mm: Add pending configuration for mm node struct and precding

pending memory block node precding and the entire struct, after turning on this bit, the size of each memory block wil be aligned to MM_ALIGN

Signed-off-by: wangmingrong1 <[email protected]>

Author: W-M-R

mm/Kconfig

@@ -69,6 +69,14 @@ config MM_DEFAULT_ALIGNMENT
 		memory default alignment is equal to sizoef(uintptr), if this value
 		is not 0, this value must be 2^n and at least sizeof(uintptr).
 
+config MM_NODE_PENDING
+	bool "Enable pending memory node"
+	default n
+	---help---
+		Pending memory block node precding and the entire struct,
+		After turning on this bit, the size of each memory block
+		will be aligned to MM_ALIGN
+
 config MM_SMALL
 	bool "Small memory model"
 	default n

mm/mm_heap/mm.h

@@ -143,7 +143,15 @@
  * previous freenode
  */
 
-#define MM_ALLOCNODE_OVERHEAD (MM_SIZEOF_ALLOCNODE - sizeof(mmsize_t))
+#ifdef CONFIG_MM_NODE_PENDING
+#  define MM_NODE_PENDING aligned_data(MM_ALIGN)
+#  define MMSIZE_T_LEN    MM_ALIGN
+#else
+#  define MM_NODE_PENDING
+#  define MMSIZE_T_LEN    sizeof(mmsize_t)
+#endif
+
+#define MM_ALLOCNODE_OVERHEAD (MM_SIZEOF_ALLOCNODE - MMSIZE_T_LEN)
 
 /* Get the node size */
 
@@ -173,23 +181,41 @@ typedef size_t mmsize_t;
 
 struct mm_allocnode_s
 {
-  mmsize_t preceding;                       /* Physical preceding chunk size */
-  mmsize_t size;                            /* Size of this chunk */
+  union
+  {
+    mmsize_t preceding;                     /* Physical preceding chunk size */
+    uint8_t  preceding_align[MMSIZE_T_LEN];
+  };
+  union
+  {
+    mmsize_t size;                          /* Physical preceding chunk size */
+    uint8_t  size_align[MMSIZE_T_LEN];
+  };
+
 #if CONFIG_MM_BACKTRACE >= 0
   pid_t pid;                                /* The pid for caller */
   unsigned long seqno;                      /* The sequence of memory malloc */
 #  if CONFIG_MM_BACKTRACE > 0
   FAR void *backtrace[CONFIG_MM_BACKTRACE]; /* The backtrace buffer for caller */
 #  endif
 #endif
-};
+}MM_NODE_PENDING;
 
 /* This describes a free chunk */
 
 struct mm_freenode_s
 {
-  mmsize_t preceding;                       /* Physical preceding chunk size */
-  mmsize_t size;                            /* Size of this chunk */
+  union
+  {
+    mmsize_t preceding;                     /* Physical preceding chunk size */
+    uint8_t  preceding_align[MMSIZE_T_LEN];
+  };
+  union
+  {
+    mmsize_t size;                          /* Physical preceding chunk size */
+    uint8_t  size_align[MMSIZE_T_LEN];
+  };
+
 #if CONFIG_MM_BACKTRACE >= 0
   pid_t pid;                                /* The pid for caller */
   unsigned long seqno;                      /* The sequence of memory malloc */
@@ -199,7 +225,7 @@ struct mm_freenode_s
 #endif
   FAR struct mm_freenode_s *flink;          /* Supports a doubly linked list */
   FAR struct mm_freenode_s *blink;
-};
+}MM_NODE_PENDING;
 
 static_assert(MM_SIZEOF_ALLOCNODE <= MM_MIN_CHUNK,
               "Error size for struct mm_allocnode_s\n");

mm/mm_heap/mm_realloc.c

@@ -153,7 +153,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
           heap->mm_curused += newsize - oldsize;
           mm_shrinkchunk(heap, oldnode, newsize);
           kasan_poison((FAR char *)oldnode + MM_SIZEOF_NODE(oldnode) +
-                       sizeof(mmsize_t), oldsize - MM_SIZEOF_NODE(oldnode));
+                       MMSIZE_T_LEN, oldsize - MM_SIZEOF_NODE(oldnode));
         }
 
       /* Then return the original address */