 @@ static inline void _raw_spin_lock_flags(spinlock_t *lock, unsigned long flags)
__asm__ __volatile__(
"1: ldstub [%2], %0\n"
" brnz,pn %0, 2f\n"
" membar #StoreLoad | #StoreStore\n"
" brnz,pn %0, 2f\n"
" nop\n"
" .subsection 2\n"
"2: rdpr %%pil, %1\n"
" wrpr %3, %%pil\n"
"3: ldub [%2], %0\n"
" brnz,pt %0, 3b\n"
" membar #LoadLoad\n"
" brnz,pt %0, 3b\n"
" nop\n"
" ba,pt %%xcc, 1b\n"
" wrpr %1, %%pil\n"
" wrpr %1, %%pil\n"
" .previous"
: "=&r" (tmp1), "=&r" (tmp2)
: "r"(lock), "r"(flags)
@ -162,12 +166,14 @@ static void inline __read_lock(rwlock_t *lock)
"4: add %0, 1, %1\n"
" cas [%2], %0, %1\n"
" cmp %0, %1\n"
" membar #StoreLoad | #StoreStore\n"
" bne,pn %%icc, 1b\n"
" membar #StoreLoad | #StoreStore\n"
" nop\n"
" .subsection 2\n"
"2: ldsw [%2], %0\n"
" membar #LoadLoad\n"
" brlz,pt %0, 2b\n"
" membar #LoadLoad\n"
" nop\n"
" ba,a,pt %%xcc, 4b\n"
" .previous"
: "=&r" (tmp1), "=&r" (tmp2)
@ -204,12 +210,14 @@ static void inline __write_lock(rwlock_t *lock)
"4: or %0, %3, %1\n"
" cas [%2], %0, %1\n"
" cmp %0, %1\n"
" membar #StoreLoad | #StoreStore\n"
" bne,pn %%icc, 1b\n"
" membar #StoreLoad | #StoreStore\n"
" nop\n"
" .subsection 2\n"
"2: lduw [%2], %0\n"
" membar #LoadLoad\n"
" brnz,pt %0, 2b\n"
" membar #LoadLoad\n"
" nop\n"
" ba,a,pt %%xcc, 4b\n"
" .previous"
: "=&r" (tmp1), "=&r" (tmp2)
@ -240,8 +248,9 @@ static int inline __write_trylock(rwlock_t *lock)
" or %0, %4, %1\n"
" cas [%3], %0, %1\n"
" cmp %0, %1\n"
" membar #StoreLoad | #StoreStore\n"
" bne,pn %%icc, 1b\n"
" membar #StoreLoad | #StoreStore\n"
" nop\n"
" mov 1, %2\n"
"2:"
: "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)

1
include/asm-sparc64/spitfire.h
View file

@ -111,7 +111,6 @@ static __inline__ void spitfire_put_dcache_tag(unsigned long addr, unsigned long
"membar #Sync"
: /* No outputs */
: "r" (tag), "r" (addr), "i" (ASI_DCACHE_TAG));
__asm__ __volatile__ ("membar #Sync" : : : "memory");
}
/* The instruction cache lines are flushed with this, but note that