Initialize per-task memory spaces at creation

Allocate a dedicated memory space for each task and register the task stack as a flexpage. This establishes the memory protection metadata that will be loaded into hardware regions during context switches.

Author: HeatCrab

arch/riscv/pmp.h

@@ -10,6 +10,8 @@
 #include <sys/memprot.h>
 #include <types.h>
 
+#include "csr.h"
+
 /* PMP Region Priority Levels (lower value = higher priority)
  *
  * Used for eviction decisions when hardware PMP regions are exhausted.

kernel/task.c

@@ -760,6 +760,30 @@ static int32_t task_spawn_impl(void *task_entry,
  panic(ERR_STACK_ALLOC);
  }
 
+ /* Create memory space for task */
+ tcb->mspace = mo_memspace_create(kcb->next_tid, 0);
+ if (!tcb->mspace) {
+ free(tcb->stack);
+ free(tcb);
+ panic(ERR_TCB_ALLOC);
+ }
+
+ /* Register stack as flexpage */
+ fpage_t *stack_fpage =
+ mo_fpage_create((uint32_t) tcb->stack, new_stack_size,
+ PMPCFG_R | PMPCFG_W, PMP_PRIORITY_STACK);
+ if (!stack_fpage) {
+ mo_memspace_destroy(tcb->mspace);
+ free(tcb->stack);
+ free(tcb);
+ panic(ERR_TCB_ALLOC);
+ }
+
+ /* Add stack to memory space */
+ stack_fpage->as_next = tcb->mspace->first;
+ tcb->mspace->first = stack_fpage;
+ tcb->mspace->pmp_stack = stack_fpage;
+
  /* Minimize critical section duration */
  CRITICAL_ENTER();