8a8be1b8c3
fix acquire() to cli() *before* incrementing nlock make T_SYSCALL a trap gate, not an interrupt gate sadly, various crashes if you hold down a keyboard key...
67 lines
1.3 KiB
C
67 lines
1.3 KiB
C
#include "types.h"
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#include "defs.h"
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#include "x86.h"
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#include "mmu.h"
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#include "param.h"
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#include "proc.h"
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#include "spinlock.h"
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// Can't call cprintf from inside these routines,
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// because cprintf uses them itself.
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//#define cprintf dont_use_cprintf
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extern int use_console_lock;
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void
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getcallerpcs(void *v, uint pcs[])
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{
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uint *ebp = (uint*)v - 2;
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int i;
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for(i = 0; i < 10 && ebp && ebp != (uint*)0xffffffff; ebp = (uint*)*ebp, i++){
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pcs[i] = *(ebp + 1);
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}
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for( ; i < 10; i++)
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pcs[i] = 0;
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}
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void
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acquire(struct spinlock * lock)
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{
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if(holding(lock))
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panic("acquire");
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if(cpus[cpu()].nlock == 0)
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cli();
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cpus[cpu()].nlock++;
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while(cmpxchg(0, 1, &lock->locked) == 1)
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;
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cpuid(0, 0, 0, 0, 0); // memory barrier
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getcallerpcs(&lock, lock->pcs);
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lock->cpu = cpu() + 10;
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cpus[cpu()].lastacquire = lock;
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}
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void
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release(struct spinlock * lock)
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{
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if(!holding(lock))
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panic("release");
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cpus[cpu()].lastrelease = lock;
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lock->pcs[0] = 0;
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lock->cpu = 0xffffffff;
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cpuid(0, 0, 0, 0, 0); // memory barrier
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lock->locked = 0;
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if(--cpus[cpu()].nlock == 0)
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sti();
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// xxx we may have just turned interrupts on during
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// an interrupt, is that ok?
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}
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int
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holding(struct spinlock *lock)
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{
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return lock->locked && lock->cpu == cpu() + 10;
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}
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