mirror of
https://github.com/freebsd/freebsd-src
synced 2024-09-29 13:15:05 +00:00
Optimize two cases in the MP locking code. First, it is not necessary
to use a locked cmpexg when unlocking a lock that we already hold, since
nobody else can touch the lock while we hold it. Second, it is not
necessary to use a locked cmpexg when locking a lock that we already
hold, for the same reason. These changes will allow MP locks to be used
recursively without impacting performance.
Modify two procedures that are called only by assembly and are already
NOPROF entries to pass a critical argument in %edx instead of on the
stack, removing a significant amount of code from the critical path
as a consequence.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>, Peter Wemm <peter@netplex.com.au>
This commit is contained in:
Matthew Dillon
parent
d627ab8398
commit
cd906fe3de
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=53425
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@ -26,9 +26,8 @@
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call _get_isrlock
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#define REL_FAST_INTR_LOCK \
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pushl $_mp_lock ; /* GIANT_LOCK */ \
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call _MPrellock ; \
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add $4, %esp
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movl $_mp_lock, %edx ; /* GIANT_LOCK */ \
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call _MPrellock_edx
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#endif /* FAST_SIMPLELOCK */
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@ -223,6 +223,7 @@ typedef struct IOAPIC ioapic_t;
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/* XXX these 2 don't really belong here... */
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#define COUNT_FIELD 0x00ffffff /* count portion of the lock */
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#define CPU_FIELD 0xff000000 /* cpu portion of the lock */
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#define FREE_LOCK 0xffffffff /* value of lock when free */
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/*
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@ -26,9 +26,8 @@
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call _get_isrlock
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#define REL_FAST_INTR_LOCK \
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pushl $_mp_lock ; /* GIANT_LOCK */ \
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call _MPrellock ; \
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add $4, %esp
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movl $_mp_lock, %edx ; /* GIANT_LOCK */ \
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call _MPrellock_edx
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#endif /* FAST_SIMPLELOCK */
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@ -52,7 +52,7 @@
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*/
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/* location of saved TPR on stack */
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#define TPR_TARGET 12(%esp)
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#define TPR_TARGET 8(%esp)
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/* after 1st acquire of lock we attempt to grab all hardware INTs */
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#define GRAB_HWI movl $ALLHWI_LEVEL, TPR_TARGET
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@ -72,50 +72,41 @@
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.text
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/***********************************************************************
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* void MPgetlock(unsigned int *lock)
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* void MPgetlock_edx(unsigned int *lock : %edx)
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* ----------------------------------
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* Destroys %eax, %ecx, %edx and 12(%esp).
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* Destroys %eax, %ecx. %edx must hold lock argument.
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* Note: TPR_TARGET (relative to the stack) is destroyed in GRAB_HWI
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*/
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NON_GPROF_ENTRY(MPgetlock)
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movl 4(%esp), %edx /* Get the address of the lock */
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NON_GPROF_ENTRY(MPgetlock_edx)
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1:
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movl $FREE_LOCK, %eax /* Assume it's free */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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incl %ecx /* - new count is one */
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movl (%edx), %eax /* Get current contents of lock */
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movl %eax, %ecx
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andl $CPU_FIELD,%ecx
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cmpl _cpu_lockid, %ecx /* Do we already own the lock? */
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jne 2f
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incl %eax /* yes, just bump the count */
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movl %eax, (%edx)
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ret
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2:
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movl $FREE_LOCK, %eax /* lock must be free */
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movl _cpu_lockid, %ecx
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incl %ecx
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 2f /* ...do not collect $200 */
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cmpxchg %ecx, (%edx) /* attempt to replace %eax<->%ecx */
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#ifdef GLPROFILE
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jne 3f
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incl _gethits2
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#else
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jne 1b
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#endif /* GLPROFILE */
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GRAB_HWI /* 1st acquire, grab hw INTs */
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ret
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2:
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movl (%edx), %eax /* Try to see if we have it already */
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andl $COUNT_FIELD, %eax /* - get count */
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movl _cpu_lockid, %ecx /* - get pre-shifted logical cpu id */
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orl %ecx, %eax /* - combine them */
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movl %eax, %ecx
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incl %ecx /* - new count is one more */
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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#ifdef GLPROFILE
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jne 4f /* - miss */
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incl _gethits
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#else
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jne 3f /* - miss */
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#endif /* GLPROFILE */
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ret
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#ifdef GLPROFILE
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4:
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incl _gethits3
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#endif /* GLPROFILE */
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3:
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cmpl $FREE_LOCK, (%edx) /* Wait for it to become free */
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jne 3b
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incl _gethits3
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jmp 1b
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#endif
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/***********************************************************************
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* int MPtrylock(unsigned int *lock)
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@ -163,28 +154,22 @@ NON_GPROF_ENTRY(MPtrylock)
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/***********************************************************************
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* void MPrellock(unsigned int *lock)
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* void MPrellock_edx(unsigned int *lock : %edx)
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* ----------------------------------
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* Destroys %eax, %ecx and %edx.
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* Destroys %ecx, argument must be in %edx
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*/
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NON_GPROF_ENTRY(MPrellock)
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movl 4(%esp), %edx /* Get the address of the lock */
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1:
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movl (%edx), %eax /* - get the value */
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movl %eax, %ecx
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NON_GPROF_ENTRY(MPrellock_edx)
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movl (%edx), %ecx /* - get the value */
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decl %ecx /* - new count is one less */
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testl $COUNT_FIELD, %ecx /* - Unless it's zero... */
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jnz 2f
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ARB_HWI /* last release, arbitrate hw INTs */
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movl $FREE_LOCK, %ecx /* - In which case we release it */
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2:
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lock
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cmpxchg %ecx, (%edx) /* - try it atomically */
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jne 1b /* ...do not collect $200 */
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movl %ecx, (%edx)
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ret
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/***********************************************************************
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* void get_mplock()
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* -----------------
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@ -192,12 +177,11 @@ NON_GPROF_ENTRY(MPrellock)
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*
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* Stack (after call to _MPgetlock):
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*
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* &mp_lock 4(%esp)
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* EFLAGS 8(%esp)
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* local APIC TPR 12(%esp)
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* edx 16(%esp)
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* ecx 20(%esp)
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* eax 24(%esp)
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* EFLAGS 4(%esp)
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* local APIC TPR 8(%esp) <-- note, TPR_TARGET
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* edx 12(%esp)
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* ecx 16(%esp)
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* eax 20(%esp)
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*/
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NON_GPROF_ENTRY(get_mplock)
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@ -212,9 +196,8 @@ NON_GPROF_ENTRY(get_mplock)
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jnz 1f /* INTs currently enabled */
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sti /* allow IPI and FAST INTs */
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1:
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl /* restore original EFLAGS */
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popl lapic_tpr /* restore TPR */
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@ -235,13 +218,12 @@ NON_GPROF_ENTRY(boot_get_mplock)
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pushl %edx
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#ifdef GRAB_LOPRIO
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pushl $0
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pushl $0 /* dummy TPR (TPR_TARGET) */
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pushfl
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#endif
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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#ifdef GRAB_LOPRIO
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popfl
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@ -276,15 +258,12 @@ NON_GPROF_ENTRY(try_mplock)
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*/
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NON_GPROF_ENTRY(rel_mplock)
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pushl %eax
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pushl %ecx
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pushl %edx
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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movl $_mp_lock,%edx
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call _MPrellock_edx
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popl %edx
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popl %ecx
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popl %eax
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ret
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/***********************************************************************
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@ -294,21 +273,19 @@ NON_GPROF_ENTRY(rel_mplock)
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*
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* Stack (after call to _MPgetlock):
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*
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* &mp_lock 4(%esp)
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* EFLAGS 8(%esp)
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* local APIC TPR 12(%esp)
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* EFLAGS 4(%esp)
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* local APIC TPR 8(%esp)
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*/
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NON_GPROF_ENTRY(get_isrlock)
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/* block all HW INTs via Task Priority Register */
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pushl lapic_tpr /* save current TPR */
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl /* save current EFLAGS */
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sti /* allow IPI and FAST INTs */
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl /* restore original EFLAGS */
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popl lapic_tpr /* restore TPR */
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@ -336,10 +313,8 @@ NON_GPROF_ENTRY(try_isrlock)
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*/
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NON_GPROF_ENTRY(rel_isrlock)
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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ret
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movl $_mp_lock,%edx
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jmp _MPrellock_edx
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/***********************************************************************
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@ -347,12 +322,11 @@ NON_GPROF_ENTRY(rel_isrlock)
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*/
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NON_GPROF_ENTRY(get_fpu_lock)
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pushl lapic_tpr
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl
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sti
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl
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popl lapic_tpr
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ret
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@ -365,10 +339,8 @@ NON_GPROF_ENTRY(try_fpu_lock)
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ret
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NON_GPROF_ENTRY(rel_fpu_lock)
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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ret
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movl $_mp_lock,%edx
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jmp _MPrellock_edx
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#endif /* notneeded */
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@ -377,12 +349,11 @@ NON_GPROF_ENTRY(rel_fpu_lock)
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*/
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NON_GPROF_ENTRY(get_align_lock)
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pushl lapic_tpr
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl
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sti
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl
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popl lapic_tpr
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ret
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@ -395,10 +366,8 @@ NON_GPROF_ENTRY(try_align_lock)
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ret
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NON_GPROF_ENTRY(rel_align_lock)
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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ret
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movl $_mp_lock,%edx
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jmp _MPrellock_edx
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#endif /* notneeded */
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@ -407,12 +376,11 @@ NON_GPROF_ENTRY(rel_align_lock)
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*/
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NON_GPROF_ENTRY(get_syscall_lock)
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pushl lapic_tpr
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl
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sti
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl
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popl lapic_tpr
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ret
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@ -423,13 +391,11 @@ NON_GPROF_ENTRY(try_syscall_lock)
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call _MPtrylock
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add $4, %esp
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ret
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#endif /* notneeded */
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NON_GPROF_ENTRY(rel_syscall_lock)
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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ret
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#endif /* notneeded */
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movl $_mp_lock,%edx
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jmp _MPrellock_edx
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/***********************************************************************
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@ -437,12 +403,11 @@ NON_GPROF_ENTRY(rel_syscall_lock)
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*/
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NON_GPROF_ENTRY(get_altsyscall_lock)
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pushl lapic_tpr
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl
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sti
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pushl $_mp_lock
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call _MPgetlock
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add $4, %esp
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movl $_mp_lock, %edx
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call _MPgetlock_edx
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popfl
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popl lapic_tpr
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ret
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@ -455,10 +420,8 @@ NON_GPROF_ENTRY(try_altsyscall_lock)
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ret
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NON_GPROF_ENTRY(rel_altsyscall_lock)
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pushl $_mp_lock
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call _MPrellock
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add $4, %esp
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ret
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movl $_mp_lock,%edx
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jmp _MPrellock_edx
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#endif /* notneeded */
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@ -475,13 +438,12 @@ NON_GPROF_ENTRY(get_mpintrlock)
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pushl %edx
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#ifdef GRAB_LOPRIO
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pushl lapic_tpr
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pushl lapic_tpr /* save current TPR (TPR_TARGET) */
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pushfl
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#endif
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pushl $_mpintr_lock
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call _MPgetlock
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add $4, %esp
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movl $_mpintr_lock, %edx
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call _MPgetlock_edx
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#ifdef GRAB_LOPRIO
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popfl
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@ -500,17 +462,14 @@ NON_GPROF_ENTRY(get_mpintrlock)
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*/
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NON_GPROF_ENTRY(rel_mpintrlock)
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pushl %eax
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pushl %ecx
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pushl %edx
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pushl $_mpintr_lock
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call _MPrellock
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add $4, %esp
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movl $_mpintr_lock,%edx
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call _MPrellock_edx
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popl %edx
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popl %ecx
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popl %eax
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ret
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#endif /* RECURSIVE_MPINTRLOCK */
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@ -223,6 +223,7 @@ typedef struct IOAPIC ioapic_t;
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/* XXX these 2 don't really belong here... */
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#define COUNT_FIELD 0x00ffffff /* count portion of the lock */
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#define CPU_FIELD 0xff000000 /* cpu portion of the lock */
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#define FREE_LOCK 0xffffffff /* value of lock when free */
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/*
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@ -223,6 +223,7 @@ typedef struct IOAPIC ioapic_t;
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/* XXX these 2 don't really belong here... */
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#define COUNT_FIELD 0x00ffffff /* count portion of the lock */
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#define CPU_FIELD 0xff000000 /* cpu portion of the lock */
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#define FREE_LOCK 0xffffffff /* value of lock when free */
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/*
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@ -60,7 +60,9 @@
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#define _KPTphys KPTphys
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#define _MP_GDT MP_GDT
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#define _MPgetlock MPgetlock
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#define _MPgetlock_edx MPgetlock_edx
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#define _MPrellock MPrellock
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#define _MPrellock_edx MPrellock_edx
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#define _MPtrylock MPtrylock
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#define _PTD PTD
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#define _PTDpde PTDpde
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@ -26,9 +26,8 @@
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call _get_isrlock
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#define REL_FAST_INTR_LOCK \
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pushl $_mp_lock ; /* GIANT_LOCK */ \
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call _MPrellock ; \
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add $4, %esp
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movl $_mp_lock, %edx ; /* GIANT_LOCK */ \
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call _MPrellock_edx
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#endif /* FAST_SIMPLELOCK */
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@ -174,9 +174,8 @@ doreti_exit:
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#error code needed here to decide which lock to release, INTR or giant
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#endif
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/* release the kernel lock */
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pushl $_mp_lock /* GIANT_LOCK */
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call _MPrellock
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add $4, %esp
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movl $_mp_lock, %edx /* GIANT_LOCK */
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call _MPrellock_edx
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#endif /* SMP */
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.globl doreti_popl_fs
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