Implementing memory tagging support.

4 files changed, 51 insertions, 1 deletions

diff --git a/com32/include/stdlib.h b/com32/include/stdlib.h
index d822b9b0..cd1d83c6 100644
--- a/com32/include/stdlib.h
+++ b/com32/include/stdlib.h
@@ -38,6 +38,24 @@ __extern __mallocfunc void *calloc(size_t, size_t);
 __extern __mallocfunc void *realloc(void *, size_t);
 __extern int posix_memalign(void **memptr, size_t alignment,
 		size_t size);
+
+
+
+__extern void *__mem_get_tag_global();
+__extern void __mem_set_tag_global(void *tag);
+
+__extern void *__mem_get_tag(void *memptr);
+__extern void __mem_set_tag(void *memptr, void *tag);
+
+static __inline__ void *__malloc_tagged(size_t size, void *tag) {
+	void *result = malloc(size);
+	__mem_set_tag(result, tag);
+
+	return result;
+}
+
+
+
 __extern long strtol(const char *, char **, int);
 __extern long long strtoll(const char *, char **, int);
 __extern unsigned long strtoul(const char *, char **, int);
diff --git a/com32/lib/free.c b/com32/lib/free.c
index 0cf874b4..437a8fc0 100644
--- a/com32/lib/free.c
+++ b/com32/lib/free.c
@@ -31,6 +31,7 @@ __free_block(struct free_arena_header *ah)
   } else {
     /* Need to add this block to the free chain */
     ARENA_TYPE_SET(ah->a.attrs, ARENA_TYPE_FREE);
+    ah->a.tag = NULL;
 
     ah->next_free = __malloc_head.next_free;
     ah->prev_free = &__malloc_head;
diff --git a/com32/lib/malloc.c b/com32/lib/malloc.c
index b0a8fe25..09a9989d 100644
--- a/com32/lib/malloc.c
+++ b/com32/lib/malloc.c
@@ -9,10 +9,15 @@
 #include "init.h"
 #include "malloc.h"
 
+/**
+ * The global tag used to label all the new allocations
+ */
+static void *__global_tag = NULL;
+
 struct free_arena_header __malloc_head =
 {
   {
-    (void*)0,
+    NULL,
     ARENA_TYPE_HEAD,
     &__malloc_head,
     &__malloc_head,
@@ -49,6 +54,7 @@ static void __constructor init_memory_arena(void)
   fp = (struct free_arena_header *)start;
   ARENA_TYPE_SET(fp->a.attrs, ARENA_TYPE_FREE);
   ARENA_SIZE_SET(fp->a.attrs, total_space - __stack_size);
+  fp->a.tag = NULL;
 
   /* Insert into chains */
   fp->a.next = fp->a.prev = &__malloc_head;
@@ -72,8 +78,10 @@ static void *__malloc_from_block(struct free_arena_header *fp, size_t size)
 
     ARENA_TYPE_SET(nfp->a.attrs, ARENA_TYPE_FREE);
     ARENA_SIZE_SET(nfp->a.attrs, fsize-size);
+    nfp->a.tag = NULL;
     ARENA_TYPE_SET(fp->a.attrs, ARENA_TYPE_USED);
     ARENA_SIZE_SET(fp->a.attrs, size);
+    fp->a.tag = __global_tag;
 
     /* Insert into all-block chain */
     nfp->a.prev = fp;
@@ -89,6 +97,7 @@ static void *__malloc_from_block(struct free_arena_header *fp, size_t size)
   } else {
     /* Allocate the whole block */
     ARENA_TYPE_SET(fp->a.attrs, ARENA_TYPE_USED);
+    fp->a.tag = __global_tag;
 
     /* Remove from free chain */
     fp->next_free->prev_free = fp->prev_free;
@@ -174,6 +183,7 @@ int posix_memalign(void **memptr, size_t alignment, size_t size) {
 			ARENA_TYPE_SET(nfp->a.attrs, ARENA_TYPE_FREE);
 			ARENA_SIZE_SET(nfp->a.attrs,
 					ARENA_SIZE_GET(fp->a.attrs) - ((uintptr_t)nfp - (uintptr_t)fp));
+			nfp->a.tag = NULL;
 			nfp->a.prev = fp;
 			nfp->a.next = fp->a.next;
 			nfp->prev_free = fp;
@@ -199,3 +209,21 @@ int posix_memalign(void **memptr, size_t alignment, size_t size) {
 
 	return 0;
 }
+
+void *__mem_get_tag_global() {
+	return __global_tag;
+}
+
+void __mem_set_tag_global(void *tag) {
+	__global_tag = tag;
+}
+
+void *__mem_get_tag(void *memptr) {
+	struct arena_header *ah = (struct arena_header*)memptr - 1;
+	return ah->tag;
+}
+
+void __mem_set_tag(void *memptr, void *tag) {
+	struct arena_header *ah = (struct arena_header*)memptr - 1;
+	ah->tag = tag;
+}
diff --git a/com32/lib/realloc.c b/com32/lib/realloc.c
index a9b0ca4e..ed7fc4c0 100644
--- a/com32/lib/realloc.c
+++ b/com32/lib/realloc.c
@@ -58,6 +58,7 @@ void *realloc(void *ptr, size_t size)
 	nah = (struct free_arena_header *)((char *)ah + newsize);
 	ARENA_TYPE_SET(nah->a.attrs, ARENA_TYPE_FREE);
 	ARENA_SIZE_SET(nah->a.attrs, xsize - newsize);
+	nah->a.tag = NULL;
 	ARENA_SIZE_SET(ah->a.attrs, newsize);
 
 	/* Insert into block list */
@@ -91,6 +92,8 @@ void *realloc(void *ptr, size_t size)
       newptr = malloc(size);
       if (newptr) {
 	memcpy(newptr, ptr, min(size,oldsize));
+	/* Retain tag from the old block */
+	__mem_set_tag(newptr, __mem_get_tag(ptr));
 	free(ptr);
       }
       return newptr;