Fixed threading bug

[tpg/acess2.git] / Kernel / arch / x86 / lib.c

diff --git a/Kernel/arch/x86/lib.c b/Kernel/arch/x86/lib.c
index c499c7a..2fa1e51 100644 (file)
--- a/Kernel/arch/x86/lib.c
+++ b/Kernel/arch/x86/lib.c
@@ -3,17 +3,127 @@
  * lib.c
  */
 #include <acess.h>
+#include <threads.h>
+
+extern int     GetCPUNum(void);
 
 // === CODE ===
-void Spinlock(int *lock)
+/**
+ * \brief Determine if a short spinlock is locked
+ * \param Lock Lock pointer
+ */
+int IS_LOCKED(struct sShortSpinlock *Lock)
 {
-        int    v = 1;
-       while(v)        __asm__ __volatile__ ("lock xchgl %%eax, (%%edi)":"=a"(v):"a"(1),"D"(lock));
+       return !!Lock->Lock;
 }
 
-void Release(int *lock)
+/**
+ * \brief Check if the current CPU has the lock
+ * \param Lock Lock pointer
+ */
+int CPU_HAS_LOCK(struct sShortSpinlock *Lock)
 {
-       __asm__ __volatile__ ("lock andl $0, (%0)"::"r"(lock));
+       #if STACKED_LOCKS == 1
+       return Lock->Lock == GetCPUNum() + 1;
+       #elif STACKED_LOCKS == 2
+       return Lock->Lock == Proc_GetCurThread();
+       #else
+       return 0;
+       #endif
+}
+
+/**
+ * \brief Acquire a Short Spinlock
+ * \param Lock Lock pointer
+ * 
+ * This type of mutex should only be used for very short sections of code,
+ * or in places where a Mutex_* would be overkill, such as appending
+ * an element to linked list (usually two assignement lines in C)
+ * 
+ * \note This type of lock halts interrupts, so ensure that no timing
+ * functions are called while it is held. As a matter of fact, spend as
+ * little time as possible with this lock held
+ * \note If \a STACKED_LOCKS is set, this type of spinlock can be nested
+ */
+void SHORTLOCK(struct sShortSpinlock *Lock)
+{
+        int    v = 1;
+       #if LOCK_DISABLE_INTS
+        int    IF;
+       #endif
+       #if STACKED_LOCKS == 1
+        int    cpu = GetCPUNum() + 1;
+       #elif STACKED_LOCKS == 2
+       void    *thread = Proc_GetCurThread();
+       #endif
+       
+       #if LOCK_DISABLE_INTS
+       // Save interrupt state and clear interrupts
+       __ASM__ ("pushf;\n\tpop %%eax\n\tcli" : "=a"(IF));
+       IF &= 0x200;    // AND out all but the interrupt flag
+       #endif
+       
+       #if STACKED_LOCKS == 1
+       if( Lock->Lock == cpu ) {
+               Lock->Depth ++;
+               return ;
+       }
+       #elif STACKED_LOCKS == 2
+       if( Lock->Lock == thread ) {
+               Lock->Depth ++;
+               return ;
+       }
+       #endif
+       
+       // Wait for another CPU to release
+       while(v) {
+               // CMPXCHG:
+               //  If r/m32 == EAX, set ZF and set r/m32 = r32
+               //  Else, clear ZF and set EAX = r/m32
+               #if STACKED_LOCKS == 1
+               __ASM__("lock cmpxchgl %2, (%3)"
+                       : "=a"(v)
+                       : "a"(0), "r"(cpu), "r"(&Lock->Lock)
+                       );
+               #elif STACKED_LOCKS == 2
+               __ASM__("lock cmpxchgl %2, (%3)"
+                       : "=a"(v)
+                       : "a"(0), "r"(thread), "r"(&Lock->Lock)
+                       );
+               #else
+               __ASM__("xchgl %%eax, (%%edi)":"=a"(v):"a"(1),"D"(&Lock->Lock));
+               #endif
+       }
+       
+       #if LOCK_DISABLE_INTS
+       Lock->IF = IF;
+       #endif
+}
+/**
+ * \brief Release a short lock
+ * \param Lock Lock pointer
+ */
+void SHORTREL(struct sShortSpinlock *Lock)
+{
+       #if STACKED_LOCKS
+       if( Lock->Depth ) {
+               Lock->Depth --;
+               return ;
+       }
+       #endif
+       
+       #if LOCK_DISABLE_INTS
+       // Lock->IF can change anytime once Lock->Lock is zeroed
+       if(Lock->IF) {
+               Lock->Lock = 0;
+               __ASM__ ("sti");
+       }
+       else {
+               Lock->Lock = 0;
+       }
+       #else
+       Lock->Lock = 0;
+       #endif
 }
 
 // === IO Commands ===
@@ -218,3 +328,7 @@ EXPORT(__udivdi3);  EXPORT(__umoddi3);
 
 EXPORT(LittleEndian16);        EXPORT(BigEndian16);
 EXPORT(LittleEndian32);        EXPORT(BigEndian32);
+
+EXPORT(SHORTLOCK);
+EXPORT(SHORTREL);
+EXPORT(IS_LOCKED);