X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/378393581903b274cb7a4d18e0d978071a6b592d..2d21ac55c334faf3a56e5634905ed6987fc787d4:/osfmk/i386/i386_lock.s diff --git a/osfmk/i386/i386_lock.s b/osfmk/i386/i386_lock.s index d8d36ebbd..d8ffd44e4 100644 --- a/osfmk/i386/i386_lock.s +++ b/osfmk/i386/i386_lock.s @@ -1,23 +1,29 @@ /* - * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2000-2007 Apple Inc. All rights reserved. * - * @APPLE_LICENSE_HEADER_START@ + * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * - * The contents of this file constitute Original Code as defined in and - * are subject to the Apple Public Source License Version 1.1 (the - * "License"). You may not use this file except in compliance with the - * License. Please obtain a copy of the License at - * http://www.apple.com/publicsource and read it before using this file. + * This file contains Original Code and/or Modifications of Original Code + * as defined in and that are subject to the Apple Public Source License + * Version 2.0 (the 'License'). You may not use this file except in + * compliance with the License. The rights granted to you under the License + * may not be used to create, or enable the creation or redistribution of, + * unlawful or unlicensed copies of an Apple operating system, or to + * circumvent, violate, or enable the circumvention or violation of, any + * terms of an Apple operating system software license agreement. * - * This Original Code and all software distributed under the License are - * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * Please obtain a copy of the License at + * http://www.opensource.apple.com/apsl/ and read it before using this file. + * + * The Original Code and all software distributed under the License are + * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, - * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the - * License for the specific language governing rights and limitations - * under the License. + * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * Please see the License for the specific language governing rights and + * limitations under the License. * - * @APPLE_LICENSE_HEADER_END@ + * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * @OSF_COPYRIGHT@ @@ -33,6 +39,9 @@ #include #include #include +#include +#include +#include #include "assym.s" @@ -47,7 +56,7 @@ #if BUILD_STACK_FRAMES -/* STack-frame-relative: */ +/* Stack-frame-relative: */ #define L_PC B_PC #define L_ARG0 B_ARG0 #define L_ARG1 B_ARG1 @@ -124,11 +133,6 @@ /* * Routines for general lock debugging. */ -#define S_TYPE SLOCK_TYPE(%edx) -#define S_PC SLOCK_PC(%edx) -#define S_THREAD SLOCK_THREAD(%edx) -#define S_DURATIONH SLOCK_DURATIONH(%edx) -#define S_DURATIONL SLOCK_DURATIONL(%edx) /* * Checks for expected lock types and calls "panic" on @@ -146,17 +150,6 @@ .text ; \ 1: -#define CHECK_SIMPLE_LOCK_TYPE() \ - cmpl $ USLOCK_TAG,S_TYPE ; \ - je 1f ; \ - pushl $2f ; \ - call EXT(panic) ; \ - hlt ; \ - .data ; \ -2: String "not a simple lock!" ; \ - .text ; \ -1: - /* * If one or more simplelocks are currently held by a thread, * an attempt to acquire a mutex will cause this check to fail @@ -242,6 +235,90 @@ #endif /* MACH_LDEBUG */ +#define PREEMPTION_DISABLE \ + incl %gs:CPU_PREEMPTION_LEVEL + + +#define PREEMPTION_ENABLE \ + decl %gs:CPU_PREEMPTION_LEVEL ; \ + jne 9f ; \ + pushf ; \ + testl $ EFL_IF,(%esp) ; \ + je 8f ; \ + cli ; \ + movl %gs:CPU_PENDING_AST,%eax ; \ + testl $ AST_URGENT,%eax ; \ + je 8f ; \ + movl %gs:CPU_INTERRUPT_LEVEL,%eax ; \ + testl %eax,%eax ; \ + jne 8f ; \ + popf ; \ + int $(T_PREEMPT) ; \ + jmp 9f ; \ +8: \ + popf ; \ +9: + + + +#if CONFIG_DTRACE +#define LOCKSTAT_LABEL(lab) \ + .data ;\ + .globl lab ;\ + lab: ;\ + .long 9f ;\ + .text ;\ + 9: + + .globl _lockstat_probe + .globl _lockstat_probemap + +#define LOCKSTAT_RECORD(id, lck) \ + push %ebp ; \ + mov %esp,%ebp ; \ + sub $0x38,%esp /* size of dtrace_probe args */ ; \ + movl _lockstat_probemap + (id * 4),%eax ; \ + test %eax,%eax ; \ + je 9f ; \ + movl $0,36(%esp) ; \ + movl $0,40(%esp) ; \ + movl $0,28(%esp) ; \ + movl $0,32(%esp) ; \ + movl $0,20(%esp) ; \ + movl $0,24(%esp) ; \ + movl $0,12(%esp) ; \ + movl $0,16(%esp) ; \ + movl lck,4(%esp) /* copy lock pointer to arg 1 */ ; \ + movl $0,8(%esp) ; \ + movl %eax,(%esp) ; \ + call *_lockstat_probe ; \ +9: leave + /* ret - left to subsequent code, e.g. return values */ + +#define LOCKSTAT_RECORD2(id, lck, arg) \ + push %ebp ; \ + mov %esp,%ebp ; \ + sub $0x38,%esp /* size of dtrace_probe args */ ; \ + movl _lockstat_probemap + (id * 4),%eax ; \ + test %eax,%eax ; \ + je 9f ; \ + movl $0,36(%esp) ; \ + movl $0,40(%esp) ; \ + movl $0,28(%esp) ; \ + movl $0,32(%esp) ; \ + movl $0,20(%esp) ; \ + movl $0,24(%esp) ; \ + movl $0,12(%esp) ; \ + movl $0,16(%esp) ; \ + movl lck,4(%esp) /* copy lock pointer to arg 1 */ ; \ + movl arg,8(%esp) ; \ + movl %eax,(%esp) ; \ + call *_lockstat_probe ; \ +9: leave + /* ret - left to subsequent code, e.g. return values */ +#endif + + /* * void hw_lock_init(hw_lock_t) * @@ -249,7 +326,18 @@ */ LEAF_ENTRY(hw_lock_init) movl L_ARG0,%edx /* fetch lock pointer */ - movl $0,0(%edx) /* clear the lock */ + movl $0,(%edx) /* clear the lock */ + LEAF_RET + + +/* + * void hw_lock_byte_init(uint8_t *) + * + * Initialize a hardware byte lock. + */ +LEAF_ENTRY(hw_lock_byte_init) + movl L_ARG0,%edx /* fetch lock pointer */ + movb $0,(%edx) /* clear the lock */ LEAF_RET /* @@ -261,17 +349,39 @@ LEAF_ENTRY(hw_lock_init) LEAF_ENTRY(hw_lock_lock) movl L_ARG0,%edx /* fetch lock pointer */ - movl L_PC,%ecx -1: DISABLE_PREEMPTION - movl 0(%edx), %eax + movl %gs:CPU_ACTIVE_THREAD,%ecx + PREEMPTION_DISABLE +1: + movl (%edx), %eax testl %eax,%eax /* lock locked? */ jne 3f /* branch if so */ - lock; cmpxchgl %ecx,0(%edx) /* try to acquire the HW lock */ + lock; cmpxchgl %ecx,(%edx) /* 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) + * + * Acquire byte sized lock operand, spinning until it becomes available. + * MACH_RT: also return with preemption disabled. + */ -3: ENABLE_PREEMPTION /* no reason we can't be preemptable */ +LEAF_ENTRY(hw_lock_byte_lock) + movl L_ARG0,%edx /* Load lock pointer */ + PREEMPTION_DISABLE + movl $1, %ecx /* Set lock value */ +1: + movb (%edx), %al /* Load byte at address */ + testb %al,%al /* lock locked? */ + jne 3f /* branch if so */ + lock; cmpxchgb %cl,(%edx) /* attempt atomic compare exchange */ + jne 3f + LEAF_RET /* if yes, then nothing left to do */ +3: PAUSE /* pause for hyper-threading */ jmp 1b /* try again */ @@ -284,16 +394,16 @@ LEAF_ENTRY(hw_lock_lock) LEAF_ENTRY(hw_lock_to) 1: movl L_ARG0,%edx /* fetch lock pointer */ - movl L_PC,%ecx + movl %gs:CPU_ACTIVE_THREAD,%ecx /* * Attempt to grab the lock immediately * - fastpath without timeout nonsense. */ - DISABLE_PREEMPTION - movl 0(%edx), %eax + PREEMPTION_DISABLE + movl (%edx), %eax testl %eax,%eax /* lock locked? */ jne 2f /* branch if so */ - lock; cmpxchgl %ecx,0(%edx) /* try to acquire the HW lock */ + lock; cmpxchgl %ecx,(%edx) /* try to acquire the HW lock */ jne 2f /* branch on failure */ movl $1,%eax LEAF_RET @@ -315,8 +425,6 @@ LEAF_ENTRY(hw_lock_to) adcl $0,%edx /* add carry */ mov %edx,%ecx mov %eax,%ebx /* %ecx:%ebx is the timeout expiry */ -3: - ENABLE_PREEMPTION /* no reason not to be preempted now */ 4: /* * The inner-loop spin to look for the lock being freed. @@ -324,7 +432,7 @@ LEAF_ENTRY(hw_lock_to) mov $(INNER_LOOP_COUNT),%edx 5: PAUSE /* pause for hyper-threading */ - movl 0(%edi),%eax /* spin checking lock value in cache */ + movl (%edi),%eax /* spin checking lock value in cache */ testl %eax,%eax je 6f /* zero => unlocked, try to grab it */ decl %edx /* decrement inner loop count */ @@ -337,7 +445,7 @@ LEAF_ENTRY(hw_lock_to) cmpl %ecx,%edx /* compare high-order 32-bits */ jb 4b /* continue spinning if less, or */ cmpl %ebx,%eax /* compare low-order 32-bits */ - jb 5b /* continue if less, else bail */ + jb 4b /* continue if less, else bail */ xor %eax,%eax /* with 0 return value */ pop %ebx pop %edi @@ -348,10 +456,9 @@ LEAF_ENTRY(hw_lock_to) * Here to try to grab the lock that now appears to be free * after contention. */ - movl 8+L_PC,%edx /* calling pc (8+ for pushed regs) */ - DISABLE_PREEMPTION - lock; cmpxchgl %edx,0(%edi) /* try to acquire the HW lock */ - jne 3b /* no - spin again */ + movl %gs:CPU_ACTIVE_THREAD,%edx + lock; cmpxchgl %edx,(%edi) /* try to acquire the HW lock */ + jne 4b /* no - spin again */ movl $1,%eax /* yes */ pop %ebx pop %edi @@ -365,8 +472,40 @@ LEAF_ENTRY(hw_lock_to) */ LEAF_ENTRY(hw_lock_unlock) movl L_ARG0,%edx /* fetch lock pointer */ - movl $0,0(%edx) /* clear the lock */ - ENABLE_PREEMPTION + movl $0,(%edx) /* clear the lock */ + PREEMPTION_ENABLE + LEAF_RET +/* + * void hw_lock_byte_unlock(uint8_t *lock_byte) + * + * Unconditionally release byte sized lock operand. + * MACH_RT: release preemption level. + */ + +LEAF_ENTRY(hw_lock_byte_unlock) + movl L_ARG0,%edx /* Load lock pointer */ + movb $0,(%edx) /* Clear the lock byte */ + PREEMPTION_ENABLE + LEAF_RET + +/* + * void i386_lock_unlock_with_flush(hw_lock_t) + * + * Unconditionally release lock, followed by a cacheline flush of + * the line corresponding to the lock dword. This routine is currently + * used with certain locks which are susceptible to lock starvation, + * minimizing cache affinity for lock acquisitions. A queued spinlock + * or other mechanism that ensures fairness would obviate the need + * for this routine, but ideally few or no spinlocks should exhibit + * enough contention to require such measures. + * MACH_RT: release preemption level. + */ +LEAF_ENTRY(i386_lock_unlock_with_flush) + movl L_ARG0,%edx /* Fetch lock pointer */ + movl $0,(%edx) /* Clear the lock */ + mfence /* Serialize prior stores */ + clflush (%edx) /* Write back and invalidate line */ + PREEMPTION_ENABLE LEAF_RET /* @@ -376,18 +515,19 @@ LEAF_ENTRY(hw_lock_unlock) LEAF_ENTRY(hw_lock_try) movl L_ARG0,%edx /* fetch lock pointer */ - movl L_PC,%ecx - DISABLE_PREEMPTION - movl 0(%edx),%eax + movl %gs:CPU_ACTIVE_THREAD,%ecx + PREEMPTION_DISABLE + movl (%edx),%eax testl %eax,%eax jne 1f - lock; cmpxchgl %ecx,0(%edx) /* try to acquire the HW lock */ + lock; cmpxchgl %ecx,(%edx) /* try to acquire the HW lock */ jne 1f movl $1,%eax /* success */ LEAF_RET -1: ENABLE_PREEMPTION /* failure: release preemption... */ +1: + PREEMPTION_ENABLE /* failure: release preemption... */ xorl %eax,%eax /* ...and return failure */ LEAF_RET @@ -399,7 +539,7 @@ LEAF_ENTRY(hw_lock_try) LEAF_ENTRY(hw_lock_held) movl L_ARG0,%edx /* fetch lock pointer */ - movl 0(%edx),%eax /* check lock value */ + movl (%edx),%eax /* check lock value */ testl %eax,%eax movl $1,%ecx cmovne %ecx,%eax /* 0 => unlocked, 1 => locked */ @@ -421,90 +561,190 @@ LEAF_ENTRY(mutex_init) LEAF_RET -NONLEAF_ENTRY2(mutex_lock,_mutex_lock) +/* + * Reader-writer lock fastpaths. These currently exist for the + * shared lock acquire and release paths (where they reduce overhead + * considerably)--more can be added as necessary (DRK). + */ + +/* + * These should reflect the layout of the bitfield embedded within + * the lck_rw_t structure (see i386/locks.h). + */ +#define LCK_RW_INTERLOCK 0x1 +#define LCK_RW_WANT_UPGRADE 0x2 +#define LCK_RW_WANT_WRITE 0x4 +#define LCK_R_WAITING 0x8 +#define LCK_W_WAITING 0x10 + +#define RW_LOCK_SHARED_MASK ((LCK_RW_INTERLOCK<<16) | \ + ((LCK_RW_WANT_UPGRADE|LCK_RW_WANT_WRITE) << 24)) +/* + * void lck_rw_lock_shared(lck_rw_t*) + * + */ + +Entry(lck_rw_lock_shared) + movl S_ARG0, %edx +1: + movl (%edx), %eax /* Load state bitfield and interlock */ + testl $(RW_LOCK_SHARED_MASK), %eax /* Eligible for fastpath? */ + jne 3f + movl %eax, %ecx + incl %ecx /* Increment reader refcount */ + lock + cmpxchgl %ecx, (%edx) /* Attempt atomic exchange */ + jne 2f + +#if CONFIG_DTRACE + /* + * Dtrace lockstat event: LS_LCK_RW_LOCK_SHARED_ACQUIRE + * Implemented by swapping between return and no-op instructions. + * See bsd/dev/dtrace/lockstat.c. + */ + LOCKSTAT_LABEL(_lck_rw_lock_shared_lockstat_patch_point) + ret + /* Fall thru when patched, counting on lock pointer in %edx */ + LOCKSTAT_RECORD(LS_LCK_RW_LOCK_SHARED_ACQUIRE, %edx) +#endif + ret + +2: + PAUSE + jmp 1b +3: + jmp EXT(lck_rw_lock_shared_gen) + + +/* + * lck_rw_type_t lck_rw_done(lck_rw_t*) + * + */ + +.data +rwl_release_error_str: + .asciz "Releasing non-exclusive RW lock without a reader refcount!" +.text + +#define RW_LOCK_RELEASE_MASK ((LCK_RW_INTERLOCK<<16) | \ + ((LCK_RW_WANT_UPGRADE|LCK_RW_WANT_WRITE|LCK_R_WAITING|LCK_W_WAITING) << 24)) +Entry(lck_rw_done) + movl S_ARG0, %edx +1: + movl (%edx), %eax /* Load state bitfield and interlock */ + testl $(RW_LOCK_RELEASE_MASK), %eax /* Eligible for fastpath? */ + jne 3f + movl %eax, %ecx + /* Assert refcount */ + testl $(0xFFFF), %ecx + jne 5f + movl $(rwl_release_error_str), S_ARG0 + jmp EXT(panic) +5: + decl %ecx /* Decrement reader count */ + lock + cmpxchgl %ecx, (%edx) + jne 2f + movl $(RW_SHARED), %eax /* Indicate that the lock was shared */ +#if CONFIG_DTRACE + /* Dtrace lockstat probe: LS_RW_DONE_RELEASE as reader */ + LOCKSTAT_LABEL(_lck_rw_done_lockstat_patch_point) + ret + /* + * Note: Dtrace's convention is 0 ==> reader, which is + * a different absolute value than $(RW_SHARED) + * %edx contains the lock address already from the above + */ + LOCKSTAT_RECORD2(LS_LCK_RW_DONE_RELEASE, %edx, $0) + movl $(RW_SHARED), %eax /* Indicate that the lock was shared */ +#endif + ret + +2: + PAUSE + jmp 1b +3: + jmp EXT(lck_rw_done_gen) + + +NONLEAF_ENTRY2(mutex_lock_spin,_mutex_lock_spin) movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ CHECK_MUTEX_TYPE() CHECK_NO_SIMPLELOCKS() CHECK_PREEMPTION_LEVEL() - pushf /* save interrupt state */ - cli /* disable interrupts */ - -ml_retry: - movl B_PC,%ecx - -ml_get_hw: movl M_ILK,%eax /* read interlock */ testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp ml_get_hw /* try again */ -1: + jne Lmls_ilk_loop /* no, go spin */ +Lmls_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne ml_get_hw /* branch on failure to retry */ + jne Lmls_ilk_fail /* branch on failure to spin loop */ movl M_LOCKED,%ecx /* get lock owner */ testl %ecx,%ecx /* is the mutex locked? */ - jne ml_fail /* yes, we lose */ - movl %gs:CPU_ACTIVE_THREAD,%ecx - movl %ecx,M_LOCKED - + jne Lml_fail /* yes, fall back to a normal mutex lock */ + movl $(MUTEX_LOCKED_AS_SPIN),M_LOCKED /* indicate ownership as a spin lock */ + #if MACH_LDEBUG + movl %gs:CPU_ACTIVE_THREAD,%ecx movl %ecx,M_THREAD movl B_PC,%ecx movl %ecx,M_PC #endif - - pushl %edx /* save mutex address */ - pushl %edx - call EXT(lck_mtx_lock_acquire) - addl $4,%esp - popl %edx /* restore mutex address */ - - xorl %eax,%eax - movl %eax,M_ILK - + PREEMPTION_DISABLE + popf /* restore interrupt state */ + leave /* return with the interlock held */ +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_lock_spin_lockstat_patch_point) + ret + /* %edx contains the lock address from above */ + LOCKSTAT_RECORD(LS_MUTEX_LOCK_SPIN_ACQUIRE, %edx) +#endif + ret + +Lmls_ilk_fail: popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ - NONLEAF_RET +Lmls_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lmls_retry /* yes, go for it */ + jmp Lmls_ilk_loop /* no, keep spinning */ -ml_fail: -ml_block: - CHECK_MYLOCK(M_THREAD) - pushl M_LOCKED - pushl %edx /* push mutex address */ - call EXT(lck_mtx_lock_wait) /* wait for the lock */ - addl $8,%esp - movl B_ARG0,%edx /* refetch mutex address */ - jmp ml_retry /* and try again */ -NONLEAF_ENTRY2(mutex_try,_mutex_try) +NONLEAF_ENTRY2(mutex_lock,_mutex_lock) movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ CHECK_MUTEX_TYPE() CHECK_NO_SIMPLELOCKS() + CHECK_PREEMPTION_LEVEL() - movl B_PC,%ecx - - pushf /* save interrupt state */ + movl M_ILK,%eax /* is interlock held */ + testl %eax,%eax + jne Lml_ilk_loop /* yes, go do the spin loop */ +Lml_retry: cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx -mt_get_hw: - movl M_ILK,%eax /* read interlock */ - testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp mt_get_hw /* try again */ -1: + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne mt_get_hw /* branch on failure to retry */ + jne Lml_ilk_fail /* branch on failure to spin loop */ movl M_LOCKED,%ecx /* get lock owner */ testl %ecx,%ecx /* is the mutex locked? */ - jne mt_fail /* yes, we lose */ + jne Lml_fail /* yes, we lose */ +Lml_acquire: movl %gs:CPU_ACTIVE_THREAD,%ecx movl %ecx,M_LOCKED @@ -513,236 +753,1308 @@ mt_get_hw: movl B_PC,%ecx movl %ecx,M_PC #endif + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lml_waiters /* yes, more work to do */ +Lml_return: + xorl %eax,%eax + movl %eax,M_ILK + + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_lock_lockstat_patch_point) + ret + /* %edx still contains the lock pointer */ + LOCKSTAT_RECORD(LS_MUTEX_LOCK_ACQUIRE, %edx) +#endif + ret + /* + * We got the mutex, but there are waiters. Update information + * on waiters. + */ +Lml_waiters: pushl %edx /* save mutex address */ pushl %edx call EXT(lck_mtx_lock_acquire) addl $4,%esp popl %edx /* restore mutex address */ + jmp Lml_return - xorl %eax,%eax - movl %eax,M_ILK - +Lml_restart: +Lml_ilk_fail: popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ - movl $1,%eax +Lml_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lml_retry /* yes, go try to grab it */ + jmp Lml_ilk_loop /* no - keep spinning */ - NONLEAF_RET +Lml_fail: + /* + * Check if the owner is on another processor and therefore + * we should try to spin before blocking. + */ + testl $(OnProc),ACT_SPF(%ecx) + jz Lml_block -mt_fail: + /* + * Here if owner is on another processor: + * - release the interlock + * - spin on the holder until release or timeout + * - in either case re-acquire the interlock + * - if released, acquire it + * - otherwise drop thru to block. + */ xorl %eax,%eax - movl %eax,M_ILK + movl %eax,M_ILK /* zero interlock */ + popf + pushf /* restore interrupt state */ + + push %edx /* lock address */ + call EXT(lck_mtx_lock_spinwait) /* call out to do spinning */ + addl $4,%esp + movl B_ARG0,%edx /* refetch mutex address */ + + /* Re-acquire interlock - interrupts currently enabled */ + movl M_ILK,%eax /* is interlock held */ + testl %eax,%eax + jne Lml_ilk_reloop /* yes, go do the spin loop */ +Lml_reget_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Lml_ilk_refail /* branch on failure to spin loop */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex free? */ + je Lml_acquire /* yes, acquire */ + +Lml_block: + CHECK_MYLOCK(M_THREAD) + pushl M_LOCKED + pushl %edx /* push mutex address */ + call EXT(lck_mtx_lock_wait) /* wait for the lock */ + addl $8,%esp /* returns with interlock dropped */ + movl B_ARG0,%edx /* refetch mutex address */ + jmp Lml_restart /* and start over */ +Lml_ilk_refail: popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ - xorl %eax,%eax +Lml_ilk_reloop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lml_reget_retry /* yes, go try to grab it */ + jmp Lml_ilk_reloop /* no - keep spinning */ - NONLEAF_RET + + +NONLEAF_ENTRY2(mutex_try_spin,_mutex_try_spin) -NONLEAF_ENTRY(mutex_unlock) movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ CHECK_MUTEX_TYPE() - CHECK_THREAD(M_THREAD) - - movl B_PC,%ecx + CHECK_NO_SIMPLELOCKS() - pushf /* save interrupt state */ + movl M_ILK,%eax + testl %eax,%eax /* is the interlock held? */ + jne Lmts_ilk_loop /* yes, go to spin loop */ +Lmts_retry: cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx -mu_get_hw: - movl M_ILK,%eax /* read interlock */ - testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp mu_get_hw /* try again */ -1: + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne mu_get_hw /* branch on failure to retry */ - - cmpw $0,M_WAITERS /* are there any waiters? */ - jne mu_wakeup /* yes, more work to do */ + jne Lmts_ilk_fail /* branch on failure to spin loop */ -mu_doit: + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Lmt_fail /* yes, we lose */ +Lmts_acquire: + movl $(MUTEX_LOCKED_AS_SPIN),M_LOCKED /* indicate ownership as a spin lock */ #if MACH_LDEBUG - movl $0,M_THREAD /* disown thread */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + movl %ecx,M_THREAD + movl B_PC,%ecx + movl %ecx,M_PC #endif + PREEMPTION_DISABLE /* no, return with interlock held */ + popf /* restore interrupt state */ + movl $1,%eax + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_try_spin_lockstat_patch_point) + ret + /* %edx inherits the lock pointer from above */ + LOCKSTAT_RECORD(LS_MUTEX_TRY_SPIN_ACQUIRE, %edx) + movl $1,%eax +#endif + ret - xorl %ecx,%ecx - movl %ecx,M_LOCKED /* unlock the mutex */ - - movl %ecx,M_ILK - +Lmts_ilk_fail: popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ - NONLEAF_RET +Lmts_ilk_loop: + PAUSE + /* + * need to do this check outside of the interlock in + * case this lock is held as a simple lock which means + * we won't be able to take the interlock + */ + movl M_LOCKED,%eax + testl %eax,%eax /* is the mutex locked? */ + jne Lmt_fail_no_ilk /* yes, go return failure */ -mu_wakeup: - pushl M_LOCKED - pushl %edx /* push mutex address */ - call EXT(lck_mtx_unlock_wakeup)/* yes, wake a thread */ - addl $8,%esp - movl B_ARG0,%edx /* restore lock pointer */ - jmp mu_doit + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lmts_retry /* yes, go try to grab it */ + jmp Lmts_ilk_loop /* keep spinning */ -/* - * lck_mtx_lock() - * lck_mtx_try_lock() - * lck_mutex_unlock() - * - * These are variants of mutex_lock(), mutex_try() and mutex_unlock() without - * DEBUG checks (which require fields not present in lck_mtx_t's). - */ -NONLEAF_ENTRY(lck_mtx_lock) - movl B_ARG0,%edx /* fetch lock pointer */ - cmpl $(MUTEX_IND),M_ITAG /* is this indirect? */ - cmove M_PTR,%edx /* yes - take indirection */ - CHECK_NO_SIMPLELOCKS() - CHECK_PREEMPTION_LEVEL() +NONLEAF_ENTRY2(mutex_try,_mutex_try) + movl B_ARG0,%edx /* fetch lock pointer */ pushf /* save interrupt state */ - cli /* disable interrupts */ -lml_retry: - movl B_PC,%ecx + CHECK_MUTEX_TYPE() + CHECK_NO_SIMPLELOCKS() -lml_get_hw: movl M_ILK,%eax /* read interlock */ testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp lml_get_hw /* try again */ -1: + jne Lmt_ilk_loop /* yes, go try to grab it */ +Lmt_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne lml_get_hw /* branch on failure to retry */ + jne Lmt_ilk_fail /* branch on failure to spin loop */ movl M_LOCKED,%ecx /* get lock owner */ testl %ecx,%ecx /* is the mutex locked? */ - jne lml_fail /* yes, we lose */ + jne Lmt_fail /* yes, we lose */ +Lmt_acquire: movl %gs:CPU_ACTIVE_THREAD,%ecx movl %ecx,M_LOCKED - pushl %edx /* save mutex address */ +#if MACH_LDEBUG + movl %ecx,M_THREAD + movl B_PC,%ecx + movl %ecx,M_PC +#endif + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lmt_waiters /* yes, more work to do */ +Lmt_return: + xorl %eax,%eax + movl %eax,M_ILK + popf /* restore interrupt state */ + + movl $1,%eax + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_try_lockstat_patch_point) + ret + /* inherit the lock pointer in %edx from above */ + LOCKSTAT_RECORD(LS_MUTEX_TRY_LOCK_ACQUIRE, %edx) + movl $1,%eax +#endif + ret + +Lmt_waiters: + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_acquire) + addl $4,%esp + popl %edx /* restore mutex address */ + jmp Lmt_return + +Lmt_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ + +Lmt_ilk_loop: + PAUSE + /* + * need to do this check outside of the interlock in + * case this lock is held as a simple lock which means + * we won't be able to take the interlock + */ + movl M_LOCKED,%eax /* get lock owner */ + testl %eax,%eax /* is the mutex locked? */ + jne Lmt_fail_no_ilk /* yes, go return failure */ + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lmt_retry /* yes, go try to grab it */ + jmp Lmt_ilk_loop /* no - keep spinning */ + +Lmt_fail: + xorl %eax,%eax + movl %eax,M_ILK + +Lmt_fail_no_ilk: + xorl %eax,%eax + popf /* restore interrupt state */ + NONLEAF_RET + + + +LEAF_ENTRY(mutex_convert_spin) + movl L_ARG0,%edx /* fetch lock pointer */ + + movl M_LOCKED,%ecx /* is this the spin variant of the mutex */ + cmpl $(MUTEX_LOCKED_AS_SPIN),%ecx + jne Lmcs_exit /* already owned as a mutex, just return */ + + movl M_ILK,%ecx /* convert from spin version to mutex */ + movl %ecx,M_LOCKED /* take control of the mutex */ + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lmcs_waiters /* yes, more work to do */ + +Lmcs_return: + xorl %ecx,%ecx + movl %ecx,M_ILK /* clear interlock */ + PREEMPTION_ENABLE +Lmcs_exit: +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_convert_spin_lockstat_patch_point) + ret + /* inherit %edx from above */ + LOCKSTAT_RECORD(LS_MUTEX_CONVERT_SPIN_ACQUIRE, %edx) +#endif + ret + + +Lmcs_waiters: + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_acquire) + addl $4,%esp + popl %edx /* restore mutex address */ + jmp Lmcs_return + + + +NONLEAF_ENTRY(mutex_unlock) + movl B_ARG0,%edx /* fetch lock pointer */ + + movl M_LOCKED,%ecx /* is this the spin variant of the mutex */ + cmpl $(MUTEX_LOCKED_AS_SPIN),%ecx + jne Lmu_enter /* no, go treat like a real mutex */ + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lmus_wakeup /* yes, more work to do */ + +Lmus_drop_ilk: + xorl %ecx,%ecx + movl %ecx,M_LOCKED /* yes, clear the spin indicator */ + movl %ecx,M_ILK /* release the interlock */ + PREEMPTION_ENABLE /* and re-enable preemption */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_unlock_lockstat_patch_point) + ret + /* inherit lock pointer in %edx from above */ + LOCKSTAT_RECORD(LS_MUTEX_UNLOCK_RELEASE, %edx) +#endif + ret + +Lmus_wakeup: + pushl %edx /* save mutex address */ + pushl %edx /* push mutex address */ + call EXT(lck_mtx_unlockspin_wakeup) /* yes, wake a thread */ + addl $4,%esp + popl %edx /* restore mutex pointer */ + jmp Lmus_drop_ilk + +Lmu_enter: + pushf /* save interrupt state */ + + CHECK_MUTEX_TYPE() + CHECK_THREAD(M_THREAD) + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Lmu_ilk_loop /* yes, go try to grab it */ +Lmu_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Lmu_ilk_fail /* branch on failure to spin loop */ + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lmu_wakeup /* yes, more work to do */ + +Lmu_doit: +#if MACH_LDEBUG + movl $0,M_THREAD /* disown thread */ +#endif + xorl %ecx,%ecx + movl %ecx,M_LOCKED /* unlock the mutex */ + movl %ecx,M_ILK /* release the interlock */ + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_mutex_unlock2_lockstat_patch_point) + ret + /* inherit %edx from above */ + LOCKSTAT_RECORD(LS_MUTEX_UNLOCK_RELEASE, %edx) +#endif + ret + +Lmu_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ + +Lmu_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Lmu_retry /* yes, go try to grab it */ + jmp Lmu_ilk_loop /* no - keep spinning */ + +Lmu_wakeup: + pushl M_LOCKED + pushl %edx /* push mutex address */ + call EXT(lck_mtx_unlock_wakeup)/* yes, wake a thread */ + addl $8,%esp + movl B_ARG0,%edx /* restore lock pointer */ + jmp Lmu_doit + +/* + * void lck_mtx_assert(lck_mtx_t* l, unsigned int) + * void _mutex_assert(mutex_t, unsigned int) + * Takes the address of a lock, and an assertion type as parameters. + * The assertion can take one of two forms determine by the type + * parameter: either the lock is held by the current thread, and the + * type is LCK_MTX_ASSERT_OWNED, or it isn't and the type is + * LCK_MTX_ASSERT_NOT_OWNED. Calls panic on assertion failure. + * + */ + +Entry(lck_mtx_assert) +Entry(_mutex_assert) + movl S_ARG0,%edx /* Load lock address */ + movl %gs:CPU_ACTIVE_THREAD,%ecx /* Load current thread */ + + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + + movl M_LOCKED,%eax /* Load lock word */ + cmpl $(MUTEX_LOCKED_AS_SPIN),%eax /* check for spin variant */ + cmove M_ILK,%eax /* yes, spin lock owner is in the interlock */ + + cmpl $(MUTEX_ASSERT_OWNED),S_ARG1 /* Determine assert type */ + jne 2f /* Assert ownership? */ + cmpl %eax,%ecx /* Current thread match? */ + jne 3f /* no, go panic */ +1: /* yes, we own it */ + ret /* just return */ +2: + cmpl %eax,%ecx /* Current thread match? */ + jne 1b /* No, return */ + movl %edx,S_ARG1 /* Prep assertion failure */ + movl $(mutex_assert_owned_str),S_ARG0 + jmp 4f +3: + movl %edx,S_ARG1 /* Prep assertion failure */ + movl $(mutex_assert_not_owned_str),S_ARG0 +4: + jmp EXT(panic) + +.data +mutex_assert_not_owned_str: + .asciz "mutex (%p) not owned\n" +mutex_assert_owned_str: + .asciz "mutex (%p) owned\n" +.text + +/* This preprocessor define controls whether the R-M-W update of the + * per-group statistics elements are atomic (LOCK-prefixed) + * Enabled by default. + */ +#define ATOMIC_STAT_UPDATES 1 + +#if defined(ATOMIC_STAT_UPDATES) +#define LOCK_IF_ATOMIC_STAT_UPDATES lock +#else +#define LOCK_IF_ATOMIC_STAT_UPDATES +#endif /* ATOMIC_STAT_UPDATES */ + + +/* + * lck_mtx_lock() + * lck_mtx_try_lock() + * lck_mutex_unlock() + * lck_mtx_lock_spin() + * lck_mtx_convert_spin() + * + * These are variants of mutex_lock(), mutex_try(), mutex_unlock() + * mutex_lock_spin and mutex_convert_spin without + * DEBUG checks (which require fields not present in lck_mtx_t's). + */ + +NONLEAF_ENTRY(lck_mtx_lock_spin) + + movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ + + CHECK_NO_SIMPLELOCKS() + CHECK_PREEMPTION_LEVEL() + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llmls_eval_ilk /* no, go see if indirect */ +Llmls_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llmls_ilk_fail /* branch on failure to spin loop */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Llml_fail /* yes, fall back to a normal mutex */ + +Llmls_acquire: + movl $(MUTEX_LOCKED_AS_SPIN),M_LOCKED /* indicate ownership as a spin lock */ + PREEMPTION_DISABLE + popf /* restore interrupt state */ + NONLEAF_RET /* return with the interlock held */ + +Llmls_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ + +Llmls_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llmls_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llmls_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llmls_ilk_loop + + +Llmls_eval_ilk: + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + jne Llmls_ilk_loop /* If not, go to spin loop */ + +Llmls_lck_ext: + pushl %esi /* Used to hold the lock group ptr */ + pushl %edi /* Used for stat update records */ + movl MUTEX_GRP(%edx),%esi /* Load lock group */ + xorl %edi,%edi /* Clear stat update records */ + /* 64-bit increment of acquire attempt statistic (per-group) */ + LOCK_IF_ATOMIC_STAT_UPDATES + addl $1, GRP_MTX_STAT_UTIL(%esi) + jnc 1f + incl GRP_MTX_STAT_UTIL+4(%esi) +1: + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llmls_ext_ilk_loop /* no, go to spin loop */ +Llmls_ext_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llmls_ext_ilk_fail /* branch on failure to retry */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Llml_ext_fail /* yes, we lose */ + + popl %edi + popl %esi + jmp Llmls_acquire + +Llmls_ext_ilk_fail: + /* + * Slow path: call out to do the spinning. + */ + movl 8(%esp),%ecx + pushl %ecx + popf /* restore interrupt state */ + +Llmls_ext_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llmls_ext_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llmls_ext_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llmls_ext_ilk_loop /* no - keep spinning */ + + + +NONLEAF_ENTRY(lck_mtx_lock) + + movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ + + CHECK_NO_SIMPLELOCKS() + CHECK_PREEMPTION_LEVEL() + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llml_eval_ilk /* no, go see if indirect */ +Llml_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llml_ilk_fail /* branch on failure to spin loop */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Llml_fail /* yes, we lose */ +Llml_acquire: + movl %gs:CPU_ACTIVE_THREAD,%ecx + movl %ecx,M_LOCKED + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Lml_waiters /* yes, more work to do */ +Llml_return: + xorl %eax,%eax + movl %eax,M_ILK + + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_lck_mtx_lock_lockstat_patch_point) + ret + /* inherit lock pointer in %edx above */ + LOCKSTAT_RECORD(LS_LCK_MTX_LOCK_ACQUIRE, %edx) +#endif + ret + +Llml_waiters: + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_acquire) + addl $4,%esp + popl %edx /* restore mutex address */ + jmp Llml_return + +Llml_restart: +Llml_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ + +Llml_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llml_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llml_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llml_ilk_loop /* no - keep spinning */ + +Llml_fail: + /* + * Check if the owner is on another processor and therefore + * we should try to spin before blocking. + */ + testl $(OnProc),ACT_SPF(%ecx) + jz Llml_block + + /* + * Here if owner is on another processor: + * - release the interlock + * - spin on the holder until release or timeout + * - in either case re-acquire the interlock + * - if released, acquire it + * - otherwise drop thru to block. + */ + xorl %eax,%eax + movl %eax,M_ILK /* zero interlock */ + popf + pushf /* restore interrupt state */ + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_spinwait) + addl $4,%esp + popl %edx /* restore mutex address */ + + /* Re-acquire interlock */ + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llml_ilk_refail /* no, go to spin loop */ +Llml_reget_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llml_ilk_refail /* branch on failure to retry */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex free? */ + je Llml_acquire /* yes, acquire */ + +Llml_block: + CHECK_MYLOCK(M_THREAD) + pushl %edx /* save mutex address */ + pushl M_LOCKED + pushl %edx /* push mutex address */ + /* + * N.B.: lck_mtx_lock_wait is called here with interrupts disabled + * Consider reworking. + */ + call EXT(lck_mtx_lock_wait) /* wait for the lock */ + addl $8,%esp + popl %edx /* restore mutex address */ + jmp Llml_restart /* and start over */ + +Llml_ilk_refail: + popf /* restore interrupt state */ + pushf /* resave interrupt state on stack */ + +Llml_ilk_reloop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llml_reget_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llml_ilk_reloop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llml_ilk_reloop /* no - keep spinning */ + + +Llml_eval_ilk: + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + jne Llml_ilk_loop /* If not, go to spin loop */ + +/* + * Entry into statistics codepath for lck_mtx_lock: + * EDX: real lock pointer + * first dword on stack contains flags + */ + +/* Enable this preprocessor define to record the first miss alone + * By default, we count every miss, hence multiple misses may be + * recorded for a single lock acquire attempt via lck_mtx_lock + */ +#undef LOG_FIRST_MISS_ALONE + +/* + * N.B.: On x86, statistics are currently recorded for all indirect mutexes. + * Also, only the acquire attempt count (GRP_MTX_STAT_UTIL) is maintained + * as a 64-bit quantity (this matches the existing PowerPC implementation, + * and the new x86 specific statistics are also maintained as 32-bit + * quantities). + */ + +Llml_lck_ext: + pushl %esi /* Used to hold the lock group ptr */ + pushl %edi /* Used for stat update records */ + movl MUTEX_GRP(%edx),%esi /* Load lock group */ + xorl %edi,%edi /* Clear stat update records */ + /* 64-bit increment of acquire attempt statistic (per-group) */ + LOCK_IF_ATOMIC_STAT_UPDATES + addl $1, GRP_MTX_STAT_UTIL(%esi) + jnc 1f + incl GRP_MTX_STAT_UTIL+4(%esi) +1: + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llml_ext_ilk_loop /* no, go to spin loop */ +Llml_ext_get_hw: + cli + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llml_ext_ilk_fail /* branch on failure to retry */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Llml_ext_fail /* yes, we lose */ + +Llml_ext_acquire: + movl %gs:CPU_ACTIVE_THREAD,%ecx + movl %ecx,M_LOCKED + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Llml_ext_waiters /* yes, more work to do */ +Llml_ext_return: + xorl %eax,%eax + movl %eax,M_ILK + + popl %edi + popl %esi + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_lck_mtx_lock_ext_lockstat_patch_point) + ret + /* inherit lock pointer in %edx above */ + LOCKSTAT_RECORD(LS_LCK_MTX_EXT_LOCK_ACQUIRE, %edx) +#endif + ret + +Llml_ext_waiters: + pushl %edx /* save mutex address */ pushl %edx call EXT(lck_mtx_lock_acquire) addl $4,%esp popl %edx /* restore mutex address */ + jmp Llml_ext_return + +Llml_ext_restart: +Llml_ext_ilk_fail: + movl 8(%esp),%ecx + pushl %ecx + popf /* restore interrupt state */ + +Llml_ext_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llml_ext_get_hw /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llml_ext_ilk_loop /* no - keep spinning */ + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llml_ext_ilk_loop + + +Llml_ext_fail: +#ifdef LOG_FIRST_MISS_ALONE + testl $1, %edi + jnz 1f +#endif /* LOG_FIRST_MISS_ALONE */ + /* Record that a lock acquire attempt missed (per-group statistic) */ + LOCK_IF_ATOMIC_STAT_UPDATES + incl GRP_MTX_STAT_MISS(%esi) +#ifdef LOG_FIRST_MISS_ALONE + orl $1, %edi +#endif /* LOG_FIRST_MISS_ALONE */ +1: + /* + * Check if the owner is on another processor and therefore + * we should try to spin before blocking. + */ + testl $(OnProc),ACT_SPF(%ecx) + jnz 2f + /* + * Record the "direct wait" statistic, which indicates if a + * miss proceeded to block directly without spinning--occurs + * if the owner of the mutex isn't running on another processor + * at the time of the check. + */ + LOCK_IF_ATOMIC_STAT_UPDATES + incl GRP_MTX_STAT_DIRECT_WAIT(%esi) + jmp Llml_ext_block +2: + /* + * Here if owner is on another processor: + * - release the interlock + * - spin on the holder until release or timeout + * - in either case re-acquire the interlock + * - if released, acquire it + * - otherwise drop thru to block. + */ xorl %eax,%eax - movl %eax,M_ILK + movl %eax,M_ILK /* zero interlock */ - popf /* restore interrupt state */ + pushl 8(%esp) /* Make another copy of EFLAGS image */ + popf /* Restore interrupt state */ + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_spinwait) + addl $4,%esp + popl %edx /* restore mutex address */ - NONLEAF_RET + /* Re-acquire interlock */ + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llml_ext_ilk_refail /* no, go to spin loop */ +Llml_ext_reget_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx -lml_fail: + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llml_ext_ilk_refail /* branch on failure to spin loop */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex free? */ + je Llml_ext_acquire /* yes, acquire */ + +Llml_ext_block: + /* If we wanted to count waits just once per lock acquire, we'd + * skip over the stat update here + */ + LOCK_IF_ATOMIC_STAT_UPDATES + /* Record that a lock miss proceeded to block */ + incl GRP_MTX_STAT_WAIT(%esi) +1: CHECK_MYLOCK(M_THREAD) pushl %edx /* save mutex address */ pushl M_LOCKED pushl %edx /* push mutex address */ + /* + * N.B.: lck_mtx_lock_wait is called here with interrupts disabled + * Consider reworking. + */ call EXT(lck_mtx_lock_wait) /* wait for the lock */ addl $8,%esp popl %edx /* restore mutex address */ - jmp lml_retry /* and try again */ + jmp Llml_ext_restart /* and start over */ -NONLEAF_ENTRY(lck_mtx_try_lock) +Llml_ext_ilk_refail: + movl 8(%esp),%ecx + pushl %ecx + popf /* restore interrupt state */ + +Llml_ext_ilk_reloop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llml_ext_reget_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llml_ext_ilk_reloop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llml_ext_ilk_reloop + + + +NONLEAF_ENTRY(lck_mtx_try_lock_spin) movl B_ARG0,%edx /* fetch lock pointer */ - cmpl $(MUTEX_IND),M_ITAG /* is this indirect? */ - cmove M_PTR,%edx /* yes - take indirection */ + pushf /* save interrupt state */ CHECK_NO_SIMPLELOCKS() CHECK_PREEMPTION_LEVEL() - movl B_PC,%ecx - - pushf /* save interrupt state */ + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llmts_eval_ilk /* no, go see if indirect */ +Llmts_retry: cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ + lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ + jne Llmts_ilk_fail /* branch on failure to retry */ + + movl M_LOCKED,%ecx /* get lock owner */ + testl %ecx,%ecx /* is the mutex locked? */ + jne Llmt_fail /* yes, we lose */ + + movl $(MUTEX_LOCKED_AS_SPIN),M_LOCKED /* no, indicate ownership as a spin lock */ + PREEMPTION_DISABLE /* and return with interlock held */ + + movl $1,%eax /* return success */ + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_lck_mtx_try_lock_spin_lockstat_patch_point) + ret + /* inherit lock pointer in %edx above */ + LOCKSTAT_RECORD(LS_LCK_MTX_TRY_SPIN_LOCK_ACQUIRE, %edx) + movl $1,%eax /* return success */ +#endif + ret + +Llmts_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state */ + +Llmts_ilk_loop: + PAUSE + /* + * need to do this check outside of the interlock in + * case this lock is held as a simple lock which means + * we won't be able to take the interlock + */ + movl M_LOCKED,%eax /* get lock owner */ + testl %eax,%eax /* is the mutex locked? */ + jne Llmt_fail_no_ilk /* yes, go return failure */ -lmt_get_hw: movl M_ILK,%eax /* read interlock */ testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp lmt_get_hw /* try again */ + je Llmts_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llmts_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llmts_ilk_loop + +Llmts_eval_ilk: + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + jne Llmts_ilk_loop /* If not, go to spin loop */ + + /* + * bump counter on indirect lock + */ + pushl %esi /* Used to hold the lock group ptr */ + movl MUTEX_GRP(%edx),%esi /* Load lock group */ + /* 64-bit increment of acquire attempt statistic (per-group) */ + LOCK_IF_ATOMIC_STAT_UPDATES + addl $1, GRP_MTX_STAT_UTIL(%esi) + jnc 1f + incl GRP_MTX_STAT_UTIL+4(%esi) 1: + popl %esi + jmp Llmts_ilk_loop + + + +NONLEAF_ENTRY(lck_mtx_try_lock) + + movl B_ARG0,%edx /* fetch lock pointer */ + pushf /* save interrupt state */ + + CHECK_NO_SIMPLELOCKS() + CHECK_PREEMPTION_LEVEL() + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + jne Llmt_eval_ilk /* no, go see if indirect */ +Llmt_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne lmt_get_hw /* branch on failure to retry */ + jne Llmt_ilk_fail /* branch on failure to retry */ movl M_LOCKED,%ecx /* get lock owner */ testl %ecx,%ecx /* is the mutex locked? */ - jne lmt_fail /* yes, we lose */ + jne Llmt_fail /* yes, we lose */ +Llmt_acquire: movl %gs:CPU_ACTIVE_THREAD,%ecx movl %ecx,M_LOCKED + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Llmt_waiters /* yes, more work to do */ +Llmt_return: + xorl %eax,%eax + movl %eax,M_ILK + + popf /* restore interrupt state */ + + movl $1,%eax /* return success */ + leave +#if CONFIG_DTRACE + /* Dtrace probe: LS_LCK_MTX_TRY_LOCK_ACQUIRE */ + LOCKSTAT_LABEL(_lck_mtx_try_lock_lockstat_patch_point) + ret + /* inherit lock pointer in %edx from above */ + LOCKSTAT_RECORD(LS_LCK_MTX_TRY_LOCK_ACQUIRE, %edx) + movl $1,%eax /* return success */ +#endif + ret + +Llmt_waiters: pushl %edx /* save mutex address */ pushl %edx call EXT(lck_mtx_lock_acquire) addl $4,%esp popl %edx /* restore mutex address */ + jmp Llmt_return - xorl %eax,%eax +Llmt_ilk_fail: + popf /* restore interrupt state */ + pushf /* resave interrupt state */ + +Llmt_ilk_loop: + PAUSE + /* + * need to do this check outside of the interlock in + * case this lock is held as a simple lock which means + * we won't be able to take the interlock + */ + movl M_LOCKED,%eax /* get lock owner */ + testl %eax,%eax /* is the mutex locked? */ + jne Llmt_fail_no_ilk /* yes, go return failure */ + + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llmt_retry /* yes - go try to grab it */ + + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llmt_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llmt_ilk_loop + +Llmt_fail: + xorl %eax,%eax /* Zero interlock value */ movl %eax,M_ILK +Llmt_fail_no_ilk: popf /* restore interrupt state */ - movl $1,%eax /* return success */ - NONLEAF_RET + cmpl %edx,B_ARG0 + jne Llmt_fail_indirect -lmt_fail: xorl %eax,%eax - movl %eax,M_ILK + /* Note that we don't record a dtrace event for trying and missing */ + NONLEAF_RET - popf /* restore interrupt state */ +Llmt_fail_indirect: + pushl %esi /* Used to hold the lock group ptr */ + movl MUTEX_GRP(%edx),%esi /* Load lock group */ + + /* Record mutex acquire attempt miss statistic */ + LOCK_IF_ATOMIC_STAT_UPDATES + incl GRP_MTX_STAT_MISS(%esi) - xorl %eax,%eax /* return failure */ + popl %esi + xorl %eax,%eax NONLEAF_RET +Llmt_eval_ilk: + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + jne Llmt_ilk_loop /* If not, go to spin loop */ + + /* + * bump counter for indirect lock + */ + pushl %esi /* Used to hold the lock group ptr */ + movl MUTEX_GRP(%edx),%esi /* Load lock group */ + + /* 64-bit increment of acquire attempt statistic (per-group) */ + LOCK_IF_ATOMIC_STAT_UPDATES + addl $1, GRP_MTX_STAT_UTIL(%esi) + jnc 1f + incl GRP_MTX_STAT_UTIL+4(%esi) +1: + pop %esi + jmp Llmt_ilk_loop + + + +LEAF_ENTRY(lck_mtx_convert_spin) + movl L_ARG0,%edx /* fetch lock pointer */ + + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + + movl M_LOCKED,%ecx /* is this the spin variant of the mutex */ + cmpl $(MUTEX_LOCKED_AS_SPIN),%ecx + jne Llmcs_exit /* already owned as a mutex, just return */ + + movl M_ILK,%ecx /* convert from spin version to mutex */ + movl %ecx,M_LOCKED /* take control of the mutex */ + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Llmcs_waiters /* yes, more work to do */ + +Llmcs_return: + xorl %ecx,%ecx + movl %ecx,M_ILK /* clear interlock */ + PREEMPTION_ENABLE +Llmcs_exit: + LEAF_RET + +Llmcs_waiters: + pushl %edx /* save mutex address */ + pushl %edx + call EXT(lck_mtx_lock_acquire) + addl $4,%esp + popl %edx /* restore mutex address */ + jmp Llmcs_return + + + NONLEAF_ENTRY(lck_mtx_unlock) movl B_ARG0,%edx /* fetch lock pointer */ - cmpl $(MUTEX_IND),M_ITAG /* is this indirect? */ - cmove M_PTR,%edx /* yes - take indirection */ - movl B_PC,%ecx + cmpl $(MUTEX_IND),M_ITAG /* Is this an indirect mutex? */ + cmove M_PTR,%edx /* If so, take indirection */ + + movl M_LOCKED,%ecx /* is this the spin variant of the mutex */ + cmpl $(MUTEX_LOCKED_AS_SPIN),%ecx + jne Llmu_enter /* no, go treat like a real mutex */ + + cmpw $0,M_WAITERS /* are there any waiters? */ + jne Llmus_wakeup /* yes, more work to do */ + +Llmu_drop_ilk: + xorl %eax,%eax + movl %eax,M_LOCKED /* clear spin indicator */ + movl %eax,M_ILK /* release the interlock */ + + PREEMPTION_ENABLE /* and re-enable preemption */ + leave +#if CONFIG_DTRACE + /* Dtrace: LS_LCK_MTX_UNLOCK_RELEASE */ + LOCKSTAT_LABEL(_lck_mtx_unlock_lockstat_patch_point) + ret + /* inherit lock pointer in %edx from above */ + LOCKSTAT_RECORD(LS_LCK_MTX_UNLOCK_RELEASE, %edx) +#endif + ret + +Llmus_wakeup: + pushl %edx /* save mutex address */ + pushl %edx /* push mutex address */ + call EXT(lck_mtx_unlockspin_wakeup) /* yes, wake a thread */ + addl $4,%esp + popl %edx /* restore mutex pointer */ + jmp Llmu_drop_ilk + +Llmu_enter: pushf /* save interrupt state */ - cli /* disable interrupts */ -lmu_get_hw: movl M_ILK,%eax /* read interlock */ testl %eax,%eax /* unlocked? */ - je 1f /* yes - attempt to lock it */ - PAUSE /* no - pause */ - jmp lmu_get_hw /* try again */ -1: + jne Llmu_ilk_loop /* no - go to spin loop */ +Llmu_retry: + cli /* disable interrupts */ + movl %gs:CPU_ACTIVE_THREAD,%ecx + + /* eax == 0 at this point */ lock; cmpxchgl %ecx,M_ILK /* atomic compare and exchange */ - jne lmu_get_hw /* branch on failure to retry */ + jne Llmu_ilk_fail /* branch on failure to spin loop */ cmpw $0,M_WAITERS /* are there any waiters? */ - jne lmu_wakeup /* yes, more work to do */ + jne Llmu_wakeup /* yes, more work to do */ -lmu_doit: +Llmu_doit: xorl %ecx,%ecx movl %ecx,M_LOCKED /* unlock the mutex */ + movl %ecx,M_ILK /* clear the interlock */ - movl %ecx,M_ILK + popf /* restore interrupt state */ + leave +#if CONFIG_DTRACE + LOCKSTAT_LABEL(_lck_mtx_unlock2_lockstat_patch_point) + ret + /* inherit lock pointer in %edx above */ + LOCKSTAT_RECORD(LS_LCK_MTX_UNLOCK_RELEASE, %edx) +#endif + ret +Llmu_ilk_fail: popf /* restore interrupt state */ + pushf /* resave interrupt state */ + +Llmu_ilk_loop: + PAUSE + movl M_ILK,%eax /* read interlock */ + testl %eax,%eax /* unlocked? */ + je Llmu_retry /* yes - go try to grab it */ - NONLEAF_RET + cmpl $(MUTEX_DESTROYED),%eax /* check to see if its marked destroyed */ + jne Llmu_ilk_loop /* no - keep spinning */ + + pushl %edx + call EXT(lck_mtx_interlock_panic) + /* + * shouldn't return from here, but just in case + */ + popl %edx + jmp Llmu_ilk_loop -lmu_wakeup: +Llmu_wakeup: pushl %edx /* save mutex address */ pushl M_LOCKED pushl %edx /* push mutex address */ call EXT(lck_mtx_unlock_wakeup)/* yes, wake a thread */ addl $8,%esp popl %edx /* restore mutex pointer */ - jmp lmu_doit + xorl %ecx,%ecx + movl %ecx,M_LOCKED /* unlock the mutex */ + + movl %ecx,M_ILK + + popf /* restore interrupt state */ + + leave +#if CONFIG_DTRACE + /* Dtrace: LS_LCK_MTX_EXT_UNLOCK_RELEASE */ + LOCKSTAT_LABEL(_lck_mtx_ext_unlock_lockstat_patch_point) + ret + /* inherit lock pointer in %edx from above */ + LOCKSTAT_RECORD(LS_LCK_MTX_EXT_UNLOCK_RELEASE, %edx) +#endif + ret + LEAF_ENTRY(lck_mtx_ilk_unlock) movl L_ARG0,%edx /* no indirection here */ @@ -751,7 +2063,8 @@ LEAF_ENTRY(lck_mtx_ilk_unlock) movl %eax,M_ILK LEAF_RET - + + LEAF_ENTRY(_disable_preemption) #if MACH_RT _DISABLE_PREEMPTION @@ -840,16 +2153,17 @@ LEAF_ENTRY(i_bit_set) movl L_ARG0,%edx movl L_ARG1,%eax lock - bts %dl,(%eax) + bts %edx,(%eax) LEAF_RET LEAF_ENTRY(i_bit_clear) movl L_ARG0,%edx movl L_ARG1,%eax lock - btr %dl,(%eax) + btr %edx,(%eax) LEAF_RET + LEAF_ENTRY(bit_lock) movl L_ARG0,%ecx movl L_ARG1,%eax @@ -859,6 +2173,7 @@ LEAF_ENTRY(bit_lock) jb 1b LEAF_RET + LEAF_ENTRY(bit_lock_try) movl L_ARG0,%ecx movl L_ARG1,%eax @@ -876,3 +2191,71 @@ LEAF_ENTRY(bit_unlock) lock btr %ecx,(%eax) LEAF_RET + +/* + * Atomic primitives, prototyped in kern/simple_lock.h + */ +LEAF_ENTRY(hw_atomic_add) + movl L_ARG0, %ecx /* Load address of operand */ + movl L_ARG1, %eax /* Load addend */ + movl %eax, %edx + lock + xaddl %eax, (%ecx) /* Atomic exchange and add */ + addl %edx, %eax /* Calculate result */ + LEAF_RET + +LEAF_ENTRY(hw_atomic_sub) + movl L_ARG0, %ecx /* Load address of operand */ + movl L_ARG1, %eax /* Load subtrahend */ + negl %eax + movl %eax, %edx + lock + xaddl %eax, (%ecx) /* Atomic exchange and add */ + addl %edx, %eax /* Calculate result */ + LEAF_RET + +LEAF_ENTRY(hw_atomic_or) + movl L_ARG0, %ecx /* Load address of operand */ + movl (%ecx), %eax +1: + movl L_ARG1, %edx /* Load mask */ + orl %eax, %edx + lock + cmpxchgl %edx, (%ecx) /* 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) + movl L_ARG0, %ecx /* Load address of operand */ + movl L_ARG1, %edx /* Load mask */ + lock + orl %edx, (%ecx) /* Atomic OR */ + LEAF_RET + +LEAF_ENTRY(hw_atomic_and) + movl L_ARG0, %ecx /* Load address of operand */ + movl (%ecx), %eax +1: + movl L_ARG1, %edx /* Load mask */ + andl %eax, %edx + lock + cmpxchgl %edx, (%ecx) /* 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) + movl L_ARG0, %ecx /* Load address of operand */ + movl L_ARG1, %edx /* Load mask */ + lock + andl %edx, (%ecx) /* Atomic OR */ + LEAF_RET