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-rw-r--r--arch/arc/Kconfig5
-rw-r--r--arch/arc/include/asm/atomic.h46
-rw-r--r--arch/arc/include/asm/spinlock.h293
3 files changed, 4 insertions, 340 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index be9d0b5ae0cc..0d3e59f56974 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -389,11 +389,6 @@ config ARC_HAS_LLSC
default y
depends on !ARC_CANT_LLSC
-config ARC_STAR_9000923308
- bool "Workaround for llock/scond livelock"
- default n
- depends on ISA_ARCV2 && SMP && ARC_HAS_LLSC
-
config ARC_HAS_SWAPE
bool "Insn: SWAPE (endian-swap)"
default y
diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index 75c8226317f4..dd683995bc9d 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -25,51 +25,17 @@
#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
-#ifdef CONFIG_ARC_STAR_9000923308
-
-#define SCOND_FAIL_RETRY_VAR_DEF \
- unsigned int delay = 1, tmp; \
-
-#define SCOND_FAIL_RETRY_ASM \
- " bz 4f \n" \
- " ; --- scond fail delay --- \n" \
- " mov %[tmp], %[delay] \n" /* tmp = delay */ \
- "2: brne.d %[tmp], 0, 2b \n" /* while (tmp != 0) */ \
- " sub %[tmp], %[tmp], 1 \n" /* tmp-- */ \
- " asl.f %[delay], %[delay], 1 \n" /* delay *= 2 */ \
- " mov.z %[delay], 1 \n" /* handle overflow */ \
- " b 1b \n" /* start over */ \
- "4: ; --- success --- \n" \
-
-#define SCOND_FAIL_RETRY_VARS \
- ,[delay] "+&r" (delay),[tmp] "=&r" (tmp) \
-
-#else /* !CONFIG_ARC_STAR_9000923308 */
-
-#define SCOND_FAIL_RETRY_VAR_DEF
-
-#define SCOND_FAIL_RETRY_ASM \
- " bnz 1b \n" \
-
-#define SCOND_FAIL_RETRY_VARS
-
-#endif
-
#define ATOMIC_OP(op, c_op, asm_op) \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
- unsigned int val; \
- SCOND_FAIL_RETRY_VAR_DEF \
+ unsigned int val; \
\
__asm__ __volatile__( \
"1: llock %[val], [%[ctr]] \n" \
" " #asm_op " %[val], %[val], %[i] \n" \
" scond %[val], [%[ctr]] \n" \
- " \n" \
- SCOND_FAIL_RETRY_ASM \
- \
+ " bnz 1b \n" \
: [val] "=&r" (val) /* Early clobber to prevent reg reuse */ \
- SCOND_FAIL_RETRY_VARS \
: [ctr] "r" (&v->counter), /* Not "m": llock only supports reg direct addr mode */ \
[i] "ir" (i) \
: "cc"); \
@@ -78,8 +44,7 @@ static inline void atomic_##op(int i, atomic_t *v) \
#define ATOMIC_OP_RETURN(op, c_op, asm_op) \
static inline int atomic_##op##_return(int i, atomic_t *v) \
{ \
- unsigned int val; \
- SCOND_FAIL_RETRY_VAR_DEF \
+ unsigned int val; \
\
/* \
* Explicit full memory barrier needed before/after as \
@@ -91,11 +56,8 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
"1: llock %[val], [%[ctr]] \n" \
" " #asm_op " %[val], %[val], %[i] \n" \
" scond %[val], [%[ctr]] \n" \
- " \n" \
- SCOND_FAIL_RETRY_ASM \
- \
+ " bnz 1b \n" \
: [val] "=&r" (val) \
- SCOND_FAIL_RETRY_VARS \
: [ctr] "r" (&v->counter), \
[i] "ir" (i) \
: "cc"); \
diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
index 5e01bdf968ea..cded4a9b5438 100644
--- a/arch/arc/include/asm/spinlock.h
+++ b/arch/arc/include/asm/spinlock.h
@@ -20,11 +20,6 @@
#ifdef CONFIG_ARC_HAS_LLSC
-/*
- * A normal LLOCK/SCOND based system, w/o need for livelock workaround
- */
-#ifndef CONFIG_ARC_STAR_9000923308
-
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
unsigned int val;
@@ -238,294 +233,6 @@ static inline void arch_write_unlock(arch_rwlock_t *rw)
smp_mb();
}
-#else /* CONFIG_ARC_STAR_9000923308 */
-
-/*
- * HS38x4 could get into a LLOCK/SCOND livelock in case of multiple overlapping
- * coherency transactions in the SCU. The exclusive line state keeps rotating
- * among contenting cores leading to a never ending cycle. So break the cycle
- * by deferring the retry of failed exclusive access (SCOND). The actual delay
- * needed is function of number of contending cores as well as the unrelated
- * coherency traffic from other cores. To keep the code simple, start off with
- * small delay of 1 which would suffice most cases and in case of contention
- * double the delay. Eventually the delay is sufficient such that the coherency
- * pipeline is drained, thus a subsequent exclusive access would succeed.
- */
-
-#define SCOND_FAIL_RETRY_VAR_DEF \
- unsigned int delay, tmp; \
-
-#define SCOND_FAIL_RETRY_ASM \
- " ; --- scond fail delay --- \n" \
- " mov %[tmp], %[delay] \n" /* tmp = delay */ \
- "2: brne.d %[tmp], 0, 2b \n" /* while (tmp != 0) */ \
- " sub %[tmp], %[tmp], 1 \n" /* tmp-- */ \
- " asl.f %[delay], %[delay], 1 \n" /* delay *= 2 */ \
- " mov.z %[delay], 1 \n" /* handle overflow */ \
- " b 1b \n" /* start over */ \
- " \n" \
- "4: ; --- done --- \n" \
-
-#define SCOND_FAIL_RETRY_VARS \
- ,[delay] "=&r" (delay), [tmp] "=&r" (tmp) \
-
-static inline void arch_spin_lock(arch_spinlock_t *lock)
-{
- unsigned int val;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[slock]] \n"
- " breq %[val], %[LOCKED], 1b \n" /* spin while LOCKED */
- " scond %[LOCKED], [%[slock]] \n" /* acquire */
- " bz 4f \n" /* done */
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val)
- SCOND_FAIL_RETRY_VARS
- : [slock] "r" (&(lock->slock)),
- [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
- : "memory", "cc");
-
- smp_mb();
-}
-
-/* 1 - lock taken successfully */
-static inline int arch_spin_trylock(arch_spinlock_t *lock)
-{
- unsigned int val, got_it = 0;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[slock]] \n"
- " breq %[val], %[LOCKED], 4f \n" /* already LOCKED, just bail */
- " scond %[LOCKED], [%[slock]] \n" /* acquire */
- " bz.d 4f \n"
- " mov.z %[got_it], 1 \n" /* got it */
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val),
- [got_it] "+&r" (got_it)
- SCOND_FAIL_RETRY_VARS
- : [slock] "r" (&(lock->slock)),
- [LOCKED] "r" (__ARCH_SPIN_LOCK_LOCKED__)
- : "memory", "cc");
-
- smp_mb();
-
- return got_it;
-}
-
-static inline void arch_spin_unlock(arch_spinlock_t *lock)
-{
- smp_mb();
-
- lock->slock = __ARCH_SPIN_LOCK_UNLOCKED__;
-
- smp_mb();
-}
-
-/*
- * Read-write spinlocks, allowing multiple readers but only one writer.
- * Unfair locking as Writers could be starved indefinitely by Reader(s)
- */
-
-static inline void arch_read_lock(arch_rwlock_t *rw)
-{
- unsigned int val;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- /*
- * zero means writer holds the lock exclusively, deny Reader.
- * Otherwise grant lock to first/subseq reader
- *
- * if (rw->counter > 0) {
- * rw->counter--;
- * ret = 1;
- * }
- */
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[rwlock]] \n"
- " brls %[val], %[WR_LOCKED], 1b\n" /* <= 0: spin while write locked */
- " sub %[val], %[val], 1 \n" /* reader lock */
- " scond %[val], [%[rwlock]] \n"
- " bz 4f \n" /* done */
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val)
- SCOND_FAIL_RETRY_VARS
- : [rwlock] "r" (&(rw->counter)),
- [WR_LOCKED] "ir" (0)
- : "memory", "cc");
-
- smp_mb();
-}
-
-/* 1 - lock taken successfully */
-static inline int arch_read_trylock(arch_rwlock_t *rw)
-{
- unsigned int val, got_it = 0;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[rwlock]] \n"
- " brls %[val], %[WR_LOCKED], 4f\n" /* <= 0: already write locked, bail */
- " sub %[val], %[val], 1 \n" /* counter-- */
- " scond %[val], [%[rwlock]] \n"
- " bz.d 4f \n"
- " mov.z %[got_it], 1 \n" /* got it */
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val),
- [got_it] "+&r" (got_it)
- SCOND_FAIL_RETRY_VARS
- : [rwlock] "r" (&(rw->counter)),
- [WR_LOCKED] "ir" (0)
- : "memory", "cc");
-
- smp_mb();
-
- return got_it;
-}
-
-static inline void arch_write_lock(arch_rwlock_t *rw)
-{
- unsigned int val;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- /*
- * If reader(s) hold lock (lock < __ARCH_RW_LOCK_UNLOCKED__),
- * deny writer. Otherwise if unlocked grant to writer
- * Hence the claim that Linux rwlocks are unfair to writers.
- * (can be starved for an indefinite time by readers).
- *
- * if (rw->counter == __ARCH_RW_LOCK_UNLOCKED__) {
- * rw->counter = 0;
- * ret = 1;
- * }
- */
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[rwlock]] \n"
- " brne %[val], %[UNLOCKED], 1b \n" /* while !UNLOCKED spin */
- " mov %[val], %[WR_LOCKED] \n"
- " scond %[val], [%[rwlock]] \n"
- " bz 4f \n"
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val)
- SCOND_FAIL_RETRY_VARS
- : [rwlock] "r" (&(rw->counter)),
- [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
- [WR_LOCKED] "ir" (0)
- : "memory", "cc");
-
- smp_mb();
-}
-
-/* 1 - lock taken successfully */
-static inline int arch_write_trylock(arch_rwlock_t *rw)
-{
- unsigned int val, got_it = 0;
- SCOND_FAIL_RETRY_VAR_DEF;
-
- smp_mb();
-
- __asm__ __volatile__(
- "0: mov %[delay], 1 \n"
- "1: llock %[val], [%[rwlock]] \n"
- " brne %[val], %[UNLOCKED], 4f \n" /* !UNLOCKED, bail */
- " mov %[val], %[WR_LOCKED] \n"
- " scond %[val], [%[rwlock]] \n"
- " bz.d 4f \n"
- " mov.z %[got_it], 1 \n" /* got it */
- " \n"
- SCOND_FAIL_RETRY_ASM
-
- : [val] "=&r" (val),
- [got_it] "+&r" (got_it)
- SCOND_FAIL_RETRY_VARS
- : [rwlock] "r" (&(rw->counter)),
- [UNLOCKED] "ir" (__ARCH_RW_LOCK_UNLOCKED__),
- [WR_LOCKED] "ir" (0)
- : "memory", "cc");
-
- smp_mb();
-
- return got_it;
-}
-
-static inline void arch_read_unlock(arch_rwlock_t *rw)
-{
- unsigned int val;
-
- smp_mb();
-
- /*
- * rw->counter++;
- */
- __asm__ __volatile__(
- "1: llock %[val], [%[rwlock]] \n"
- " add %[val], %[val], 1 \n"
- " scond %[val], [%[rwlock]] \n"
- " bnz 1b \n"
- " \n"
- : [val] "=&r" (val)
- : [rwlock] "r" (&(rw->counter))
- : "memory", "cc");
-
- smp_mb();
-}
-
-static inline void arch_write_unlock(arch_rwlock_t *rw)
-{
- unsigned int val;
-
- smp_mb();
-
- /*
- * rw->counter = __ARCH_RW_LOCK_UNLOCKED__;
- */
- __asm__ __volatile__(
- "1: llock %[val], [%[rwlock]] \n"
- " scond %[UNLOCKED], [%[rwlock]]\n"
- " bnz 1b \n"
- " \n"
- : [val] "=&r" (val)
- : [rwlock] "r" (&(rw->counter)),
- [UNLOCKED] "r" (__ARCH_RW_LOCK_UNLOCKED__)
- : "memory", "cc");
-
- smp_mb();
-}
-
-#undef SCOND_FAIL_RETRY_VAR_DEF
-#undef SCOND_FAIL_RETRY_ASM
-#undef SCOND_FAIL_RETRY_VARS
-
-#endif /* CONFIG_ARC_STAR_9000923308 */
-
#else /* !CONFIG_ARC_HAS_LLSC */
static inline void arch_spin_lock(arch_spinlock_t *lock)
generated by cgit (git 2.34.1) at 2024-06-08 12:58:32 +0000