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* malloc/arena.c (heap_info): Add mprotect_size field, adjust pad.

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(new_heap): Initialize mprotect_size. 
(grow_heap): When growing, only mprotect from mprotect_size till 
new_size if mprotect_size is smaller.  When shrinking, use PROT_NONE 
MMAP for __libc_enable_secure only, otherwise use MADV_DONTNEED.
2007-05-07  Ulrich Drepper  <drepper@redhat.com>
	    Jakub Jelinek  <jakub@redhat.com>

	* malloc/arena.c (heap_info): Add mprotect_size field, adjust pad.
	(new_heap): Initialize mprotect_size.
	(grow_heap): When growing, only mprotect from mprotect_size till
	new_size if mprotect_size is smaller.  When shrinking, use PROT_NONE
	MMAP for __libc_enable_secure only, otherwise use MADV_DONTNEED.
This commit is contained in:
Jakub Jelinek 2007-05-07 15:30:57 +00:00
parent 6780bc44e8
commit c7fd336280
3 changed files with 39 additions and 8 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2007-05-07 Ulrich Drepper <drepper@redhat.com>
Jakub Jelinek <jakub@redhat.com>
* malloc/arena.c (heap_info): Add mprotect_size field, adjust pad.
(new_heap): Initialize mprotect_size.
(grow_heap): When growing, only mprotect from mprotect_size till
new_size if mprotect_size is smaller. When shrinking, use PROT_NONE
MMAP for __libc_enable_secure only, otherwise use MADV_DONTNEED.
2007-04-30 Steven Munroe <sjmunroe@us.ibm.com>
Peter Bergner <bergner@us.ibm.com>

1
malloc/Makefile
View File

@ -104,6 +104,7 @@ $(objpfx)memusagestat: $(memusagestat-modules:%=$(objpfx)%.o)
include ../Rules
CFLAGS-mcheck-init.c = $(PIC-ccflag)
CFLAGS-malloc.c += -DMALLOC_DEBUG
$(objpfx)libmcheck.a: $(objpfx)mcheck-init.o
-rm -f $@

29
malloc/arena.c
View File

@ -1,5 +1,6 @@
/* Malloc implementation for multiple threads without lock contention.
Copyright (C) 2001,2002,2003,2004,2005,2006 Free Software Foundation, Inc.
Copyright (C) 2001,2002,2003,2004,2005,2006,2007
Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
@ -59,10 +60,12 @@ typedef struct _heap_info {
mstate ar_ptr; /* Arena for this heap. */
struct _heap_info *prev; /* Previous heap. */
size_t size; /* Current size in bytes. */
size_t mprotect_size; /* Size in bytes that has been mprotected
PROT_READ|PROT_WRITE. */
/* Make sure the following data is properly aligned, particularly
that sizeof (heap_info) + 2 * SIZE_SZ is a multiple of
MALLOG_ALIGNMENT. */
char pad[-5 * SIZE_SZ & MALLOC_ALIGN_MASK];
MALLOC_ALIGNMENT. */
char pad[-6 * SIZE_SZ & MALLOC_ALIGN_MASK];
} heap_info;
/* Get a compile-time error if the heap_info padding is not correct
@ -692,6 +695,7 @@ new_heap(size, top_pad) size_t size, top_pad;
}
h = (heap_info *)p2;
h->size = size;
h->mprotect_size = size;
THREAD_STAT(stat_n_heaps++);
return h;
}
@ -714,17 +718,34 @@ grow_heap(h, diff) heap_info *h; long diff;
new_size = (long)h->size + diff;
if((unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE)
return -1;
if(mprotect((char *)h + h->size, diff, PROT_READ|PROT_WRITE) != 0)
if((unsigned long) new_size > h->mprotect_size) {
if (mprotect((char *)h + h->mprotect_size,
(unsigned long) new_size - h->mprotect_size,
PROT_READ|PROT_WRITE) != 0)
return -2;
h->mprotect_size = new_size;
}
} else {
new_size = (long)h->size + diff;
if(new_size < (long)sizeof(*h))
return -1;
/* Try to re-map the extra heap space freshly to save memory, and
make it inaccessible. */
#ifdef _LIBC
if (__builtin_expect (__libc_enable_secure, 0))
#else
if (1)
#endif
{
if((char *)MMAP((char *)h + new_size, -diff, PROT_NONE,
MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
return -2;
h->mprotect_size = new_size;
}
#ifdef _LIBC
else
madvise ((char *)h + new_size, -diff, MADV_DONTNEED);
#endif
/*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/
}
h->size = new_size;