* register initially, and then either a byte or register-sized
* word is loaded/stored to the pointer
*/
-
-/*
- * void hw_lock_init(hw_lock_t)
- *
- * Initialize a hardware lock.
- */
-LEAF_ENTRY(hw_lock_init)
- movq $0, (%rdi) /* clear the lock */
- LEAF_RET
-
/*
* void hw_lock_byte_init(volatile uint8_t *)
movb $0, (%rdi) /* clear the lock */
LEAF_RET
-/*
- * void hw_lock_lock(hw_lock_t)
- *
- * Acquire lock, spinning until it becomes available.
- * MACH_RT: also return with preemption disabled.
- */
-LEAF_ENTRY(hw_lock_lock)
- mov %gs:CPU_ACTIVE_THREAD, %rcx /* get thread pointer */
-
- PREEMPTION_DISABLE
-1:
- mov (%rdi), %rax
- test %rax,%rax /* lock locked? */
- jne 3f /* branch if so */
- lock; cmpxchg %rcx,(%rdi) /* try to acquire the HW lock */
- jne 3f
- movl $1,%eax /* In case this was a timeout call */
- LEAF_RET /* if yes, then nothing left to do */
-3:
- PAUSE /* pause for hyper-threading */
- jmp 1b /* try again */
-
/*
* void hw_lock_byte_lock(uint8_t *lock_byte)
*
PAUSE /* pause for hyper-threading */
jmp 1b /* try again */
-/*
- * unsigned int hw_lock_to(hw_lock_t, unsigned int)
- *
- * Acquire lock, spinning until it becomes available or timeout.
- * MACH_RT: also return with preemption disabled.
- */
-LEAF_ENTRY(hw_lock_to)
-1:
- mov %gs:CPU_ACTIVE_THREAD, %rcx
-
- /*
- * Attempt to grab the lock immediately
- * - fastpath without timeout nonsense.
- */
- PREEMPTION_DISABLE
-
- mov (%rdi), %rax
- test %rax,%rax /* lock locked? */
- jne 2f /* branch if so */
- lock; cmpxchg %rcx,(%rdi) /* try to acquire the HW lock */
- jne 2f /* branch on failure */
- movl $1,%eax
- LEAF_RET
-
-2:
-#define INNER_LOOP_COUNT 1000
- /*
- * Failed to get the lock so set the timeout
- * and then spin re-checking the lock but pausing
- * every so many (INNER_LOOP_COUNT) spins to check for timeout.
- */
- push %r9
- lfence
- rdtsc /* read cyclecount into %edx:%eax */
- shlq $32, %rdx
- orq %rdx, %rax /* load 64-bit quantity into %rax */
- addq %rax, %rsi /* %rsi is the timeout expiry */
-
-4:
- /*
- * The inner-loop spin to look for the lock being freed.
- */
- mov $(INNER_LOOP_COUNT),%r9
-5:
- PAUSE /* pause for hyper-threading */
- mov (%rdi),%rax /* spin checking lock value in cache */
- test %rax,%rax
- je 6f /* zero => unlocked, try to grab it */
- decq %r9 /* decrement inner loop count */
- jnz 5b /* time to check for timeout? */
-
- /*
- * Here after spinning INNER_LOOP_COUNT times, check for timeout
- */
- lfence
- rdtsc /* cyclecount into %edx:%eax */
- shlq $32, %rdx
- orq %rdx, %rax /* load 64-bit quantity into %rax */
- cmpq %rsi, %rax /* compare to timeout */
- jb 4b /* continue spinning if less, or */
- xor %rax,%rax /* with 0 return value */
- pop %r9
- LEAF_RET
-
-6:
- /*
- * Here to try to grab the lock that now appears to be free
- * after contention.
- */
- mov %gs:CPU_ACTIVE_THREAD, %rcx
- lock; cmpxchg %rcx,(%rdi) /* try to acquire the HW lock */
- jne 4b /* no - spin again */
- movl $1,%eax /* yes */
- pop %r9
- LEAF_RET
-
-/*
- * void hw_lock_unlock(hw_lock_t)
- *
- * Unconditionally release lock.
- * MACH_RT: release preemption level.
- */
-LEAF_ENTRY(hw_lock_unlock)
- movq $0, (%rdi) /* clear the lock */
- PREEMPTION_ENABLE
- LEAF_RET
-
/*
* void hw_lock_byte_unlock(uint8_t *lock_byte)
*
PREEMPTION_ENABLE
LEAF_RET
-/*
- * unsigned int hw_lock_try(hw_lock_t)
- * MACH_RT: returns with preemption disabled on success.
- */
-LEAF_ENTRY(hw_lock_try)
- mov %gs:CPU_ACTIVE_THREAD, %rcx
- PREEMPTION_DISABLE
-
- mov (%rdi),%rax
- test %rax,%rax
- jne 1f
- lock; cmpxchg %rcx,(%rdi) /* try to acquire the HW lock */
- jne 1f
-
- movl $1,%eax /* success */
- LEAF_RET
-
-1:
- PREEMPTION_ENABLE /* failure: release preemption... */
- xorl %eax,%eax /* ...and return failure */
- LEAF_RET
-
-/*
- * unsigned int hw_lock_held(hw_lock_t)
- * MACH_RT: doesn't change preemption state.
- * N.B. Racy, of course.
- */
-LEAF_ENTRY(hw_lock_held)
- mov (%rdi),%rax /* check lock value */
- test %rax,%rax
- movl $1,%ecx
- cmovne %ecx,%eax /* 0 => unlocked, 1 => locked */
- LEAF_RET
-
-
/*
* Reader-writer lock fastpaths. These currently exist for the
* shared lock acquire, the exclusive lock acquire, the shared to
.text
-LEAF_ENTRY(_disable_preemption)
-#if MACH_RT
- PREEMPTION_DISABLE
-#endif /* MACH_RT */
- LEAF_RET
-
-LEAF_ENTRY(_enable_preemption)
-#if MACH_RT
-#if MACH_ASSERT
- cmpl $0,%gs:CPU_PREEMPTION_LEVEL
- jg 1f
- movl %gs:CPU_PREEMPTION_LEVEL,%esi
- ALIGN_STACK()
- LOAD_STRING_ARG0(_enable_preemption_less_than_zero)
- CALL_PANIC()
- hlt
- .cstring
-_enable_preemption_less_than_zero:
- .asciz "_enable_preemption: preemption_level(%d) < 0!"
- .text
-1:
-#endif /* MACH_ASSERT */
- PREEMPTION_ENABLE
-#endif /* MACH_RT */
- LEAF_RET
-
-LEAF_ENTRY(_enable_preemption_no_check)
-#if MACH_RT
-#if MACH_ASSERT
- cmpl $0,%gs:CPU_PREEMPTION_LEVEL
- jg 1f
- ALIGN_STACK()
- LOAD_STRING_ARG0(_enable_preemption_no_check_less_than_zero)
- CALL_PANIC()
- hlt
- .cstring
-_enable_preemption_no_check_less_than_zero:
- .asciz "_enable_preemption_no_check: preemption_level <= 0!"
- .text
-1:
-#endif /* MACH_ASSERT */
- _ENABLE_PREEMPTION_NO_CHECK
-#endif /* MACH_RT */
- LEAF_RET
-
-
-LEAF_ENTRY(_mp_disable_preemption)
-#if MACH_RT
- PREEMPTION_DISABLE
-#endif /* MACH_RT */
- LEAF_RET
-
-LEAF_ENTRY(_mp_enable_preemption)
-#if MACH_RT
-#if MACH_ASSERT
- cmpl $0,%gs:CPU_PREEMPTION_LEVEL
- jg 1f
- movl %gs:CPU_PREEMPTION_LEVEL,%esi
- ALIGN_PANIC()
- LOAD_STRING_ARG0(_mp_enable_preemption_less_than_zero)
- CALL_PANIC()
- hlt
- .cstring
-_mp_enable_preemption_less_than_zero:
- .asciz "_mp_enable_preemption: preemption_level (%d) <= 0!"
- .text
-1:
-#endif /* MACH_ASSERT */
- PREEMPTION_ENABLE
-#endif /* MACH_RT */
- LEAF_RET
-
-LEAF_ENTRY(_mp_enable_preemption_no_check)
-#if MACH_RT
-#if MACH_ASSERT
- cmpl $0,%gs:CPU_PREEMPTION_LEVEL
- jg 1f
- ALIGN_STACK()
- LOAD_STRING_ARG0(_mp_enable_preemption_no_check_less_than_zero)
- CALL_PANIC()
- hlt
- .cstring
-_mp_enable_preemption_no_check_less_than_zero:
- .asciz "_mp_enable_preemption_no_check: preemption_level <= 0!"
- .text
-1:
-#endif /* MACH_ASSERT */
- _ENABLE_PREEMPTION_NO_CHECK
-#endif /* MACH_RT */
- LEAF_RET
-
-/*
- * Atomic primitives, prototyped in kern/simple_lock.h
- */
-LEAF_ENTRY(hw_atomic_add)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- movl %esi, %eax /* Load addend */
- lock xaddl %eax, (%rdi) /* Atomic exchange and add */
- addl %esi, %eax /* Calculate result */
- LEAF_RET
-
-LEAF_ENTRY(hw_atomic_sub)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- negl %esi
- movl %esi, %eax
- lock xaddl %eax, (%rdi) /* Atomic exchange and add */
- addl %esi, %eax /* Calculate result */
- LEAF_RET
-
-LEAF_ENTRY(hw_atomic_or)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- movl (%rdi), %eax
-1:
- movl %esi, %edx /* Load mask */
- orl %eax, %edx
- lock cmpxchgl %edx, (%rdi) /* Atomic CAS */
- jne 1b
- movl %edx, %eax /* Result */
- LEAF_RET
-/*
- * A variant of hw_atomic_or which doesn't return a value.
- * The implementation is thus comparatively more efficient.
- */
-
-LEAF_ENTRY(hw_atomic_or_noret)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- lock
- orl %esi, (%rdi) /* Atomic OR */
- LEAF_RET
-
-
-LEAF_ENTRY(hw_atomic_and)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- movl (%rdi), %eax
-1:
- movl %esi, %edx /* Load mask */
- andl %eax, %edx
- lock cmpxchgl %edx, (%rdi) /* Atomic CAS */
- jne 1b
- movl %edx, %eax /* Result */
- LEAF_RET
-/*
- * A variant of hw_atomic_and which doesn't return a value.
- * The implementation is thus comparatively more efficient.
- */
-
-LEAF_ENTRY(hw_atomic_and_noret)
-#if MACH_LDEBUG
- test $3, %rdi
- jz 1f
- ud2
-1:
-#endif
- lock andl %esi, (%rdi) /* Atomic OR */
- LEAF_RET
-
projects / apple / xnu.git / blobdiff