#define KERNEL_BASE 0xC0000000
#define BITS 32
+// Allow nested spinlocks?
+#define STACKED_LOCKS 1
+#define LOCK_DISABLE_INTS 0
+
// - Processor/Machine Specific Features
#if ARCH != i386 && ARCH != i486 && ARCH != i586
# error "Unknown architecture '" #ARCH "'"
*/
struct sShortSpinlock {
volatile int Lock; //!< Lock value
+ #if LOCK_DISABLE_INTS
int IF; //!< Interrupt state on call to SHORTLOCK
+ #endif
+ #if STACKED_LOCKS
+ int Depth;
+ #endif
};
/**
* \brief Determine if a short spinlock is locked
static inline int IS_LOCKED(struct sShortSpinlock *Lock) {
return !!Lock->Lock;
}
+
+/**
+ * \brief Check if the current CPU has the lock
+ * \param Lock Lock pointer
+ */
+static inline int CPU_HAS_LOCK(struct sShortSpinlock *Lock) {
+ extern int GetCPUNum(void);
+ return Lock->Lock == GetCPUNum() + 1;
+}
+
/**
* \brief Acquire a Short Spinlock
* \param Lock Lock pointer
* 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.
+ * functions are called while it is held. As a matter of fact, spend as
+ * little time as possible with this lock held
*/
static inline void SHORTLOCK(struct sShortSpinlock *Lock) {
int v = 1;
+ #if LOCK_DISABLE_INTS
int IF;
- // int val = GetCPUNum() + 1;
+ #endif
+ #if STACKED_LOCKS
+ extern int GetCPUNum(void);
+ int cpu = GetCPUNum() + 1;
+ #endif
+ #if LOCK_DISABLE_INTS
// Save interrupt state and clear interrupts
- __ASM__ ("pushf;\n\tcli;\n\tpop %%eax" : "=a"(IF));
- IF &= 0x200;
+ __ASM__ ("pushf;\n\tpop %%eax\n\tcli" : "=a"(IF));
+ IF &= 0x200; // AND out all but the interrupt flag
+ #endif
+
+ #if STACKED_LOCKS
+ if( Lock->Lock == cpu ) {
+ Lock->Depth ++;
+ return ;
+ }
+ #endif
// Wait for another CPU to release
- while(v)
- __ASM__("xchgl %%ecx, (%%edi)":"=c"(v):"a"(1),"D"(&Lock->Lock));
+ while(v) {
+ #if STACKED_LOCKS
+ // CMPXCHG:
+ // If r/m32 == EAX, set ZF and set r/m32 = r32
+ // Else, clear ZF and set EAX = r/m32
+ __ASM__("lock cmpxchgl %2, (%3)"
+ : "=a"(v)
+ : "a"(0), "r"(cpu), "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
*/
static inline 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;
else {
Lock->Lock = 0;
}
+ #else
+ Lock->Lock = 0;
+ #endif
}
// === MACROS ===