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>

ldso/ldso/dl-elf.c

@@ -376,7 +376,7 @@ struct elf_resolve *_dl_load_elf_shared_library(int secure,
 		}
 	}
 	header = _dl_mmap((void *) 0, _dl_pagesize, PROT_READ | PROT_WRITE,
-			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_UNINITIALIZE, -1, 0);
 	if (_dl_mmap_check_error(header)) {
 		_dl_dprintf(2, "%s:%i: can't map '%s'\n", _dl_progname, __LINE__, libname);
 		_dl_internal_error_number = LD_ERROR_MMAP_FAILED;

ldso/ldso/ldso.c

@@ -193,7 +193,7 @@ void *_dl_malloc(size_t size)
 
 		_dl_debug_early("mmapping more memory\n");
 		_dl_mmap_zero = _dl_malloc_addr = _dl_mmap((void *) 0, rounded_size,
-				PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+				PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_UNINITIALIZE, -1, 0);
 		if (_dl_mmap_check_error(_dl_mmap_zero)) {
 			_dl_dprintf(_dl_debug_file, "%s: mmap of a spare page failed!\n", _dl_progname);
 			_dl_exit(20);

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,

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
 

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 */

libc/sysdeps/linux/alpha/bits/mman.h

@@ -71,6 +71,8 @@
 # define MAP_NORESERVE	  0x10000	/* Don't check for reservations.  */
 # define MAP_POPULATE	  0x20000	/* Populate (prefault) pagetables.  */
 # define MAP_NONBLOCK	  0x40000	/* Do not block on IO.  */
+# define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					   be uninitialized. */
 #endif
 
 /* Flags to `msync'.  */

libc/sysdeps/linux/hppa/bits/mman.h

@@ -45,6 +45,8 @@
 #define MAP_GROWSDOWN	0x8000		/* stack-like segment */
 #define MAP_POPULATE	0x10000		/* populate (prefault) pagetables */
 #define MAP_NONBLOCK	0x20000		/* do not block on IO */
+#define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					  be uninitialized. */
 
 #define MS_SYNC		1		/* synchronous memory sync */
 #define MS_ASYNC	2		/* sync memory asynchronously */

libc/sysdeps/linux/mips/bits/mman.h

@@ -66,6 +66,8 @@
 # define MAP_LOCKED	0x8000		/* pages are locked */
 # define MAP_POPULATE   0x10000         /* populate (prefault) pagetables */
 # define MAP_NONBLOCK   0x20000         /* do not block on IO */
+# define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					   be uninitialized. */
 #endif
 
 /* Flags to `msync'.  */

libc/sysdeps/linux/powerpc/bits/mman.h

@@ -63,6 +63,8 @@
 # define MAP_NORESERVE	0x00040		/* Don't check for reservations.  */
 # define MAP_POPULATE	0x08000		/* Populate (prefault) pagetables.  */
 # define MAP_NONBLOCK	0x10000		/* Do not block on IO.  */
+# define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					   be uninitialized. */
 #endif
 
 /* Flags to `msync'.  */

libc/sysdeps/linux/sparc/bits/mman.h

@@ -65,6 +65,8 @@
 # define _MAP_NEW	0x80000000	/* Binary compatibility with SunOS.  */
 # define MAP_POPULATE	0x8000		/* Populate (prefault) pagetables.  */
 # define MAP_NONBLOCK	0x10000		/* Do not block on IO.  */
+# define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					   be uninitialized. */
 #endif
 
 /* Flags to `msync'.  */

libc/sysdeps/linux/xtensa/bits/mman.h

@@ -64,6 +64,8 @@
 # define MAP_NORESERVE	0x0400		/* Don't check for reservations.  */
 # define MAP_POPULATE	0x10000		/* Populate (prefault) pagetables.  */
 # define MAP_NONBLOCK	0x20000		/* Do not block on IO.  */
+# define MAP_UNINITIALIZE 0x4000000     /* For anonymous mmap, memory could
+					   be uninitialized. */
 #endif
 
 /* Flags to `msync'.  */