Thread kernel stacks are now reused

kernel/cpu/i386/isr.c

@@ -291,7 +291,7 @@ void isr_handler(registers_t* r) {
         break;
       default:
         break;
-      } 
+      }
       break;
     }
   }
@@ -310,13 +310,17 @@ void isr_register_handler(int n,isr_t handler) {
  * \param r The saved state of the CPU
 */
 void irq_handler(registers_t* r) {
-    /* After every interrupt we need to send an EOI to the PICs
-     * or they will not send another interrupt again */
-    if (r->int_no >= 40) port_byte_out(0xA0,0x20); /* slave */
-    port_byte_out(0x20,0x20); /* master */
-    /* Handle the interrupt in a more modular way */
-    if (irq_handlers[r->int_no-32] != NULL) {
-        isr_t handler = irq_handlers[r->int_no-32];
-        handler(r);
+  /* After every interrupt we need to send an EOI to the PICs
+    * or they will not send another interrupt again */
+  if (r->int_no >= 40) port_byte_out(0xA0,0x20); /* slave */
+  port_byte_out(0x20,0x20); /* master */
+  /* Handle the interrupt in a more modular way */
+  if (irq_handlers[r->int_no-32] != NULL) {
+    isr_t handler = irq_handlers[r->int_no-32];
+    if((uint32_t)handler<32768) {
+      kernel_rpc_call((pid_t)handler,"irq_handler",NULL,NULL);
+    } else {
+      handler(r);
     }
+  }
 }

kernel/cpu/i386/paging.c

@@ -33,12 +33,8 @@ static pg_struct_entry kstack_page_tables[218*1024] __attribute__((aligned(4096)
 static pg_struct_entry kmalloc_page_tables[4*1024] __attribute__((aligned(4096))); //!< Page tables for the kmalloc heap
 static pg_struct_entry* pagdirmap=(pg_struct_entry*)0xFFFFF000; //!< Pointer to the page directory entries in the recursive mapping
 static pg_struct_entry* page_table_map=(pg_struct_entry*)0xFFC00000; //!< Pointer to the page table entries in the recursive mapping
-/**
- * Checks whether a page is present
- * \param page The page number to check
- * \return Whether the page is present
-*/
-static char is_page_present(size_t page) {
+
+char is_page_present(size_t page) {
    int table=page>>10;
    page=page&0x3FF;
    if (!pagdirmap[table].pres) {

kernel/cpu/i386/tasking_helpers_c.c

@@ -7,6 +7,7 @@
 #include "../tasking_helpers.h"
 #include "../../pmem.h"
 #include <stddef.h>
+#include <stdint.h>
 
 static void** kstacks=(void*)0xC8000000; //!< Pointer to all the thread kernel stacks
 static char kstack_bmap[(218*1024)/8]={0}; //!< Bitmap of what kernel stacks have been allocated
@@ -49,7 +50,9 @@ static int new_kstack() {
     return -1;
   }
   mark_kstack_allocated(num);
-  map_pages(((char*)kstacks+num*0x1000),pmem_alloc(1),1,1,1);
+  if (!is_page_present(((uint32_t)((char*)kstacks+num*0x1000))>>12)) {
+    map_pages(((char*)kstacks+num*0x1000),pmem_alloc(1),1,1,1);
+  }
   return num;
 }
 
@@ -76,3 +79,12 @@ void setup_kstack(Thread* thread,void* param1,void* param2,char kmode,void* eip)
     kstacks[top_idx-1]=(void*)eip;
   }
 }
+
+void free_kstack(void* stack_ptr) {
+  uint32_t stack=(uint32_t)stack_ptr;
+  stack-=0xC8000000;
+  stack=stack>>12;
+  size_t byte=stack/8;
+  size_t bit=stack%8;
+  kstack_bmap[byte]=kstack_bmap[byte]&(~(1<<bit));
+}

kernel/cpu/paging.h

@@ -5,6 +5,7 @@
 #ifndef PAGING_H
 #define PAGING_H
 
+#include <stddef.h>
 
 /**
  * Run a block of code in a different address space
@@ -87,4 +88,11 @@ void* find_free_pages(int num_pages);
 */
 void* get_address_space();
 
+/**
+ * Checks whether a page is present
+ * \param page The page number to check
+ * \return Whether the page is present
+*/
+char is_page_present(size_t page);
+
 #endif

kernel/cpu/tasking_helpers.h

@@ -34,4 +34,10 @@ void wait_for_unblocked_thread_asm();
 */
 void setup_kstack(Thread* thread,void* param1,void* param2,char kmode,void* eip);
 
+/**
+ * Frees a kernel stack so it can be used again
+ * \param stack_ptr The kernel stack to free
+*/
+void free_kstack(void* stack_ptr);
+
 #endif

kernel/tasking.c

@@ -274,6 +274,9 @@ void tasking_block(thread_state newstate) {
     }
   }
   current_thread->process->num_threads_blocked++;
+  if (current_thread->process->num_threads_blocked==current_thread->process->num_threads) {
+    unmark_proc_scheduled(current_thread->process->pid);
+  }
   tasking_yield();
 }
 
@@ -332,7 +335,7 @@ void tasking_exit(int code) {
     ready_to_run_tail=ready_to_run_tail->prev_ready_to_run;
     if (ready_to_run_tail==NULL) {
       ready_to_run_head=NULL;
-      
+
     }
   }
   if (ready_to_run_head&&ready_to_run_head->next_ready_to_run) {
@@ -348,7 +351,10 @@ void tasking_exit(int code) {
   }
   unmark_proc_scheduled(current_thread->process->pid);
   for (Thread* thread=current_thread->process->first_thread;thread!=NULL;thread=thread->next_thread_in_process) {
-    thread->state=THREAD_EXITED;
+    if (thread->state!=THREAD_EXITED) {
+      thread->state=THREAD_EXITED;
+      free_kstack(thread->kernel_esp_top);
+    }
   }
   current_thread->process->num_threads_blocked=current_thread->process->num_threads;
   num_procs--;
@@ -383,6 +389,7 @@ void* tasking_get_rpc_ret_buf() {
 
 void tasking_thread_exit() {
   tasking_block(THREAD_EXITED);
+  free_kstack(current_thread->kernel_esp_top);
 }
 
 char tasking_check_proc_exists(pid_t pid) {