sbrk() need to initialized the memory manager on the first call

arch/arm/src/armv7-a/arm_pgalloc.c

@@ -186,9 +186,24 @@ static int get_pgtable(FAR group_addrenv_t *addrenv, uintptr_t vaddr)
  *   Therefore, it is a system interface and follows a different naming
  *   convention.
  *
+ * Input Parameters:
+ *   brkaddr - The heap break address.  The next page will be allocated and
+ *     mapped to this address.  Must be page aligned.  If the memory manager
+ *     has not yet been initialized and this is the first block requested for
+ *     the heap, then brkaddr should be zero.  pgalloc will then assigned the
+ *     well-known virtual address of the beginning of the heap.
+ *   npages - The number of pages to allocate and map.  Mapping of pages
+ *     will be contiguous beginning beginning at 'brkaddr'
+ *
+ * Returned Value:
+ *   The (virtual) base address of the mapped page will returned on success.
+ *   Normally this will be the same as the 'brkaddr' input. However, if
+ *   the 'brkaddr' input was zero, this will be the virtual address of the
+ *   beginning of the heap.  Zero is returned on any failure.
+ *
  ****************************************************************************/
 
-int pgalloc(uintptr_t vaddr, unsigned int npages)
+uintptr_t pgalloc(uintptr_t brkaddr, unsigned int npages)
 {
   FAR struct tcb_s *tcb = sched_self();
   FAR struct task_group_s *group;
@@ -209,24 +224,24 @@ int pgalloc(uintptr_t vaddr, unsigned int npages)
 
   DEBUGASSERT((group->flags & GROUP_FLAG_ADDRENV) != 0);
 
-  /* vaddr = 0 means that no heap has yet been allocated */
+  /* brkaddr = 0 means that no heap has yet been allocated */
 
-  if (vaddr == 0)
+  if (brkaddr == 0)
     {
-      vaddr = CONFIG_ARCH_HEAP_VBASE;
+      brkaddr = CONFIG_ARCH_HEAP_VBASE;
     }
 
-  DEBUGASSERT(vadddr >= CONFIG_ARCH_HEAP_VBASE && vaddr < ARCH_HEAP_VEND);
-  DEBUGASSERT(MM_ISALIGNED(vaddr));
+  DEBUGASSERT(vadddr >= CONFIG_ARCH_HEAP_VBASE && brkaddr < ARCH_HEAP_VEND);
+  DEBUGASSERT(MM_ISALIGNED(brkaddr));
 
   for (; npages > 0; npages--)
     {
       /* Get the physical address of the level 2 page table */
 
-      paddr = get_pgtable(&group->addrenv, vaddr);
+      paddr = get_pgtable(&group->addrenv, brkaddr);
       if (paddr == 0)
         {
-          return -ENOMEM; /* ENOMEM might have correct meaning for sbrk? */
+          return 0;
         }
 
       /* Temporarily map the level 2 page table into the "scratch" virtual
@@ -245,7 +260,7 @@ int pgalloc(uintptr_t vaddr, unsigned int npages)
         {
           mmu_l1_restore(ARCH_SCRATCH_VBASE, l1save);
           irqrestore(flags);
-          return -EAGAIN; /* ENOMEM has different meaning for sbrk */
+          return 0;
         }
 
       /* The table divides a 1Mb address space up into 256 entries, each
@@ -253,13 +268,13 @@ int pgalloc(uintptr_t vaddr, unsigned int npages)
        * related to the offset from the beginning of 1Mb region.
        */
 
-      index = (vaddr & 0x000ff000) >> 12;
+      index = (brkaddr & 0x000ff000) >> 12;
 
        /* Map the .text region virtual address to this physical address */
 
       DEBUGASSERT(l2table[index] == 0);
       l2table[index] = paddr | MMU_L2_UDATAFLAGS;
-      vaddr += MM_PGSIZE;
+      brkaddr += MM_PGSIZE;
 
       /* Make sure that the modified L2 table is flushed to physical
        * memory.
@@ -274,7 +289,7 @@ int pgalloc(uintptr_t vaddr, unsigned int npages)
       irqrestore(flags);
     }
 
-  return OK;
+  return brkaddr;
 }
 
 #endif /* CONFIG_MM_PGALLOC && CONFIG_ARCH_USE_MMU */

include/nuttx/arch.h

@@ -678,10 +678,25 @@ void up_allocate_pgheap(FAR void **heap_start, size_t *heap_size);
  *   Therefore, it is a system interface and follows a different naming
  *   convention.
  *
+ * Input Parameters:
+ *   brkaddr - The heap break address.  The next page will be allocated and
+ *     mapped to this address.  Must be page aligned.  If the memory manager
+ *     has not yet been initialized and this is the first block requested for
+ *     the heap, then brkaddr should be zero.  pgalloc will then assigned the
+ *     well-known virtual address of the beginning of the heap.
+ *   npages - The number of pages to allocate and map.  Mapping of pages
+ *     will be contiguous beginning beginning at 'brkaddr'
+ *
+ * Returned Value:
+ *   The (virtual) base address of the mapped page will returned on success.
+ *   Normally this will be the same as the 'brkaddr' input. However, if
+ *   the 'brkaddr' input was zero, this will be the virtual address of the
+ *   beginning of the heap.  Zero is returned on any failure.
+ *
  ****************************************************************************/
 
 #ifdef CONFIG_ARCH_ADDRENV
-int pgalloc(uintptr_t vaddr, unsigned int npages);
+uintptr_t pgalloc(uintptr_t brkaddr, unsigned int npages);
 #endif
 
 /****************************************************************************

mm/mm_sbrk.c

@@ -93,9 +93,10 @@ FAR void *mm_sbrk(FAR struct mm_heap_s *heap, intptr_t incr,
                   uintptr_t maxbreak)
 {
   uintptr_t brkaddr;
+  uintptr_t allocbase;
   unsigned int pgincr;
+  size_t bytesize;
   int err;
-  int ret;
 
   DEBUGASSERT(incr >= 0);
   if (incr < 0)
@@ -104,7 +105,10 @@ FAR void *mm_sbrk(FAR struct mm_heap_s *heap, intptr_t incr,
       goto errout;
     }
 
-  /* Get the current break address (NOTE: assumes region 0) */
+  /* Get the current break address (NOTE: assumes region 0).  If
+   * the memory manager is uninitialized, mm_brkaddr() will return
+   * zero.
+   */
 
   brkaddr = (uintptr_t)mm_brkaddr(heap, 0);
   if (incr > 0)
@@ -122,19 +126,35 @@ FAR void *mm_sbrk(FAR struct mm_heap_s *heap, intptr_t incr,
         }
 
       /* Allocate the requested number of pages and map them to the
-       * break address.
+       * break address.  If we provide a zero brkaddr to pgalloc(),  it
+       * will create the first block in the correct virtual address
+       * space and return the start address of that block.
        */
 
-      ret = pgalloc(brkaddr, pgincr);
-      if (ret < 0)
+      allocbase = pgalloc(brkaddr, pgincr);
+      if (allocbase == 0)
         {
-          err = -ret;
+          err = EAGAIN;
           goto errout;
         }
 
-      /* Extend the heap (region 0) */
+      /* Has the been been initialized?  brkaddr will be zero if the
+       * memory manager has not yet been initialized.
+       */
 
-      mm_extend(heap, (FAR void *)brkaddr, pgincr << MM_PGSHIFT, 0);
+      bytesize = pgincr << MM_PGSHIFT;
+      if (brkaddr != 0)
+        {
+          /* No... then initialize it now */
+
+          mm_initialize(heap, (FAR void *)allocbase, bytesize);
+        }
+      else
+        {
+          /* Extend the heap (region 0) */
+
+          mm_extend(heap, (FAR void *)allocbase, bytesize, 0);
+        }
     }
 
   return (FAR void *)brkaddr;

sched/init/os_start.c

@@ -220,7 +220,7 @@ static FAR const char g_idlename[] = "Idle Task";
 
 /* This the IDLE idle threads argument list. */
 
-static char *g_idleargv[2];
+static FAR char *g_idleargv[2];
 
 /****************************************************************************
  * Private Function Prototypes
@@ -321,7 +321,7 @@ void os_start(void)
   g_idleargv[0]  = (FAR char *)g_idlename;
 #endif /* CONFIG_TASK_NAME_SIZE */
   g_idleargv[1]  = NULL;
-  g_idletcb.argv = &g_idleargv;
+  g_idletcb.argv = g_idleargv;
 
   /* Then add the idle task's TCB to the head of the ready to run list */