nommu: use MAP_UNINITIALIZE for mallocs

Now that the kernel supports MAP_UNINITIALIZE, have the malloc places use
it to get real uninitialized memory on no-mmu systems.  This avoids a lot
of normally useless overhead involved in zeroing out all of the memory
(sometimes multiple times).

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

3 files changed, 3 insertions, 3 deletions

diff --git a/libc/stdlib/malloc-simple/alloc.c b/libc/stdlib/malloc-simple/alloc.c
index 36355c1e9..51da14ac8 100644
--- a/libc/stdlib/malloc-simple/alloc.c
+++ b/libc/stdlib/malloc-simple/alloc.c
@@ -36,7 +36,7 @@ void *malloc(size_t size)
 #ifdef __ARCH_USE_MMU__
 # define MMAP_FLAGS MAP_PRIVATE | MAP_ANONYMOUS
 #else
-# define MMAP_FLAGS MAP_SHARED | MAP_ANONYMOUS
+# define MMAP_FLAGS MAP_SHARED | MAP_ANONYMOUS | MAP_UNINITIALIZE
 #endif
 
 	result = mmap((void *) 0, size + sizeof(size_t), PROT_READ | PROT_WRITE,
diff --git a/libc/stdlib/malloc-standard/malloc.h b/libc/stdlib/malloc-standard/malloc.h
index 90c9fd14d..7a2e66d16 100644
--- a/libc/stdlib/malloc-standard/malloc.h
+++ b/libc/stdlib/malloc-standard/malloc.h
@@ -356,7 +356,7 @@ __UCLIBC_MUTEX_EXTERN(__malloc_lock);
 #else
 
 #define MMAP(addr, size, prot) \
- (mmap((addr), (size), (prot), MAP_SHARED|MAP_ANONYMOUS, 0, 0))
+ (mmap((addr), (size), (prot), MAP_SHARED|MAP_ANONYMOUS|MAP_UNINITIALIZE, 0, 0))
 
 #endif
 
diff --git a/libc/stdlib/malloc/malloc.c b/libc/stdlib/malloc/malloc.c
index f4bbc71a2..337206f09 100644
--- a/libc/stdlib/malloc/malloc.c
+++ b/libc/stdlib/malloc/malloc.c
@@ -124,7 +124,7 @@ __malloc_from_heap (size_t size, struct heap_free_area **heap
 		    MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
 #else
       block = mmap ((void *)0, block_size, PROT_READ | PROT_WRITE,
-		    MAP_SHARED | MAP_ANONYMOUS, 0, 0);
+		    MAP_SHARED | MAP_ANONYMOUS | MAP_UNINITIALIZE, 0, 0);
 #endif
 
 #endif /* MALLOC_USE_SBRK */