Interrupts on/off is a semaphore

kernel/include/system.h

@@ -18,8 +18,11 @@
 #define asm __asm__
 #define volatile __volatile__
 
-#define IRQ_OFF asm volatile ("cli")
-#define IRQ_ON  asm volatile ("sti")
+extern unsigned int __irq_sem;
+
+#define IRQ_OFF { asm volatile ("cli"); __irq_sem++; }
+#define IRQ_ON  { if (__irq_sem > 0) __irq_sem--; if (!__irq_sem) asm volatile ("sti"); }
+#define IRQ_RES { __irq_sem = 0; asm volatile ("sti"); }
 #define PAUSE   asm volatile ("hlt")
 
 #define STOP while (1) { PAUSE; }

kernel/mem/mem.c

@@ -7,7 +7,7 @@
 #include <process.h>
 #include <logging.h>
 
-extern uintptr_t end;
+extern void *end;
 uintptr_t placement_pointer = (uintptr_t)&end;
 uintptr_t heap_end = (uintptr_t)NULL;
 

kernel/misc/kprintf.c

@@ -169,12 +169,19 @@ void
 kgets_handler(
 		char ch
 		) {
+	IRQ_OFF;
+	if (current_process != kgets_client) {
+		/* Switch page directories into the caller so we can write to its buffers */
+		switch_page_directory(kgets_client->thread.page_directory);
+	}
 	if (kgets_special == 1) {
 		if (ch == 91) {
 			kgets_special = 2;
+			IRQ_ON;
 			return;
 		}
 		kgets_special = 0;
+		IRQ_ON;
 		return;
 	}
 	if (kgets_special == 2) {
@@ -228,6 +235,7 @@ kgets_handler(
 				break;
 		}
 		kgets_special = 0;
+		IRQ_ON;
 		return;
 	}
 
@@ -235,6 +243,7 @@ kgets_handler(
 		/* Backspace */
 		if (kgets_collected != 0) {
 			if (kgets_offset == 0) {
+				IRQ_ON;
 				return;
 			}			/* Clear the previous character */
 			kwrite(0x08);
@@ -243,10 +252,6 @@ kgets_handler(
 			if (kgets_offset != kgets_collected) {
 				int remaining = kgets_collected - kgets_offset;
 				for (int i = 0; i < remaining; ++i) {
-					if (current_process != kgets_client) {
-						/* Switch page directories into the caller so we can write to its buffers */
-						switch_page_directory(kgets_client->thread.page_directory);
-					}
 					kwrite(kgets_buffer[kgets_offset + i]);
 					kgets_buffer[kgets_offset + i - 1] = kgets_buffer[kgets_offset + i];
 				}
@@ -261,14 +266,11 @@ kgets_handler(
 				redraw_cursor();
 			} else {
 				/* Erase the end of the buffer */
-				if (current_process != kgets_client) {
-					/* Switch page directories into the caller so we can write to its buffers */
-					switch_page_directory(kgets_client->thread.page_directory);
-				}
 				kgets_buffer[--kgets_collected] = '\0';
 				kgets_offset--;
 			}
 		}
+		IRQ_ON;
 		return;
 	} else if (ch == '\x0c') {
 		kprintf("\033[H\033[2J");
@@ -276,6 +278,7 @@ kgets_handler(
 			kgets_redraw_func();
 		}
 		kgets_redraw_buffer();
+		IRQ_ON;
 		return;
 	} else if (ch == '\t' && kgets_tab_complete_func) {
 		if (current_process != kgets_client) {
@@ -285,9 +288,11 @@ kgets_handler(
 		kgets_tab_complete_func(kgets_buffer);
 		kgets_collected = strlen(kgets_buffer);
 		kgets_offset = kgets_collected;
+		IRQ_ON;
 		return;
 	} else if (ch == 27) {
 		kgets_special = 1;
+		IRQ_ON;
 		return;
 	} else if (ch == '\n') {
 		/* Newline finishes off the kgets() */
@@ -299,10 +304,10 @@ kgets_handler(
 		}
 		kwrite('\n');
 		kgets_newline = 1;
+		IRQ_ON;
 		return;
 	}	/* Add this character to the buffer. */
 	if (kgets_offset != kgets_collected) {
-		IRQ_OFF;
 		if (current_process != kgets_client) {
 			/* Switch page directories into the caller so we can write to its buffers */
 			switch_page_directory(kgets_client->thread.page_directory);
@@ -324,11 +329,9 @@ kgets_handler(
 			kwrite(68);
 		}
 		redraw_cursor();
-		IRQ_ON;
 	} else {
 		kwrite(ch);
 		if (kgets_collected < kgets_want) {
-			IRQ_OFF;
 			if (current_process != kgets_client) {
 				/* Switch page directories into the caller so we can write to its buffers */
 				switch_page_directory(kgets_client->thread.page_directory);
@@ -336,9 +339,9 @@ kgets_handler(
 			kgets_buffer[kgets_collected] = ch;
 			kgets_buffer[++kgets_collected] = '\0';
 			kgets_offset++;
-			IRQ_ON;
 		}
 	}
+	IRQ_ON;
 }
 
 void kgets_redraw_buffer() {

kernel/sys/syscall.c

@@ -44,9 +44,8 @@ static int exit(int retval) {
 static int read(int fd, char * ptr, int len) {
 #ifdef SPECIAL_CASE_STDIO
 	if (fd == 0) {
-		IRQ_ON;
+		IRQ_RES;
 		kgets(ptr, len);
-		IRQ_OFF;
 		if (strlen(ptr) < (uint32_t)len) {
 			int j = strlen(ptr);
 			ptr[j] = '\n';
@@ -182,7 +181,7 @@ static int kbd_mode(int mode) {
 
 static int kbd_get() {
 	/* If we're requesting keyboard input, we better damn well be getting it */
-	IRQ_ON;
+	IRQ_RES;
 	char x = kbd_last;
 	kbd_last = 0;
 	return (int)x;

kernel/sys/system.c

@@ -9,6 +9,7 @@
  */
 #include <system.h>
 
+unsigned int __irq_sem = 0;
 
 void spin_lock(uint8_t volatile * lock) {
 	while(__sync_lock_test_and_set(lock, 0x01)) {

kernel/sys/task.c

@@ -186,7 +186,7 @@ fork() {
 		make_process_ready(new_proc);
 
 		/* Reenable interrupts */
-		IRQ_ON;
+		IRQ_RES;
 
 		/* Return the child PID */
 		return new_proc->id;
@@ -239,7 +239,7 @@ switch_task() {
 				reap_process(proc);
 			}
 		}
-		IRQ_ON;
+		IRQ_RES;
 		return;
 	}